| Honey is a natural health food which is nutritious and has great market potential.However,in recent years,honey adulteration incidents occurred frequently,seriously damaging the legitimate rights and interests of consumers.Therefore,the quality control of honey is of great significance.High quality honey is not allowed to add any exogenous syrups and other additives,but also not to be heated and concentrated.?-dicarbonyl compounds are kind of typical productions of Maillard reaction,are widely used to monitor nutritional quality during food processing.At present,the research on ?-dicarbonyl compounds in beeproducts is limited.In this study,?-dicarbonyl compounds were used as potential markers to study the application of rapid screening of adulterated honey,detection of syrup adulterated honey,discrimination of natural and heated honey.Research on application in the rapid screening of adulterated honey: the quinoxaline compound formed by the reaction of ?-dicarbonyl compound with o-phenylenediamine is a rigid structure with strong fluorescent properties.Therefore,the difference of ?-dicarbonyl compounds between honey and syrup directly causes a difference in fluorescence spectra.Significantly,it has been found that the intensity of the second harmonic generation(SHG)peak in 740 nm can effectively distinguish honey from syrup.According to the characteristic fluorescence spectrum combined with the intensity of SHG,honey adulterated with 30% syrup can be effectively recognized.Advantageously,the fluorescence method is simple to operate,and the data acquisition time is as low as about 1 min,which can be used as a routine method for rapid screening of adulterated honey.Research on application in the detection of syrup adulterated honey: Currently,commercial standard products of ?-dicarbonyl compounds is difficult to obtain.In our study,the reaction system of ?-dicarbonyl compounds is optimized according to several published researches,and the main the quinoxaline compounds formed by the reaction of ?-dicarbonyl compounds with o-phenylenediamine were prepared and obtained,including glucosone(GS),glyoxal(GO),methylglyoxal(MGO),2,3-butanedione(2,3-BD),3-deoxyglucosone(3-DG),1-deoxyglucosone(1-DG),3,4-dideoxyglucosone-3-ENE(3,4-DGE),2,3-pentosulose(2,3-PS),1,4-dideoxypentosulose(1,4-DDP),1,4-dideoxyglucosone(1,4-DDG),1-deoxy-2,3-pentosulose(1-DP),3-deoxy-1,2-pentosulose(3-DP).All is more than 95%(HPLC purity).Based on mass,MS/MS fragmentation analysis,and literature comparisons,the structure of 12 ?-dicarbonyl compounds were confirmed.A new method for detemination of 12 ophenylenediamine derivatives of ?-dicarbonyl compounds by Ultra-high performance liquid chromatography-ultraviolet-quadrupole time-of-flight mass spectrometry(UHPLC-UV-Q-TOF/MS)was developed.And the distribution of 12 ?-dicarbonyl compounds were investigated in honey and syrup samples.The result showed that the content of ?-dicarbonyl compounds in syrup is generally higher than that of honey,and its total content is 3-5 times than that of honey.And 1,4-DDP is an unique ?-dicarbonyl compound in syrup,which is not detected in honey and can be used as a potential marker for identifying the adulterated honey with syrup.Research on application in the identification of natural and heated honey: Heated honey loses a lot of nutrients and may contain some harmful substances.The acacia honey was taken as the research object,and heated at temperatures of 45 ?,50 ?,55 ?,60 ?,65 ?,70 ?,75 ?,80 ? under certain vacuum to investigate the variation of ?-dicarbonyl compounds at different temperatures.Due to the high-content and relative stability,3-DG was selected as the characteristic compound for evaluating the heating process.3-DG in natural and heated honey was accurately quantified.The result showed that the content of 3-DG in the heated acacia honey was much higher than that of the natural acacia honey. |
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