Producing Technology And Quality Analysis On Nicandra Physaloides Jelly By Lactic Acid Bacteria Fermented

In this study,N.physaloides gum was used as experimental material,and N.physaloides jelly was made by combining lactic acid bacteria and adding appropriate amount of milk and sucrose.By comparing the comprehensive scores of the gel characteristics,water holding capacity,number of lactic acid bacteria and sensory evaluation of N.physaloides jelly,the technological parameters of N.physaloides jelly were adjusted,and the technological process was constructed and optimized.Nutritional components,active components,antioxidant capacity,types and contents of free amino acids,limited microorganisms and shelf life of N.physaloides jelly were tested and studied.The main research results are as follows:1.Screening of the optimal compound ratio of lactic acid bacteria in lactic acid bacteria fermentation of N.physaloides jelly:In order to ensure that lactic acid bacteria can make good use of nutrients in the gel environment,the growth curves of three strains（Streptococcus thermophilus,Lactobacillus bulgaricus and Lactobacillus acidophilus）applied in the production process of lactic acid bacteria fermentation of N.physaloides jelly were measured and the total number of colonies were counted.Finally,it was determined that the three lactic acid bacteria were cultured by secondary activation,and Streptococcus thermophilus was cultured after primary activation（culture conditions:M17 broth medium,static culture,37℃,12 h,1%inoculum）and then cultured according to the above culture conditions for 8h,lactic acid bacteria number of 8.10×10⁸ CFU·m L^-1 can be obtained as the fermentation liquid.Lactobacillus bulgaricus and Lactobacillus acidophilus after a single activation（culture conditions:MRS Broth medium,static culture,37℃,12 h,1%inoculum）,and then cultured to10 h and 8 h according to the above culture conditions,lactic acid bacteria fermentation liquid with the number of 2.80×10⁹ CFU·m L^-1 and 1.62×10⁹ CFU·m L^-1 could be obtained,respectively.All of them met the national standard(lactic acid bacteria number>1×10⁸CFU·m L^-1).The above three strains of lactic acid bacteria were composed of different complex ratios respectively,and inoculated into the pseudo-lactic acid jelly gel environment.The acid producing ability（p H,acidity）,aroma producing ability（acetaldehyde,diacetyl）and the number of lactic acid bacteria in the gel environment were used as the evaluation criteria.The results showed that when the complex ratio of lactic acid bacteria was St:Lb:La=1:1:2,it would be more suitable for the gel environment of N.physaloides jelly.2.Production process of lactic acid bacteria fermentation N.physaloides jelly:On the basis of the optimal compound ratio experiment of lactic acid bacteria,A single-factor experiment was conducted to determine the range of influence of each experimental factor,and an additional Plackett-Burman experiment was performed to screen for experimental factors that had a significant influence on the fermentation process of the lactic acid bacteria N.physaloides jelly.Finally,Box-Behnken experiment was carried out to optimize the production process of lactic acid bacteria fermented N.physaloides jelly.The experimental results show that:The ratio of material to liquid,the amount of milk added,the amount of sucrose added and the fermentation temperature had significant effects on the production process of lactic acid bacteria fermented N.physaloides jelly,and the influence degree was milk added>fermentation temperature>the ratio of material to liquid>the amount of sucrose added.In addition,Box-Behnken experiment showed that the optimal technological conditions of lactic acid bacteria fermentation of f N.physaloides jelly were as follows:solid-liquid ratio of 1:18（g:m L）,milk content of 5%,sucrose content of 7%,fermentation temperature of 38℃.Under these technological conditions,the comprehensive score was 72.11 points.3.Quality analysis of lactic acid bacteria fermentation N.physaloides jelly:Nutritional composition,active ingredient,free amino acid type and content,antioxidant capacity and microbial content of N.physaloides jelly under the optimal production process were determined,and compared with commercially available lactic acid bacteria jelly,the results showed that:In terms of nutrient composition,the energy of N.physaloides jelly was 114.00 k J·（100g）^-1,the protein content was 0.43 g·（100g）^-1,the fat content was0.27 g·（100g）^-1,the carbohydrate content was 6.67 g·（100g）^-1,and the protein content was 0.43 g·（100g）^-1.Trace elements sodium ion and calcium ion are 5.17 g·（100g）^-1,64.87 g·（100g）^-1,and lactic acid bacteria count is3.08x10⁸ CFU·g^-1.Compared with commercially available lactic acid bacteria jelly,it has higher nutritional value,and is rich in probiotics.More beneficial to human health.In terms of active ingredients,the total flavonoid content and total polyphenol content of N.physaloides jelly were 0.09 mg·g^-1 and 122.46 mg·g^-1,respectively.Compared with the commercial lactic acid bacteria jelly and N.physaloides jelly,N.physaloides jelly had stronger antioxidant capacity（DPPH clearance rate was 5.03%,ABTS clearance rate was 8.11%）.These results indicated that lactic acid bacteria fermentation could significantly increase the contents of total flavonoids and total polyphenols in N.physaloides jelly.so as to improve the antioxidant capacity of N.physaloides jelly.In addition,N.physaloides jelly also contains 12 types of amino acids,the content of essential amino acid LYS is the highest,which is 5.57 mg·g^-1,followed by the content of non-essential amino acid SER,which is 6.03 mg·g^-1.Compared with commercially available lactic acid bacteria jelly,it has more amino acid types and higher amino acid content.The results of E.coli,mold,yeast and other microorganisms were in line with national standards.4.Storage experiment of lactic acid bacteria fermentation pseudo-sour jelly:The pseudo-sour jelly was placed in the refrigerator at 4℃,and the changes of p H,acidity,number of lactic acid bacteria,water holding capacity,elasticity and sensory perception were explored within 15days.Finally,combined with the experimental results of each index,it was determined that the pseudo-sour jelly would have a better taste after eating within 7 days.