Studies On The Process Technology Of Producing Liquid Milk With High CLA Content By Fermented And Additive Methods

Conjugated linoleic acid(CLA),as a new type of functional fatty acids,more and more received people's attention because of the functions of adjusting body composition and decreasing the fat accumulation.Currently,there is few kinds of food contain the conjugated linoleic acid.The thesis studied the methods of increasing the CLA content in the milk by ferment and adding it into milk directly,including the measuring methods,microbial synthesis methods and its steady properties.The industry production-line of CLA liquid milk with the annual output of 6000 tons was also designed in this thesis.Studied the method of measuring CLA content by the UV spectrophotometry.The maximum absorbance wavelength of CLA methyl ester is 230～234nm;the effective measurement range of the CLA concentration is 0.01～0.05g/L;the regressive formula of CLA concentration and its absorption was that Y=52.175X+0.0856(R~2=0.9789);and the empirical formula for them was that the content of CLA(g/L)=1.5097×absorbance(ABS)/ hexane solution sample concentration.Also the conjugated linoleic acid samples were measured,which were produced though using alkali catalyse and isomeric soybean oil,and its content was 41.98mg/mL.The factors such as fermentation temperature,nitrogen,linoleic acid concentration and buffer were studied for producing CLA by fermented milk,and the compound starter culture were made from Lactobacillus plantarum,Streptococcus thermophilus and Lactobacillus bulgaricus.The efficiency was the highest when linoleic acid turned into CLA under the conditions that temperature of the compound starter culture was 39℃,0.3%sodium caseinate was nitrogen,linoleic acid concentration was 0.037%and the buffer was added. The highest efficiency was 49.33%,and the products contained 0.037%CLA.The production process of CLA milk and the stability of the milk with emulsifiers and homogeneous were studied.Conditions of the best process of CLA milk were about 9.0 HLB value of the compound emulsifiers.And through experiments the stabilizer formula was that monoglycerides 0.06%,sucrose esters 0.03%,hydrophilic single 0.06%. Formation of fatty layer and slowdown speed of the particles were reduced.So it improved the stability,taste and brightness of the products.According to the enterprise standard,feasible production process and reasonable formula(1.6%of CLA,3%of sugar,pH 6.5 and 1.2%compounded emulsifier)the product with high content of CLA was produced.The factory of annual output of 6,000 tons liquid milk was designed.The design included producing plan,process technology,material balance,equipment type selection,energy balance,labor balance,management structure, costs and profits estimation,process programme,equipment layout picture,workshop pipe picture and the whole plant map.