Process Optimization Of Sour Cream Fermented By Lactobacillus Acidophilus Compound Strain

Lactobacillus acidophilus is one of the important probiotics in many lactic acid bacteria, and has been valued by many experts and conducted in-depth research and development at present. Therefore, it is regarded as “the third generation of yogurt starter strains” by dairy fermentation community. Lactobacillus acidophilus is very important in people’s gut microbes, it is closely related to people’s health. When the body of the number of living bacterium lactobacillus acidophilus to reach a certain number(generally not less than 106 cfu/m L, it not only can people keep gut microbial flora in equilibrium state and can also improve the body’s immunity so as to promote health. And using these unique properties of lactobacillus acidophilus, it can ferment sour cream. This not only can enrich the dairy market and increase product of design and color, more can give full play to unique health promotion of lactobacillus acidophilus.The author in the experiment adopts centrifugation to separate cream and do the systematic, in-depth and comparative study on the physiological characteristics of lactobacillus acidophilus, streptococcus thermophilic and streptococcus butanedione and the interaction of bacterial growth and the number changes of living bacterium when three kinds of lactic acid bacteria as a compound starter fermented sour cream, the optimization of fermentation process conditions and microbiological characteristics, product appearance, physical and chemical properties, organization structure and other characteristics of final products in the process of quality guarantee period. The main research results in the experiment are as follows:1.On the basis of single factor to obtain FT15 disk centrifuge cream optimum conditions optimized by orthogonal test as follows: the separation time is 25 min, the separation speed is 9000 rpm, separation temperature is 40 ℃. Under these conditions, the yield of fresh cream per 1000 m L is 163.67 m L cream, sensory composite score is 92.33. The fat content of cream is 34.73%, the protein content is 1.76%, reducing sugars content is 1.07%, ash content is 0.30%, moisture content is 47%. By analysis of variance, separation temperature and rotating speed on the yield of fresh cream has a significant effect(p < 0.05), the higher the separation in a certain range of temperature, the greater the yield of fresh cream, but lower in fat.2.The optimization of single fermented sausages are as follows: the optimal harvest time of(Dc) is 8h, the best harvest time of lactobacillus acidophilus is 12 h, the most important indicators of fermented dairy products is the viable count, when the fermentation of Dc is 8h, at this point the number of living bacterium is 3.2×108 cfu/m L。, the number of living bacterium on St is 1.3×108 cfu/m L。 the number of living bacterium on La is 2.3×108 cfu/m L。 There exists obvious symbiosis when St and Dc using culture blends mixed culture, mixed cultivation than single strain rate of acid production much faster, producing more flavor substances, Dc is mainly responsible for producing lactic streptococcus is given priority to with butyl diketone of flavor substances, so that the fermentation cream has a better taste and aroma.3.The optimum technologies of lactobacillus acidophilus compound strain fermented sour cream are as follows: fermentation temperature is 39℃, the ratio of lactobacillus acidophilus and compound strain is 1:1:1, the inoculation amount is 7%. In this condition the living bacterium number of lactobacillus acidophilus of lactobacillus acidophilus compound strains of fermented sour cream is 2.3×108 cfu/m L。no peculiar smell, and soft sour organization status, exquisite and smooth, curd time reduced to 6h, basically no whey separation.Through the gas chromatography experiment, we can see that single cream samples containing nutmeg acid, palmitic acid, stearic acid, oleic acid and linoleic acid. By comparing the results, it shows that the strains of lactobacillus acidophilus compound fermented sour cream samples has more linolenic acid and arachidonic acid than single cream sample, composite strains of lactobacillus acidophilus fermented yogurt oil unsaturated fatty acid respectively in oleic acid, linoleic acid, linolenic acid, arachidonic acid.From the composite strains of lactobacillus acidophilus fermented yogurt sensory evaluation, product of uniform fine texture, smooth surface, no bubbles, no whey separation. Colour and lustre is uniform white. delicate taste, lubrication, moderate acidity; In aroma, with strong acid fragrance; the physical and chemical indexes of composite strains of lactobacillus acidophilus fermented sour cream, we can see that its fat content was 33%, the total ash content was 0.28%, 1.01% of total sugar, protein was 1.74%, the moisture is 46%; we can see that the living bacterium number of lactobacillus acidophilus in the compound strains of lactobacillus acidophilus fermented sour cream is 2.3×108 cfu/m L。...