Screening And Popularization Of Fine Varieties Of Rice

Conjugated linoleic acid is a kind of octadecadienoic acid which containing the cis or trans conjugated double bonds between 9 and 11,10 and 12 or 11 and 13 carbon atoms,and is a general term of linoleic acid which have a group of conformation and position isomer.Conjugated linoleic acid have many important physiological functions,such as anti-cancer,anti atherosclerosis,weight loss,promote growth,and improve immune function,so it has a broad many application prospect in medicine,food,health care products,cosmetics and so on.Through the preliminary work,a high yield CLA strains was obtained.In order to further understand its growth characteristics and improve the yield CLA,single factor and orthogonal experiments were used to optimize the fermentation conditions and fermentation medium formula,meanwhile,we explored a new multiple bacteria compound fermentation to improve the CLA content in the fermented milk.Considering the factors that affect the quality of fermented milk and CLA content,single factor and orthogonal experiments were used to get the best condition of fermented milk.At the same time,we evaluated the CLA yogurt.The experimental results are as follows:By single factor and orthogonal experiments,the fermentation medium formula was determined:malt extract medium was selected as basal medium;lactose and peptone were selected as optimum carbon source and optimum nitrogen sources,the adding amount were 25 g/L and 7 g/L,respectively.Meanwhile,The best inorganic salt contents was drawn as follows:sodium acetate 0.7 g/L,potassium hydrogen phosphate 0.3 g/L,magnesium sulfate 0.05 g/L,manganese sulfate 0.035 g/L.At this point,the maximum CLA production reached 368.41?g/mL.By single factor and orthogonal experiments,the best fermentation condition was drawn as follows:fermentation temperature 37 ?,fermentation time 38 h,initial pH 7.5,inoculation amount 1.75%.In this condition,the CLA production reached 461.2?g/mL.Furthermore,mixed strains fermentation proposal was obtained through single factor experiment and orthogonal test,They are as follows:the inoculation proportion of three strains(Lactobacillus plantarum,Streptococcus thermophilus and Lactobacillusdelbrueckii subsp.Bulgaricus)was 1:1:1.the content of linoleic acid,fermentation time,concentration of skim milk and fermentation temperature were 0.125%(v/v),32 h,11%(w/w),38?,respectively.According to the fermentation proposal,the viscosity,acidity,water retention,number of viable count and the content of CLA were 3450 mPa.s,102°T,60%,3.1×109cfu/mL,981.2 ?g/mL,respectively.Sensory evaluation determined the yogurt meets the quality requirements of National Food Safety Standard and people's demand for high quality products.This yogurt product can satisfy the consumer's demands for new type and healthy functions of yogurt.