| This study focuses on the Xinjiang flavor of local cheese, using foreign advanced processing technology of surface mold cheese to develop mold cheese product with national characteristic.Firstly, the preliminary identification and toxicologic study of mold starter which used to produce Camembert-type cheese was studied. And then the selection of bacterial strains for the Camembert-type cheese production was studied. Secondly, the influence of curd technology and processing technology in quality of Camembert-type cheese was studied, and the processing technology was optimized by Response Surface Methodology. Finally, the non-volatile flavor compounds was studied . Main contents and conclusions are as follows.1. Through the observation of the colony shape and individual shape, the mold we used was initially Identified as Penicillium caseicolum Bainier which belongs to Penicillium Camemberti. And the study result of its physiological property was that the optimum medium of Penicillium caseicolum Bainier is BSE. Its logarithmic growth phase is on day 3 to 4. In the same time, it can endure the environment of pH3.0, 4℃and the salinity tolerance of 9%.2. The toxicology study of Penicillium extract was studied. The acute toxicity test result shows that it's no toxic on mice, and the result of seven-day-feed cumulative toxicity test is that its toxicity on mice suggesting no accumulative effect. And the observation result of liver and kidney slices shows that it has no conspicuous lesions.3. The lactic acid bacteria starter which saved in the laboratory was selected in this research. The strains which are fit to manufacture cheese were obtained by study, which are Lactococcus lactis and the ratio of Lactobacillus Helveticus and Lactobacillus casi is 1 to 1. The reasearch result of the optimal proportion of mixed strains shows that the best ratio of Lactobacillus Helveticus to Lactobacillus casi is 1 to 2.4. The influence of each single factor on the curd technology and quality of Camembert-type cheese were studied. Results indicated the optimum process parameters: bacteria starter addition was about 3%, and curd temperature of 34℃or so, pre-acidification pH value of 5.8-6.2, and CaCl2 addition was 5-10g/100kg, and rennet addition was1.5-2.5g/100kg, and mold addition was about 1×106cfu/kg, and the concentration of NaCl was about 21%.5. The influence of bacteria starter addition, rennet addition and mold addition on the quality of cheese were studied by three elements quadratic current revolving design. The mathematic models were obtained, which revealed the relationship between the three elements and sensory value, pH 4.6soluble Nitrogen, total content of FAA. The processing technology was optimized, and the optimal processing parameters were obtained. Bacteria starter addition was 2.65%, and rennet addition was 2.32g/100kg, and the mold addition was 1.84×106cfu/kg. Results also indicated the mold addition had the most important influence on the sensory value and pH 4.6soluble Nitrogen, rennet addition was less important, and starter addition was least. And the mold addition had the most important influence on the total content of FAA, starter addition was less important, and rennet addition was least.Starter addition and rennet addition had obvious mutual effect on the sensory value, at the same time, the starter addition and mold addition also had the same effect.6. The changes of each target during maturation and the non-volatile flavor compounds in cheese which were produced by the opimized technology were study. Results revealed that the ripening time was about 30d, and during maturation of cheese, the pH value of surface and internal decreased firstly, and then increased, the moisture content decreased firstly, and tended to be stable at last. The total amounts of lactic acid bacterium decreased gradually, and tended to be stable finally. The content of pH 4.6soluble Nitrogen, the content of 12% TCA soluble Nitrogen and the total content of FAA increased gradually. The cheese begin to decompose large number of casein to produce small molecules from the 10th day.The study result of FAA and fatty acid in cheese shows that the content of FAA in experimental group was significantly higher than that in control group, and among them, the content of glutamate and threonine was the highest. And the total amount of FAA in experimental group was 71.6% higher than in the control group. The main fatty acid in Camembert-type cheese is saturated fatty acid, especially the 14-carbon and 16-carbon fatty acid, while the main unsaturated fatty acid is oleic acid. |
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