Technological Optimization And Changes Of Main Aroma Components In Cyclocarya Paliurus Tea Wine

Cyclocarya paliurus leaves are rich in natural bioactive components such as flavonoids,polysaccharides,triterpenoid saponins,alkaloids,organic acids,vitamins and a variety of trace elements.These active components and elements can effectively regulate human function.Among them,flavonoids and polysaccharides,the main active components of cyclocarya paliurus,have the functions of regulating blood lipid,reducing blood sugar,immune regulation,anti-tumor,antioxidant and so on.In this study,the freeze-dried leaves of cyclocarya paliurus were used as raw materials to develop a fermented cyclocarya paliurus tea wine.The physicochemical indexes,stability,antioxidant activity and main aroma components of the wine were determined and analyzed,the results are as follows:(1)Using freeze-dried cyclocarya paliurus leaves as raw materials,smash them through a 60-mesh sieve,and takes flavone and polysaccharide yield as the main measurement index.The single factor test is carried out on 8 factors,including enzyme type,enzyme addition,enzyme hydrolysis temperature,enzyme solution time,material liquid ratio,extraction temperature and extraction time.The optimum technological parameters of enzymatic extraction are preliminarily determined.Then,the process was further optimized by weighted comprehensive score method and response surface method,and the optimal extraction conditions were obtained as follows: single cellulase,enzyme addition 1.55%,p H4.6,enzymatic hydrolysis temperature 39.4 ℃,enzymatic hydrolysis time 90 min,material-liquid ratio 1:21 extraction temperature60 ℃,extraction time 121 min.Under the optimal conditions,the yield of flavonoids and polysaccharides were 15.18% and 9.74% respectively.(2)The fermentation technology of tea wine was studied by using the optimal extraction technology of cyclocarya paliurus tea.The influence of initial sugar degree,yeast inoculation amount and fermentation temperature on SSC change trend,alcohol degree and sensory evaluation during fermentation was studied through single factor test and orthogonal optimization test.The optimum fermentation conditions were determined as follows: the initial sugar degree was 14 °BX,the inoculation amount of yeast was 5%,the fermentation temperature was 25 ℃,and the main fermentation days were 10 days.The tea wine obtained under the best fermentation conditions has brownish red color,transparent and bright,no precipitation,and has both wine and tea flavor.The tea flavor is slightly weaker than the wine flavor,and the taste is mellow and harmonious,and the style is different and has its characteristics.The results showed that the final SSC of tea wine was 4.6%,p H 3.55,alcohol 8% vol,total acid content 3.02 g/l,tea polyphenol content 471.20 mg/L,flavonoid and polysaccharide yield 11.68%,9.43%.(3)The stability of the finished tea wine after fermentation,clarification and sterilization was studied.The results show that the cold treatment stability,tartar stability,and alcohol stability of the cyclocarya paliurus finished wine are better,but the stability of heat treatment,photooxidation and oxidation are poor.Meanwhile,the experiment of biological treatment showed that the color,flavor and aroma of the wine were significantly affected when placed in a high temperature environment.The reduction ability,DPPH free radical and hydroxyl radical scavenging ability of cyclocarya paliurus tea wine were measured by in vitro oxidation resistance method.The results showed that compared with ascorbic acid solution of 0.1g/l,cyclocarya paliurus tea decoction and tea wine had stronger reduction ability and DPPH free radical scavenging ability,the antioxidant activity was similar.The ability of cyclocarya paliurus tea decoction to remove hydroxyl radicals was slightly higher than that of tea wine,but both of them were better than ascorbic acid solution.(4)Using HP-SPME and GC-MS combined technology to detect and analyze the aroma components of cyclocarya paliurus tea wine before and after fermentation and the finished wine,combined with retention index,similarity comparison,and consulting related literature for joint analysis.It is preliminarily identified that there are 86 main aroma components in cyclocarya paliurus tea,of which alcohol compounds account for the largest proportion,with a total of 27,accounting for about31% of the total number,and the proportion of each aroma component is relatively dispersed.There are 57 kinds of main aroma components in cyclocarya paliurus tea wine after fermentation,including 15 alcohols,15 esters,7 acids,7 alkanes,6 ketones,2 olefins,2 phenols and 1 aldehydes.The highest content of the compounds were ethanol(26.40%),isopentyl alcohol(25.60%),1,3-butanediol(25.39%),α-terpineol(3.88%),phenylethanol(2.98%),2-chloro-2-nitropropane(2.64%),octanoic acid(1.34%),ethyl octanoate(0.85%),ethyl n-hexanoate(0.61%).There are 44 kinds of main aroma components in the finished wine,and the alcohol accounts for 86.22%.Comprehensive analysis shows that the main aroma components of cyclocarya paliurus tea wine changed significantly before and after fermentation.Alcohols,aldehydes,ketones,alkanes,olefins and phenols were all decreased,among the types of alcohols and aldehydes compounds changed the most,the types of esters and acid compounds have increased,and the types of aroma components of the finished wine are slightly lower than that of the tea wine after fermentation,but the changes are not significant.