Study On The Relevance Between Strains Dynamic Changes And Flavor Compounds Of Xinjiang Characteristics Cheese

Object: This study revealed the relationship between the fermentation process, change of the functionmicroorganism and the flavor, quality of the kazak s traditional fermented dairy products in Aleitai,Xinjiang. It provided the scientific basis to give a scientific assessment for the fermentatiion process ofnatural fermentation dairy products and the in situ protection of lactic bacterial.Methods: This study was aimed to determine the optimal combination of Xinjiang characteristics cheesefermentation agent by optimizing the combination of the strains isolated from Xinjiang dairy products. Thecheese was processed by the bacteria mixture which had been selected. The physicochemical characteristicswere detected, changing of flavor compounds were detected by GC, LC and SPME-GC/MS and the thestrains dynamic changes during the ripening of cheese was analyzed by PCR-DGGE.Results:1In this paper, the character of acidity, flavor, viscisity and hydrolyze protein of6mixed bacteriawas studied, using the zymogens which were isolated from the traditional dairy products of Xinjiang. Theresults showed that the adjunct culture of X6(Lactobacillus helveticus: Lactococcus lactis=1:1) was foundto be suitable as Xinjiang characteristics cheese, and the addition quantity was5%.2The study on the physicochemical characteristics of Xinjiang characteristics cheese within aripening period of50days showed that the moisture and the content of fat decreased; The pH value reducedrapidly and reached the lowest value when ripened20days; The content of pH4.6soluble nitrogen washigher than12%TCA soluble nitrogen and both of them were increased to some degree; It was got that thedegree of protein degradation were deep after30days ripening through the analysis of electrophoretogram;The sensory value increased with the ripening, and it was lower in the initial period, however, it got thehighest value when ripened50days.3The study on the flavor compounds contents changes of Xinjiang characteristics cheese duringripening period showed that the contents total organic acids and the individual organic acids were found insignificant changes(P<0.01), the content of lactic acid, the dominant organic acid was10.75mg/g; thecontents of different free amino acids displayed the dynamic changes, the total contents of free amino acidschanged significantly(P<0.05)ï¼›Valine and Leucine were the main free amino acids and the maximumcontents of them were35.19mg/100g and27.06mg/100g; the total contents free fatty acids represented asignificant changes(P<0.01);25volatile flavor compounds were detected, including mainly alkanes,ketones, alcohols, esters, aldehydes and acids. The kinds of volatile flavor compounds increased with theripening of cheese, also, it was rich at50days ripening and had a good distribution.4This study analyzed microbial flora changes during cheese aturation process. The number ofbacteria in cheese and lactic acid bacteria increased rapidly, then decreased slowly. The number of bacteriain cheese and lactic acid bacteria increased rapidly, then disappeared Yeast count showed an upward trendin the maturation process. PCR-DGGE was used to analyzed bacteria ferment changes during the cheeseripening, The results showed that the dominant bacteria was Lactobacillus helveticus, and Lactococcuslactis was extinction after20days ripening, It had a high correlativity between strains dynamic changes andthe formation of flavor compounds.