Bulk and fatty acid-specific stable isotope analysis coupled with multivariate modeling for differentiating free-range grass-fed and captive grain-fed yak meat

Abstract

The husbandry pattern of yak meat is a crucial factor for its market price and competitiveness; deliberately mislabeling of the production information will cause consumer confidence crisis. In this work, stable isotope signatures of free-range grass-fed (FRG) and captive grain-fed (CG) yak meat were analyzed for their discrimination. δ13C, δ2H, δ18O, δ15N, δ34S of bulk muscle and δ13C of six fatty acids were respectively determined by EA–IRMS and GC–C–IRMS. ANOVA and correlation analysis of stable isotope ratios of yak muscle and fatty acids against its feed indicated that their δ13C, δ15N, δ34S significantly are related, which provides the evidence of diet and trophic information. δ13C of six fatty acids (FAs) are significantly different (p < 0.05) between two patterns; all FAs of FRG yak meat are highly related to grass silage (R > 0.70), but saturated and unsaturated FAs of CG yak meat are respectively related to soybean silage (R > 0.70) and maize silage (R > 0.56). PLS-DA and LDA modeling based on stable isotope ratios of yak muscle and FAs together discriminate yak meat from these two husbandry patterns with accuracies of 100 %. This strategy may be promising as a feasible method for confirming the husbandry patterns of yak meat, ensuring label authenticity and food safety.