Preparation And Functional Evaluation Of The Fermented Juice Of Lonicera Caerulea And Hippophae Rhamnoides

The Lonicera caerulea and Hippophae rhamnoides are rare small berries with both nutritional value and nutritional function.As new characteristic small berries in Heilongjiang Province,they have attracted wide attention in recent years.However,the fruit is small and the seed coat is thin,so it is difficult to pick and transport,and it is easy to break and cause rot and deterioration.Therefore,the sales range of fresh fruit is small and it cannot be widely promoted.In order to solve the above problems,it can be considered to carry out deep processing,change the product form,expand the scope of sales.Lactic acid bacteria not only have the function of probiotics,but also can improve the functional characteristics of fermentation substrate,enhance its stability,change the flavor of food,and improve the nutritional value through fermentation.Therefore,the research on the fermentation technology of Lonicera caerulea and Hippophae rhamnoides compound juice by lactic acid bacteria can provide a new direction for its further processing,and provide a reference for the subsequent processing of Lonicera caerulea and Hippophae rhamnoides rel ated products.In this experiment,Lactobacillus rhamnosus and Lactobacillus acidophilus,which had the probiotic function screened in the laboratory,were used to ferment the fruit juice mixed with Lonicera caerulea and Hippophae rhamnoides,and the pectinase enzymatic hydrolysis process,fermentation substrate and fermentation process were optimized.The functional changes of the fermented beverage with Lonicera caerulea and Hippophae rhamnoides lactic acid bacteria before and after fermentation and during storage were measured.The main research results are as follows:(1)Based on the juice yield of mixed fruit pulp,the optimal conditions of enzymatic hydrolysis were determined by single factor and orthogonal experiments as follows:enzymatic hydrolysis temperature 50 ℃,enzymatic hydrolysis time 2 h,enzyme dosage 0.3%,and the juice yield of mixed fruit pulp reached the highest of(65.38±0.25)%.Compared with the mixture without pectinase enzymatic hydrolysis,the juice yield of the mixed fruit pul p was increased by25.78%.(2)Based on the number of viable bacteria in the fermentation broth at the end of the final fermentation,the best combination of fermentation substrate was determined by single factor and orthogonal experiments as the ratio of Lactobacillus rhanosum to Lactobacillus acidophilus 1:2,the addition amount of carbon source 10%,and the addition amount of nitrogen source 1%.Under these conditions,the maximum number of viable bacteria in the total fermentation broth was4.8×10~8 CFU/m L.(3)Based on the content of polyphenols in the fermentation broth and DPPH free radical scavenging rate at the end of the final fermentation,the optimal combination of fermentation process was determined by single factor and orthogonal tests as fol lows:inoculation amount of lactic acid bacteria 4%,fermentation time 24 h and fermentation temperature 37 ℃.Under these conditions,the content of polyphenols in the final fermentation broth was(2232.35±10.96)g/m L,and the scavenging rate of DPPH free radical was(95.23±0.10)%.(4)After fermentation by lactic acid bacteria,the content of polyphenols in the mixed fruit juice of Lonicera caerulea and Hippophae rhamnoides was significantly increased(P<0.05),which was about 16.74%higher than that before fermentation.The content of flavonoids before fermentation was(2981.30±19.77)g/m L,which was significantly higher than the content of flavonoids in fermentation liquid after fermentation.The scavenging rate of DPPH free radical,hydroxyl free radical and ABTS free radical after fermentation were significantly increased(P<0.05),which were increased by 31.72%,45.66%and 41.50%,respectively,compared with that before fermentation.The results showed that the antioxidant capacity of t he mixed juice of Lonicera caerulea and Hippophae rhamnoides was significantly increased after fermentation by lactic acid bacteria.(5)Under different storage temperature monitoring within 21 d Lonicera caerulea-Hippophae rhamnoides antioxidant activity substance content of lactic acid bacteria fermentation drink,antioxidant capacity,p H value and the change of the sensory evaluation,found that polyphenols and superoxide dismutase(sod)in 37 ℃ as the extension of storage time content is falling fast,flavonoids content is little affected by temperature;The variation trend of antioxidant capacity was similar to that of polyphenol content.Under the condition of 4 ℃,the p H value of the fermented beverage almost did not change,while under the condition of 20 ℃ and 37 ℃,the p H value of the fermented beverage always showed a downward trend,and the higher the temperature was,the faster the decrease rate was.The fermented beverage can maintain good flavor at 4 ℃.