Investigation On Processing And Ripening Of Blue Cheese

The parameters of cheese processing technology was optimized through single factor and orthogonal experiments.The content of the added lactic acid bacteria starter was 0.01%; Rennet enzyme was added 0.0025%when pH fell to 6.10 for milk coagulation,The temperature was 36℃for cheese production.In the course of cheese ripening,TN slightly increased in the maturity period due to moisture evaporation from the surface and whey drainage from cheese,pH 4.6 water-soluble nitrogen(WSN),TCA soluble nitrogen(TCA-SN),water-soluble nitrogen phosphotungstic acid(PTA-SN),of the three components of nitrogen rate less increased from 5 d to 20 d,rapidly from 20 d to 70 d,and tended to increase slowly from 70 d to 90 d. These changes were related to rennet enzyme and microbial enzyme activity in cheese, especially,the activity of P.roqueforti.pH descended during the early maturity,and increasing in medium,late-term of maturity.The pH value of cheese rose to 5.98 after three months ripening.blue cheese samples were analyzed by using HITACHI L-8800 amino acid analyzer.17 kinds of amino acid were indentified and their content trends were displayed.From 30 d to 60 d,all 17 amino acids increased.From 90 d,aspartic acid,glutamic acid,valine, methionine,leucine,phenylalanine and arginine,and proline content declined but glutamate, leucine,proline,lysine,tyrosine remained higher levels.Cheese flavors changes during mature time were exploided in this paper.From 1 d to 55 d and 90 d,of blue cheese,of the total content of volatile substances,ketones substances accounted for 28.94%,36.29%,62.93%,respectively.With the ripening going, ketones content gradually increased.The FFA of ripened blue cheese was analyzed by using GC-MS.The higher content is Myristic acid,Palmitic acid,Octanoic acid and Linolenic acid.Cheese texture was analyzed by using texturator.Hardness,Chewiness and Gumminess of 40 d ripened cheese were higher than 7 d,but descended after 40 d.Cohesiveness ascended and Springiness descended during ripening time.Adhesiveness got the somallest value of 40 d and ascended after 40 d.Resilience ascended from 7 d to 40 d,but descended after 40 d,and kept same during 60 d to 90 d.