对云南牟定腐乳中的霉菌进行分离纯化,获得适用于腐乳发酵的菌种,并将其应用于低盐腐乳生产中,探讨低盐发酵对腐乳品质的影响。通过形态学和分子生物学鉴定筛选菌种;采用标准法、扫描电子显微镜、顶空固相微萃取-气质联用技术和感官评价分别分析了低盐腐乳的理化性质、微观结构、挥发性风味成分和感官品质。从腐乳前发酵毛坯中分离纯化获得了白色的优质总状毛霉(M2)并应用于低盐腐乳的制备;随着盐含量的降低,腐乳中总酸、氨基酸态氮、水溶性蛋白、游离氨基酸含量逐渐升高,蛋白质水解程度逐渐增大,腐乳凝胶孔径逐渐缩小,结构更加致密均一。低盐腐乳中共检测出了45种挥发性风味物质,且盐含量对挥发性风味物质含量有较大影响,感官评定结果表明,盐含量对腐乳的滋味和质地影响较大,且M2-70%的接受度最高。实验所获得的总状毛霉适用于云南腐乳的发酵,适当的低盐发酵可提高腐乳的品质。
Microorganisms were isolated from sufu produced in Mouding, Yunnan Province, and the strains suitable for sufu fermentation were identified and selected. The isolated strains were then applied to the sufu fermentation, and effects of salt content on sufu quality were determined. The strains were identified using morphological and molecular biological methods. The physicochemical properties, microstructures, volatile flavor compounds, and sensory quality of the low-salt sufu were analyzed by standard methods, scanning electron microscopy, headspace solid-phase microextraction and gas chromatography-mass spectrometry (GC-MS) and sensory evaluation. The wheaten Mucor racemosus(M2) was obtained from fresh soybean curds overgrown with fungus. With decrease in salt content, the contents of total acid, amino acid nitrogen, water soluble protein, and free amino acids gradually increased, and protein hydrolysis degree also gradually increased, the pores of sufu gradually shrank and the structure became more homogeneous and compact. A total of 45 volatile flavor compounds were identified in low-salt sufu, and salt content had a great impact on the volatile flavor compounds content. Sensory evaluation results showed that salt content had a significant influence on the taste and texture of sufu, and samples of M2-70% has the highest acceptability. In conclusion, the isolated Mucor racemosus is suitable for Yunnan sufu fermentation, and proper reduction of salt content can improve the quality of sufu.
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