Protective influence of heat treatment on the light-induced riboflavin (vitamin B2) degradation in dairy products

Milk is the most important source of riboflavin (Vitamin B2) in many nations. Riboflavin absorbs light in the ultraviolet region and generates singlet oxygen in milk leading to the oxidation of nutrient components and affects the sensory quality of dairy products. The purpose of this work was to elucidate the effect of heat-treatment on the light-induced riboflavin degradation in the model solution of milk bases and milk samples. Although the photo-degradation of riboflavin in all samples was decreased with the increasing of illumination time, the reductions of riboflavin light oxidation were found in all milk model samples and heated milks in according to the formation of Maillard reaction products during heating. The amount of riboflavin remained in control sample (1.5 mg/l riboflavin) was 1.67 % after 2.5 hour illumination. But, it was 34 % and 60 % in the heated lactose and casein solution and milk at 120oC, 45 min, respectively. The increasing of heating time leaded to the increasing of protective ability of milk and model samples against riboflavin photo-degradation. The study clarified that heat treatment of whey proteins, casein and milk might induce the formation of Maillard reaction products that enhanced the protective ability against photo-degradation of riboflavin.