Summary Use of an argentometric-amperometric titration procedure has revealed that the only source of -SH groups in skimmilk is the serum proteins. Casein and protein-free milk serum were found devoid of such groups. Praetionation of the serum protein material into a number of components by (NH4)2 SO4 additions and pH adjustments revealed that β-lactoglobulin can account for practically all the -SH groups present. Study of the contributions of various major serum protein fractions to heat-induced cooked flavor in skimmilk demonstrated βlacto-globulin to be responsible for the flavor. Conversion of -SH groups to H2S as a result of heat treatment may explain, in a general way, the mechanism whereby β-lactoglobulin gives rise to cooked flavor. The AgNO3 titration, when conducted in aqueous medium, appears to measure the same quantity of -SH groups in heated milk as nitroprusside and thiamin disulfide. When conducted in alcoholic medium the total number of -SH groups capable of activation by heat treatment presumably can be determined in unheated skimmilk. The argentometric-amperometric method gives values for -SH content of slightly less than half of those obtained with o-iodosobenzoate for both skimmilk and β-lactoglobulin.

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heatinduced cooked flavor sh content oiodosobenzoate conversion argentometricamperometric titration procedure h2s

J.T. Hutton and S. Patton,.The Origin of Sulfhydryl Groups in Milk Proteins and their Contributions to “Cooked” Flavor. 35 (8),699-705.

J.T. Hutton and S. Patton,"The Origin of Sulfhydryl Groups in Milk Proteins and their Contributions to “Cooked” Flavor" 35

J.T. Hutton and S. Patton,"The Origin of Sulfhydryl Groups in Milk Proteins and their Contributions to “Cooked” Flavor"