Preliminary Study On The Evaluation Index Of Maturity In Natural Ripening Process Of Rape Honey

China is the biggest beekeeping country,which its honey production and export volume have consistently ranked the first in the world.However,China isn’t a strong beekeeping country for the reason that the major honey producers of the world,only China produces and exports processed honey,which is extremely inconsistent with the development trend of the world’s beekeeping industry.The immature honey cause the increase of honey storage and processing cost and the instability of a number of indicators.Besides,the quality of domestic honey can’t be compared with similar foreign products,and the price is significantly lower.At present,there is no definition of mature honey in China,and few relevant studies.In order to establish the identification system of mature honey,it is necessary to firstly make clear the relevant indexes of mature honey.And the research on the natural ripening process of honey is helpful for the formulation of the relevant standards of mature honey.We taked rape honey samples in different ripening days as research subjects,and measured conventional physicochemical parameters,related enzymes activities,antioxidant activity,antibacterial activity and volatile substances.We found that some indicators of rape honey changed regularly during ripening process.The results of this study are as follows:1.We measured the conventional physicochemical parameters of different maturity rape honey.It is found that with the increase of the ripening days of rape honey,the decrease of the water content,sucrose,maltose of honey samples was observed.Glucose,fructose and protein concentration was increased,while the conductivity and pH showed no obvious changes.2.We measured the activities of amylase,sucrose,β-glucosidase and glucose oxidase of rape honey.We found that with the increase of the ripening days of rape honey,the activities of amylase,invertase and β-glucosidase showed an increase.The activities of glucose oxidase increased during the whole ripening process,but slightly declined after being completely capped.3.The antioxidant capacity of the samples was evaluated by DPPH and FRAP methods,and the antibacterial activity against staphylococcus aureus was investigated by agar diffusion experiment.We found that antioxidant capacity and antibacterial activity was enhanced with the increase of the ripening days of rape honey.The contents of total phenols,total flavonoids and proline were positively correlated with the antioxidant capacity.The antibacterial activity enhanced and reached the maximum before being completely capped.H2O2 was the main antibacterial component of rape honey,and its concentration was positively correlated with the activity of glucose oxidase.4.We used headspace gas chromatography-ion mobility spectrometry(HS-GC-IMS)to determine the volatile substances of different ripening days of rape honey.A total of 34 volatile substances were identified.Eight volatile substances including octanol,propyl butyrate,hexanal dimer,propyl acetate,1-butanol monomer,pentanal,butyl acetate and hexanal monomer showed a decline with the increase of ripening days.However,eight volatile substances including nonanal,2-methylbutanoic acid dimer,isovaleric acid,z-3-hexen-1-ol-dimer,acetic acid,furfural,ethyl 2-methylbutyrate and 2-hexanone showed an increase.With the increase of ripening days,benzaldehyde monomer and benzaldehyde dimer decreased first and then increased,while 1-butanol dimer,2-butanone dimer,acetone and methyl isobutyl ketone monomer increased first and then decreased.Among them,hexanal dimer and z-3-hexen-1-ol-dimer maybe potential indicators for identification of rape mature honey.It can identify mature and immature honey by the principal component analysis of volatile substances of rape honey.