EVALUATION OF RIBOFLAVIN CONTENT IN DAIRY PRODUCTS AND NON-DAIRY SUBSTITUTES

The riboflavin content was determined in different types of milk and non-dairy substitutes. A protein precipitation with HClO4 and quantification of riboflavin by isocratic HPLC-FLD, that allows enough sensitivity, precision and accuracy are presented. The advantages of the method are the use of small volumes of less toxic solvents and reagents, simple sample pre-treatment and short time of analysis. The mean value of the riboflavin content was 1.81 mu g/mL in UHT milk, 1.51 mu g/mL in pasteurized milk and 1.34 mu g/mL in yogurt. The average riboflavin content of 2.3 mu g/mL was found in raw goat milk, 1.66 mu g/mL in raw cow milk, 0.14 mu g/mL in soymilk, and 4.79 mu g/mL in rice milk. These data show the wide variability in the levels of riboflavin in different types of milk and dairy products. When UHT milks packages were opened and stored in refrigerator for 5 days, the significant degradation of riboflavin was not observed (p < 0.01). The loss of riboflavin was in the range from 0.66 to 7.14% for these storage conditions.