The Difference Of Components Between Mature Honey And Immature Honey By Metabolomics

Honey maturity is an important factor in evaluating the quality of honey;however,there are few studies on the metabolites difference of the formation of mature honey.To confirm the identity of immature honey and mature honey and know them better,the physicochemical and antioxidant activity analysis in rape(Brassica rapa L.),acacia(Robinia pseudacacia L.)and jujube(Ziziphus jujuba Mill.)honey at different maturity stages were firstly performed.Furthermore,mature honey was found to have a distinct fatty acids profile to immature honey,and 2-decenedioic acid was further recognized as a potential marker to discriminate immature honey and mature honey.This study could not only provide research direction and theories for revealing the molecular mechanism of mature honey formation,but also provide reference for the authenticity identification on the other bee-products.The thesis was divided into five chapters and results are as follows:1.Based on the determination of ten of physicochemical parameters,the difference of antioxidant activity in vitro in three types of honey at different maturity stages was further analyzed.The results showed that the contents of water and sucrose were decreased whileα-amylase activity,frucose and glucose were increased;and the content of total phenol was increased,besides,ferric reducing power,DPPH radical scavenging activity and ferrous ionchelating activity were consistently enhanced during honey ripening.2.The metabolites of rape stomach honey,immature honey and mature honey were identified by UPLC-QTOF-MS/MS combined with untargeted metabolomics.Mature honey was found to have a distinct metabolic profile to immature honey,and a total of 9 different metabolites were obtained by multivariate statistical analysis,6 of which were accumulated in immature honey and 3 of which,including 2-decenedioic acid,were accumulated in mature honey(P<0.01).3.The differences of free fatty acids in mature and immature rape,acacia and jujube honey were identified by GC-MS combined with targeted metabolomics.The results showed that the responses of 2-decenedioic acid in mature rape,acacia and jujube honey were consistently 2.40,2.38,and 4.88 times higher those that in immature honey,respectively(P<0.01),and regarded as a potential marker to discriminate the immature honey and mature honey.Besides,myristic,myristoleic,and behenic acids were significantly accumulated in mature honeys(P<0.05).4.The differences of bee-originated fatty acids in mature and immature rape,acacia and jujube honey were identified by GC-MS combined with targeted metabolomics.The results showed that the contents of 2-decenedioic acid in mature rape(18.63±1.70 mg/kg honey),acacia(12.15±1.54 mg/kg honey)and jujube honey(35.63±1.21 mg/kg honey)were significantly higher than that in immature honeys(P<0.05).Besides,the contents of azelaic acid in acacia honey and 7 and 8-hydroxyoctanoic acid,3,10-dihydroxydecanoic acid,3-hydroxydecanoic acid in jujube honey were significantly richer in mature samples(P<0.01),oppositely,the contents of 3,10-dihydroxydecanoic acid,3-hydroxysebacic acid and 10-hydroxydecanoic acid in acacia honey and 9-hydroxy-2-decenoic acid in jujube honey were significantly richer in immature samples(P<0.05).