Study On The Changes Of Major Functional Component During The Brewing Of Wolfberry Dry Wine And The Comparison Of Different Methods For Accelerating Ageing

As a homologous plant of medicine and food,wolfberry has a long history as a medicinal material and food in China,and is distributed in northwestern China such as Ningxia and Qinghai province.Fresh wolfberry is rich in polysaccharides,flavonoids and other nutrients.However,it is extremely perishable after harvesting,which is not conducive to preservation.Nowadays,wolfberry processed food market is relatively simple,mainly dry products,followed by wolfberry soaked wine and a small amount of fermented wine.The experiment used the fresh fruit of Dulan in Qinghai as raw material to compare and screen the fermentation performance of six kinds of fruit wine yeasts by whole juice fermentation method,and explored the changes of main functional components in the main fermentation stage;the physical method of aging the dry wine,and the method of improving the non-biological stability of the wine,brewing a fragrant,pure taste of dry wine.The study obtained the following results:(1)Comparing the fermentation performances of six kinds of fruit wine yeasts,the test screened out the suitable yeast EC1118 by comprehensive physical and chemical indicators.During fermentation,the wine with EC1118 yeast was rapidly fermented,the rate of hypoglycemic was fast,the ability of alcohol conversion was strong,the content of dry extract was high,and the fermentation was relatively complete;the total acid and total phenol content of obtained yak wine were suitable,and the wine was orange-yellow;the wine was rich in aroma and taste,it also had the typical style and characteristics of wolfberry dry wine and a higher sensory evaluation score.(2)Wolfberry is rich in a variety of functional ingredients,in the main fermentation process,polysaccharides and betaine showed a tendency to change first and then stabilized.Among the main components affecting the color of alcoholism,the content of polyphenols did not change much;the content of flavonoids and carotenoids decreased rapidly at the initial stage of fermentation,and then increased with the increase of alcohol content,the former increased slightly more than the latter.(3)Based on the results of comprehensive physical and chemical indicators,microbial indicators and two oxidase activities,the suitable process parameters of the four physical aging methods were screened.Ultrasonic treatment was carried out at 40℃,500 w power for 30 min;RF aging was 105 mm with plate spacing,40 mm for wine level,and 25 min for 27.12 MHz;60 Co-γ ray and high-energy electron beam irradiation were better at 3 KGy.Electron beam treatment can effectively retain or even enhance the content of polyphenols,polysaccharides and flavonoids in dry wine,and quickly produce various organic acids and esters to promote the ripening of fruit wine and improve the flavor and taste of alcohol.The wine sample after the electron beam treatment,which is an excellent method for assisting the wine,can reach or exceed the aging effect of the control group for 90 d.(4)By single factor test and orthogonal test optimization comparison,the membrane filtration with 0.8 μm pore size had the best clarification effect,which was better than the clarification effect of cold treatment at-4℃ for 20 d,bentonite and composite clarifying agent.The four physical aging methods had a certain effect on improving the non-biological stability of the dry wine,but the overall effect was not satisfactory,and the problems such as pigmentation were still prominent.Membrane filtration combined with cold treatment is a better way to improve the non-biological stability of dry wine.