Photolysis of Riboflavin in Milk

Abstract

Milk exposed to direct sunlight in clear glass quart bottles lost about 40% riboflavin in 2 hrs., but in shade max. loss was 6.8%. ! Raw milk lost 40%, pasteurized 35%, and pasteurized- homogenized 28% using milk from same lot and 2 hrs.'' sunlight exposure. Photolysis of riboflavin in milk was much greater at near boiling temp. than at near freezing. Brown glass bottles and paper containers gave good protection against photolysis, but this quality in 4 paper containers varied slightly. In store showcases facing large windows there was a small loss in 48 hrs., but practically no loss in mainly artificially lighted showcases. About 10-12% riboflavin was lost in cooking milk for 30 min. in a glass or uncovered pan, but almost no loss when cooked in a covered aluminum pan.