Study On The Application Of Lactobacillus Plantarum P9 In Fermented Milk

In this study,Lactobacillus plantarum P9 with pesticide degradation ability and commercial starter YF-L904(including Streptococcus thermophilus and Lactobacillus bulgaricus)were used for the fermentation of set milk.The comprehensive evaluation were based on the fermentation characteristics,rheological,texture,storage stability,exopolysaccharide content and the microstructure of fermented milk.The potential application of Lactobacillus plantarum P9 in fermented milk was discussed systematically.On basis of results,the conclusions are made as follows:(1)The commercial fermentation starter YF-L904 and Lactobacillus plantarum P9(1.0×105 CFU/mL,1.0×106 CFU/mL,1.0×107 CFU/mL)with different inoculation amount were used for fermentation.All the four groups reached the end of fermentation in 6 hours(pH<4.6);During storage,the group Lactobacillus plantarum P9-1.0×106 were suitable for the requirements of set yogurt,because of the stable acidity,smooth,stable viable counts,high hardness,high sensory evaluation score.(2)During the storage,the content of exopolysaccharide in the Lactobacillus plantarum P9-1.0×106 was significantly higher than that in the other groups(p<0.05),reaching 55 mg/L at 14 days;Thixotropy analysis showed that under the action of external force,the structure recovery ability was the slowest on the first day,faster on the seventh day,and the overall recovery ability was the best(p<0.05);The particle stability index of the sample was low and the stability was high;the microstructure of the sample changed little at 28 days,illustrate the quality of probiotic fermented milk was stable.In summary,Lactobacillus plantarum P9 was mixed with commercial fermentation agent in the amount of 1.0×106 CFU/mL to Obtain probiotic fermented milk with excellent sensory properties and texture.It provides theoretical data support for the development of fermented milk products.