Study On The Detection Method Of Monofloral Honey Adulteration

As the available sweetener honey has unique flavor, taste and nutritive value. Honey consists mostly of glucose and fructose and other minor components including vitamins, organic acids, minerals and trace elements. Different nutritional studies have confirmed various effects after honey ingestion, e.g. enhance gastroenterological health and immunity, it also be used to treat wounds, burns and prevent cardiovascular diseases. In recent years, as the honey on nutritional and health aspects have been commonly known, the production of honey does not cover market demand, therefore honey is always the target of food adulteration. The most commom type of adulteration is the addition of sugar or more cheapy honey to honey in order to increase the yield of honey. Such behaviors have severely disrupted the market order and damaged the interests of beekeepers and normal companies. For honey adulteration, the equipments adopted by the methods generally used for honey adulteration are expensive and not popular, therefore, this study used two more popular methods, high-performance liquid chromatography combined with together with evaporative light scattering detection(HPLC-ELSD), and liquid chromatography-mass spectrometry(LC-MS) to determin adulterated honey, meanwhile, the study explored preliminarily the discriminating ability of proton nuclear magnetic resonance spectroscopy(1H-NMR).In this study, the objective is to find the adulteration of honey with the help of different methods on model honey samples adulterated with high fructose corn syrup(HFCS) and maltose syrup and investigate the detection ability of the methods, and to provide appropriate test methods for testing agencies with different instruments. At first, stable carbon isotopic ratio analysis(SCIRA) and pollen analysis determined the different botanical origins of honey authenticity. The adulterated samples were preparaed by adding 10%, 20%,30% of syrup(w/w) to authentic honey. Then HPLC-ELSD, LC-MS and 1H-NMR were used to determin the difference between authentic honey and adulterate ones. Then the information of selected different signals was used as input variables for partial least squares-discriminant analysis(PLS-DA) to detect adulterants in honey. The results show that:1. Pollen analysis was undertaken as an additional confimation of the correct assignment of floral type.The result of the pollen analysis confirmed that all of the honey samples could be classified as monofloral. However, in one instance a honey had been misclassified. SCIRA not detected adulteration of the selected honey using C4 sugar syrups. The preliminary results show that the honey samples were authentic.2. Taking advantage of hydrophilic interaction liquid chromatographic(HILIC) mode that could best separate galactooligosaccharides(GOS), HPLC-ELSD analysed the saccharide profile comparison between pure honey and sugar syrups. PLS-DA was performed on 8 characteristic peaks of chromatogram. The result shows that the correct classification of the training set is 94.2% and the prediction set is 100%. HPLC-ELSD coupled with PLS-DA was a potential technique for detecting adulterants(HFCS above 10%,maltose above 5%) in honey.3. LC-MS was conducted by using selected ion monitoring(SIM) to analysis the selected parention, including m/z 341, 503, 665, 827 of honey and sugar syrups.Through contrasting the SIM chromatograms of honey and syrups in negative-ion mode, the obvious differences had been found.The signal intensities of every time region where the peak was different were the variables for PLS-DA. This method could successfully classfied the adulterate honey, and there was no overlap in PLS-DA score plot of the honey classification model.4. From a comparison of the 1H-NMR spectrum of an authentic honey with that of an adulterated one, it should be noted that some signals were present only in the adulterated honey or at least were of greater intensity. The signal intensities as a data set were used for PLS-DA model. The model was able to identify honey adultrated with HFCS and authentic honey, while honey adultrated with maltose syrup could not be classfied satisfied.