| Gegen is a commonly used medicine and food resource in China,and it is used as a raw material for health foods or medicines because it is rich in starch and flavonoids.In order to develop Gegen fermented wine,Gegen was used as the raw material,and ultrasonic-assisted double enzyme was used to treat puerarin starch.The liquefaction and saccharification conditions,yeast strain and fermentation parameters of Gegen starch were optimized.The physicochemical properties of Gegen wine during fermentation and aging,the changes of aroma components and main functional components were both analyzed.And the antioxidant activity in vitro was studied to provide theoretical support and process reference for the development of Gegen wine products with rich nutrition and unique flavor.The main conclusions of the study are as follows:(1)Ultrasound-assisted double enzyme was used to study the liquefaction and saccharification process of Gegen starch,and the optimal liquefaction conditions were determined: ultrasonic power 150 W,ultrasonic time 3 min,?-amylase addition amount 25 U/g,liquefaction time 3 h,liquefaction temperature 60 ?;The optimal saccharification process was: ultrasonic power of 200 W,ultrasonic time of 10 min,glucoamylase addition of 100 U/g,saccharification time of 3 h,and saccharification temperature of 65 ?.The final saccharification liquid reducing sugar and total flavonoid content were 14.56 g/100 mL and 64.02 mgRE/100 mL,under the liquefaction and saccharification conditions,which was 11.74% and 14.31% higher than that of the control group respectively.The micro-structure of pueraria starch showed that the ultrasonic treatment improved the liquefaction effect due to the improvement of the structural damage of puerarin starch,but it had little effect on the saccharification effect.(2)It was determined that Lalvin EC1118 yeast is the most suitable yeast for Gegen wine fermentation by comparing the fermentation effects of five kinds of Saccharomyces cerevisiae on Gegen wine.The optimum fermentation conditions of Gegen wine were obtained by single factor and response surface method: the ratio of material to liquid was 1:5,the initial pH of fermentation was 5.6,the fermentation temperature was 27 °C,and the yeast addition was 0.5%.At this time,the obtained Gegen wine with 8.04% alcohol concentration,82.56 mg RE/100 mL total flavonoid content,and 1.20 sensory evaluation grade was yellow,clear and transparent.The fragrance of Pueraria and the wine were harmonious and balanced,and the taste was clear and refreshing.(3)Studies on the aroma components of Gegen wine showed that 43 species were detected in 7 days of fermentation,46 species in 30 days,42 species in 60 days,48 species in 90 days,including alcohols,esters,aldehydes.Classes,ketones,acids and other substances.And 18 key flavor compounds in Gegen wine,5 flavor compounds,and 12 potential flavor compounds were found in Gegen wine by analysis of the key aroma components.Damasone,?-ionone,isoamyl acetate,ethyl octanoate,ethyl hexanoate,etc.are important aroma components after the germination of pueraria.(4)The study on the functional components of Gegen wine during the fermentation and its antioxidant activity in vitro showed,the content of total flavonoids and puerarin in wine both increased gradually in the fermentation process,however the total flavonoids decreased slightly and there was no significant difference in the content of puerarin during the aging process.The antioxidant activity of Gegen wine in vitro was determined as follows: hydroxyl radical scavenging ability > ABTS free radical scavenging capacity > DPPH free radical scavenging ability.In the FRAP evaluation system,Pueraria wine shows better antioxidant capacity in Kudzu wine The FRAP value reached 1204.04 ?mol/L when the addition amount was 0.2 mL. |
PDF Full Text Request