Protein deamidation to produce processable ingredients and engineered colloids for emerging food applications

Abstract

With the ever‐increasing demands for functional and sustainable foods from the general public, there is currently a paradigm shift in the food industry toward the production of novel protein‐based diet. Food scientists are therefore motivated to search for natural protein sources and innovative technologies to modify their chemical structure for desirable functionality and thus utilization. Deamidation is a viable, efficient, and attractive approach for modifying proteins owing to its ease of operating, specificity, and cost‐effective processes. Over the past three decades, the knowledge of protein deamidation for food applications has evolved drastically, including the development of novel approaches for deamidation, such as protein‐glutaminase and ion exchange resin, and their practices in new protein substrate. Thanks to deamidation, enhanced functionalities of food proteins from cereals, legumes, milk, oil seeds and others, and thereby their processabilities as food ingredients have been achieved. Moreover, deamidated proteins have been used to fabricate engineered food colloids, including self‐assembled protein particles, protein–metallic complexes, and protein–carbohydrate complexes, which have demonstrated tailored physicochemical properties to modulate oral perception, improve gastrointestinal digestion and bioavailability, and protect and/or deliver bioactive nutrients. Novel bioactivity, altered digestibility, and varied allergenicity of deamidated proteins are increasingly recognized. Therefore, deamidated proteins with novel techno‐functional and biological properties hold both promise and challenges for future food applications, and a comprehensive review on this area is critically needed to update our knowledge and provide a better understanding on the protein deamidation and its emerging applications.

Protein-Glutaminase Engineering Based on Isothermal Compressibility Perturbation for Enhanced Modification of Soy Protein Isolate

“…Proteins derived from plants and animals are the main sources of food protein, but plant-based proteins are the preferred choice as a result of their versatility, affordability, lower incidence of contamination, etc. , However, glutamine and asparagine groups rich in plant-based proteins are prone to hydrogen-bond cross-linking, leading to protein aggregation or precipitation, which generally results in low solubility and lack of elasticity. − Plant-based proteins can be successfully modified by deamidation to improve their properties or boost their functionality. − The conventional methods of deamidation mainly include physical, chemical, and enzymatic methods . The enzymatic deamidation reaction is rapid and highly safe and has minimal toxic side effects, mild conditions, and strong specificity .…”

Application Prospect of Protein-Glutaminase in the Development of Plant-Based Protein Foods

“…However, it is worth noting that most plant-based proteins with high contents of glutamine residues induce the aggregation and precipitation of proteins by hydrophobic or hydrogen bond interactions [5], which limit their use and application in the food industry [6]. Protein deamidation mainly occurs through the transformation of the amide side chains of asparagine and glutamine into negatively charged carboxyl groups via the release of ammonia, so as to stretch the structure of the protein and improve the solubility of the protein [7]. In terms of using deamidation to improve the functional properties of plant-based proteins, enzymatic modification of proteins can be carried out under mild conditions, which has great advantages over other treatments [8].…”

“…In terms of using deamidation to improve the functional properties of plant-based proteins, enzymatic modification of proteins can be carried out under mild conditions, which has great advantages over other treatments [8]. For example, chemical approaches to deamidation, such as hydrothermal treatment under acidic [9] or alkali conditions [10], and/or with anions [11], can cause unfavorable peptide bond hydrolysis and possible amino acid isomerization/racemization, consequently leading to protein damage or safety issues [7]. Therefore, enzymatic approaches to protein deamidation are widely recognized as the desirable method owing to their high reaction specificity under mild environmental conditions and food safety [12].…”

“…The negative charge of the glutamyl residue contributes to the electrostatic repulsion of proteins and enables food manufacturers to increase the solubility of proteins, improving their flavor-enhancing properties and techno-functional attributes within a food matrix [6,15]. Protein-glutaminase treatment can also avoid excessive hydrolysis caused by chemical and other protease treatments [7]. Enzymatic deamidation by protein-glutaminase can enhance the physical and chemical properties of plant-based proteins, which may open opportunities for researchers to design plant-based protein foods which are comparable to animal counterparts in appearance, texture, and flavor.…”

The characteristics of protein-glutaminase from an isolated Chryseobacterium cucumeris strain and its deamidation application

“…Protein deamidation is a reaction that converts amide groups in proteins into acid residues (carboxyl groups) via the liberation of ammonia ( Liu et al, 2022 ). As the number of negatively charged carboxyl groups increases, the isoelectric point of proteins decreases, and protein solubility improves in many mildly acidic food systems ( Chen et al, 2021 ). Deamidation can be classified as chemical deamidation and enzymatic deamidation.…”