Modification of Ovalbumin with Glucose 6-Phosphate by Amino-Carbonyl Reaction. Improvement of Protein Heat Stability and Emulsifying Activity

Abstract

Ovalbumin (OVA) was modified with glucose (Glu) and glucose 6-phosphate (G6P) through the amino-carbonyl reaction (Maillard reaction), and heat-induced aggregation and emulsifying activity of the modified proteins were investigated. G6P reacted with the free amino groups in a similar manner to Glu; about 70-80% of the total amino groups were blocked by the reaction at 50 "C, and 65% relative humidity for 3 days. However, the reaction with G6P induced protein polymerization and brown-color development more strongly than that of Glu. OVA modified with G6P was much more acidic than either native OVA or the Glu-modified OVA, and it was highly soluble and quite resistant to heat-induced aggregation, i.e., its high-concentration solution (5%) was still completely soluble and transparent even aRer being heated at 100 "C for 10 min. Furthermore, OVA emulsifying activity was increased about 5-fold by the modification with G6P.

Effect of conjugation with glucosamine on the functional properties of lysozyme and casein

“…It is probable that some carboxyl groups of caseins were also activated by EDC and reacted with amino groups of other protein molecules, resulting in intermolecular covalent crosslinking. The formation of such electrophoretic patterns has been reported previously for various polysaccharides attached to lysozyme, 10,15,21 gluten, 12 ovalbumin, 13 soybean proteins 42 and β-lactoglobulin.…”

“…These results are similar to those of Nagasawa et al, 26 Hattori et al 24 and Aminlari et al 35 The fact that coupling of carbohydrates (simple sugars and polysaccharides) to proteins improves their properties as emulsifiers has been confirmed by many researchers. 8,12,13,17,19,21,23,24,26,35 The true mechanism(s) of adsorption of proteins to the interface and the structural changes at the interface are still unclear. 49 In general, it is well documented that the absorption of protein molecules to the surface is accompanied by changes in protein structure resulting in unfolding, molecular reorientation and aggregation processes within the surface layer.…”

Modification of functional properties of egg‐white proteins

“…This phenomenon is supported by other experimental data, which revealed that the polymerisation of OVA resulting from glucose and glucose-6-phosphate attachment to the protein backbone (50 8C, 0-5 days, 65% relative humidity) gave rise to a sugar modified protein molecule with improved heat stability [27]. At high solution concentration (5%) the protein was still completely soluble and transparent even after treatment at extreme conditions (100 8C, 10 min).…”

“…Covalent attachment of sugar residues, using mild, nondenaturing heat-treatment, has been reported to increase the heat stability of globular proteins [27] and to improve emulsifying ability [28]. Although sugars protect proteins from thermal denaturation by enhancing protein-protein interactions, once denatured they appear to have improved functional properties due to the enhanced amphiphilic character caused by the sugar attachment.…”

A New Approach to the Functional Improvement of Fish Meat Proteins

“…There are some reports in which the glycosylation enhances the thermal stability of food proteins [2,6,16,26,42], and the same functional improvement was also observed in fish Mf [7,19]. Figure 30.4 shows the thermal stability of carp Mf conjugated with alginate oligosaccharide (Mf-AO conjugate) under different NaCl concentrations and pH levels [34].…”