Measuring Protein in Frozen Dairy Desserts by Dye Binding

Abstract

The protein content of 24 samples of vanilla ice cream, ice milk and related frozen dairy desserts was determined by the Kjeldahl method and Acid Orange 12 dye binding method. Statistical analysis showed the correlation between the two methods was highly significant. Excepting two samples, the Kjeldahl protein results based on total nitrogen consistently gave higher protein values than dye binding, the difference averaging +.11%. When the Kjeldahl protein results were corrected for the non-protein nitrogen present, the resulting protein values averaged .20% lower than the dye binding values. These results indicate that the dye binding method is sufficiently accurate for monitoring protein concentration in the frozen dairy desserts studied.