Crosslinking Food Proteins for Improved Functionality

Abstract

Different possibilities for protein crosslinking are examined in this review, with special emphasis on enzymatic crosslinking and its impact on food structure. Among potential enzymes for protein crosslinking are transglutaminase (TG) and various oxidative enzymes. Crosslinking enzymes can be applied in cereal, dairy, meat, and fish processing to improve the texture of the product. Most of the current commercial applications are based on TG. The reaction mechanisms of the crosslinking enzymes differ, which in turn results in different technological properties.

Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their Applications

“…The economically feasible production of a calcium-independent TGase from microbial origin together with its mild reaction optima (pH ~ 6-7, ~ 40-50 °C) led to increased utilisation in the food industry [21,22]. The reaction mechanisms and possible applications in dairy products and other protein-based foods were extensively reviewed in the past, e.g., [22][23][24][25][26][27][28]. Besides the characterisation of the polymers, the number of cross-links formed by TGase can also be determined.…”

“…Nevertheless, the Maillard reaction, also referred to as Besides TGase, oxidoreductases were applied, which have a completely different cross-linking mechanism: firstly, the enzymes oxidise specific functional groups that react further in non-enzymatic reactions. This leads to a variety of covalent bonds so that the total number of cross-links can hardly be determined by amino acid analysis [23]. Monogioudi et al [33] applied 31 P nuclear magnetic resonance spectroscopy after phosphorylation of hydroxyl groups to quantify cross-links formed in β-casein after oxidation of tyrosine residues by tyrosinase (EC 1.14.18.1).…”

“…The chemistry of the reaction products and the mechanisms of their formation are still not fully explored. Nevertheless, the Maillard reaction, also referred to as glycation, and its possible application in food manufacturing were extensively reviewed in recent years, e.g., [23,[38][39][40][41].…”

“…Separations 2018, 5, x FOR PEER REVIEW 4 of 34 glycation, and its possible application in food manufacturing were extensively reviewed in recent years, e.g., [23,[38][39][40][41]. Certain conditions during food processing can facilitate the formation of protein cross-links even in the absence of carbohydrates.…”

“…They contribute essentially to the three-dimensional structure of protein molecules but are also formed from free thiol groups as well as in disulphide exchange reactions as a consequence of heat treatment or mechanical stress [23,42,50]. In contrast to other cross-links, disulphide bonds can be easily cleaved in redox reactions with reducing agents such as dithiothreitol or β-mercaptoethanol.…”