Simultaneous determination of B-group vitamins in enriched Brazilian dairy products

In addition to serving as good natural sources of vitamin B(2), milk and milk products are currently being enriched with the vitamins B(1), B(2), B(6), and nicotinamide in Brazil. The objective of this research was to evaluate the levels of enrichment of these products according to their availability in supermarkets in the Campinas (SP, Brazil) region. The separation of the vitamins was carried out on a C 18 column with gradient elution with acetonitrile and aqueous phase. Detection of vitamins was effected in the ultraviolet region and quantification by an external standard. The levels of vitamin B(2) determined in powdered whole milk, skimmed milk powder, and one brand of flavored lactic beverage, were practically double those stated on the packages. The same occurred with vitamins B(6) and PP (nicotinic acid + nicotinamide), when determined in the same lactic beverage and with vitamin B(6), determined in acidified milk. The high levels of vitamin B(2), naturally present in whole milk, and the predominance of the free form, allowed for the determination of this vitamin in non-enriched milk.