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

Abstract

RationaleThe 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 δ13C, δ2H, and δ18O 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.MethodsTraceability methods based on elemental analyzer isotope ratio mass spectrometry and liquid chromatography isotope ratio mass spectrometry were established for geographical origin of rape honey.ResultsRape honey harvested in the high‐altitude region (QH; Qinghai) had significantly higher values (1.4 to 5.3‰ for δ13C, 7.9 to 12.9‰ for δ2Hprotein) for the δ13C of whole honey (−23.8‰), its protein (−24.4‰), fructose (−23.5‰), glucose (−23.6‰), and disaccharide (−24.7‰), and also δ2H of the protein (103.5‰) than those in low‐altitude regions (HB; Hubei, SC; Sicuan, and JS; Jingsu). The δ18Orape honey was a useful index to differentiate whether rape honey from coastal (JS) or non‐coastal (HB, SC, and QH) regions. The δ13C, δ2H, and δ18O values in rape honey are affected by geographical factors, such as temperature and altitude. The δ13Cprotein and δ13Crape honey values were better to identify the geographical origin of rape honey than δ13Csaccharides. The δ18O and δ2H values of rape honey protein were more suitable for traceability than those of rape honey. The combination of the δ13C, δ2H, and δ18O 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%).ConclusionsStable isotopes could be significant predictors in determining the geographical origin of rape honey.