Study On The Cholesterol-lowering Activity And Quality Of Low-fat Cheese With Probiotics And Prebiotics

Cheese is a good carrier of probiotics,with the improvement of the nutritional awareness of the consumers,and increasing demand for low-fat cheese.Probiotics low-fat cheese can not only reduce fat intake,but also better protect the functional properties of probiotics.Excessive cholesterol intake is the main cause of cardiovascular and cerebrovascular diseases and the study on how to reduce the level of serum cholesterol is widely concerned.The study found that some probiotics and their dairy products have the ability to reduce human serum cholesterol and regulate blood lipid metabolism.The key to play its cholesterol-lowering activity is to maintain the bacterial activity and make it stable proliferate in the intestines.Prebiotics can selectively stimulate the gastrointestinal tract in the growth of beneficial bacteria and auxiliary probiotics play its function,and can be probiotic fermentation to produce substances that regulate blood lipids.At present,the research of low fat diet and the probiotics cheese that can reduce human serum cholesterol has been widely concerned by the academic circles.However,the specific screening of cholesterol-lowering strains,the retention of the cholesterol-lowering activity of cheese and the cholesterol-degradation mechanism in the body have not been clear.The main topic is the screening of probiotics has high cholesterol-lowering activity,combined with prebiotics used in low-fat cheese,and study on the effect of probiotics and probiotics combination on the cholesterol-lowering activity and quality of low-fat cheese,then optimal process conditions for cheese are optimized.The effect of probiotics low-fat cheese on cholesterol-lowering in vivo was explored by mouse experiment and its mechanism was explored,so as to provide theoretical basis for the application of cholesterol-lowering strain and the development of dairy products with cholesterol-lowering function.The conclusions are as follows:1.Lactobacillus plantarum KLDS 1.0320 was cultivated and determined its growth curve.Compared to seven probiotics isolated from the laboratory were studied.A strain was screened by cholesterol-lowering property,acid resistance,bile salt tolerance and bile salt hydrolytic enzyme activity.The results showed that Lactobacillus plantarum KLDS 1.0320 has better cholesterol-lowering activity than other strains,and the degradation rate of cholesterol reached63.72%,and the number of living bacteria in the simulated gastrointestinal tract was 6.89lg(CFU/g).The activity of bile salt solution was 0.71 U/m L.Its biological characteristics test results show that 37? is the most suitable growth temperature and the growth of the strain is more vigorous,it is studied as the target strain for the next step.2.Study on factors affecting the activity and quality of cholesterol-lowering low-fat cheese.Study on the effect of the dosage of the starter,the amount of probiotics,the optimum probiotics and the amount of its addition on the cholesterol lowering activity.The optimal fermentation conditions were: the dosage of the fermentation agent 0.02%(w/w),the amount of probiotics2.00%(v/v),the optimum probiotics is Inulin and the addition of probiotics 2.00%(w/w).With these conditions,the model predicted response sensory score of the low-fat cheese was 87.36.Making low-fat cheddar cheese with optimized process,and actual sensory scores of the half-fat cheese was up to 86.78,basically coincide with the predicted value.3.Study on the properties of low-fat cheddar cheese ripening.Making five batches cheeses with optimized process,and testing group and control group cheese composition and physical and chemical characteristics at different maturity.The fat content of the probiotic cheese was 14.08%.The degree of hydrolysis of probiotic cheese protein increased,resulting in more free amino acids.Cheese texture and sensory characteristics were better than those in low-fat blank group,close to full cheese.Indicating that the addition of inulin to promote the survival rate of Lactobacillus plantarum after gastrointestinal digestion,so as to better ensure the cholesterol-lowering activity of cheese.4.The number of viable bacteria reached 8.43 lg(CFU/g),which was 20.08% higher than that of Lactobacillus plantarum only(P<0.05).At the same time found that adding probiotics and inulin did not have significant effects on the activity of Lactococcus ferment;After simulated gastrointestinal digestion,the number of viable bacteria reached 7.52 lg(CFU/g).It was 17.31%(P<0.05)higher than that of probiotics group.5.Mice were fed with high-fat formula diet to establish a high-fat model.The cholesterol-lowering effect of probiotics cheese was studied by measuring serum cholesterol related indicators in mice.Compared with hyperlipidemia model,the contents of total cholesterol(TC),total triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)in D and E groups were significantly inhibited(P<0.05),and atherogenic index(AI)values in D and E groups decreased by 35.05% and 43.81%,respectively.The TC and TG in the liver of D and E were significantly decreased(P<0.05),but TC and TG in the feces were significantly higher(P<0.05),and TC and TG in the liver of the group E were lower than those in the D group.Above mentioned,the synergistic application of Lactobacillus plantarum and inulin to cheese can better reduce the cholesterol level in the body.