Chemical characterization of raw milk samples with and without oxidative off-flavor
1995
Barrefors, P. | Granelli, K. | Appelqvist, L.A. | Bjoerck, L.
Milk samples with and without oxidized flavor were obtained from two different commercial dairy herds. Milk components that are important for the susceptibility of milk fat to spontaneous oxidation, (i.e., fatty acid composition and the concentrations of alpha-tocopherol, beta-carotene, and ascorbic acid) were analyzed to describe the variation in the susceptibility of milk fat to oxidation in raw milk. The samples were also analyzed using dynamic headspace gas chromatography to determine volatile oxidation products, primarily straight-chain aldehydes. The results showed that milk samples exhibiting off-flavor had higher linoleic acid content in the neutral fat fraction. At one farm, the concentrations of both alpha-tocopherol and beta-carotene were lower in samples that demonstrated off-flavor. At the other farm, this difference was not statistically significant. Milk with off-flavor also had significantly higher concentrations of hexanal. The data were also analyzed by principal component regression. The results from this analysis indicated that the causative factors for the oxidation were different for the two herds.
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