C/H/O stable isotope of rape honey and its components combined with machine learning algorithms to identify geographical origin.

RATIONALE: The distribution of rape honey is among the largest and most diverse of all honeys available to humankind with respect to the geographical origin. Accurate isotopic reference values for rape honey are therefore important for precise verification of honey origin and its traceability. New combined rape honey δ13 C, δ2 H, and δ18 O values in combination with values on its compounds (protein and saccharides) were used to complement existing databases to better identify the geographical origin of Chinese rape honey. METHODS: Traceability methods based on elemental analyzer isotope ratio mass spectrometry and liquid chromatography isotope ratio mass spectrometry were established for geographical origin of rape honey. RESULTS: Rape honey harvested in the high-altitude region (QH; Qinghai) had significantly higher values (1.4 to 5.3‰ for δ13 C, 7.9 to 12.9‰ for δ2 Hprotein ) for the δ13 C of whole honey (-23.8‰), its protein (-24.4‰), fructose (-23.5‰), glucose (-23.6‰), and disaccharide (-24.7‰), and also δ2 H of the protein (103.5‰) than those in low-altitude regions (HB; Hubei, SC; Sicuan, and JS; Jingsu). The δ18 Orape honey was a useful index to differentiate whether rape honey from coastal (JS) or non-coastal (HB, SC, and QH) regions. The δ13 C, δ2 H, and δ18 O values in rape honey are affected by geographical factors, such as temperature and altitude. The δ13 Cprotein and δ13 Crape honey values were better to identify the geographical origin of rape honey than δ13 Csaccharides . The δ18 O and δ2 H values of rape honey protein were more suitable for traceability than those of rape honey. The combination of the δ13 C, δ2 H, and δ18 O values of rape honey and its extracted protein and saccharides improved the precision of three models (linear discriminant analysis, SVM, and random forest) used to discriminate rape honey from different regions in China. The SVM model obtained the best accuracy (93.2%). CONCLUSIONS: Stable isotopes could be significant predictors in determining the geographical origin of rape honey.