DETERMINATION OF THE DEGREE OF HYDROLYSIS OF FOOD PROTEIN HYDROLYSATES BY TRINITROBENZENESULFONIC ACID

An accurate, reproducible and generally applicable procedure for determining the degree of hydrolysis of food protein hydrolysates has been developed. The protein hydrolysate is dissolved/dispersed in hot 1% sodium dodecyl sulfate to a concentration of 0.25-2.5 X 10-3 amino equivalents/L. A sample solution (0.250 mL) is mixed with 2.00 mL of 0.2125 M sodium phosphate buffer (pH 8.2) and 2.00 mL of 0.10% trinitrobenzenesulfonic acid, followed by incubation in the dark for 60 min at 50μC. The reaction is quenched by adding 4.00 mL of 0.100 N HC1, and the absorbance is read at 340 nm. A 1.500 mM L-leucine solution is used as the standard. Transformation of the measured leucine amino equivalents to degree of hydrolysis is carried out by means of a standard curve for each particular protein substrate. © 1979, American Chemical Society. All rights reserved.