Changes in the chemical composition of traditional Chinese‐type soy sauce at different stages of manufacture and its relation to taste

Chemical composition of traditional Chinese‐type soy sauce (TCSS) at different stages of manufacture (moromi fermentation and pasteurisation) were analysed. Results showed that total nitrogen, formaldehyde nitrogen, total titratable acid, reducing sugar, NaCl, water soluble peptides, free amino acids (FAAs) and Maillard reaction products in TCSS changed significantly during manufacture. Most of FAAs were released during initial stage (0–15 days) of moromi fermentation, peptides (1–5 kDa) kept dominant (69.34–80.88%) among all peptides during manufacture and Maillard reaction products increased progressively during moromi fermentation and increased sharply during pasteurisation. According to hierarchical cluster analysis and sensory evaluation, there were obvious correlation between FAAs and sensory score of over‐all in TCSS during manufacture, which indicated that balanced FAAs composition might be mainly responsible for the taste formation of TCSS. Besides, pasteurisation can further improve the over‐all taste of TCSS.     

Characterizing Soy Sauce Moromi Manufactured by High‐Salt Dilute‐State and Low‐Salt Solid‐State Fermentation Using Multiphase Analyzing Methods

Present study was to characterize the physiochemical properties, free amino acids (FAAs), volatiles and microbial communities of various moromi, respectively sampled from different stages of high‐salt dilute‐state (HSDS) and low‐salt solid‐state (LSSS) fermentation, using multiphase analyzing methods. Phospholipid fatty acids (PLFA) analysis indicated that Gram‐positive bacteria were dominant bacteria and fungi were principal microbes. For DGGE analysis, dominant microbes in moromi were mainly fell into Weissella, Tetragenococcus, Candida, Pichia, and Zygosaccharomyces. During fermentation, the dominant microbes shifted from nonhalophilic and less acid‐tolerant species to halophilic and acid‐tolerant species. Total of 15 FAAs and 44 volatiles were identified in moromi, mainly Glu, Asp, Tyr, and acids, alcohols, esters, aldehydes, respectively. Odor activity values analysis suggested that the final moromi of LSSS fermentation had more complicated odors than that of HSDS fermentation. Conclusively, technological parameters, microbial communities, raw materials and fermentation process may result in the discrepancy of HSDS and LSSS moromi.     

耐盐乳酸菌和酵母菌强化技术对高盐稀态发酵酱醪品质的影响

分别将耐盐乳酸菌Tetragenococcus halophilus CGMCC 3792、耐盐酵母菌Zygosaccharomyces rouxii CGM-CC 3791和Candida versatilis CGMCC 3790菌悬液接入酱醪中,利用顶空-固相微萃取偶联气质联用技术(HS-SPME/GC-MS)检测了发酵125 d酱醪中挥发性组分的变化。研究结果表明,T.halophilus CGMCC 3792强化的酱醪中酸类、醇类、酮类、呋喃类、吡嗪类和其他组分的相对含量降低,酯类、醛类和酚类组分的相对含量增加,其中苯乙醇、乙酸乙酯、辛酸乙酯、癸酸乙酯和4-乙基愈创木酚等的相对含量显著增加,而Z.rouxii CGMCC 3791、C.versatilis CGMCC 3790共培养强化的酱醪中醇类、酯类、醛类和其他组分的相对含量增加,酸类、酚类、呋喃类和吡嗪类组分的相对含量降低,其中苯乙醇、长链脂肪酸乙酯(月桂酸乙酯、棕榈酸乙酯、亚油酸乙酯等)的相对含量显著增加。此外,本研究中T.halophilus CGMCC 3792强化的酱醪中4-乙基愈创木酚的相对含量大幅增加,且在整个发酵过程中其含量也单调增加,对于T.halophilus CGMCC 3792是否具有分泌4-乙基愈创木酚的能力以及是否冷温工艺赋予该菌株合成4-乙基愈创木酚的能力需进一步探究。     

耐盐米曲霉CICIM F0899在酱油酿造过程中的应用

耐高盐环境的蛋白酶对酱油工业有着积极作用。该实验对1株产耐盐蛋白酶的米曲霉CICIM F0899在高盐稀态酱油发酵过程中的作用进行了研究,并同沪酿3042进行了比较。结果表明,在酱醪发酵阶段,微生物代谢产酸使酱醪pH持续下降,影响了蛋白酶的活性,导致酱油中氨基态氮和风味物质含量的变化,在180天时氨基态氮含量达到0.62 g/100 mL,比沪酿3042高11.11%。利用气相色谱-质谱联用(GC-MS)对挥发性成分进行了分析鉴定,检测出酱醪中7大类共49种挥发性化合物,其中酯类、杂环类化合物的含量明显高于沪酿3042,而醛类物质的含量相对较少。因此,米曲霉CICIM F0899在氨基态氮含量和风味组成方面都具有更加明显的优势。     

传统酿造酱油酱醪中的霉菌筛选及其部分酶系特征分析

传统酿造酱油发酵过程中,微生物种类繁多,多数为环境中自然落入并参与发酵,本研究旨在从传统酿造酱醪中筛选不同的霉菌并探究其酶活力特性。本研究从酱醪中分离到49株霉菌,挑选形态有差异的18株霉菌进行分子生物学鉴定,鉴定结果归属于4个菌属,即青霉属、枝孢霉属、曲霉属和链格孢菌。对这些霉菌进行酶系分析,结果表明霉菌的酶系特点与霉菌类型密切相关,其中黑曲霉的酸性蛋白酶和β-葡萄糖苷酶突出,米曲霉、红绶曲霉和链格孢菌中性蛋白酶、糖化酶和氨肽酶活力突出。根据酶活及菌种特性,选用黑曲霉AN1和AN2分别与米曲霉进行混合制曲,发现黑曲霉AN2和米曲霉混合制曲效果更佳,相比于米曲霉大曲,其中性蛋白酶与酸性蛋白酶分别提高了42.84%和22.27%,且糖化酶和氨肽酶提高117.54%和15.10%,具有较好的应用价值,该研究为筛选酱醪中优质的霉菌提供理论依据。     

促酱醪发酵芽孢杆菌的筛选及应用

用酪素平板法从高盐稀态酱醪中筛选出56 株蛋白酶活性较好的菌株,牛津杯法复筛后制曲测定酶活性,得到淀粉酶活性最高的菌株CS1.11、蛋白酶活性最高的菌株CS1.13及纤维素酶活性最高的菌株CS1.17;16S rRNA序列测定结合形态学分析,CS1.11、CS1.13、CS1.17分别鉴定为贝莱斯芽孢杆菌（Bacillus velezensis）、甲基营养型芽孢杆菌（B. methylotrophicus）、枯草芽孢杆菌（B. subtilis）;分别将3 株实验菌与对照菌枯草芽孢杆菌CS1.03单独进行制曲后盐卤发酵,发现CS1.13发酵酱油氨态氮质量浓度最高,为5.12 g/L,CS1.11发酵酱油还原糖质量浓度最高,为27.20 g/L,与其酶活性结果一致,4 株菌对酱油总酸含量影响不大;顶空固相微萃取气相色谱-质谱联用内标法定性及定量分析发酵酱油发现,3 株实验菌与对照菌均具有产生吡嗪类物质及其前体乙偶姻和2,3-丁二醇的优势,且3 株实验菌优于对照菌;吡嗪类物质能赋予酱油良好的风味及健康因子,是芽孢杆菌酱油发酵的特征风味物质。筛选自高盐稀态酱醪的芽孢杆菌CS1.11、CS1.13、CS1.17有促酱醪发酵、丰富酱油风味、增进健康因子的潜力,具备良好的应用前景。