Effect of gliadin/glutenin ratio on pasting, thermal, and structural properties of wheat starch

doi:10.1016/j.jcs.2020.102973

Journal of Cereal Science

Volume 93, May 2020, 102973

https://doi.org/10.1016/j.jcs.2020.102973 Get rights and content

Highlights

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Effect of Gliadin and glutenin on starch pasting were different.
•
In the case of pasting viscosity, the effect of gliadin is greater than that of glutenin.
•
The method for the determination of the structure of mixtures gelatinization processing is new.
•
Glutenin delayed the retrogradation of starch.

Abstract

Gluten-starch interactions are of specific importance during the processing of cereal-based products. However, the mechanisms for gluten-starch interactions have not been illuminated. The effects of various gliadin/glutenin (gli-glu) ratios (0:10, 3:7, 5:5, 7:3, and 10:0) on the pasting, thermal, and structural properties of wheat gluten-starch mixtures were investigated. The peak, through, and final viscosities were obviously decreased, and the setback value initially increased and then decreased with increasing gli-glu ratios during the rapid viscosity analysis (RVA). Differential scanning calorimetry showed that the enthalpy changes increased with increasing gli-glu ratios. Thermogravimetric analysis showed a slight increase in the degradation temperature of the mixtures as the gli-glu ratio increased, although it was still lower than that of wheat flour. However, there was no significant difference in the weight loss among different gli-glu ratios. Rheometer-Fourier transform infrared (FTIR) spectroscopy showed that the C-6 peak at 996 cm⁻¹ for all the samples was displaced or disappeared due to the hydrogen bond fracture caused by water molecules entering the starch granules. It was also found that the absorption peak in amide II of gli-starch was more obvious than that of glu-starch. The CLSM obviously described the change structure of mixtures with different gli-glu ratio during starch gelatinizaton. By studying the changes in gluten protein components and how they affected the thermal and structural properties of starch, a simple model was proposed to describe the gelatinization process of the mixtures with different ratios of gli-glu and briefly describe the interactions between starch and wheat gluten components. Optimization of the proportion of protein components in wheat flour will enable greater control over the structural characteristics and elasticity of wheat food products.

Graphical abstract

Introduction

Starch and protein are the two main components of wheat flour, in which the starch content is approximately 75% and the protein content is approximately 12%. Starch gelatinization is one of the most important factors affecting the quality of wheat flour products. Previous studies have found that wheat starch gelatinization viscosity and temperature affected the color, hardness, and viscoelasticity of noodles (Song et al., 2004), steamed bread (Zhang et al., 2007).

Starch gelatinization is influenced by other ingredients, and a previous study revealed that sugar, salt, and proteins compete with starch for the available water in the system and affect starch gelatinization (Wootton and Bamunuarachchi, 1979). The effect of gluten content on the starch gelatinization has been studied to illuminate the relationship between the gluten-starch interaction and food product quality (Tester and Morrison, 1990). The endothermic changes during the gelatinization of starch in the presence of gluten have also been investigated by differential scanning calorimetry (DSC) (Doublier et al., 1979). Eliasson (1983) found that the addition of gluten decreased the transition enthalpies but increased the transition temperatures of starch. This may be due the fact that gluten reduces water available for starch during gelatinization and thus reduces the degree of gelatinization, which is considered to be the main trigger.

The interactions between gluten and starch during starch gelatinization have also been studied (Jekle et al., 2016). It is known that in starch-gluten model systems, the hydration properties play a major role during gelatinization. Starch gelatinization is a process of hydrogen bond breaking and rearrangement, and the addition of gluten may affect these bond changes. In addition to the influence of hydration, the influence of molecular interaction between starch and gluten during starch gelatinization may also be important, although few relevant studies have been performed to examine this.

Glutenin and gliadin are the two major storage proteins in the endosperm of wheat, which account for more than 85% of total wheat protein. Gliadin is a single-chain polypeptide, without the disulfide bonds and subunits of the peptide chains.Glutenin is a multiple-chain polymeric protein in which individual polypeptides are thought to be linked into a network by intermolecular disulfide and hydrogen bonds. (Carceller and Aussenac, 2001). The contributions of gliadins and glutenins to dough properties have been widely studied, and it has been suggested that the gliadins generally contribute to dough viscosity, and glutenins contribute to dough elasticity (Uthayakumaran et al., 1999). It has also been suggested that the volume of a loaf of bread is significantly correlated with the gli-glu ratio. A previous study reported that the addition of water-insoluble proteins from rice could affect the pasting and textural properties of rice starch (Baxter et al., 2014). The effects of the types and amount of additive gluten on the starch pasting properties was investigated (Chen et al., 2010). However, there are few studies on the influence of the gli-glu ratio on gelatinization, thermal properties, and the molecular structure of wheat starch.

In the current study, the effect of the gli-glu ratio on the pasting, thermal, and structural properties of mixtures recombined from wheat starch and gli or glu were studied by rapid viscosity analysis (RVA), DSC, TGA, and rheometer-Fourier transform infrared spectroscopy. The purpose of this study is to clarify the effect of gluten composition on the physicochemical and structural properties of gluten-starch mixtures during heating and/or cooling, which will help us to understand the interaction mechanism of starch and protein during flour product processing.

Section snippets

Materials

The AK58 wheat, which is widely cultivated in China, was provided by Henan Academy of Agricultural Sciences, China. The protein, ash, and starch content of the AK58 wheat flour was 12.6% (14% moisture basis), 0.44%, and 74.22% (14% moisture basis), respectively.

Wheat starch and gluten preparation

Wheat starch was isolated based on a previously described method (Czuchajowska and Pomeranz, 1994). After measurement, the starch, protein, and moisture content of the isolated starch fraction were determined to be 90.02%, 2.60%, and

Pasting properties

The pasting properties of starch-gluten mixtures with different gli-glu ratios are shown in Table 1. It was found that the viscosities of all materials except the breakdown of wheat flour were lower than those of native starch during gelatinization. This may be due to the fact that adsorption of gluten to starch granules, through hydrophobic interactions, may restrict the diffusion of water into the starch granules (Martin et al., 1991), resulting in an inhibition of starch swelling and

Conclusions

This study showed that different gli-glu ratios in gluten significantly influenced the physicochemical properties of gluten-starch mixtures. In the case of viscosity, the effect of gliadin is greater than that of glutenin. The results was also observed in CLSM. With increasing gli-glu ratios, decreases in peak viscosity, through viscosity, and increases in enthalpy change were found in blends, and these were lower than those observed in native starch. With changes in temperature, hydrophobic

CRediT authorship contribution statement

Mingfei Li: Writing - original draft, Formal analysis, Investigation. Qinghua Yue: Formal analysis. Chong Liu: Conceptualization, Methodology, Writing - review & editing. Jing Hong: Investigation. Limin Li: Investigation, Supervision. Ke Bian: Resources.

Declaration of competing interest

The manuscript has not been published or submitted to other journals for publication. Each author has read the manuscript and approved to submit it to this journal for possible publication.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (U1604235, 31671810), the Special Fund for the Construction of Wheat Technology System in Henan Province (S2017-01-G06).

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Effect of gliadin/glutenin ratio on pasting, thermal, and structural properties of wheat starch

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials

Wheat starch and gluten preparation

Pasting properties

Conclusions

CRediT authorship contribution statement

Declaration of competing interest

Acknowledgements

J. Cereal. Sci.

Carbohydr. Polym.

J. Cereal. Sci.

Agric. Sci. China

J. Cereal. Sci.

Ind. Crop. Prod.

Food Hydrocolloids

Vib. Spectrosc.

Food Chem.

Food Chem.

Food Hydrocolloids

J. Cereal. Sci.

J. Cereal. Sci.

Carbohydr. Res.

Trends Food Sci. Technol.