浏阳豆豉晾曲阶段相关指标的变化研究

Changes of related indexes of Liuyang Douchi during koji-cooling

为明确浏阳豆豉生产过程中晾曲阶段对豆豉品质的影响,测定不同晾曲时间下微生物数量、理化指标和关键酶活性。结果表明,晾曲过程中,豆豉曲的菌落总数、真菌总数均呈逐渐上升的趋势,并在96 h达到最大值,分别为5.9×10^(9)CFU/g和7.6×10^(6)CFU/g;水分含量减少至23.80%,总糖含量下降至5.09%,而总酸、氨基酸态氮和苷元型异黄酮含量分别上升至1.46%、0.88%、1 383.90 mg/kg;除中性蛋白酶外,α-淀粉酶、脂肪酶、纤维素酶、酸性蛋白酶和碱性蛋白酶的活力整体均先升高后降低,且在晾曲阶段中性蛋白酶为主要酶。相关性分析结果表明,浏阳豆豉晾曲阶段,水分含量与菌落总数,总糖含量与菌落总数、α-淀粉酶、纤维素酶活力,以及氨基酸态氮含量与中性蛋白酶活力呈显著正相关(P<0.05),而氨基酸态氮含量与水分含量呈显著负相关(P<0.05)。该结果可为浏阳传统曲霉型豆豉的工艺优化提供理论依据。

In order to clarify the influence of the koji-cooling stage on the quality of Douchi during the Liuyang Douchi production process,the microbial quantities,physicochemical indexes and key enzyme activities at different koji-cooling times were determined.The results showed that the total colonies counts and fungi counts increased gradually and reached the maximum at 96 h,which were 5.9×10^(9) CFU/g and 7.6×10^(6) CFU/g,respectively.The moisture content decreased to 23.80%,the total sugar contents decreased to 5.09%,while the total acid,amino acid nitrogen and glycosidic isoflavone contents increased to 1.46%,0.88%,1383.90 mg/kg,respectively.Except for neutral protease,the activity ofα-amylase,lipase,cellulase,acidic protease and alkaline protease all increased at first and then decreased,and the neutral protease was the main enzyme in the koji-cooling stage.The results of correlation analysis showed that during koji-cooling stage of Liuyang Douchi,there were significant positive correlation between moisture content and total colonies counts,total sugar content and total colonies counts,α-amylase and cellulase activities,and amino acid nitrogen content and neutral protease activity(P<0.05),while amino acid nitrogen content was significantly negatively correlated with moisture content(P<0.05).The results could provide theoretical basis for the process optimization of traditional Aspergillus type Douchi in Liuyang.