Optimization of enzymatic oligomerization reaction conditions for three milk protein products via ceteris-paribus approach

Via a ceteris-paribus approach, optimum reaction conditions for an oxidoreductase- (lactoperoxidase; laccase; glucose oxidase) induced oligomerization of milk proteins were assessed for three different milk protein products (sodium caseinate; whey protein isolate; skim milk powder).Optimum protein monomer modification conditions were enzyme- and substrate-specifically identified, yielding protein monomer modification levels of, e.g., 58% in case of lactoperoxidase-induced (w/w = 5% protein; 1.8 μmol hydrogen peroxide/mg protein; 4.8 U lactoperoxidase/mg protein; 50 °C; 1 h; pH 7.0), 92% in case of laccase-induced (w/w = 5% protein; 0.02 μmol chlorogenic acid/mg protein; 0.01 U laccase/mg protein; 40 °C; 1 h; pH 7.0) and 86% in case of glucose oxidase-induced (w/w = 1% protein; 0.5 U glucose oxidase/mg protein; 40 °C; 16 h; pH 7.0) modification of total milk proteins from skim milk powder.The study for the first time provides a comprehensive overview over reaction conditions facilitating high degrees of milk protein monomer modification upon oxidoreductase-induced oligomerization in regard to food protein tailoring via application of less substrate- and reaction-specific enzymes than transglutaminase.

► Enzymatic oligomerization has developed basic tool for food protein tailoring.
► Oxidoreductase-induced oligomerization has recently successfully been applied.
► Minor specificity of oxidoreductases necessitates optimized reaction conditions.
► Reaction conditions aiding optimum protein monomer modification were identified.
► The results allow protein tailoring via less specific enzymes than transglutaminase.