The Nutrient Requirements Of Lactobacillus Rhamnosus ATCC 53103 And Their Application To Fermented Milk

There are many fermented dairy products prepared by probiotics alone,such as Yakult?Lactobacillus casei strain Shirota?,LAJOIE?Lactobacillus paracasei LPC-37?and Cherita?Lactobacillus rhamnosus GG ATCC 53103?.These fermented dairy products have longer fermentation time.Lactobacillus rhamnosus has many beneficial physiological functions,but the fermentation time is long when fermented milk is prepared by Lactobacillus rhamnosus alone.To shorten the fermentation time,the nutrient consumption and necessary patterns and the essential nutrients of Lactobacillus rhamnosus GG?LGG?were analyzed.Based on the nutrient consumption and necessary patterns and the essential nutrients of LGG,it was compared with the nutrients contained in milk,including amino acids,vitamins,purines and pyrimidines and other growthpromoting factors.Some nutrients lacking in milk were determined,and the effects of these nutrients on the fermentation time with LGG alone were evaluated.And then the nutrients capable of shortening the fermentation time were added to the milk together.The effects of fermented milk by LGG alone with some nutrients lacking in milk on the fermentation time,quality and sensory properties and flavor of fermented milk were evaluated.According to the single omission experiment,Arg,Val,Ile,Phe,Thr,Ser,Gly,Try,Tyr,Cys,pyridoxine,riboflavin and niacinic acid were the essential nutrients of the growth of L.rhamnosus ATCC 53103.According to the consumption patterns of amino acids,it was concluded that the consumption patterns of Thr and Cys were the highest in L.rhamnosus ATCC 53103,respectively 50.77% and 49.60%.Next,Arg,Ile,Phe,Tyr,Leu,Pro,Lys,Asp+Asn and Met were followed,and consumptions of these amino acids exceeded 30% of their initial addition,especially the consumptions of Ile and Leu exceeded 40% of the initial additive amounts.According to the consumption patterns of vitamins,it was concluded that riboflavin was consumed most during the whole growth process,which was 44.55%.According to the consumption patterns of purines and pyrimidines,the consumption patterns of uracil,adenine,guanine and xanthine were 90.44%,88.47%,83.03% and 96.78% respectively in the whole growth process.These purines and pyrimidines were almost consumed completely in the whole growth process of L.rhamnosus ATCC 53103,and the consumptions exceeded 80% of the initial addition.According to the consumption patterns of inorganic salt ions,the consumption of Mn²⁺ exceeded 90% of the initial additive amount,and it was almost consumed completely for the growth and proliferation of L.rhamnosus ATCC 53103.According to the necessary profiles of amino acids,the most necessary amount was Val,and its necessary account was 15.59% of the total necessary accounts of amino acids,which was significantly higher than the necessary accounts of other amino acids for the growth of L.rhamnosus ATCC 53103.They were followed by Glu+Gln,Phe and Asp+Asn,respectively 9.60%,8.81% and 8.31%.Leu,Lys,Tyr,Cys,Met and Ala were next,and the necessary patterns were between 5% and 7%.According to the consumption and necessary patterns of amino acids,the consumption patterns of purine,pyrimidine,vitamins,metal ions and essential nutrients of L.rhamnosus ATCC 53103 as well as nutrients in milk,some nutrients shortening fermentation time were selected,and Cys,Ser,Arg,Pro,Asp,Glu,guanine,uracil,and xanthine were selected to supplement milk.Compared with fermented milk prepared with unmodified milk by L.rhamnosus ATCC 53103 alone,the fermentation time was shortened by 5 hours through nutrient supplements in milk.Furthermore,the cell viable counts,titratable acidity and water-retaining capability were improved through nutrient supplements.The textural properties,flavor compounds and sensory properties of fermented milk prepared by L.rhamnosus ATCC 53103 alone with unmodified milk and modified milk had no obvious differences.According to the nutrient consumption and necessary patterns and the essential nutrients of L.rhamnosus ATCC 53103,the fermentation time of fermented milk prepared by Lactobacillus rhamnosus alone was reduced by supplementing some nutrients lacking in milk in the present study.And the cell viable counts,titratable acidity and water-retaining capability were improved significantly.Furthermore,the supplementation of nutrients did not obviously change the texture and sensory characteristics and flavor compounds of fermented milk.