Effect of oxidative enzymes on structure-function of wheat proteins

Manu, B. T. (2008) Effect of oxidative enzymes on structure-function of wheat proteins. PhD thesis, University of Mysore.

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Abstract

Wheat is an important cereal crop of the world. Food products made from wheat are the staple food for the majority of world population. Wheat is unique among the cereals because of its ability to form visco-elastic dough, when mixed with water. A variety of leavened and unleavened food products are made from wheat dough. The balance between elasticity and viscocity is wheat variety dependent and can differ greatly between varieties. This property has a major influence on the type of food product that can be prepared. The visco-elastic property of the dough is mainly attributed to the gluten proteins namely gliadins, and glutenin. The polymeric glutenin provides elasticity and the monomeric gliadin provides viscosity to the dough. Glutenin contains subunits namely high molecular weight glutenin subunits and low molecular weight glutenin subunits, cross-linked by disulfide and dityrosine bonds. The composition of glutenin subunits profoundly affects the rheological properties of dough and quality of products made from dough. The wheat protein cross-linking also has an influence on the properties of the dough and the subsequent baked product. Many chemical agents have been used in bakery industry as dough improvers. But there is a paradigm shift towards the use of enzymes because of the toxicity of chemicals used as dough improvers. Many enzymes such as protease, amylase, lipase, oxidative enzymes like glucose oxidase, hexose oxidase, polyphenol oxidase, peroxidase etc., are reported to improve the quality of dough. Wheat also contains a few endogenous oxidative enzymes like peroxidase, polyphenol oxidase, and super Synopsis ii oxide dismutase etc. Peroxidases are ubiquitous enzymes and reported to have various physiological roles and industrial applications. Exact mechanism by which peroxidase enzyme improves the dough quality is not understood. However, peroxidases from different sources have been shown to cross-link several food proteins including bovine serum albumin and β-lactoglobulin. Peroxidase may have a similar role in cross-linking of wheat proteins and dough formation. Therefore, the major focus of the present thesis was to study the role of peroxidase in wheat dough formation. Thus, the present study has following three objectives: a) To purify and characterize the enzyme peroxidase from wheat bran b) To elucidate the role of peroxidase in cross-linking of wheat proteins c) To study the role of wheat proteins in rheological properties of dough and chapati texture.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Wheat grain-; Structure; Proteins; Oxidative enzymes; Peroxide purification; Glutenin
Subjects:	600 Technology > 08 Food technology > 21 Cereals > 04 Wheat 600 Technology > 08 Food technology > 16 Nutritive value > 03 Proteins 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 16 Enzyme Chemistry
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	18 Mar 2010 07:09
Last Modified:	18 Mar 2010 07:09
URI:	http://ir.cftri.res.in/id/eprint/9401

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