Subcritical water hydrolysis of poultry feathers for amino acids production

https://doi.org/10.1016/j.supflu.2021.105492Get rights and content

Highlights

  • Subcritical water hydrolysis (SWH) was used to obtain amino acids from poultry feathers.

  • Hydrolysis temperature and water flow rate were investigated.

  • The highest amino acid yield was 2.7 ± 0.2 g L−1 at 250 °C and 5 mL min−1.

  • Alanine, proline, and tryptophan were the main amino acids recovered.

  • SWH is a chemical-free alternative to produce amino acids from poultry feathers.

Abstract

This study assessed the subcritical water hydrolysis (SWH) of poultry feathers to recover amino acids. Experiments were conducted in a semi-continuous flow-through subcritical reactor (110 mL), which was operated over a range of temperatures (210–250 °C) and water flow rates (5–15 mL min–1), combined through a 22 central composite design, at constant feed (10 g) and pressure (15 MPa). The results demonstrated that non-essential and essential amino acids were obtained from SWH of poultry feathers. The highest hydrolysis temperature resulted in the highest concentrations of valine, methionine, tryptophan, phenylalanine, isoleucine, leucine, and lysine. Otherwise, threonine, histidine, and arginine were obtained more effectively at lower temperatures. The response surface methodology was adopted to identify the best conditions for amino acid production, and it was possible to identify the ranges of temperatures and water flow rates to be used to recover specific amino acids. This study allowed concluding that SWH is a promising eco-friendly technology to recover amino acids from protein-rich wastes.

Introduction

Responsible disposal and re-use of agro-industrial residues are critical for the economy and the environment [1]. The circular economy attempts to place an added value on wastes to divert them from environmental disposal, incineration, or landfills, representing a new concept for the re-use and valorization of agro-industrial residues [2], [3]. Successful implementation of the circular economy will require judicious use of existing technologies and the development of new ones, especially for the valorization of wastes with unusual properties [4].

Protein-rich residues, including poultry feathers, have potential as a feed for the production of amino acids [5], [6]. Poultry feathers are generated in large quantities during chicken and turkey production [7]. Worldwide, approximately 8.5 × 107 tons of chicken are annually produced in the poultry industry, and roughly 10% of the chicken mass are feathers, resulting in approximately 8.5 × 106 tons of chicken feathers [8]. Unfortunately, poultry feathers are treated as wastes without commercial value. Innovative technologies to waste management must be studied to decrease the environmental impact caused by the generation and disposal of poultry feathers.

Valorizing poultry feathers requires some understanding of their composition [9]. Feathers are a keratin-based material composed of α-keratin and β-keratin [10]. The crude protein content ranges from 85% to 90% [8], [10]. The substantial protein content of feathers suggests valorization avenues in feed and nutrition applications [11], [12].

Commercial practices handle poultry feathers in several different ways [13]. Most feathers have been landfilled or incinerated, and in some cases, part of the feathers is processed into meals for use in the poultry industry and fertilizers [14]. Unfortunately, this meal contains low-quality proteins resulting from the hydrolytic and thermal processes that the feed undergoes. Accordingly, converting feathers into meals results in the degradation of amino acids while consuming large amounts of energy [12]. More energy-efficient methods are required for poultry feather valorization to yield valuable products than low-quality meals.

Converting the protein in chicken feathers directly into amino acids can solve the problems associated with meal production. Amino acids present several applications for medical, food, pharmaceutical, animal, and cosmetic purposes [15]. Regarding food applications, amino acids can be used as flavor enhancers and specialty nutrients. Amino acids can also be used as animal feed additives [16]. In addition, in the pharmaceutical and cosmetic industries, the main use of amino acids is as an ingredient for various products, such food supplements, infant formula, masks, and skin moisturizers [16].

Several technological routes can be used to obtain amino acids from chicken feathers, and the most common methods are chemical and enzymatic hydrolysis, followed by extraction [17], [18]. Unfortunately, both methods have substantial disadvantages, including the high cost of enzymes and the generation of toxic wastes from chemical hydrolysis. Therefore, a new environmentally friendly approach for amino acid conversion with high efficiency is urgently required. In this context, green techniques using environmentally benign solvents have been studied as an efficient recovery method that eliminates waste generation, inspiring amino acid recovery from poultry feathers [19].

Among several plausible solvent options like alkalis and acids, subcritical water is attractive for transforming protein residues into amino acids. Water at subcritical conditions (typically defined as temperature ranging from 100° to 374°C and pressures higher than the corresponding saturation point) has received particular attention as an environmentally benign reaction and extraction solvent [20]. Subcritical water behaves as a non-polar solvent that hydrolyzes and extracts organic molecules from complex matrices, including bio-based compounds [21], [22], [23]. Simultaneously, the ionic product of subcritical water is much greater than in water at ambient temperature and pressure, resulting in the promotion of both acid and base-catalyzed reactions [24], [25]. The result is rapid hydrolysis of the peptide bonds responsible for linking amino acids into proteins without adding acid or base catalysts that would otherwise contribute to waste production [26].

Several studies evaluated the use of subcritical water hydrolysis (SWH) to convert biomass residues into amino acids. For instance, Park et al. [27] treated Pyropia yezoensis (a type of edible seaweed) with hot water, ethanol, and SWH, finding that SWH treatment resulted in the most significant number of bioactive compounds, such as amino acids with antioxidant activity. Similarly, Ahmed and Chun [28] reported SWH treatment of tuna skin and collagen to decompose proteins to release peptides and amino acids. Lee et al. [29] recovered amino acids from comb pen shell (Atrina pectinata) by SWH. The highest amount of crude protein was obtained at 200 °C (36.14 mg g–1). In comparison, the highest amino acid yield was observed at 230 °C, (74.80 mg g–1), which indicated that temperature in the range of 170–230 °C is suitable for obtaining protein-rich compounds using SHW [29]. Therefore, SWH has been considered a promising technology to recover amino acids for application in the food and pharmaceutical industries [30].

The poultry feathers composition indicates its feasibility for amino acid recovery [8], [15]. Still, studies considering the use of SWH are insufficient. Fortunately, abundant literature describes the use of subcritical water to hydrolyze vegetable wastes containing lignocellulosic biopolymers [31]. Previous studies of SWH of lignocellulosic materials demonstrate that temperature and water flow rates are critical variables defining performance that must be balanced for optimal performance [32], [33], [34], [35]. Biopolymer hydrolysis rates increase with increasing reaction temperature, thereby releasing soluble monomers for extraction [36]. Unfortunately, monomer degradation rates also increase with increasing temperature, meaning a balance between hydrolysis and degradation must exist. Minimizing monomer retention in the heated zone – for example, by continuous removal in an extraction flow – can reduce degradation and maximize monomer yields [37]. Otherwise, operating SWH at high flow rates has the disadvantage of product dilution, complicating the recovery and purification processes [36]. No theory can predict the tradeoffs between these factors, meaning that the response of each feedstock must be evaluated on its own.

Based on the above, this study evaluated the use of SWH of poultry feathers to recover amino acids. The objective was to determine the best operational parameters of the semi-continuous hydrolysis process and the amino acid composition of the hydrolysates obtained. A complete factorial experimental design and the Response Surface Methodology (RSM) were used to examine the effects of temperature and flow rate on amino acid content. The values of temperature and flow rate selected for this analysis were based on previous studies on SWH of protein-rich wastes [29], [38], [39]. The results presented here can guide future efforts to use SWH for chemical-free poultry feather valorization as amino acids without waste generation, acting as a strategic and sustainable mechanism for the circular economy approach in the poultry industry.

Section snippets

Raw material

Poultry feathers were supplied by the Oriente Company (Videira City, São Paulo, Brazil). Before use, the poultry feathers were shredded in a knife mill (Marconi Equipment, model MA 340, Piracicaba, SP, Brazil). The resulting particles were sifted by a Tyler magnetic vibratory stirrer (Bertel, model N1868, Caieiras, SP, Brazil). Due to the high surface area to volume ratio, dried particles between 297 and 710 µm in diameter were selected as the feed to SWH experiments. The milled material was

Poultry feathers characterization

Table 2 presents the characterization of poultry feathers used for SWH experiments. After drying the poultry feathers, the sample presented 7% of moisture. The feather showed high protein content (87.4% ± 0.6) and low ash content, demonstrating that this feedstock can be used as a feedstock for amino acid recovery. Other studies showed that feathers generated mainly from poultry slaughterhouses are composed of more than 90% of proteins (keratin) [45].

Some proteinaceous vegetable wastes, such as

Conclusions

SWH technology was evaluated as a chemical-free technology to obtain amino acids from poultry feathers. The effects of reaction temperature (210, 230, 250 °C) and water flow rate (5, 7.5, and 10 mL min–1) on the amino acid content of the hydrolysate were investigated. Aspartic acid and serine concentrations were maximized at the highest flow rate (10 mL min–1) and the lowest temperature (210 °C). In comparison, isoleucine and methionine were maximized at the opposite extreme (250 °C and 5 mL min

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors thank Dr. Sioji Kuana of Três Fronteiras (Seara, SC, Brazil) Company. The authors acknowledge the financial support from the Brazilian Science and Research Foundation (CNPq) and Higher-Level Personnel Improvement Coordination (CAPES) – Brazil – Finance code 001. The financial support from the São Paulo Research Foundation – FAPESP (2018/05999-0; 2018/14938-4). W.G. Sganzerla thanks FAPESP for the doctorate scholarship (2019/26925-7). T. Forster-Carneiro thanks CNPq for the

References (58)

  • I. Okajima et al.

    Energy conversion of biomass with supercritical and subcritical water using large-scale plants

    J. Biosci. Bioeng.

    (2014)
  • J.-S. Park et al.

    Physiological activities and bioactive compound from laver (Pyropia yezoensis) hydrolysates by using subcritical water hydrolysis

    J. Supercrit. Fluids

    (2019)
  • R. Ahmed et al.

    Subcritical water hydrolysis for the production of bioactive peptides from tuna skin collagen

    J. Supercrit. Fluids

    (2018)
  • W.A.S. Chamika et al.

    In vitro characterization of bioactive compounds extracted from sea urchin (Stomopneustes variolaris) using green and conventional techniques

    Food Chem.

    (2021)
  • F.W. Maciel-Silva et al.

    Integration of subcritical water pretreatment and anaerobic digestion technologies for valorization of açai processing industries residues

    J. Clean. Prod.

    (2019)
  • L.C. Ampese et al.

    Valorization of Macaúba husks from biodiesel production using subcritical water hydrolysis pretreatment followed by anaerobic digestion

    J. Environ. Chem. Eng.

    (2021)
  • J.M. Prado et al.

    Hydrolysis of sugarcane bagasse in subcritical water

    J. Supercrit. Fluids

    (2014)
  • J.M. Prado et al.

    Sub- and supercritical water hydrolysis of agricultural and food industry residues for the production of fermentable sugars: a review

    Food Bioprod. Process.

    (2016)
  • W.G. Sganzerla et al.

    Techno-economic assessment of subcritical water hydrolysis process for sugars production from brewer’s spent grains

    Ind. Crops Prod.

    (2021)
  • D. Lachos-Perez et al.

    Subcritical water extraction of flavanones from defatted orange peel

    J. Supercrit. Fluids

    (2018)
  • P.C. Torres-Mayanga et al.

    Production of biofuel precursors and value-added chemicals from hydrolysates resulting from hydrothermal processing of biomass: a review

    Biomass Bioenergy

    (2019)
  • A.K.M. Asaduzzaman et al.

    Characterization of pepsin-solubilised collagen recovered from mackerel (Scomber japonicus) bone and skin using subcritical water hydrolysis

    Int. J. Biol. Macromol.

    (2020)
  • I. Marcet et al.

    The use of sub-critical water hydrolysis for the recovery of peptides and free amino acids from food processing wastes

    Rev. Sources Main. Parameters, Waste Manag.

    (2016)
  • D. Lachos-Perez et al.

    Sugars and char formation on subcritical water hydrolysis of sugarcane straw

    Bioresour. Technol.

    (2017)
  • D. Lachos-Perez et al.

    Subcritical water hydrolysis of sugarcane bagasse: an approach on solid residues characterization

    J. Supercrit. Fluids

    (2016)
  • I. Sereewatthanawut et al.

    Extraction of protein and amino acids from deoiled rice bran by subcritical water hydrolysis

    Bioresour. Technol.

    (2008)
  • G. Zhu et al.

    Recovery of biomass wastes by hydrolysis in sub-critical water

    Resour., Conserv. Recycl.

    (2011)
  • M.B. Esteban et al.

    Sub-critical water hydrolysis of hog hair for amino acid production

    Bioresour. Technol.

    (2010)
  • V.A. Schommer et al.

    Anaerobic co-digestion of swine manure and chicken feathers: effects of manure maturation and microbial pretreatment of feathers on methane production

    Renew. Energy

    (2020)
  • Cited by (18)

    View all citing articles on Scopus
    View full text