The Influence Of Caseinomacropeptide On The Denaturation／agreggation Of β-lactoglobin

Whey protein is widely adopted in food industry due to its superiorphysiochemical features including interfacial characteristics and gelatination.Caseino-macropeptide （CMP） is a hydrolysate of k-casein, and is existing in mostwhey powders. Due to different production methods, commercial whey proteinconcentrated （WPC） and whey proteinisolated （WPI） are different in CMP. Thephysiochemical properties of CMP may change the functions of whey proteins whenused as ingredient, which may limit its use in some productions. In this paper, the heatdenaturation dynamics affluence by CMP to β-lactoglobulin under different heattreatment temperatures is studied; the size and structure of CMP-β Lg polymerizationproducts under different heat denaturation circumstances are compared; the reactionmechanism of heat denaturation and heat aggregation of CMP/ββ-Lg is also discussed.In this paper, the natural ββ-Lg residue in heating process is analyzed by HPLC,and the dynamic influence of heat denaturation/aggregation from CMP to ββ-Lg isdiscussed in four aspects: pH, mass proportion, heating temperature and strength ofcalcium-ion. The result shows, pH and CMP mass proportion are able to influence thespeed of heat denaturation process （P<0.05）. When pH=6.7, Ca²⁺could markedlyaccelerate the heat denaturation and CMP could lessen its significance. However;when pH=4.0, Ca²⁺is insignificant in the acceleration of ββ-Lg heat denaturationprocess, but it will lessen the significance of the influence of CMP.Besides that, scattered spectrum method is adopted for analyzing the moleculeradius of the resulting aggregates, and non-degenerate gelatin electrophoresis isadopted to analyze the aggregation degree of the resulting aggregate. The result shows,the reaction mechanism of heat denaturation/aggregation and the affection mechanismof CMP to the reaction are different when pH=6.7and4.0. When pH=6.7, the maininfluence is the reaction between exposed hydrophobic grouping and the hydrophobicregions. And when pH=4.0, the influence mainly come from the static effect betweenelectronegative CMP and electropositive ββ-Lg. as a result, the influence of CMP toββ-Lg in heat denaturation/aggregation is more significant in pH=4.0than pH=6.7.Whey protein is composed of multiple types of proteins, therefore a series ofcomplex reactions will come into effect in the heat treatment of whey protein, whichare influenced by multiple factors. Some issues such as the affluence mechanisms ofthe former to the later in denaturation/aggregation process and the way to recognizehow the ingredients in whey protein influence each other in heat processing from theaspects of the composition and treatment environment are yet for further study.