The Nutrient Requirements Of Lactobacillus Casei Shirota And Their Application To Fermented Milk

In order to meet market demand and avoid the phenomenon of homogenization of fermented milk,and to strengthen the personalized special physiological functions of probiotics,some single probiotic fermented milk,for example,yakult（Lactobacillus casei Shirota）,LAJOIE（L.paracasei LPC-37）,Cherita（L.rhamnosus GG ATCC 53103）,etc.,appears on the market These fermented milk is fermented by single probiotics,which has the problem of too long fermentation time Lactobacillus casei Shirota has many probiotic functions,but fermented milk prepared with L.casei Shirota as the sole starter needs a long fermentation time.In order to shorten the fermentation time of fermented milk prepared by L.casei Shirota,this thesis studies the necessity of nutrients for the growth of L.casei Shirota,analyzes the consumption patterns and demand patterns,also analyzes necessary nutrients,stimulating nutrients and non-essential nutrients of L.casei Shirota.By comparing with the type and contents of nutrients contained i n cow’s milk,the types and contents of nutritional components that are lacking in the growth of L.casei Shirota in cow’s milk were obtained through analysis.Then the single nutritional components were added to the milk to evaluate the effect of nutritional factors on the fermentation time of L.casei Shirota,and the nutritional components that promoted the fermentation of L.casei Shirota were screened.After these nutritional components were added to cow’s milk to prepare L.casei Shirota fermented milk,the effects of compound nutritional components on the viable count,fermentation time,quality and flavor of fermented milk were analyzed.The experimental results of amino acid consumption model showed that during the entire growth process of L.casei Shirota,the consumption rates of Thr,Leu and Ile were the highest,which were 42.02%,40.04%,and 39.14%,respectively;followed by Phe,Lys,Tyr,Arg,Met,Asp+Asn,Val,Pro,Ser,Cys and Gly,whose consumption rate all exceeded 30%.The results of the metal ion consumption mode test showed that the consumption rate of Mn²⁺was the highest,being97.35%,and almost all of the consumed Mn²⁺was consumed for the growth and proliferation of L.casei Shirota.The results of the vitamin consumption pattern test showed that riboflavin and calcium pantothenate consumption rates were the highest,which can reach to 38.12%and 27.07%,respectively.The experimental results of the consumption pattern of base substances show that xanthine,uracil,adenine and guanine all have higher consumption rates,and the consumption amounts exceed 80%of the initial addition amount.All four bases are also consumed during the growth and proliferation of l.casei Shirot.The results of the amino acid demand model test show that the demand for Ala is the highest,which can accounts for 12.83%of the total amino acid demand,higher than other amino acids required for the growth of L.casei Shirota.Consumption rates of Val,Glu+Gln,and Asp+Asn,are 12.74%,10.17%,and 9.76%,respectively.The results of single factor removal test of nutritional components showed that Arg,Phe,Leu,Ile,Val,Tyr,Ser,Cys,Trp,calcium pantothenate,pyridoxine,ribof lavin,Mg²⁺and glucose were essential nutrients for the growth of L.casei Shirota..Selecting the high consumption rate nutritional components,high demand rate nutritional components and essential nutritional components which are determined according to the amino acid,vitamin,metal ion,base consumption pattern,amino acid demand pattern analysis results and single factor removal test results of nutritional components to compare with the types and contents of nutrients contained in cow’s milk,then nutrient components that shorten fermentation time of fermented milk are screened out.These nutritional components are Asn,Cys,Pro,Gly,Glu,Try,guanine,xanthine,calcium pantothenate,pyridoxine,Mn²⁺and Mg²⁺,which were added to cow’s milk for the L.casei Shirota fermentation test.The effect of formulation nutritional components on L.casei Shirota fermented milk test showed that the fermentation time of fermented milk samples with nutrient components was 15hours shorter than that without nutrient components.The main flavor substances of L.casei Shirota fermented milk are 2-nonanone,ethanol,dodecyl alcohol,acetic acid,propionic acid,hexanoic acid,and octanoic acid.The addition of nutrients did not adversely affect the quality and flavor of fermented milk,as there were no significant differences in the content of flavor substances in the two groups of fermented milk.The addition of nutritional components to cow milk has improved the water retention of fermented milk prepared by L.casei Shirota to a certain extent.No significant difference was detected in the hardness,viscosity,elasticity,and cohesiveness of the L.casei Shirota fermented milk sample with added nutritional components compared with the sample without added nutritional components,indicating that the addition of nutrients to cow’s milk has no significant effect on the texture of fermented milk prepared by L.casei Shirota.In addition,during the 28-day storage period of the two groups of fermented milk samples,the number of viable bacteria in L.casei Shirota remained above 107 cfu/m L,and the number of viable bacteria in L.casei Shirota fermented milk samples with added nutritional components was higher than that without addition.Nutritional component L.casei Shirota fermented milk sample.