The Research Of Technology And Functional Active Ingredients For Litchi Juice Mixed Strains Fermentation

This paper takes litchi juice as raw material,inoculating yeast and lactic acid bacteria fermentation,mainly discussed from the strains screening,process optimization,detection of fermented functional ingredients,analysis of fermented liquid antioxidant activity and so on.The main results were as follows:(1)Through drawing the yeast and lactic acid bacteria strains growth curve,getting the optimal litchi fermentation strains respectively.Yeast strains screening results for wine and fruit wine yeast mix fermentation,strain ratio of 3:7(v/v),lactic acid bacteria strains screening results for streptococcus thermophilus and lactobacillus Bulgaria mixed fermentation,strain ratio of 8:2(v/v).(2)The experiment on the basis of single factor and orthogonal experiment getting the yeast and lactic acid bacteria optimal fermentation conditions was fermentation time 24 and16 h,fermentation temperature 25 °C and 37 °C,inoculum size 4% and 2%,Then on the basis of single factor and response surface experiment getting the optimal fermentation substrate was initial soluble solids content at 20 °Brix,N source content at 1.0%,phosphate content at 0.4% and pH 3.0,the superoxide dismutase(SOD),amylase activity and total phenolic content were 52.17 U/m L,12.15 U/m L and 12.76 mg /100 m L.(3)The fermented liquid four functional enzyme activity were increased during the process of fermentation,the maximum of SOD enzyme,amylase,protease,lipase activity was 51.69 U/m L,12.34 U/m L,4.89 U/m L,0.53 U/m L;Total sugar content gradually reduce,microbes for glucose utilization ratio up to 87.11%,followed by sugar 76.54% and fructose 60.25%;Total phenol and total acid content increased gradually,tartaric acid content reduced,the content of lactate,oxalic acid,malic acid,citric acid,succinic acid increased and pyruvic acid content showed a trend of increased after the first reduced.(4)The litch fermented liquid antioxidant activity enhanced gradually during the process of fermentation,and fermented liquid ABTS radical scavenging capacity >Hydroxyl rsc > Superoxide rsc> DPPH rsc.there was no significant correlation between hydroxyl radical scavenging ability with other antioxidant index,total phenol content andenzyme activity,DPPH,ABTS,superoxide radical scavenging ability with total phenol content and enzyme activity were significant or extremely significant correlation.(5)The vitro digestion experiments show that,during the process of simulated stomach digestive the litch fermented liquid total phenol content was promote,caused by gastric acid environment and stomach digestive enzymes,the liquid SOD and amylase activity promoted smaller,and the liquid antioxidant capacity has a promoting effect on the whole,but main caused by stomach digestive enzyme.During the simulated intestinal digestion the litch fermented liquid total phenol content and amylase activity were promoting,the SOD enzyme activity had not significant inhibition,the hydroxyl removal ability had certain inhibition,and ABTS removal ability had a promotion.(6)The litch fermented liquid under the condition of four types of(sterile 4 °C and25 °C,non-sterili 4 °C and 25 °C)storage experiments show that,the sterile fermented liquid reducing sugar content and antioxidant activity is slightly higher,however total phenol content,total acid contentand SOD activity decreased,4 °C storage fermented liquid reducing sugar content,total phenol content and SOD activity changes were relatively stable,non-sterili groups fermented liquid total acid content have a certain decline,steril groups total acid content was relatively stable,4 °C groups hydroxyl and ABTS radical scavenging ability is higher than 25 °C storage fermented liquid.(7)By the amino acid detection for before and after fermentation and 40 days storage fermented liquid,the fermented liquid total amino acid drop after fermentation,g-ABA content increased,the sterili storage groups fermented liquid amino acids higher than non-sterili groups,low temperature 4 °C storage groups fermented liquid remained higher content of amino acid,this suggests that low temperature conditions conducive to the retention and stability of the amino acids.