Dye-Binding Capacity of Milk Proteins for Amido Black 10B and Orange G

Abstract

Orange G dye shows more stoichiometry in its reaction with milk proteins than does Amido Black, although the latter gives a higher dye-binding capacity (DBC). DBC values for the major milk proteins have been determined at three levels of protein and for both dyes. In general, there is a parallel trend in the amount of each dye bound, showing that the same protein groups are involved. DBC values for Amido Black decrease more rapidly with increasing protein :dye ratios than do the corresponding values for Orange G. Absorbancy indices for the purest dyes available were determined: K = 46.9 for Orange G at 475 mµ, and K = 81.5 for Amido Black at 615 mµ. These values are for concentrations expressed as mg/ml in a 1-cm cuvette. Since there is so much variability in dye assays, it is recommended that absorbancy index be used to standardize the dye reagent. © 1962, American Dairy Science Association. All rights reserved.