Aroma analysis of light-exposed milk stored with and without natural and synthetic antioxidants.

The effect of antioxidants, added in a single initial dose or in weekly additions to extended shelf life milk, was evaluated over 6 wk of lighted storage at 4 degrees C. Light-induced oxidation was measured by determining pentanal, hexanal, heptanal, and 1-octen-3-ol contents. Weekly addition of a combination of butylated hydroxyanisole and butylated hydroxytoluene (100 mg/kg of milk fat, each) maintained heptanal content of milk at levels comparable to light-protected milk, whereas an initial single addition of alpha-tocopherol significantly decreased hexanal content over the first 4 wk of storage. Odor-active compounds associated with light-induced oxidation included 2,3-butanedione, pentanal, dimethyl disulfide, hexanal, 1-hexanol, heptanal, 1-heptanol, and nonanal. The addition of butylated hydroxyanisole and butylated hydroxytoluene in a single initial addition resulted in decreases in pentanal and hexanal odor, but not in heptanal and 1-heptanol odor, whereas the addition of alpha-tocopherol and ascorbyl palmitate decreased pentanal and heptanol odor, but not hexanal and heptanal odor.