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  • Inhibition mechanism of cardamom essential oil on methicillin-resistant Staphylococcus aureus biofilm
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Haiying Cui; Chenghui Zhang; Changzhu Li; Lin Lin

    In recent years, studies have found that in addition to nosocomial infections, methicillin-resistant Staphylococcus aureus (MRSA) can even cause community-associated infections, and MRSA spreads through food and animal that produce products in the community. In addition, MRSA can colonize the surface of food and food container and form biofilms by secreting extracellular polymers, leading to cross-infection. Cardamom essential oil has been found to be highly active against MRSA. Therefore, this study aimed to investigate the inhibitory effect of cardamom essential oil on MRSA biofilm and its mechanism. The semi-quantitative test results of crystal violet and the removal of MRSA biofilm on different food container materials show that cardamom essential oil can effectively remove MRSA biofilm and can be applied to the surface of food container materials. Meanwhile, the inhibition mechanism of cardamom essential oil on MRSA biofilm was studied by measuring the metabolic activity, extracellular polymer content and relative expression of MRSA biofilm formation related genes. Based on results, it is presumed that cardamom essential oil can function to scavenge MRSA biofilm by inhibiting the metabolic activity of bacteria, inhibiting the formation of extracellular polymers, and regulating the expression of genes involved in biofilm formation.

    更新日期:2020-01-21
  • Delaying ripening of ‘Bartlett’ pears (Pyrus communis) during long-term simulated industrial cold storage: Mechanisms and validation of chitosan coatings with cellulose nanocrystals Pickering emulsions
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Rachel A. Rosenbloom; Wenjun Wang; Yanyun Zhao

    Chitosan edible coatings with cellulose nanocrystals Pickering emulsions were investigated at different oleic acid concentrations as coatings to extend storage of ‘Bartlett’ pears by delaying ripening. Pear coatings contained 10 or 20 g oleic acid/kg emulsion (1OA, 2OA). A 7-month simulated industrial storage trial (−1.1 °C) was conducted against carnauba wax-based coating, controlled atmosphere storage (CAS), and uncoated control. The 2OA maintained the highest peel chlorophyll (P < 0.05) when ripened after 3 months, significantly higher than control and carnauba wax throughout the 7 months. Respiration rate and ethylene production peak of 2OA and CAS pears while ripening in ambient conditions were delayed 2 months compared with control pears, and ethylene production peak of 2OA pears had the lowest intensity (31.91 μL/Lgh), significantly (P < 0.05) lower than CAS and control pears. When ripened after 7 months, 2OA and 1OA pears maintained equivalent titratable acidity (∼0.23 g/100 mL) and total soluble solids (12.8 g/100 g) to each other, significantly (P < 0.05) different from all other treatments. The 2OA emulsion coating therefore preserved ‘Bartlett’ pears better than 1OA and carnauba wax coatings and competitively with CAS, providing a feasible and accessible postharvest preservation alternative.

    更新日期:2020-01-21
  • Synergistic properties of citral and eugenol for the inactivation of foodborne molds in vitro and on bread
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Jian Ju; Yunfei Xie; Hang Yu; Yahui Guo; Yuliang Cheng; Ying Chen; Lijun Ji; Weirong Yao

    To control the spoilage of bread products and reduce the costs associated with preventing their spoilage, the synergistic antifungal effects of natural agents against the main bread spoilage fungi Penicillium roqueforti and Aspergillus niger were studied. After screening 66 groups antifungals using the checkerboard method, only one combination, i.e., that of eugenol and citral (SEC), showed synergistic effects against both the fungi. Their average minimal inhibitory concentrations (MICs) decreased significantly when they were present as a combination, i.e., by 3.40-fold, compared to the case when each agent was used separately. SEC inhibited the spore germination of both the fungi by more than 95% at 2 × MIC. At the same time, their mycelial growth was almost completely inhibited. The morphology of the mycelia was further observed by SEM. Serious wrinkles and deformations were found on the surface of the mycelia at 2 × MIC. Finally, the shelf life tests showed that treatment with SEC significantly prolonged the molding time of bread. These results showed that SEC may serve as a spoilage control measure and reduce the costs associated with preventing bread spoilage.

    更新日期:2020-01-21
  • Using a combined neural network ─ genetic algorithm approach for predicting the complex rheological characteristics of microfluidized sugarcane juice
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Ayon Tarafdar; Barjinder Pal Kaur; Prabhat K. Nema; Onkar A. Babar; Deepak Kumar

    The effect of multi-cycle multi-pressure microfluidization on the rheological properties of sugarcane juice has been reported for the first time in this work. Microfluidization pressure was varied in defined steps from 50 to 200 MPa with 1–7 cycles of processing. Rheological measurements were carried out at 30, 40 and 50 °C. Increase in microfluidization pressure up to 150 MPa showed an increase in consistency index. Beyond 150 MPa, an observed reduction in consistency index was attributed to the reduction in carbohydrate polymer chains, agglomeration and molecular degradation. At low processing pressures, microfluidized sugarcane juice exhibited pseudoplastic behavior but showed a dilatant tendency at higher pressures (>150 MPa). Microfluidization increased the flow behavior index by 24–38% as compared to unprocessed sugarcane juice. No prominent trend in rheological data was observed with change in microfluidization cycles. Consistency index was reduced with increase in temperature and was found in the range of 1.5 × 10−3 ─ 5.3 × 10−3 Pa.sn whereas the flow behavior index was found in the range of 0.71 ─ 0.99. A GA mediated ANN model with 12 hidden layer neurons was found to predict the rheological properties of microfluidized sugarcane juice with a reasonable level of accuracy (R2 = 0.86–0.93).

    更新日期:2020-01-21
  • Antibacterial activities of a polyphenolic-rich extract prepared from American cranberry (Vaccinium macrocarpon) fruit pomace against Listeria spp.
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Moussa S. Diarra; Yousef I. Hassan; Glenn S. Block; John C.G. Drover; Pascal Delaquis; B. Dave Oomah

    Cranberry (Vaccinium macrocarpon) fruits are known for their high polyphenolics content making them a rich source of antioxidants. These polyphenolics have been reported to promote human health and are gaining attention for their antimicrobial activities against foodborne pathogens. We investigated the antimicrobial activity of an ethanolic extract #(FC111-1) prepared from cranberry pomace against Listeria spp. Many polyphenolics were identified in this extract which could be responsible for growth-inhibitory effects against 12 Listeria strains including L. monocytogenes. The minimum inhibitory concentration (MIC) of #FC111-1 determined in cation-adjusted Muller Hinton broth (CAMHB) was approximately 2 mg/mL for 11 (91.7%) of these strains. The inclusion of 2–8 mg/mL (1–4 × MIC) of #FC111-1 decreased (>3 log10) viable bacterial cells of all Listeria strains in CAMHB over a 24 h period, while dose-dependently reducing bacterial salt tolerance, bacterial bile-salt hydrolase activity, bacterial biofilm formation capacity, and increasing cell-membrane permeability. The #FC111-1 extract (0.4 and 0.8% concentrations) had no effect on L. monocytogenes survival in a cooked chicken-breast meat model, highlighting the influence of protein-rich matrices on antibacterial activity and the need to consider the role of food composition when using extracts or polyphenolics from cranberry fruits to improve food-safety.

    更新日期:2020-01-21
  • Effects of microbial fermentation and microwave treatment on the composition, structural characteristics, and functional properties of modified okara dietary fiber
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Derong Lin; Xiaomei Long; Yichen Huang; Yuanmeng Yang; Zhijun Wu; Hong Chen; Qing Zhang; Dingtao Wu; Wen Qin; Zongcai Tu

    The effects of mixed fermentation by lactic acid bacteria and Neurospora crassa, and microwave treatment on the composition, structure, and functional properties of okara DF were studied. The results of SEM and EDX showed that the honeycomb structure was more obvious and the content of elemental components was changed after fermentation and microwave treatment. The result of TGA-DSC showed that the thermal stability of the sample improved following microwave treatment. The FT-IR results showed that fermentation and microwave treatment have an effect on the functional groups of cellulose and hemicellulose consistent with the composition of the samples, and the crystal structure of samples was slightly damaged after modification. After mixed fermentation and microwave treatment, the adsorption effect of cholesterol and sodium cholate was not obviously changed. However, the α-Amylase activity inhibition ratio of fermented DF increased from 9.55% to 15.04% and 20.92% respectively. The glucose dialysis retardation of fermented DF doubled at 30 min. Overall, both methods improve the availability of DF in okara. Modified DF from soybean residue can be used as a functional ingredient in diverse food products.

    更新日期:2020-01-21
  • Effect of replacing backfat with vegetable oils during the shelf-life of cooked lamb sausages
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Francisco Allan L. de Carvalho; Paulo E.S. Munekata; Mirian Pateiro; Paulo Cezar Bastianello Campagnol; Rubén Domínguez; Marco Antonio Trindade; Jose M. Lorenzo

    The effects of chia, linseed, and olive oils as backfat replacers on the physico-chemical, oxidative stability and sensory attributes of lamb sausages storage at 2 °C were assessed. Four batches were studied: a control (CONT; with pork fat); and three with fat replaced by commercial vegetable oils: chia (CHIA), linseed (LINS), and olive (OLIV). The incorporation of vegetable oils led to consistent improvement in the fatty acid profile and nutritional indexes. CHIA, LINS, and OLIV batches decreased the atherogenicity (IA) and thrombogenicity (IT) indexes (P < 0.05); however, only the CHIA and LINS groups showed a n-6/n-3 ratio (0.86 and 0.92, respectively) and PUFA/SFA within the recommended. Regarding sensory analysis of the cooked products, LINS treatment did not differ from CONT group, while CHIA and OLIV batches caused damage to taste. During storage, there was no difference in the color, discoloration, and odor of the raw products (P > 0.05). The CONT group presented the highest a* value over time, but this was not noticed by the panelists. CHIA and OLIV batches had an increase in the hardness over time. Protein oxidation increased until day 60; showing only significant difference at the beginning of the display since OLIV group presented the highest value (7.96 nmol carbonyl/mg).

    更新日期:2020-01-21
  • Evaluating technological quality of okara flours obtained by different drying processes
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-20
    Rafaiane Macedo Guimarães; Elza Iouko Ida; Heloísa Gabriel Falcão; Thaisa Alves Matos de Rezende; Jhessika de Santana Silva; Cassia Cristina Fernandes Alves; Marco Antônio Pereira da Silva; Mariana Buranelo Egea
    更新日期:2020-01-21
  • Bioaccessibility of anti-AGEs activity, antioxidant capacity and phenolics from water biscuits prepared from fermented buckwheat flours
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-18
    Henryk Zieliński; Dorota Szawara-Nowak; Małgorzata Wronkowska

    The bioaccessible anti-AGEs activity of buckwheat biscuits (BB) was studied in bovine serum albumin/glucose model and its relationship to the bioaccessible antioxidant/reducing capacity measured by ABTS test and FRAP assay, and bioaccessible total phenolic compounds was addressed. The BB were baked from common buckwheat flours after liquid-state fermentation (LSF) by select lactic acid bacteria (LAB) and fungi Rhizopus oligosporus 2740. The LAB and fungi-dependent variation in AGEs inhibition by BB extracts was noted. A high bioaccessible anti-AGEs activity, antioxidant/reducing capacity and TPC from BB was found after digestion in vitro of BB. The positive correlation noted between the anti-AGEs bioaccessibility indexes, antioxidant/reducing bioaccessibility indexes and total phenolic compounds bioaccessibility indexes indicated for the contribution of the bioaccessible phenolic antioxidants to the inhibitory activity of buckwheat biscuits against AGEs formation.

    更新日期:2020-01-21
  • Prevention of protein and lipid oxidation in freeze-thawed bighead carp (Hypophthalmichthys nobilis) fillets using silver carp (Hypophthalmichthys molitrix) fin hydrolysates
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-18
    Longteng Zhang; Yuankai Shan; Hui Hong; Yongkang Luo; Xiaohui Hong; Weijian Ye

    Conversion of aquatic by-products into value-added food ingredients has gained great interest worldwide, and enzymatic hydrolysis is one of the most accepted methods for the recovery of by-product proteins. In our study, fins from silver carp (Hypophthalmichthys molitrix) were hydrolyzed by four enzymes (trypsin, alcalase, papain, and neutrase) and the antioxidant activity of the derived fin hydrolysates was evaluated both in vitro and in freeze-thawed bighead carp (Hypophthalmichthys nobilis) fillets. The results showed that fin hydrolysates by trypsin and alcalase exhibited strong in vitro scavenging activity against 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals and chelating activity to ferrous ions. Freeze-thaw-induced protein oxidation (the formation of carbonyls and disulfide bonds) and degradation (the loss of Ca2+-ATPase activity) were significantly (P < 0.05) inhibited by fin hydrolysates. In addition, fin hydrolysates reduced lipid oxidation as evidenced by decreased free fatty acid content, peroxide value, thiobarbituric acid reactive substances (TBARS), and fluorescent compounds after multiple freeze-thaw cycles. Therefore, fin hydrolysates by trypsin and alcalase could be potential natural antioxidants in preservation of fish fillets.

    更新日期:2020-01-21
  • Improvement of storage quality of strawberries by pullulan coatings incorporated with cinnamon essential oil nanoemulsion
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-18
    Yifu Chu; ChengCheng Gao; Xiaoya Liu; Ni Zhang; Tian Xu; Xiao Feng; Yuling Yang; Xinchun Shen; Xiaozhi Tang

    This study was aimed at evaluating the effect of pullulan coating incorporated with cinnamon essential oil (CEO) nanoemulsion on the shelf life and senescence of fresh strawberries during room storage. Pullulan-CEO nanoemulsion prepared using ultrasound treatment had smaller particle size (162.1 nm) and more uniform distribution of oil droplets. After six days of storage, pullulan-CEO nanoemulsion coating remarkably lowered the loss in fruit mass, firmness, total soluble solids and titratable acidity of strawberries. In addition, pullulan-based nanoemulsion coated strawberries showed the strongest antimicrobial activity against bacteria and molds (2.544 and 1.958 log CFU/g, respectively) compared to control and pure pullulan coating groups. It is mainly due to the antimicrobial activities of CEO dispersed in nano size in pullulan matrix. This study revealed that pullulan-CEO nanoemulsion coating showed great potential to prolong the shelf life of fresh strawberries during room storage.

    更新日期:2020-01-21
  • Exopolysaccharides production by Lactobacillus rhamnosus strains – Optimization of synthesis and extraction conditions
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-18
    Magdalena Oleksy-Sobczak; Elżbieta Klewicka; Lidia Piekarska

    Exopolysaccharides (EPS) synthesised by the tested strains of Lactobacillus rhamnosus bacteria (marked with symbols 0943, 0935 and OM-1) with probiotic properties are promising natural alternatives for commercial additives in the food, cosmetic and pharmaceutical industries. However, the low efficiency of synthesis and high acquisition cost make research and its industrial implementation much more difficult. In this paper, the environmental conditions and EPS extraction parameters were modelled. The culture medium used in the study was developed in the earlier stages of research on the basis of multi-parametric modelling. Thanks to a series of analyses, such cultivation parameters were developed which ensure high efficiency of EPS synthesis and a significantly reduced technological cost. The best results were obtained in stationary cultures cultivated for 24 h at 25 °C with the initial pH of 5.7 and the inoculum of 5% v/v. Unlike to other examined strains in case of Lb. rhamnosus ŁOCK 0943 prolongation of the incubation time and application of mixing (80 rpm) in the process of cultivation significantly increased the efficiency of EPS synthesis. The outcome sheds a new light on the possibility of the industrial application of the exopolysaccharides produced by Lb. rhamnosus bacteria in the “new generation” products.

    更新日期:2020-01-21
  • Characterization of Lactococcus strains isolated from artisanal Oaxaca cheese
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-16
    I. Caro; E.J. Quinto; L. Fuentes; V. Alessandria; L.S. Cocolin; M.P. Redondo-del-Río; B. Mayo; A.B. Flórez; J. Mateo

    Lactococci strains obtained from raw-milk Oaxaca cheese through its production process in two factories from the Tulancingo Valley, Mexico, were isolated and characterized. A total of 120 colonies were selected from the growth in M17 and MRS agars. Twenty were identified as lactococci strains, all Lactococcus lactis, and were characterized by molecular and phenotypic methods including carbohydrate use, enzymatic profile, acidifying capacity, and antibiotic and phage resistance. High phenotypic diversity was observed and confirmed among the Lactococcus lactis strains by rep-PCR fingerprints. Fifty percent of the strains were resistant to streptomycin and 35% to erythromycin. Nine isolates were considered as fast acidifying strains. The predominant volatile compounds produced were 3-methylbutanol, 3-methylbutanal and butane-2,3-dione. A selection of strains isolated in this study has shown satisfactory characteristics to be used as potential starters for the industrial production of Oaxaca cheese.

    更新日期:2020-01-16
  • A sensitive colorimetric immunoassay based on poly(dopamine) modified magnetic nanoparticles for meat authentication
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-14
    Narjiss Seddaoui; Aziz Amine

    Magnetic nanoparticles as solid substrate and polydopamine as coating polymer were combined for the construction of a sensitive colorimetric immunoassay aimed at the quantification of pork associated with meat fraud. In this study, a competitive assay was conducted between purified IgGs and porcine IgGs covalently immobilized on magnetic nanoparticles, for the binding sites of peroxidase-labelled antibody. The recognition of porcine IgG was monitored by a simple colorimetric method in the presence of peroxidase substrate. The performed immunoassay was successfully employed for the screening of pork in adulterated meat, allowing low level of 0.01% to be detected in short time of analysis. The specificity of the immunoassay was tested against five different meat species (pork, lamb, turkey, chicken and beef) and it was found to be highly specific towards pork. Furthermore, the used magnetic probe has maintained a satisfactory stability enabling sensitive detection of pork within 20 days of storage. With the versatility and facile-preparation of polydopamine modified magnetic nanoparticles as well as the easy handling of the whole assay, this colorimetric method provides a specific and sensitive in-field-test for the detection of pork in adulterated meat and thus verifying halal meat authenticity.

    更新日期:2020-01-14
  • Rediscovering bread quality of “old” Italian wheat (Triticum aestivum L. ssp. aestivum.) through an integrated approach: Physicochemical evaluation and consumers’ perception
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-13
    Fatma Boukid; Valentina Gentilucci; Elena Vittadini; Andrea Demontis; Roberta Rosta; Sara Bosi; Giovanni Dinelli; Eleonora Carini

    The present work aimed to assess flour properties and bread-making quality of “old” Italian wheat (Triticum aestivum L. ssp. aestivum.) cultivars (n = 7) by combining physicochemical evaluation and consumers’ perception. Old cultivars-flours and deriving bread had interesting physicochemical features when compared to a new one (Aquilante). Notably, bread derived from Abbondanza (old wheat cultivar) had the highest specific volume and bread made with Verna (old wheat cultivar) flour had comparable textural properties to Aquilante-based bread. These results suggested relevant impact of breeding on bread properties, but no trend was observed as function of the release year. For sensory evaluation, acceptability test revealed that bread made with Abbondanza cultivar gave the most appreciated bread similar to that made by the new cultivar. Check-all-that-apply test showed that none of the old cultivars-based breads directly matched the ideal product, but bread made with Abbondanza flour was the closest. Overall, physicochemical and sensory evaluations were aligned in their main outputs enabling the identification of some old cultivars with interesting bread-making quality that can be potentially used and further improved with an optimized breadmaking process for advanced breeding programs.

    更新日期:2020-01-13
  • Rapid determination of emulsion stability by rheology-based thermal loop test
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-13
    Zeynep Hazal Tekin; Esra Avcı; Salih Karasu; Omer Said Toker

    This study aimed to determine the stability of oil-in-water emulsions using the thermal loop test as a novel method. Samples with xanthan gum concentrations of 0.1 g, 0.2 g, 0.3 g, 0.4 g or 0.5 g/100 g were subjected to 10 thermal cycles from 5 to 23 °C (low-temperature stability test) and 23–45 °C (high-temperature stability test). In the low-temperature stability test, the relative change of G* for the samples (Δ) was 4.15%, 2.82%, 1.32%, 1.17%, and 4.68%, respectively. In the high-temperature stability test, the Δ values were 7.7%, 0.58%, and 7.22% for samples 3–5, respectively. However, samples 1 and 2 had dramatic changes in G*. This was also confirmed by a visual test, zeta potential measurement, polydispersity index, and particle size distribution. Moreover, a low zeta potential, high polydispersity indexes, and phase separations yielded high Δ values. This study implies that the thermal loop test could be successfully applied to determine the emulsion stability in food emulsions.

    更新日期:2020-01-13
  • Effect of buckwheat incorporation on batter fermentation, rheology, phenolic, amino acid composition and textural properties of idli
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-13
    Supriya Kumari; Seerat Bhinder; Balwinder Singh; Amritpal Kaur; Narpinder Singh

    The effect of replacement of rice with buckwheat (BW) at levels of 10, 30 and 50% in idli on batter fermentation and rheology, idli textural and nutritional quality was studied. Also, two idli variants containing parboiled rice (PR) and raw rice (RR) were evaluated and compared for the suitability of BW incorporation. Idli batters prepared with PR had higher fermentation activity and yielded batters with higher reducing sugar (RS) and rise in volume. RS content (268.91–467.34 mg/g) was highest for 50% BW incorporated PR batter and lowest for 30% BW incorporated RR batter. The rise in batter volume decreased and titrable acidity increased with addition of BW. Furthermore, with an increase in BW, storage and loss modulus of idli batters increased. All idli batters containing PR had lower tan δ and higher amounts of RS, indicating a greater degree of fermentation which resulted in a light and highly aerated batter. Idlis containing PR had better textural attributes, particularly lower hardness (5.43–8.98 N) than RR idli variants (8.87–9.89 N) and good overall sensorial acceptability. BW incorporation improved the amino acid and phenolic profile and antioxidant activity of idli.

    更新日期:2020-01-13
  • Physical and microbiological properties of powdered Lactobacillus salivarius NRRL B-30514 as affected by relative amounts of dairy proteins and lactose
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-13
    Anyi Wang; Jun Lin; Qixin Zhong

    The objective of this study was to characterize physical and microbiological properties of powders prepared by mixing Lactobacillus salivarius NRRL B-30514 suspensions with skim milk powder (SMP), spray-dried lactose (SDL), milk protein concentrate (MPC), or MPC/SDL at a mass ratio of 1:2, 1:1 or 2:1 to understand the relative significance of proteins and lactose in bacterial survival. The probiotic viability and storage stability were significantly improved with the increase of dairy protein content. Based on water sorption isotherms and X-ray diffraction spectroscopy, MPC was suggested to preferentially absorb water in cell suspensions, which inhibited the hydration of SDL and therefore lowered the hypertonic pressure to the adhered cells. The LIVE/DEAD® BacLight™ and CTC reduction assays detected higher membrane integrity and respiratory activity of bacteria for treatments with more proteins. Findings from the current study indicated the more significant role of milk proteins than lactose protecting bacteria during dehydration.

    更新日期:2020-01-13
  • Cronobacter sakazakii CICC 21544 responds to the combination of carvacrol and citral by regulating proton motive force
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-11
    Yifang Cao; Ailian Zhou; Donggen Zhou; Xinglong Xiao; Yigang Yu; Xiaofeng Li

    Response mechanism of Cronobacter sakazakii under stress of combination of citral and carvacrol was investigated by transcriptome sequencing. Twenty-five significantly differentially expressed genes were identified to be closely related to the ability of C. sakazakii tolerating the stress after analysis, mainly involving glycerol metabolism; citrate metabolism; formate metabolism; ribosome function and transmembrane transport system. Combination of carvacrol and citral could cause dissipation of proton motive force (PMF) and the psp regulon is an important switch in the response of C. sakazakii to this condition. To maintain PMF, psp regulated cellular processes to reduce the consumption of cellular energy for cell membrane repair and proton consumption. In T1 group (low concentration group), C. sakazakii remained aerobic metabolism and expression of glycerol metabolism related genes were upregulated for cell membrane repair and proton consumption. In T2 group (high concentration group), bacteria convert from aerobic metabolism to anaerobic metabolism to reduce energy consumption and expression of genes in formate metabolism were upregulated to consume excessive intracellular protons; citrate lyase-related genes were upregulated to decompose citrate, the intermediate of the tricarboxylic acid cycle, to generate acetyl CoA for production of cell membrane phospholipids.

    更新日期:2020-01-13
  • Bio-control of Salmonella spp. in carrot salad and raw chicken skin using lytic bacteriophages
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-11
    Ramachandrappa Naveen Kumar; Bhukya Bhima; Putchaa Uday Kumar; Sudip Ghosh

    Salmonella spp., one of the major causes of foodborne diseases and a public health burden worldwide. Lytic bacteriophages NINP13076 and NINP1162 infecting Salmonella spp were isolated from sewage water with host strains Salmonella enteritidis (ATCC 13076) and Salmonella spp (MTCC 1162) respectively. The morphology of phages by Transmission electron microscopy revealed that they belong to the family Siphoviridae. Turbidometric assay, spot test assay, and plating methods done to see the effect of bacteriophages on Salmonella in-vitro. The impact of bacteriophage NINP13076 on Salmonella in vitro at different multiplicity of infection by plating method indicated that significant reduction (8.3–5.3 log CFU/g) in Salmonella count observed at 101 multiplicity of infection. Raw chicken skin contaminated with Salmonella spp, treated with bacteriophages showed significant reduction (6.7–5.4 log CFU/g) of Salmonella after 3h of incubation at room temperature when compared to untreated control. The results of the experiment on the lytic effect of NINP13076 phages on Salmonella enteritidis (log CFU/ml) in experimentally contaminated carrot salads showed a significant reduction in Salmonella population (1 log) after 4h of incubation. These results show the potential effectiveness of this bacteriophage as a biocontrol agent against Salmonella spp in raw chicken skin and carrot salad.

    更新日期:2020-01-13
  • A low-cost novel lateral flow nucleic acid assay (LFNAA) for yak milk authentication
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-11
    Zhiying Wang; Tingting Li; Wenjie Yu; Lu Qiao; Shuming Yang; Ailiang Chen

    A low-cost novel lateral flow nucleic acid assay (LFNAA) was developed for rapid and sensitive authentication of yak milk on-site. In this method, a special abasic spacer C3 and tail nucleotide sequence modified reverse primers were innovatively designed for rapid isothermal recombinant polymerase amplification (RPA) to obtain a double-stranded amplicon with a single-stranded DNA tail, which could directly bind to gold nanoparticle (AuNP)-labeled detection probes, and produce a sandwich complex to show a red color on the test line of the strip. Compared to conventional RPA-lateral flow assay based on expensive antibodies, the proposed method in this work demonstrated massive cost reduction, avoided time-consuming and laborious AuNP-antibody conjugation process. The LFNAA revealed high specificity and sensitivity, which allowed detecting as low as 5% of yak milk within 40 min. This LFNAA facilitated non-specialized operators to field determine the authenticity of yak milk by naked eyes, and could be readily applied to other nucleic acid detection such as food safety inspection and point-of-care medical tests.

    更新日期:2020-01-13
  • Production of phenolic enriched mushroom powder as affected by impregnation method and air drying temperature
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-10
    Fatih Mehmet Yılmaz; Aslı Zungur Bastıoğlu

    This study aimed to develop a functional food ingredient by incorporating grape pomace extract into mushroom slices using both vacuum impregnation (VI) and simultaneous application of ultrasound assisted vacuum impregnation (VI+US) techniques with further air drying at 55, 65 and 75 °C. Drying kinetics of processes as well as bioactive compounds and physical properties of mushroom powders belonging to VI and VI+US treatments were assessed and compared with non-treated (N-T) samples. The activation energies of drying for VI (27.05 kJ mol−1) and VI+US (16.24 kJ mol−1) treatments were found significantly lower than N-T (43.42 kJ mol−1) samples, and VI+US samples exhibited highest total phenolic and total flavonoid contents with highest antioxidant capacity values. Physical properties of the mushroom powders were affected by both impregnation techniques and air-drying temperatures. Impregnation treatments increased D[3,2] values (surface area mean) of the samples dried at higher temperatures, and the ultrasound application resulted in the highest values. Both VI and VI+US treatments improved flowability (Carr index) compared to N-T samples. The highest oil and water holding capacity values were determined in VI+US samples while sole VI treatment revealed lowest water holding capacity.

    更新日期:2020-01-11
  • Characterization of a novel T7-like Salmonella Typhimurium (ATCC13311) bacteriophage LPST144 and its endolysin
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-09
    Qile Yang; Yifeng Ding; Ruonan Nie; Lan Yao; Xinyue Wang; Min Zhou; Jia Wang; Xiaohong Wang

    Salmonella Typhimurium, one of the most common Salmonella spp. serovars, is recognized as a globally important foodborne pathogen. In this study, bacteriophage LPST144 against S. Typhimurium (ATCC13311) was isolated from sewage and selected owing to its excellent lytic capacity. After genome sequence analysis, the endolysin from LPST144 was cloned and expressed, and its lytic activity was verified. Morphological analysis showed that bacteriophage LPST144 belongs to Podoviridae family and Caudovirales order, and could completely inhibit host bacterial growth within 7 h at multiplicity of infection of 0.01–1000. Genome analysis indicated LPST144 genome comprised a 39,050 bp DNA with 43 putative open reading frames, of which 27 were annotated to known functions. No genes associated with lysogeny, antibiotic resistance and virulence factor were found. Putative endolysin LysT144 could significant decrease OD600nm from 0.80 to 0.14 against chloroform-treated S. Typhimurium within 30 min. Endolysin LysT144 remained highly active at pH ranging from 6.0 to 12.0, temperature below 50 °C, and NaCl concentration below 300 mM. Besides, LysT144 also exhibited extensive and broad spectrum of host bacteria strains, including multiple antibiotic-resistant Salmonella. Therefore, the bacteriophage LPST144 and its endolysin could be used as potential antibacterial agents for Salmonella control in food industry.

    更新日期:2020-01-09
  • Decontamination effect of hot-air drying against bacterial pathogen and surrogate strains on basil leaves, from laboratory to pilot scale settings
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-09
    Zijin Zhou; Sophie Zuber; Matteo Campagnoli; Mireille Moser; Frank Devlieghere; Mieke Uyttendaele

    Drying technologies are often evaluated on their efficiency to remove moisture and impact on sensory quality of products. The decontamination effect against foodborne pathogens, however, is rarely investigated. This study investigated the inactivation of foodborne pathogens and surrogates on basil leaves during drying, from characterizing thermal resistance of strains in aw-adjusted basil to collecting decontamination data under various drying processes. Salmonella Senftenberg was the most resistant pathogenic strain tested during heating on basil leaves. A treatment of 20 min at 60 °C reduced S. Senftenberg by 4.7 and 3.7-log on basil leaves at water activity of 0.99 and 0.95, respectively. The pronounced increase in strains’ thermal resistance at reduced water activity was also observed during dynamic hot-air drying. Overall, more than 4-log reduction of S. Senftenberg was achieved after 90 min, 40 min and 20 min drying in a laboratory oven at 60 °C, 80 °C and 100 °C, respectively. Upscaling experiments in a pilot dryer using surrogate strains provided additional confirmation on the decontamination efficiency and effect of product moisture content during drying. Results from surrogate strains suggested that Escherichia coli P1 showed to be a more suitable surrogate for hot-air drying processes of basil leaves than Enterococcus faecium.

    更新日期:2020-01-09
  • Development of a microencapsulated synbiotic product and its application in yoghurt
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-09
    Hongbo Li; Tianqi Zhang; Chunshuang Li; Shan Zheng; Hongjuan Li; Jinghua Yu

    The effect of ten commercial prebiotics on the growth ability of four Lactobacillus strains was studied to develop a synbiotic product. The prebiotic score was calculated to assess the capability of prebiotics that stimulated the growth of Lactobacillus compared to potential pathogens. Although both galacto-oligosaccharide (GOS) and lactitol (LAC) could enhance growth, LAC had a highest prebiotic score value for four Lactobacillus strains. Survival of encapsulated synbiotics forming by Lactobacillus casei 30–1 and LAC in simulated gastrointestinal condition was evaluated. 15 g l−1 LAC provided effective protection with 72.62% encapsulation efficiency and a 3.65 logs reduction. The microcapsules were then added into yoghurt and the result showed that there was an increased survival of probiotics due to the protection of cells by microencapsulation and the promoting effect of LAC on the probiotics growth. However, yoghurt with synbiotic microcapsules showed a reduced quality compared to controls over the storage period. This study had shown that microencapsulation and addition of LAC help to enhance the survival of probiotic stains in yoghurts during storage, but had a negative relationship between the improvement of yoghurt quality and the addition of synbiotic microcapsules.

    更新日期:2020-01-09
  • Effect of freeze-thaw pretreatment on yield and quality of perilla seed oil
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Kyo-Yeon Lee; M. Shafiur Rahman; Ah-Na Kim; Yejin Son; Suyeon Gu; Myoung-Hee Lee; Jung In Kim; Tae Joung Ha; Doyeon Kwak; Hyun-Jin Kim; William L. Kerr; Sung-Gil Choi

    This work investigated the effect of freeze-thaw (FT) pretreatment on the yield and quality of oil cold-pressed from perilla seeds. FT pretreatment ruptured the perilla seed coat and internal structure, resulting in an oil yield of 78.71%, about 2.5-times greater than the yield from untreated control perilla seeds. Acid values were relatively low (0.54 mg KOH/g) and not different in the FT-treated and control oil. Likewise, peroxide values were low (1.34 meq/kg) and not different amongst the treatment groups. Viscosity values (96.5 mPa s) were indicative of a light oil while color values (L*a*b*) indicated a light yellow-green color. The major unsaturated fatty acids were identified as linolenic acid (C18:3, ω−3), linoleic acid (C18:2, ω−6), and oleic acid (C18:1, ω−9). The most abundant volatiles were 1-(furan-2-yl)-4-methylpentan-1-one and 3-(4-methyl-3-pentenyl)-furan in both of the oil samples. However, the normalized relative intensity of the volatile compounds was reduced in the FT-treated PO. The acylglycerol profile in FT-treated and control PO was not different, yet another indication that FT pretreatment did not increase oil rancidity or oxidative instability. FT pretreatment on oil seeds before cold-pressing is an attractive technique for obtaining high oil yield without deteriorative effects on the quality characteristics of edible oil.

    更新日期:2020-01-07
  • Utilization of egg white solids to improve the texture and cooking quality of cooked and frozen pasta
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Liyang Xie; Noriaki Nishijima; Yoshifumi Oda; Akihiro Handa; Kaustav Majumder; Changmou Xu; Yue Zhang

    Frozen cooked pasta meals are offered to meet the increasing demand for high-quality pasta products with ready-to-eat convenience. However, textural changes during freezing and after thawing may consequently modify pasta quality, which requires strategies to minimize texture deterioration. Two egg white powders (EWP), namely, P110 and M200 from Henningsen Foods, Inc. were incorporated at different levels (0, 3 and 5 g/100 g semolina flour) into cooked and frozen wheat semolina pasta to improve their texture and cooking quality. The water absorption of pasta was greatly improved, while the cooking loss was significantly reduced by EWP. The negative effect of freezing and reheating processes on the pasta texture could be significantly minimized by EWP, especially M200 at 3 g/100 g semolina flour. The dynamic rheology on pasta dough and total sulfhydryl and disulfide in two egg white solutions were measured. It can be seen that M200 could form a stronger gel-like structure than P110, which may contribute to significant free sulfhydryl/disulfide exchange with gluten. It could be seen that the findings in this work demonstrated the potential of using EWP especially M200 to improve fresh and frozen pasta texture and quality.

    更新日期:2020-01-07
  • NIR spectroscopy-multivariate analysis for rapid authentication, detection and quantification of common plant adulterants in saffron (Crocus sativus L.) stigmas
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Eman Shawky; Rasha A. Abu El-Khair; Dina A. Selim

    The presented work discusses the development of a rapid and precise analytical protocol using near infrared spectroscopy combined with multivariate data analysis to authenticate, detect and quantify most of the commonly encountered plant adulterants used in fraud of saffron stigmas including safflower, pomegranate fruit peel, calendula flower, paprika, curcuma, hibiscus, saffron stamens and exhaustively-extracted saffron stigmas. A Soft Independent Modelling of Class Analogies (SIMCA) model was constructed for authentication of saffron stigmas with 100% sensitivity and a Partial Least Squares-Discriminant Analysis (PLS-DA) model was successfully utilized for correct discrimination of unadulterated and intentionally adulterated saffron samples as it showed 100% sensitivity and 99% specificity. Quantitation of the amount of each individual adulterant was achieved through construction of partial least squares regression (PLSR) models accompanied by variable importance to projection (VIP) method for variable selection which revealed that bands in the spectral ranges 6000-5800 cm−1 followed by 4600–4200 cm−1 and 5400-5000 cm−1 were the most important for correct prediction with detection limits as low as 1%. The models performance was tested using internal and external validation sets indicating their reliability in providing a useful quality assessment tool for saffron in an attempt to prevent its fraud.

    更新日期:2020-01-07
  • Relationship between the emulsifying properties and formation time of rice bran protein fibrils
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Shuxian Pang; Ping Shao; Qingjie Sun; Chuanfen Pu; Wenting Tang

    In this study, oil-in-water emulsions stabilized with rice bran protein fibrils (RBPFs) were prepared, and the effect of the fibrils’ formation time on the structural and emulsion characteristics, including droplet size, zeta-potential, and surface morphology, were analyzed. As the heating time increased to 420 min, the β-sheet structure content and surface hydrophobicity of the RBPFs increased. As the heating time continued to heat up to 600 min, a downward trend occurred. The formation time also affected the mean contour length of the fibrils, and the scale began to decrease at 540 min. The emulsion prepared by heating for 480 min showed the best emulsifying activity, and the 420-min fibril emulsion showed the best emulsion stability and the highest interfacial protein content. The rheological results showed that as the heating time increased (0–480 min), the storage modulus increased, and the loss modulus and the apparent viscosity were reduced. The emulsions in the range of 0–100 s−1 shear rate did not have gel properties and shear thinning. The results of this study will help to provide a new perspective to develop a stable food-grade emulsion in the future.

    更新日期:2020-01-07
  • Prediction of soluble solid content of Agaricus bisporus during ultrasound-assisted osmotic dehydration based on hyperspectral imaging
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Kunpeng Xiao; Qiang Liu; Liuqing Wang; Bin Zhang; Wei Zhang; Wenjian Yang; Qiuhui Hu; Fei Pei

    Soluble solid content (SSC) is a critical index to evaluate the nutrition and flavor quality of food products. This study presents a novel strategy to predict the SSC in Agaricus bisporus slices during ultrasound-assisted osmotic dehydration (UOD). The spectral signatures of Agaricus bisporus were captured via a hyperspectral imaging (HSI) system and different spectral preprocessing methods and models were used to fit and evaluate the SSC behaviour of samples during UOD. The results showed that the support vector machine (SVM) preprocessed with orthogonal signal correction (OSC) provided the best fit for the full-band spectra of samples, with a higher correlation coefficient of prediction (R2 P, 0.883) and residual predictive deviation (RPD, 3.04). Moreover, the competitive adaptive reweighted sampling (CARS) algorithm can screen 67 key wavelengths from the complex original full-band wavelengths, and the OSC-CARS-SVM model showed the best predicted performance of SSC for the simplified spectra. In addition, the distribution of SSC in different UOD periods of the samples were demonstrated in a pseudo-colour map, which further revealed the SSC distribution of samples during UOD. The overall results showed the great potential of HSI to detect and predict the SSC of Agaricus bisporus rapidly, accurately, and non-destructively.

    更新日期:2020-01-07
  • Evaluation of the contribution of trichomes to metabolite compositions of tea (Camellia sinensis) leaves and their products
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Jianlong Li; Lanting Zeng; Yinyin Liao; Jinchi Tang; Ziyin Yang

    Tea is processed from the postharvest tender leaves from tea plants (Camellia sinensis). Leaves containing more trichomes are considered to produce higher quality tea, but no evidence is available to support this opinion. In the present study, morphological and metabolic analyses of trichomes showed that tea trichomes were unicellular, simple, and rich in many water-soluble metabolites, including free catechins, caffeine, and amino acids. Furthermore, the analysis of known quality-related and non-targeted metabolites in fresh tea leaves and tea products showed that the presence of trichomes did not change the overall metabolite profiles of fresh tea leaves, white tea, and black tea, but might affect the non-targeted metabolites in green tea. Overall, more trichomes might only indicate higher quality tea leaves, while metabolites in the leaf might be the key factor. This study provides the first determination of the contribution of trichomes to tea quality.

    更新日期:2020-01-07
  • Influence of the essential oil of Mentha spicata cv. Henanshixiang on sunflower oil during the deep-frying of Chinese Maye
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Dongying Wang; Yudong Meng; Chenxi Li; Tingting Li; Dongmin Wang; Xuede Wang

    Sunflower oil is faced with serious problems including oxidation during the deep-frying of Chinese Maye, so a search for natural antioxidants is quite necessary. In the present study, after deep-fried for 30 h, the addition of the essential oil of the aerial parts from M. spicata cv. Henanshixiang (MSEO) to sunflower oil at 0.08 g/kg not only significantly restrained the increase of total polar compounds (TPC), thiobarbituric acid (TBA), conjugated dienes, conjugated trienes, polymer and viscosity of sunflower oil by 48.4%, 41.4%, 64.6%, 42.4%, 61.8 and 26.7% (p < 0.01 or p < 0.05), respectively, but also prominently restrained the decrease of the sensory properties of the fried product, Chinese Maye, including flavor, taste, crispness and overall acceptance by 26.2%, 25.3%, 59.0% and 41.6% (p < 0.01 or p < 0.05), respectively. Furthermore, by means of bioassay-guided fractionation and the repeated deep-frying process, one compound of MSEO, limonene, was demonstrated to increase the oxidative stability of sunflower oil. The result revealed that limonene was the key antioxidant compound in MSEO, and it could be used to replace synthetic antioxidants during the deep-frying of Chinese Maye using sunflower oil.

    更新日期:2020-01-07
  • Investigation on 3D printing ability of soybean protein isolate gels and correlations with their rheological and textural properties via LF-NMR spectroscopic characteristics
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Pattarapon Phuhongsung; Min Zhang; Sakamon Devahastin

    Soy protein isolate (SPI) with/without xanthan gum (at 0.5 g/30 g of SPI) and NaCl solution at different concentrations (1, 2 or 3 g in 100 mL of distilled water) was assessed for its 3D printing ability; the texture of the printed gels was also determined. To allow a priori determination of the printing ability and hence the ability to reduce the number of tedious printing experiments, correlations between rheological and textural properties as well as LF-NMR spectroscopic characteristics of the gels and their 3D printing ability were investigated. SPI gel with xanthan gum and NaCl solution at 1 g/100 mL could be successfully printed and better matched the designed 3D models than the gels of other formulations. Strong correlations between LF-NMR major peak relaxation time (T2 (MP)) and peak area (A22) with the rheological properties, which were in turn related to the printing ability, were noted.

    更新日期:2020-01-07
  • Mayonnaise as a model food for improving the bioaccessibility of carotenoids from Bactris gasipaes fruits
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Leonardo M. de Souza Mesquita; Bruna Vitória Neves; Luciana Pellegrini Pisani; Veridiana Vera de Rosso
    更新日期:2020-01-07
  • Method study on determination of total purine content in fish meat by diazotization reaction combined with SERS
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-07
    Xiaoying Guo; Xinyu Wang; Dongwei Huang; Jin-Jie Zhang; Dalun Xu; Wenge Yang; Qijie Hu; Zhongxiang Fang; Tao Huang

    A new analytical method was developed to determine total purine content in fish meat. The analysis principle is that total purine extracted from fish meat are turned into uric acid by diazotization reaction and xanthine oxidase reaction. Then, the content of uric acid is measured by surface-enhanced Raman spectroscopy (SERS). The results showed that the optimal conditions for the diazotization reaction were at 60 °C for 40 min, using 0.16 M HCl, and 3.00 g/L NaNO2. The optimal xanthine oxidase reaction conditions were using 100 U/L xanthine oxidase, conducting at 30 °C and pH 7.0 for 40 min. The calibration curve established at the characteristic Raman peak of 631 cm−1 had a good linear relationship (R2 = 0.9864). The recovery rate was between 101.7% and 105.0%. Therefore, the total purine content in the fish meat can be quantitatively determined with this new method.

    更新日期:2020-01-07
  • Identification of hydroxycinnamic acid derivatives of selected canadian and foreign commercial beer extracts and determination of their antioxidant properties
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Md Jiaur Rahman; Jingbang Liang; N.A. Michael Eskin; Peter Eck; Usha Thiyam-Holländer

    Phenolic compounds in beer are derived from grains and hops during processing and production. Thus, the total phenolic content (TPC) of beer extracts, from selected Canadian and foreign commercial, and laboratory produced beers were examined and ranged from 3.72 ± 0.23 to 13.73 ± 0.49 mg GAE/100 mL beer. The total flavonoid content (TFC) of the same beer extracts varied from 0.82 ± 0.02 to 5.28 ± 0.04 mg CE/100 mL beer. Of particular interest were the hydroxycinnamic acids (HCAs) and derivatives in beer extracts because of their antioxidant properties. Main HCAs and a key derivative of ferulic acid, 4-vinylguaiacol (4-VG), were identified in beer extracts by high performance liquid chromatography (HPLC). Significant variations in TPC, TFC, HCAs and 4-VG content were observed among the beer extracts. Antioxidant activities of beer extracts, determined by radical scavenging and ferric-reducing assays, were positively correlated (p < 0.05) with TPC, TFC, and 4-VG but observed negative correlation with individual HCAs (p > 0.05). The positive correlation of 4-VG with ABTS radical cation scavenging and reducing power assays is reported first time. These findings suggest that phenolic compounds and a key derivative of the hydroxycinnamic acid, 4-VG, may have the protective role in the beer as an antioxidant.

    更新日期:2020-01-07
  • Zein nanoparticle stabilized pickering emulsion enriched with cinnamon oil and its effects on pound cakes
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Xiao Feng; Yujia Sun; Yuyan Yang; Xin Zhou; Kaiyue Cen; Chen Yu; Tian Xu; Xiaozhi Tang

    Pickering emulsion enriched with cinnamon essential oil (EO) was applied to partially replace butter in pound cakes and to inhibit mold growth. Pickering emulsions stabilized by zein nanoparticles were dominated by elasticity (G' > Gʺ), indicating the formation of gel-like network microstructure. The aldehyde groups of cinnamaldehyde may interact with amino groups on zein nanoparticles at oil-water interface to enhance the viscoelastic properties of Pickering emulsions, which explained the increased storage modulus as the amount of EO increased. Pickering emulsion of 20 g zein nanoparticle solution (ZNS) +20 g sunflower oil significantly increased the hardness of pound cakes, while Pickering emulsion with 5 g EO addition maintained the texture and colour compared with control group. EO also exerted antimicrobial effect to pound cakes, as the yeasts and molds of 5 g and 10 g EO emulsion added cakes were 1.55 and 1.42 log CFU/g after 12-day room-temperature storage compared with 2.96 log CFU/g of control group. To conclude, Pickering emulsion of 20 g ZNS+15 g oil+5 g EO showed the best effect to replace 20% butter in pound cakes to lower the calorie intake and extend the shelf-life without altering the texture and colour.

    更新日期:2020-01-07
  • Effect of tempe fermentation by three different strains of Rhizopus oligosporus on nutritional characteristics of faba beans
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Katarzyna Polanowska; Anna Grygier; Maciej Kuligowski; Magdalena Rudzińska; Jacek Nowak

    The effect of six-day solid-state fermentation by three strains of Rhizopus oligosporus namely ATCC 48012, ATCC 42222 and ATCC 22959 on selected chemical parameters of faba bean was investigated. Tested strains contributed to significant compositional changes at different levels. All the strains caused a significant decrease in the total content of fatty acids (by 38–78%), polyphenols (by 44–50%), tannins (by 61–68%) and antiradical activity (by 40–53%). Despite the fermentation caused, a decrease in total polyphenol content, the result of LC-MS revealed that quercetin and kaempferol were released during fermentation by all strains, whereas apigenin and p-coumaric acid only by ATCC 22959. Moreover, ATCC 22959 strain increased the most the γ-aminobutyric acid (1.92 ± 0.01 mg/g DW), total amino acids (10-fold) and total sterols (2-fold) contents. All strains were able to form stigmasterol and campesterol, while the other detected sterols were degraded. To the best of authors’ knowledge, this is the first work reporting the formation of sterols by Rhizopus oligosporus other than ergosterol. Furthermore, the highest content of γ-linolenic acid was found in the sample fermented by ATCC 42222. This research showed that faba bean can be used for tempe preparation to improve some its nutritional aspects.

    更新日期:2020-01-06
  • Effect of commercial starter cultures on the quality characteristics of fermented fish-chili paste
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Qian Hua; Pei Gao; Yanshun Xu; Wenshui Xia; Yingying Sun; Qixing Jiang

    The effects of commercial starter cultures on the quality characteristics of fermented fish-chili paste were investigated. Five batches of fish-chili paste were prepared with different starter cultures, namely, SBM-52 (Staphylococcus xylosus, Staphylococcus carnosus, Pediococcus pentosaceus and Pediococcus lactis), PRO-MIX5 (Staphylococcus xylosus, Lactobacillus plantarum and Lactobacillus sakei), WBX-43 (Staphylococcus xylosus and Staphylococcus carnosus), V3 (Lactobacillus plantarum), and CO (spontaneous fermentation) as the control. The results showed that all the starter cultures accelerated the growth of lactic acid bacteria and obviously reduced the Enterobacteriaceae count compared with the CO batch. SBM-52, PRO-MIX5 and V3 quickly reduced the pH, and there was no obvious difference in the protease activities among these five batches (P > 0.05). The SBM-52 batch displayed a significantly higher level of total free amino acids than the control (P < 0.05). The accumulation of organic acids was mainly due to lactic acid in all the samples. Volatile analysis indicated that more ester compounds were detected in WBX-43 compared with the other samples. E-nose analysis showed an obvious difference in the overall odor among the different samples. In conclusion, the starter cultures of WBX-43 and SBM-52 could be used for the production of high-quality fish-chili paste with better flavor.

    更新日期:2020-01-06
  • Transfer of class 1 integron-mediated antibiotic resistance genes from Salmonella enterica of farm fly origin to susceptible Escherichia coli and Salmonella strains
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Yumin Xu; Jinru Chen

    Integrons in Salmonella are critical genetic elements with antibiotic resistance genes that could be disseminated through horizontal gene transfer, imposing risks to public health. This study was undertaken to determine the structure of integrons in Salmonella isolated from flies on cattle farms and examine the transferability of the integrons through conjugation. Results showed that 2 out of 606 isolated Salmonella, 438 and 442, harbored class 1 integrons. Integron gene cassette in Salmonella 438 carried a single gene of aadA7, and Salmonella 442, drfA12-orfF-aadA2. The two integrons were transferrable through conjugation on microbiological media to a Salmonella strain isolated from fly and to E. coli C600 at efficiencies ranging from 1.47 × 10−6 to 6.29 × 10−4. However, only Salmonella 442 was able to transfer its integron to the recipient cells in/on 3 out of 8 farm samples, with conjugation efficiencies ranging from 4.26 × 10−10 to 1.36 × 10−8. Antibiotic resistance genes not carried by integrons, e.g. genes encoding resistance to tetracycline and chloramphenicol, were co-transferred with integron-mediated antibiotic resistance genes. The data suggests that some Salmonella isolated from flies of cattle source carry integrons which could disseminate antibiotic resistance genes through horizontal gene transfer in the farm environment.

    更新日期:2020-01-06
  • Plant-based natural saponins for Escherichia coli surface hygiene management
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Rok Fink; Anja Potočnik; Martina Oder

    Cleaning the surfaces enables reducing microbial populations and consequently the risk of food contamination. The aim of this research was to study the potential of natural extracts from soap nuts, quillaja bark, and horse chestnuts for the reduction of Escherichia coli on glass surfaces. Analogous to that, we tested the efficacy of standard saponins as the active components in the plants mentioned above. The results show that the numbers of bacteria cells are decreased by increasing concentrations of all cleaning product, except for quillaja standard saponin (p < 0.05). Furthermore, the findings indicate that natural plant extracts have greater efficacy than standard saponins do. In particular, quillaja bark extract shows the potential to reduce bacterial populations by up to 66%. Moreover, the research also demonstrates that natural plant extracts have excellent abilities to reduce water surface tension (22 mN/m for soap nut extract) and emulsification potential (74 for quillaja bark extract). Natural plant extracts are inexpensive, biodegradable, and residues are less toxic than conventional ones. The evidence of this study suggests that natural plant extracts are efficient against attached E. coli cells on the glass surface and are a good candidate for surface hygiene management.

    更新日期:2020-01-06
  • Antioxidative properties of eastern prickly pear (Opuntia humifusa) fermented with lactic acid bacteria and cell wall-hydrolyzing enzymes
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Venus C. Quines-Lagmay; Beom-Gyun Jeong; William L. Kerr; Sung-Gil Choi; Jiyeon Chun

    Mucilaginous nature of Opuntia humifusa (Oh) cladodes complicates efficient extraction of bioactive compounds. To overcome this, Oh hydrolysates were prepared using cell wall-hydrolyzing enzymes (CHEs) and lactic acid bacteria (LAB) containing β-glucosidase activity. Treated Oh samples (at 37 °C for 60 h) include control-1 (LAB only, no enzyme), control-2 (no LAB, Viscozyme only), Oh-P (LAB+pectinase), Oh-C (LAB+cellulase), Oh-PC (LAB+pectinase+cellulase), Oh-V (LAB+Viscozyme), Oh-Px (LAB+Pectinex), and Oh-VPx (LAB+Viscozyme+Pectinex). On average, juice yields of fermented Oh samples were higher by 5% and 48% than those of control-2 and control-1, respectively. Total polyphenol contents increased by ∼71% in Oh-VPx. Total flavonoid contents of treated samples with CHE increased to an average 530.0 quercetin equivalent (QE)/mL after 60 h; value was four times higher than control-1 (121.99 QE/mL). Highest isorhamnetin content was in Oh-V (43.14 mg/mL). Flavonoid glycosides were gradually decreased, indicating release of flavonoid aglycone, isorhamnetin. DPPH* radical scavenging activity and reducing power increased by 58% and 98%, respectively, in Oh-VPx (14.06 μg GAE/mL and 113.75 μg GAE/mL, respectively). Hypoglycemic property of hydrolysates was also enhanced. This study shows that treatment with either β-glucosidase-active LAB or CHE might enhance the bioactivities of Oh, and combining the two might improve juice extraction and enhance bioactive properties.

    更新日期:2020-01-06
  • Effect of a water spray system on the presence of Salmonella and Listeria monocytogenes on conveyor belts in chicken slaughterhouses
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-06
    Cibeli Viana; Vanessa Mendonça Soares; Juliano Gonçalves Pereira; Leonardo Ereno Tadielo; Luís Augusto Nero; José Paes de Almeida Nogueira Pinto; Luciano dos Santos Bersot

    This study aimed to evaluate the effectiveness of a water spray system in cleaning conveyor belts contaminated with Salmonella and Listeria monocytogenes. Samples were obtained from modular and smooth conveyor belts from four slaughterhouses in Brazil, and bacterial presence was assessed in sprayed and unsprayed belts. From each conveyor belt, 400 cm2 were sampled using sponges at various time periods (T0: 5:00 h; T1: 9:00 h; T2: 17:00 h, and T3: 22:00 h), and these samples were submitted for Salmonella and L. monocytogenes detection. The results were expressed as frequencies and analyzed by Chi-square test. A low frequency of Salmonella isolation occurred at T0, and at T1 and T2, the isolation frequencies of Salmonella were higher in the unsprayed conveyor belts. Salmonella contamination throughout the process fluctuated significantly (P < 0.05), and fluctuation occurred regardless of water spray use. In regard to the effect of water spraying on the presence of L. monocytogenes, the isolation frequencies were lower (P < 0.05) at all time points when the water spray system was active. Given this, our findings indicate that although water spray hygiene influences the frequency of pathogen isolation, other factors require monitoring to control for Salmonella and L. monocytogenes contamination.

    更新日期:2020-01-06
  • Sodium chloride significantly enhances the bactericidal actions of carvacrol and thymol against the halotolerant species Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-03
    Nam Hee Kim; Hye Won Kim; Hyeree Moon; Min Suk Rhee

    This study investigated the synergistic effects of sodium chloride and essential oils (EOs) on three representative halotolerant species of foodborne pathogens, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus. When bacterial cells were treated with carvacrol or thymol alone (0.5–2.0 mM), NaCl alone (1–15%, w/w), or their combinations at 22 °C for 1, 5, or 10 min, the combinations of EOs with NaCl showed obvious synergistic effects. For instance, the combination of carvacrol or thymol (2.0 mM) plus NaCl (≥3%) completely inactivated all tested bacterial cells (initial population: 7.2–7.4 CFU/ml; detection limit: 1 CFU/ml), while there were negligible bacterial reductions in the individual treatments (maximum 0.7 log reduction). The mechanisms of the synergistic effects were primarily derived from carvacrol- or thymol-induced membrane disruption (19.6% of cells were damaged by 2.0 mM carvacrol treatment for 10 min) and the loss of the ability of the bacterial cells to maintain an osmotic balance in the presence of NaCl. The results of the present study will contribute to overcoming the disadvantages of using EOs such as decreased organoleptic quality and high costs by reducing their working concentrations in food matrices.

    更新日期:2020-01-04
  • β-glucooligosaccharides derived from barley β-glucan promote growth of lactic acid bacteria and enhance nisin Z secretion by Lactococcus lactis
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-03
    Jong Min Lee; Won Je Jang; Eun-Woo Lee; In-Soo Kong

    The present study assessed the effects of β-glucooligosaccharides (β-GOS) derived from barley β-glucan on the proliferation and antimicrobial activity of probiotics. All cocci examined in this study and several species of Lactobacilli and bifidobacteria were able to utilize β-GOS as a sole carbon source. In addition, the absence of significant growth of certain pathogens on β-GOS compared to prebiotics fructo-oligosaccharide (FOS) and inulin substrates demonstrates the probiotic specificity of β-GOS metabolism. Increased anti-microbial activities were observed in Lactococcus lactis subsp. lactis, Lactobacillus reuteri, and Pediococcus acidilactici grown in media with β-GOS as the sole carbon source over glucose. β-GOS enabled sustained L. lactis subsp. lactis growth in the exponential phase, resulting in an approximately 25% increase in nisin Z production compared with glucose. These results suggest that β-GOS can selectively modulate probiotic growth in particular cocci, and antimicrobial activity, with important implications for future research in nutrition as well as industrial applications.

    更新日期:2020-01-04
  • Characterization of microbial polysaccharides and prebiotic enrichment of wheat bread with pullulan
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2020-01-02
    S. NithyaBalaSundari; V. Nivedita; M. Chakravarthy; G. Srisowmeya; Antony Usha; Devi G. Nandhini

    The prebiotic efficacy of microbial polysaccharides pullulan, xanthan, and gellan was examined by in vitro digestion and in vitro fermentation. In vitro digestion study showed that pullulan exhibited a lower degree of hydrolysis (DOH) than xanthan and gellan. In vitro fermentation study showed that pullulan has improved the stimulating effect on the growth of probiotics. Thermo-gravimetric report showed the possible application of pullulan in bakery products. In this study, pullulan enriched bread formulations at varying concentrations with both refined wheat and wheat-based bread was done. Pullulan showed a positive correlation with probiotic growth and a negative correlation with water absorption. The nutritive value and physicochemical properties of the bread varieties were investigated. Bread samples with 2% pullulan exhibited most acceptable sensorial attributes, whereas the formulations with 8% and 10% pullulan were found to be much softer and darker. The in-vitro digestibility and fermentation of bread samples showed that Pullulan enriched breads were more resistant to hydrolysis by AGHJ than the standard bread samples. Prebiotic efficacy measured using Prebiotic Activity Score (PAS) was higher for pullulan among other polysaccharides and pullulan enriched breads against standard bread.

    更新日期:2020-01-02
  • Effect of microwave-salt synergetic pre-treatment on the 3D printing performance of SPI-strawberry ink system
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-31
    Hanzhi Fan; Min Zhang; Zhenbin Liu; Yufen Ye

    This study investigated the effect of microwave pre-treatment on the 3D printing performance and self-supporting behavior of soybean protein isolate (SPI)-strawberry ink system. The results indicated that salt and microwave treatment greatly improved the printing accuracy and self-supporting performance of the ink system. Salted sample treated with 70 W microwave obtained the best shape accuracy, the smallest transverse relaxation time and the highest hardness (676.33 g), gumminess (216.73 g), springiness (0.28 g) and cohesiveness (0.22 g). Low power microwave treated samples illustrated regular changes in terms of e-nose and chroma. As the microwave power increased, the L*, a*, b* values dropped, the E-nose response rose first and then decreased. The low power microwave enables ink printability at low power. And it could save energy and increase the acceptability of the final product. Moreover, the addition of salt promoted the formability and stability of 3D printed products. Based on the results, we conclude that the low power microwave-salt synergy pre-treatment has a positive effect on the printing performance and self-supporting behavior of the SPI-strawberry system.

    更新日期:2019-12-31
  • Influence of selected native yeast starter cultures on the antioxidant activities, fermentation index and total soluble solids of Malaysia cocoa beans: A simulation study
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-31
    T.S. Ooi; A.S.Y. Ting; L.F. Siow

    Antioxidant activity of cocoa beans is often influenced by drying and roasting stages. In this study, 13 naturally-existing yeast strains were isolated and used as a starter culture and the resulted antioxidant properties of cocoa beans were determined by total polyphenols content (TPC), 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and total flavonoids content (TFC). The isolated yeasts were identified via sequencing using universal primers ITS 1 and 4. Results revealed that the 13 naturally-existing yeast strains were Pichia kudriavzevii (MH979676, MH979680, MH979681, and MH979677), Hanseniaspora thailandica (MH979675), Hanseniaspora species (MH979678), Wickerhamomyces species (MH979679), Saccharomyces cerevisiae (MH979683), Hanseniaspora opuntiae (MH979684) and Candida quercitrusa (MH979685, MH979687, MH979686 and MH979682). Yeasts were selected based on the phylogenetic analysis, where each species of different genus (except Candida genus) was used as a starter culture. Dried cocoa beans inoculated with isolates (Hanseniaspora thailandica, Pichia kudriavzevii, Hanseniaspora opuntiae, Hanseniaspora species, Wickerhamomyces species and Saccharomyces cerevisiae) contained TPC, TFC and DPPH ranging from 21.82 to 69.81 mg/g Gallic acid (GAE), 1.68–6.33 mg/g Catechin and 113.85 to 328 ìmoles/g Trolox (TE), respectively. It is noted that there was no significant change of the antioxidant activity between isolates at 24-h to 120-h fermentation. Based on the current study, Hanseniaspora thailandica and Pichia kudriavzevii are the potential starter cultures that result in cocoa beans with higher antioxidant content (p < 0.05) compared to natural fermentation.

    更新日期:2019-12-31
  • L-ascorbyl palmitate modify the crystallization behavior of palm oil: Mechanism and application
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-30
    Xiaoyu Meng; Chunhuan Liu; Chen Cao; Zhaojun Zheng; Qingfeng Su; Yuanfa Liu
    更新日期:2019-12-30
  • Physical and sensory characteristics of cheese-flavored expanded snacks obtained using butyric acid and cysteine as aroma precursors: Effects of extrusion temperature and sunflower oil content
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-30
    Michele Eliza Cortazzo Menis-Henrique; Natália Soares Janzantti; Magali Monteiro; Ana Carolina Conti-Silva

    Pre-extrusion flavoring with butyric acid and cysteine, as aroma precursors, was used for production of cheese-flavored expanded corn-based snacks. The effects of extrusion temperature and sunflower oil sprinkled over the snacks on the physical and sensory characteristics of the products were evaluated. Both variables had influence on the expansion ratio, density, luminosity, yellow chromaticity and chroma, as well as on oil flavor, cheese odor, cheese flavor, salty taste, and umami taste (descriptive). Cheese flavor intensity (consumers) and oil odor and cereal flavor (descriptive) were influenced by sunflower oil, while yellow color, crispness and hardness (descriptive) were influenced by extrusion temperature. In terms of overall acceptability, all snacks, excepting that obtained at low extrusion temperature (91.8 °C) or that with no oil addition, showed similar acceptability. In this way, snacks with low oil content (i.e. 3.5%) may be considered as so preferred as snacks with 20.5% of sunflower oil. Therefore, the pre-extrusion flavoring with aroma precursors is feasible and a promising technology, because it allows the production of snacks with desirable physical and sensory characteristics, as well as better nutritive value, due to the low incorporation of lipids into the snacks sprinkled with the sunflower oil.

    更新日期:2019-12-30
  • A novel fat replacer composed by gelatin and soluble dietary fibers from black bean coats with its application in meatballs
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-30
    Yuge Niu; Huicheng Fang; Tianyou Huo; Xiangjun Sun; Qiang Gong; Liangli Yu

    Different edible composite gels were produced by soluble dietary fibers from black bean coats (SDF) and gelatin cross linked by calcium chloride and/or transglutaminase (TGase), which were named as IPN and semi-IPN. The gels were added to produce low-fat meatballs and compared with the control samples (20% fat added). The effects of the SDF-gelatin composite gels on cooking yield, shrinkage, color and texture of low-fat meatballs were detected. Addition of composite gels increased the content of moisture, ash, protein, Na, and Ca. Meanwhile, the composite gels had significant impact on the parameters of the L*(brightness), a*(redness) and b*(yellowness) of meatballs. The composite gels reduced the hardness and chewiness, and increased the springiness of meatballs except for SDF-semi-IPN. The results suggested that the novel composed gels with cross-linking structure could be developed as ideal fat replacers in food processing.

    更新日期:2019-12-30
  • Citric acid as crosslinking agent in starch/xanthan gum hydrogels produced by extrusion and thermopressing
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-30
    Bruno Matheus Simões; Caroline Cagnin; Fabio Yamashita; Juliana Bonametti Olivato; Patrícia Salomão Garcia; Suzana Mali de Oliveira; Maria Victória Eiras Grossmann

    Biopolymers based hydrogels could have applications in various fields, such as packaging materials, drug delivery systems, biosensors, and agricultural practices. The current work aimed to develop starch/xanthan hydrogels through extrusion and thermopressing processes, using citric acid (CA) as crosslinking agent and sodium hypophosphite (SHP) as catalyst. The hydrogels were produced with different levels of CA (0.00, 0.75, 1.50 and 2.25 g/100 g polymer). Hydration, mechanical, thermal and microstructural properties of the hydrogels were determined. Swelling behavior of the materials with CA was lower than the control. Additionally, CA ensured the preservation of hydrogels integrity after the swelling process. Gel fraction increased with CA 0.75 g/100 g. Starch/xanthan hydrogels crosslinked with CA demonstrated lower strength than non-crosslinked hydrogels, which may be related to acid hydrolysis of the polymer chains. CA-SHP increased the storage modulus of the hydrogels. Reactive extrusion and thermopressing were efficient methods in the production of crosslinked starch/xanthan based hydrogels.

    更新日期:2019-12-30
  • Effects of pressure-assisted enzymatic hydrolysis on functional and bioactive properties of tilapia (Oreochromis niloticus) by-product protein hydrolysates
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-30
    Ashutosh Kumar Hemker; Loc Thai Nguyen; Mukund Karwe; Deepti Salvi

    Fish by-product protein can be converted into valuable food and nutraceutical ingredients via proteolysis. The existing process suffers from many limitations such as extended reaction time and nonselective hydrolysis. In this study, protein from tilapia fish by-products was transformed into functional peptides using pressure-assisted enzymatic hydrolysis. Proteins were extracted from the tilapia by-products by isoelectric solubilization and precipitation method. The effects of pressure (38–462 MPa) and hydrolysis time (6–35 min) on the properties of the hydrolysates were investigated using a central composite design. Pressure enhanced protein hydrolysis with a maximum trichloroacetic acid-solubility index (TCA-SI) of 23% obtained at 250 MPa for 35 min. Pressure and time were also vital in improving soluble protein content (5.7 mg/mL), reducing power (44 μg AAE/g), and solubility (71%) of the hydrolyzed products. Improved antioxidant activity, indicated by a significant decrease in IC50 values from 653 μg/mL to 304 μg/mL, was recorded. The combined process facilitated the release of low-molecular-weight peptides and essential amino acids. However, water and oil holding capacities were found to be decreased. Pressure-assisted enzymatic hydrolysis could provide an effective approach for recovering bioactive peptides from fish by-products for industrial applications.

    更新日期:2019-12-30
  • Conformational and rheological changes of high-pressure processing treated rabbit myosin subfragments during heating
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-28
    Zhao Xue; Mengyao Wang; Xing Chen; Xinglian Xu; Guanghong Zhou

    Rabbit skeletal (M. psoas) myosin subunits, heavy meromyosin (HMM) and light meromyosin (LMM), were purified and treated by high pressure processing (HPP). The HPP (100, 200 and 300 MPa)-modified myosin subunits were subjected to thermal treatment (25–70 °C), during which their conformational and rheological properties were explored. The turbidity of all HMM and LMM samples slightly improved from 25 to 55 °C, and then sharply increased from 55 °C to 70 °C (from). Pressure ≥200 MPa changed the structural properties of HMM, exhibited as more exposed hydrophobic and sulfhydryl patches, whereas the increase of hydrophobicity induced by heating decelerated afterwards. The LMM portion exhibited inferior heating stability. Upon heating, both pressurized and nontreated HMM showed similar trends of changes of secondary structure, which included the reduction of α-helices and the increase of β-structures. Only a slight change of secondary structure occurred on LMM after HPP, indicating a higher resistance of LMM on HPP than HMM. These findings suggested that a moderate denaturation generated by HPP would not affect the thermal behavior of myosin subfragments, while pressures of ≥200 MPa might lead to disadvantageous rheological properties by mediating the thermophysical properties of HMM.

    更新日期:2019-12-29
  • Evaluation of anti-quorum sensing and antimutagenic activity of 2,3-unsaturated and 2,3-dideoxyglucosides of terpene phenols and alcohols
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-27
    D. James Bound; Pushpa S. Murthy; P.S. Negi; P. Srinivas

    The anti-quorum sensing property of terpene phenols/alcohols and their deoxyglucosides was evaluated qualitatively against Pseudomonas aeruginosa and Chromobacterium violaceum by agar well diffusion method, and their antimutagenic activity was tested by Ames test. The 2,3-unsaturated and 2,3-dideoxy 1-O-glucoside derivatives demonstrated higher inhibitory zones compared to those for the parent molecules. MIC values indicated that the derivatives of carvacrol (1.0–1.2 μmol/ml) and thymol (1.0–1.2 μmol/ml) were more effective than the other compounds (1.2–2.0 μmol/ml). The anti-quorum sensing potential of derivatives was demonstrated by the reduction in the production of pyocyanin (75–95%) and violacein (76–98%) at sub-MIC concentrations. The 2,3-unsaturated 1-O-glucosides of carvacrol and thymol exhibited superior antimutagenic properties, and 2,3-unsaturated 1-O-glucoside of thymol showed 87.7% inhibition of MMS induced mutation in Salmonella typhimurium TA 1538 at 1 μmol/plate concentration. The superior anti-quorum and antimutagenic activities exhibited by these derivatives indicate their potential application as food preservatives.

    更新日期:2019-12-29
  • Effects of Enterococcus faecium and Staphylococcus succinus starters on the production of volatile compounds during doenjang fermentation
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-27
    Do-Won Jeong; Keuncheol Jeong; Hyundong Lee; Cheong-Tae Kim; Sojeong Heo; Yeongmin Oh; Ganghun Heo; Jong-Hoon Lee

    Bacterial starters Enterococcus faecium and Staphylococcus succinus were introduced into the manufacture of doenjang, a Korean fermented soybean paste, together with a fungal starter to determine the effect of bacterial starters on flavor production during doenjang fermentation. Starters cultured on soybean flakes and rice were mixed with autoclaved soybeans and then refined salt was added to 12% (w/w) to prepare doenjang samples. The doenjang samples were ripened at 20 °C and their volatile compounds were analyzed on days 0, 28, 56, and 84. The numbers of bacteria from starter cultures in the samples decreased gradually. The content of amino-type nitrogen in samples decreased as the proportion of bacterial starter culture used in doenjang preparation increased. Nineteen volatile compounds were detected in doenjang samples by gas chromatography-mass spectrometry and were subjected to principal component analysis. Addition of bacterial starters distinctively changed the flavor of doenjang compared with that prepared with a fungal starter alone. Acetic acid, 2-methylbutanoic acid, and 3-methylbutanoic acid were important volatile compounds determining flavor development in the doenjang employing bacterial starters. Starter-specific as well as highly-produced volatile compounds determined the directionality of flavor during doenjang ripening. Raw materials used for the starter culture preparation also affected the flavor.

    更新日期:2019-12-27
  • Bacterial community succession and volatile compound changes during fermentation of shrimp paste from Chinese Jinzhou region
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-27
    Xinran Lv; Ying Li; Tianqi Cui; Mengtong Sun; Fengling Bai; Xuepeng Li; Jianrong Li; Shumin Yi

    Jinzhou shrimp paste is a traditional Chinese fermented seafood product manufactured from northern mauxia shrimp (Acete chinensis) and salt. The aims of this study were to detect the bacterial community succession using high-throughput sequencing and the volatile compound changes using headspace solid-phase microextraction combined with gas chromatography–mass spectrometry during shrimp paste fermentation. Moreover, the relationships between the bacterial community and volatile compounds were analyzed by two-way orthogonal partial least squares. The results show that various bacterial communities appeared in the fermentation process. Pseudoalteromonas and unclassified Pseudoalteromonadaceae were the dominant genera but quickly replaced by Tetragenococcus after 1 month of fermentation. Staphylococcus, Oceanobacillus and unclassified Bacillaceae became the predominant genera as fermentation progressed. In addition, a total of 25 volatile compounds were identified, including aldehydes, ketones, alcohols, esters, pyrazines, acids, and sulfides. Correlation analysis indicated that the bacteria Pseudoalteromonas, Staphylococcus, and Oceanobacillus were important in the formation of volatile compounds. Pseudoalteromonas positively correlated with ketones, alcohols, esters, and acids; Staphylococcus positively correlated with aldehydes and acids; and Oceanobacillus positively correlated with aldehydes and pyrazines. These findings not only reveal the dynamics of the bacterial community and volatile compounds in the fermentation process, but also indicate their inter-relationships during shrimp paste fermentation.

    更新日期:2019-12-27
  • Effects of metabolite changes during lacto-fermentation on the biological activity and consumer acceptability for dragon fruit juice
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-26
    Belal J. Muhialdin; Hana Kadum; Mohammad Zarei; Anis Shobirin Meor Hussin

    In this study dragon fruit juice was subjected to lacto-fermentation for 48 h at 37 °C using Lactobacillus plantarum FBS05. The antibacterial and antioxidant activity were evaluated using 96 microtiter plate, DPPH and FRAP assays. The bioactive metabolites were identified using 1H-NMR analysis with multivariate analysis. Fermented juice was mixed with fresh dragon fruit juice at different ratios to evaluate the shelf life stability and consumer acceptability. The antibacterial activity of fermented dragon fruit juice was 95.52 ± 0.002, 95.63 ± 0.005, 96.05 ± 0.009 and 93.38 ± 0.000 towards Escherichia coli, Salmonella Typhimurium, Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The antioxidant activity results demonstrated no significant differences for fermented and non-fermented juice. The principal component analyses showed the presence of 21 and 12 metabolites in the fermented and non-fermented dragon fruit juice. The major compounds contributed to the differences were lysine, alanine, acetic acid, succinic acid, lactic acid, glucose, iso-butyrate and betaine. The 1:9 ratio received the highest scores for the taste (6.24 ± 1.571), aroma (6.50 ± 1.696) and acidity (6.21 ± 1.996) and extended the shelf life for 3 months. This study demonstrated the high potential for the lacto-fermented dragon fruit juice for applications to improve the functional properties, consumer acceptability and shelf life of fresh dragon fruit juice.

    更新日期:2019-12-27
  • Evaluation of colour stability of clear red pitaya juice treated by thermosonication
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-27
    Hongmei Liao; Wenxian Zhu; Kui Zhong; Yuanfa Liu

    The impact of thermosonication (TS) processing on colour and associated properties of clear red pitaya juice was evaluated. Although a longer treatment duration and higher temperature led to a distinct colour change, the results indicated potential colour protection by TS relative to thermal treatment (83 °C, 1.5 min). Increased in the colour change during TS mainly due to decreasing a* and b* values (p < 0.05). The results of UV–visible spectroscopy, spectrophotometry, and ultra-performance liquid chromatography were consistent with a decrease in a* value, indicating decomposition of betacyanins. Further analysis revealed that the degradation and isomerisation of betanin and phyllocactin were involved in the decomposition of betacyanins by TS primarily, and which was differed with thermal processing. Besides that, an increase in 5-hydroxymethylfurfural and the absorbance at 420 nm following Millard reactions also contributed to colour change. The effective inactivation of polyphenol oxidase, and >92.97% retention of polyphenols in clear red pitaya juice was observed, suggesting that polyphenol oxidase catalysed browning was not a major contributor to colour instable during TS. Overall, results obtained in the current study suggested a potential of colour protection, and bioactive compounds retention capacity of fruit juice by TS.

    更新日期:2019-12-27
  • Microbial diversity during processing of Thai traditional fermented shrimp paste, determined by next generation sequencing
    LWT - Food Sci. Technol. (IF 3.714) Pub Date : 2019-12-26
    Apiniharn Phewpan; Preecha Phuwaprisirisan; Hajime Takahashi; Chihiro Ohshima; Kannapon Lopetcharat; Punnida Techaruvichit; Suwimon Keeratipibul

    Shrimp paste, one of the traditional Thai fermented food ingredients, is a mixture of small shrimp and salt fermented for 1–2 months which gives a unique and rich flavor to Thai dishes. Dynamics of microbial diversity during processing and its contribution to the flavor of shrimp paste was investigated by next generation sequencing. Bacteria containing aminopeptidase genes were analyzed to present the possibility relating to taste-enhancing di- and tripeptide generation. Furthermore, this study showed the difference of microbial community structure in shrimp pastes collected from various regions in Thailand. The microbial diversity structure dramatically changed from the raw materials since the first step of processing. Salimicrobium spp. (53.6%) and Salinicoccus spp. (44.0%) were the major population; however, they were decreasing during processing. Alkalibacterium, Macrococcus caseolyticus, Jeotgalicoccus psychophillus, and Staphylococcus spp. became visible. M. caseolyticus and J. psychrophilus were detected as the first time in shrimp paste products. Then in one-month fermented sample, Lentibacillus spp. was 3.3%. Although, as per our experimentation (water activity, salt and pH), we could not observe any significant difference among different products. In two-month fermented sample, Lentibacillus spp. was solely the most abundant microorganism. From aminopeptidase genes analysis, the abundance of Salinococcus spp. during preparation and Lentibacillus spp. during fermentation may relate to good flavor quality of shrimp paste.

    更新日期:2019-12-27
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