Component Analysis Of Linden Honey At Different Maturity Stages And Its Antioxidant And Antibacterial Effects In Vitro

Linden honey is a natural sweet substance collected by bees from Linden flowers and transported to the hive until it is brewed and mature.Honey brewing is a physical and biochemical transformation process,and its nutritional and functional components vary.In order to clarify the relevant changes in the process of linden honey maturation,understand the advantages of mature linden honey in quality and physiological function,and better provide reference basis for the identification of mature linden honey,in this experiment,linden honey at different maturity stages was used as raw materials to study the physical and chemical indexes,polyphenols and volatile flavor components,and to explore the antioxidant and antibacterial effects of linden honey at different maturity stages in vitro.The results were as follows:1.By measuring the physical and chemical indexes of linden honey at different maturity stages,it was found that the contents of water and total acid in mature honey were the lowest,17.62%and 21.33 m L/kg respectively;The contents of glucose,fructose and sucrose in mature honey were 36.17%,39.15%and 2.65%respectively;The content of hydroxymethylfurfural is 1.217 mg/kg（<40 mg/kg specified in GB）;The protein content in mature honey was the highest,which was 8.74 mg/g;A total of15 amino acids were detected,including 7 essential amino acids,and the total amount and content of essential amino acids in mature honey were the highest,182.99mg/100g and 46.60 mg/100g respectively;Amylase,sucrose invertase,glucose oxidaseβ-Glucosidase has the strongest activity in mature honey.2.Through the determination of polyphenols in linden honey at different maturity stages,it was found that the contents of total phenols and flavonoids in mature honey were the highest,which were 2.96 mg TE/g and 0.20 mg QE/g respectively;9 polyphenols were detected,among which syringic acid,（+）-catechin and ferulic acid were the main components,with the highest content in mature honey,6511.15 respectivelyμg/kg、1383.42μg/kg and 1262.84μg/kg.3.The electronic nose and GC-MS technology were used to analyze the volatile components of linden honey at different mature stages.It was found that the corresponding electronic nose response values of methane,terpenoids,alcohols,aldehydes and ketones in mature honey were significantly higher than those in immature honey.There are differences in the content and proportion of volatile substances in linden honey at different maturity stages by GC-MS,but they are mainly alcohols,and the volatile components in mature honey are more abundant,including,ethyl 2-（5-methyl-5-vinyltetrahydrofuran-2-yl）propan-2-yl carbonate and1,5,7-Octatrien-3-ol,3,7-dimethyl-may be the potential substances for the difference of volatile components.4.The antioxidant effect of linden honey at different mature stages in vitro was measured.The results showed that mature honey had strong DPPH·scavenging power,ABTS⁺·scavenging power and reducing power.The IC₅₀value of DPPH·scavenging rate of mature honey was 7.24 mg/m L,which was 0.11 times,0.15 times and 0.42times higher than that of flower honey,water honey and immature honey,respectively;The IC₅₀value of ABTS⁺·scavenging rate of mature honey was 20.60 mg/m L,which was 0.69 times,0.75 times and 0.84 times higher than that of flower honey,water honey and immature honey,respectively.The contents of total phenols,total flavonoids and proline in linden honey were significantly positively correlated with antioxidant activity in vitro.The results showed that the antibacterial ability of linden honey increased with the increase of brewing time,and the antibacterial effect of mature honey was the strongest.If the mic and MBC of mature honey are the lowest,the MIC and MBC of E.coli and Staphylococcus aureus are 45%,the MIC of Salmonella is 30%,and the MBC is 60%;In the study of growth kinetic parameters,it was found that the delay time of mature honey was the longest and the bacterial density was the lowest.To sum up,by studying the changes of physical and chemical indexes,polyphenols,volatile flavor components and physiological functions of linden honey during maturation,it can be seen that there are obvious differences between mature honey and immature honey,and the quality and nutritional function of mature linden honey are better than that of immature linden honey.