Discrimination of organic milk by stable isotope ratio, vitamin E, and fatty acid profiling combined with multivariate analysis: A case study of monthly and seasonal variation in Korea for 2016-2017

This study examined the monthly and seasonal variations of δ13C, δ15N, fatty acids (FAs), and vitamin E in organic milk (OM) and conventional milk (CM) collected in Korea during 2016-2017, discriminating OM authenticity with chemometric approaches. Compared to CM, the mean δ13C and δ15N values were lower in OM, whereas the mean α-tocopherol and nutritionally desirable FA contents were higher in OM. Furthermore, δ13C, δ15N, and FA contents vary significantly with the season in OM, whereas α-tocopherol does not show a specific seasonal trend in either OM or CM. Chemometric approaches provided reliable chemical markers, notably C18:3n-3, C18:2n-6, and δ13Cbulk-milk, for accurate OM discrimination according to sampling season. Our findings elucidate milk nutritional quality issues and also provide valuable insight into the control of fraudulent OM labeling in Korea, with potential application in other countries.