Study On Functional Properties And Aroma Of Rose Paste

Rose has a variety of functional activities and unique odor,and the production of rose paste has a long history.The traditional production method is made by mixed fermentation of rose petals,white sugar,brown sugar and so on.In this study,the functional properties such as antioxidant activity,Angiotensin-converting enzyme(ACE)inhibitory activity and related chemical components of rose paste were investigated,and the aroma components were analyzed.Then Lactobacillus plantarum was inoculated to ferment rose paste,and compared with uninoculated samples,the changes of chemical components,functional activity and volatile components in the fermentation process were investigated.The purpose of this paper was to deeply tap the potential value of edible roses and enrich the variety of rose paste products,in order to promote the in-depth research of rose paste products and promote the diversified development of edible rose derivative products and the development of related industries.The water extract of rose paste showed good antioxidant activity and ACE inhibitory activity,and the contents of total phenols and total flavonoids were 0.81-3.86 mg GAE/g FW and 0.17-0.81 mg CE/g FW,respectively.There was little difference in the color of the products,and polyphenol oxidase(PPO)was a common enzyme to promote the degradation of anthocyanins.The main flavor components in rose paste were alcohols,in which linalool,(R)-(+)-β-citronellol,nerol,geraniol,phenylacetaldehyde,dipentene,1-caryophyllene,benzyl alcohol,citral and 1-methyl-4-(1-methylethylidene)-cyclohexene can be regarded as the key flavor substances of rose paste.Rose paste was fermented by Lactobacillus plantarum using rose at flower bract stage as raw material.During the fermentation,the p H of the samples decreased and the total sugar content increased.Fermentation increased the brightness of the sample and browned faster,and found that PPO and peroxidase(POD)mainly affected the degradation of flower color.The antioxidant activity of fermentation samples was generally higher than that of commercial samples,and the scavenging ability of ABTS+ was the strongest.The highest inhibition rate of ACE was 88.81% at 24 mg/m L.The contents of total phenols and total flavonoids were 7.51-7.86 mg GAE/g FW and 0.95-1.28 mg CE/g FW,respectively.With the detection of more flavor substances in fermentation,the number of alcohols showed an obvious increasing trend,and its concentration was the highest.The total concentrations of alcohols,aldehydes,alkenes,esters and ketones reached the highest point in 2 days.A variety of new substances were detected in the later stage of fermentation,such as 3,7-dimethyl-2,6-Octadien-1-ol,3,7-dimethyl-6-Octen-1-ol acetate,Aromandendrene,etc.Strain fermentation enriches the flavor of rose paste,which not only has the characteristic flavor components of rose paste,but also has the flavors of fermented cocoa and coffee,nutty,malt,leaf,holly oil and clove,produced by Hexanal,2-methyl-butanal,2-Hexenal,methyl salicylate,Methyleugenol and so on.By analyzing the main metabolic pathways of different substances in the fermentation process,it was found that some pathways alone promoted the production of flavor substances,such as amino acid-related metabolism,lipid metabolism,2-methyl-D-erythritol-4-phosphate pathway(MEP)and mevalonate pathway(MVA)and so on.There are many pathways to participate,in addition to the above,it also involves special reactions of terpenes such as geraniol degradation,and the activities of different pathways are quite different.In addition,the participation of some chemical reactions and enzymes also affect the formation of flavor.It was found that the color of rose paste was also related to the aroma substances.Some chemical reactions and the participation of enzymes also affect the formation of flavor.It was also found that the color of rose paste was also related to the aroma substances.The above provides a theoretical basis for continuing to develop functional products of edible roses and promoting the enrichment of volatile flavor.