Dye Binding by Soybean and Fish Meal as an Index of Quality

Abstract
A chemical method for the determination of soybean meal quality after processing is proposed. The method is based on the reaction of the dye, Orange G, with the basic amino acids in the meal. The amount bound depends upon the availability of either free amino, imidazole, or guanidyl groups. Differences in the binding capacity of soybean meal are caused primarily by differences in the availability of the epsilon amino group of lysine. The dye binding capacity of soybean meals heated for varying periods of time was closely correlated with growth of chicks fed the meals. This method was also applied to fish meal, but because of variations in methionine (which was not detected by this method), and differences in arginine and histidine content between various meals, the correlation with chick growth was not satisfactory.