Study On The Process Of Fermentation Of High Acidity Mulberry Vinegar By Probiotics Mixed Bacteria

Mulberry fruit is rich in a variety of nutrients and has numerous biologically active ingredients hence its functional benefits.In 1993,it has been recognized as a kind of natural medicine and functional food by the ministry of health.Mulberry fruit is the main ingredient in mulberry vinegar fermentation and is not only retains the nutritional value but also maintains better sensory evaluation properties such as bright color,unique flavor,and broad development prospects.The current study is based on the acetic acid bacteria screened by the research group,first of all,study the preparation process of acetic acid bacteria HSMC-9.Secondly,in order to enhance the palatability of mulberry vinegar,add the fermentation stage of lactic acid bacteria fermentation stage,and optimize the fermentation process by response surface methodology.Finally,the end product of the mulberry vinegar was treated with different sterilization methods which enable to study its effect on the quality of the mulberry vinegar.This approach offers a theoretical foundation for the industrial production of mulberry vinegar.Research content includes:(1)The effects of different centrifugal speeds and time on the harvest rate of acetic acid bacteria HSMC-9,and determine the centrifugal conditions at 6000 rpm,15 min;establish the survival rate of the lyophilized cells using response surface methodology.The mathematical regression model between the protective agent and the parameters,according to the feasibility of the actual operation,determined the defatted milk concentration 12.1%,maltodextrin concentration 12.0%,sucrose concentration 11.0%.Using the lyophilization survival rate of bacterial cells as an indicator,the mixing ratio of bacterial sludge and compound lyophilization protective agent was determined to be1:1.5.the storage temperature of the acetic acid bacteria HSMC-9 freeze-dried powder was-20?,and the sensory evaluation was good.(2)Using the sensory score as an indicator,the effects of four kinds of lactic acid bacterial strains such as Vege 081,SH-470,KL 47,and the ratio of apple juice to mulberry juice on the quality of mulberry fruit vinegar were assessed The lactic acid bacteria SH-470 was selected and the optimal mixing ratio(2:8)of apple juice and mulberry juice.A mathematical regression model between sensory score and fermentation process parameters was established using response surface analysis,and lactic acid bacteria were determined according to the feasibility of actual operation.According to the feasibility of actual operation,the inoculation concentration of lactic acid bacteria of 1.0%,the fermentation time of lactic acid bacteria of 44h,and malolactic bacteria concentration of 15.3%were the optimum fermentation parameters.(3)The mulberry vinegar was processed by thermal process,microwave thermal processing and high hydrostatic pressure.It was found that the mulberry vinegar after the application of all the three sterilization met the GB19297-2003 health standards for fruit and vegetable juice beverages.The total acid content after high hydrostatic pressure was significantly low compared to the control(P<0.05).The total anthocyanin content,DPPH free radical scavenging capacity,ABTS~+·scavenging capacity and iron reducing capacity were significantly reduced(P<0.05)after thermal process and microwave thermal of mulberry vinegar.On the other hand,after high hydrostatic pressure,the total anthocyanin content,total polyphenol content,total flavonoid content and DPPH free radical scavenging capacity have not showed any changes significantly(P>0.05).Additionally,the characteristic aroma substances were increased substantially.Among them,the reducing power of mulberry vinegar treated with HHP 500 and HHP 600 had no significant changes compared to control(P>0.05).The total phenolic acid content of mulberry vinegar after treatment with different sterilization methods were significantly lower than that of the control(P<0.05).But the effects on p-hydroxybenzoic acid,p-hydroxycinnamic acid and total phenolic acid content of mulberry vinegar treated with HHP 500 were relatively lower with a decreasing of 6.16%,11.27%,and 7.81%,respectively.From the perspective of nutrition and flavor substance retention of mulberry fruit vinegar,mulberry fruit vinegar processed under the condition of HHP 500 was the most suitable.