Changes in Activity Coefficient γ_w of Water and the Foaming Capacity of Protein during Hydrolysis(Food & Nutrition Science)

概要

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The changes in the interaction between food proteins and water and in their surface functional property during enzymatic hydrolysis were investigated. Ovalbumin, a soy protein isolate (SPI), and casein were hydrolyzed with trypsin, and the degree of hydrolysis, water activity a_w, and foaming capacity of each hydrolysate were measured. Ovalbumin showed the minimum value for a_w, and the values for SPI and casein progressively decreased during hydrolysis. Therefore, the activity coefficient of water, γ_w ( = a_w/x_w, where x_w is the mole fraction of water) was obtained to remove the influence of mole change and to examine the interaction of protein hydrolysates with water. In order to calculate x_w in a sample during protein hydrolysis, a method for roughly estimating the number of moles of the protein hydrolysate in a solution was developed. The strategy was to modify the TNBS (2, 4, 6-trinitrobenzenesulfonic acid) method and to combine this method with the modified Ellman method and the determination of lysine by an amino acid analyzer. During enzymatic hydrolysis, each protein sample showed a minimum γ_w value and maximum foaming capacity.
社団法人日本農芸化学会の論文
2002-07-23