Study On The Functionality Of Streptococcus Thermophilus And The Development And Application Of Its DVS Starter

With the improvement of people's living standard and the change of mass consumption concept,the demand for fermented dairy products has shifted from "basic nutrition" to "green","healthy" and "functional".Low-fat/fat free,low sugar/sugar free products and functional products have gradually become the new favorite on the market.With the development trend of fermented dairy products,new requirements are put forwardfor the functions of starter cultures: the starter culturesshould not only have excellent fermentation performance,but also fine probiotic properties,and good texture characteristics.DVS is used bymost of the yogurt production enterprises,and China DVS market is monopolized by foreign enterprises,little work is done in the research and development of lactic acid bacteria starter with our own property right,which is seriouslyout of accordance with the rapid development of China's dairy industry and people's increasinglygrowingdemand.Therefore,it is imperativeto develop high-quality activestarter of with independent property rights.Streptococcus thermophilus is one of the most important bacteria for yoghurt making.This study screened superior Streptococcus thermophilus strains,researched their growth performance,conducted high density cultivation using skim milkculture medium,and harvested and frozen the bacteria,prepared it into starter,and produced yogurtinindustrial scalewith two kinds of commercial starter as control.A variety of indicators in the fermentation process and a variety ofyogurt qualitieswere determined,the fermentation performance of the starter culturewas evaluated,which providedcertain theoretical basis for the independent development of starter,and did an in-depth study combined with the development trend of the industry.Our aim was to provide a green and healthy dairy food for consumers,to enhance the competitiveness of the enterprises,and to promote the industrial development.This study completed the research such as the characteristics of Streptococcus thermophilus SY-ZJ-01,the probiotic function of fermented milk,batch production test of starter SYLP09,the application of starter SYLP09 in low sugar or sugar free yogurt,the application of starter SYLP09 in the existing products.1.The lactic acid bacteria in the DVSstarter SYLP09 was derived from the Chinese traditional fermented dairy products.It was identified as Streptococcus thermophilus andLactobacillus bulgaricus,and itwas jueged as non-toxic through the grading criteriaof acute toxicity;2.The stability,acid production characteristics and enzyme activity of SY-ZJ-01 strain were studied.It was proved that the strain had the characteristics of fast acid production,strong stability and unique enzyme activity;3.It was found that the strain couldgenerate high content of extracellular polysaccharide(EPS),which had significant immunomodulatory function,could promote the proliferation of bifidobacteria,which was extremely rare in Streptococcus thermophilus;4.The DVSstarter SYLP09 made based on SY-ZJ-01 fully met THE international standard of commercial products,could be used in functional yogurt productswith low fat,no fat,or no additive;5.Batch production was realized in four kinds of products totaling 11 tons,the overall sensory quality of the productshad no obvious differencefrom that ofthe products made with imported starter,their viscosity and flavor was better than that of the productswith imported starter.