ABSTRACT
Proteins react with certain organic dyes to produce insoluble complexes. The quantity of dye bound is proportional to (a) the dye-binding capacity (DBC)* and (b) the protein concentration. Farm-gate prices for milk (in Australia, Denmark, France, Netherlands, New Zealand, United States) is partly determined by its protein content. Dye-binding assays are widely used for milk protein determination. Amido Black 10B (C.I. 20470), Acid Orange 12 (C.I. 15970), and Orange-G (C.I. 16230) are the three main dyes used. Dye-binding assays are presented in Sections 1-3 of this chapter. Section 4 covers the chemistry of protein binding with azo dyes. Section 5 is a review of interference compounds and other sources of error. Section 6 covers applications of dye-binding assays in food protein analysis.
