相对湿度对牦牛毛霉霉菌奶酪成熟过程中品质的影响

为研究不同相对湿度对牦牛霉菌奶酪成熟过程中品质的影响,并确定其在成熟过程中的最佳相对湿度和成熟时间,本实验以牦牛霉菌奶酪为试验材料,将其分别置于相对湿度为30%、50%、70%条件下成熟,测定其在成熟过程中感官品质、质构、pH、营养成分、蛋白质和脂肪分解指标以及挥发性风味物质的变化。结果表明:相对湿度为50%,成熟6 d时,奶酪的感官评分最高且质构较佳。随着成熟时间的延长,三个实验组的水分、蛋白质和脂肪含量呈下降趋势,灰分逐渐上升;pH呈先下降后保持不变或上升。除成熟第0和8 d外,在同一成熟时间点,相对湿度为30%的水分含量均显著低于其他两组(P<0.05);灰分、蛋白质和脂肪含量变化不明显;相对湿度为50%的pH下降速度最快。pH4.6醋酸盐缓冲液可溶性氮含量、12%三氯乙酸可溶性氮含量、酸价和硫代巴比妥酸值均在奶酪成熟过程中不断升高,且相对湿度为50%时值最高。对牦牛毛霉霉菌奶酪挥发性风味物质检测发现,相对湿度为50%,成熟第6 d时,奶酪的风味物质含量较高。因此,牦牛霉菌奶酪在相对湿度为50%,成熟6 d时,其品质最佳。

Effects of Relative Humidity on the Quality of Yak Mold Cheese during Ripening

In order to study the effects of different relative humidity on the quality of yak mold cheese during ripening,and determine the optimal relative humidity and ripening time in the ripening process,the yak mold cheese was taken as the experimental materials and was ripened in the relative humidity of 30%,50%,70%. The changes of sensory quality,texture,pH value,nutrient content,the decomposition indexes of protein and fat and the changes of volative flavor compounds were measured during the ripening process. The results showed that the sensory score of the cheese was highest and the texture index was better when the ripening relative humidity was 50% and fermented for 6 days. Meanwhile,with the extension of ripening time,moisture content protein content and fat content in the three experimental groups all presented a downward trend,nevertheless,the ash content showed an upward trend,while the pH value decreased first and then remained unchanged or increased. Furthermore,except for 0 and 8 days of ripening,at the same maturity time,the relative moisture content of 30% was significantly lower than the other two groups(P<0.05). The ash content,protein content and fat content did not change significantly. The pH value of 50% relative humidity decreased the fastest. Meanwhile,the content of soluble nitrogen at pH4.6 or 12% trichloroacetic acid soluble nitrogen,thiobarbituric acid value,acid value increased gradually during cheese ripening,and the highest value was obtained at relative humidity of 50%. The detection of volatile flavor substances in yak mold cheese indicated that the flavor content of the cheese was higher when the relative humidity was 50%,and the cheese was ripened to the 6th day. Therefore,the quality of yak mold cheese was the best when the relative humidity was 50% and the ripening time was 6 days.