| In china, there are various types of honey according to their sources and constitutions. Because of the large difference in the prices and yields as well as the quantity demand among different varieties of honey, honey products have frequently been the object of fraud in Chinese and international markets. To guarantee fair play in markets and combat product fraud, we need appropriate and reliable methods to determine the legitimacy of botanical origins of honey in the markets. Several methods have been applied in identifying the botanical origins of honey including physicochemical parameters, spectral analysis and mass spectrum analysis method. However, the limitations of these method include unreliability and expertise. This study was carried out using three methods including IRMS, mineral elements and the combination of IRMS and ICP-MS method combined with chemometrics to classify honey according to their floral origins. The combination of IRMS and ICP-MS method could improve the detection technology of the floral origins of honey. Theoretically, this approach could be applied to other food products.This paper was divided into four parts:1. The floral origins of honey were identified based on the stable isotopes of carbon and its protein of carbon. According to the study of different varieties of stable isotope ratios of carbon and its protein, it was found that the range of the δ13C of honey was scattered. However, the range of δ13C of honey protein was relatively concentrated. Correlation analysis showed that the correlation coefficient of tufted vetch honey and its honey protein was above 0.8. At the same time, the correlation coefficient of acacia honey and its honey protein was above 0.8. There are the δ13C of tufted vetch honey and acacia honey represented the difference between varieties of honey. Analysis of variance and multiple comparison results showed that the δ13C of different varieties of honey were significantly differet. At the same time, the δ13C of some honey protein were also significant differences. Carbon stable isotope could be used as reference index of classifying honey according to their floral origins.2. The floral origins of honey were identified based on the stable isotopes of hydrogen and oxygen. Analysis of variance and multiple comparison results showed that the δ2H and δ18O of six varieties of honey had significant difference. Scatter plot of the δ2H and δ18O discovered that all varieties of honey can be distinguished. Therefore, the δ2H and δ18O of honey could identify the botanical origins of honey. The δ2H and δ18O can be used as reference index of classifying honey according to their floral origins.3. Mineral elements content in the honey were measured by inductively coupled plasma mass spectrometry(ICP-MS). The results showed the method of ICP-MS was feasible to determine the content of mineral elements honey. It showed that the determination method of detection limit and the recovery rate can meet the requirements of the experiment. The contents of K, Na, Ca, Mg and Fe in honey were more than 1 mg/kg. The contents of Mn, Cu, Sr and Ba in honey were in the range of 0.1 ~ 1 mg/kg. The contents of the other trace elements in honey were less than 100 μg/kg. The content of heavy metal elements in honey were less than 100 μg /kg.4. It were based on the combination of IRMS and ICP-MS methods to classify honey according to their floral origins. Principal component analysis was carried out on the six varieties of honey. Linden honey, sunflower honey and tufted vetch honey could be obviously distinct. Rape honey, acacia honey and jujube honey were not in obvious distinctions. The δ13Ch, δ2H, δ18O, K, Ca, Cu, Sr and Ba were used to identify the floral origins of honey. The δ13Ch, δ13Cp, δ2H, δ18O, Na, Mg and K content of 24 indicators were applied for classifying honey according to their floral origins in linear discriminant analysis. The cross validation discriminant rate of the isotope technology, mineral elements and the combination of IRMS and ICP-MS in honey were 71.4%, 81% and 88.1%,respectively. Therefore, the combination of IRMS and ICP-MS methods were proved to be the most effective and accurate approach for classifying honey according to their floral origins. |
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