Changes In Physicochemical Properties Of Yeast Fermented Cherry Juice And Preparation Of Cherry Fruit Powder

Cherry,also known as Warbler peach,contains more vitamins,minerals,organic acids and other health factors in its pulp.The market for cherries is very broad,and the products known to be made from cherries are: cherry pulp is used to make cherry juice or the compound drink that adds with other fruit according to certain proportion to make with cherry wine,cherry vinegar,cherry preserved fruit,can,jam and jelly.Because cherry is known as the first fruit early spring is long is fast,easy to appear cluster phenomenon in the market,and easy to rot,the technology of storage and preservation of cherries is not yet able to meet the needs of people,which makes the cherry can't open the popularity of large area,the sale is limited,The deep processing of cherry provides a basis for the development and utilization of high quality cherry products.In this study,cherry was selected as the experimental material to study the optimal technological conditions for yeast fermentation of cherry juice,the changes of its active components before and after cherry juice fermentation,the changes of its active components at different storage times,the process optimization of cherry powder preparation and the changes of its active components before and after spray drying.The main research results are as follows:1.Changes of active components in cherry juice before and after fermentation: Using cherry as raw material,the fermentation process of cherry juice by yeast was optimized by single factor test and orthogonal experiment.The activity of superoxide dismutase,scavenging rate of superoxide anion radical and sensory evaluation were used as evaluation indexes.The optimum conditions for fermentation of cherry juice by yeast were as follows: fermentation time 30 h,fermentation temperature 30 ?,inoculum volume 0.5%,under these conditions,the scavenging rate of superoxide anion radical was the highest,99.6%,the activity of superoxide dismutase was 2684.211 U / mL,and the sensory score was 94.2.Changes of active components in cherry juice before and after fermentation:The activity of SOD in fermented cherry juice was significantly higher than that before fermentation.The scavenging rates of superoxide anion free radicals,hydroxyl free radicals and DPPH free radicals in the fermented cherry juice were 99.7%,97.2% and 95.0% respectively,which were all improved to different degrees compared with those before fermentation.The contents of total flavonoids,polyphenols,ascorbic acid,pH and organic acid were significantly increased compared with those before fermentation.The total sugar content decreased significantly,from 59.18 mg/L before fermentation to 42.81 mg/L.3.The change of active components in different storage time: In different storage time,the change of SOD activity was significant,first increased and then decreased with the change of storage time.The free radical scavenging rate showed a decreasing trend,the scavenging rate of DPPH radical was lower and the decreasing trend was obvious.The content of total flavonoids,total phenol and total acid decreased rapidly in the storage process,and the content of total sugar decreased faster in the early stage of storage and slowly in the later stage of storage.On the contrary,the content of ascorbic acid decreased slowly at the early stage of storage,and decreased faster at the later stage of storage,while the value of pH increased slowly at first and then decreased at the end of storage,and the trend of decrease was faster.4.Process optimization of cherry powder preparation: In the process of preparing cherry fruit powder by spray drying,the ratio of solid to dry agent,inlet air temperature and material flow rate were used as the influencing factors,and the spray drying rate of cherry juice was used as the evaluation index,the optimum technological parameters for the preparation of cherry powder were obtained.Results show that the optimum process conditions of spray drying of solids and help dry agent ratio of 3:7,inlet air temperature of 190 ?,material flow of 600 mL/h,under these conditions,the spray drying rate of cherry juice was the highest,17.79%.5.Changes of active components before and after spray drying: After the spray drying of cherry fruit juice,most of its active components were reduced to varying degrees,including the content of total flavonoids,polyphenols,total sugars,organic acids and ascorbic acid,as well as the enzyme activity and antioxidant activity,while the pH value was slightly increased from 3.52 to 3.54.