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

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>This study examined the monthly and seasonal variations of δ<SUP>13</SUP>C, δ<SUP>15</SUP>N, 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 δ<SUP>13</SUP>C and δ<SUP>15</SUP>N values were lower in OM, whereas the mean α-tocopherol and nutritionally desirable FA contents were higher in OM. Furthermore, δ<SUP>13</SUP>C, δ<SUP>15</SUP>N, 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 δ<SUP>13</SUP>C<SUB>bulk-milk</SUB>, 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.</P> <P><B>Highlights</B></P> <P> <UL> <LI> δ<SUP>13</SUP>C, δ<SUP>15</SUP>N, fatty acids, and vitamin E in organic and conventional milk were tested. </LI> <LI> Chemometric methods provided reliable chemical markers for accurate discrimination. </LI> <LI> δ<SUP>13</SUP>C, δ<SUP>15</SUP>N, and FA contents vary significantly with the season in organic milk. </LI> <LI> Compared to conventional milk, the mean δ<SUP>13</SUP>C and δ<SUP>15</SUP>N were lower in organic milk. </LI> <LI> α-Tocopherol and nutritionally desirable FA contents were higher in organic milk. </LI> </UL> </P>