红腐乳发酵过程中滋味化合物分析及电子舌鉴别

采用离子色谱、氨基酸分析仪和电子舌对不同发酵阶段红腐乳的滋味化合物及滋味特征进行检测，并对结果进行主成分分析（principal component analysis，PCA）和层次聚类分析（hierarchical cluster analysis，HCA）。结果表明，发酵过程中红腐乳样品共鉴定出17 种游离氨基酸，6 种有机酸和8 种滋味属性。总游离氨基酸含量在前酵和后酵阶段显著增加，而总有机酸含量在前酵和后酵中期显著增长（P＜0.05）。大多数的游离氨基酸和有机酸的含量在前酵和后酵阶段均显著增加（P＜0.05）。电子舌结果表明鲜味、咸味、苦味和丰富度是红腐乳的主要滋味属性。此外，滋味化合物及滋味属性的相关性分析结果表明，游离氨基酸（谷氨酸、天冬氨酸、丙氨酸、甘氨酸、组氨酸、色氨酸、苯丙氨酸、甲硫氨酸、缬氨酸）、有机酸（乳酸、乙酸、琥珀酸）及理化成分（还原糖、氨基酸态氮、氯化钠）对红腐乳的滋味特征起着重要作用。PCA和HCA结果表明，滋味化合物及滋味特征可以用来判别红腐乳的成熟度，电子舌可以作为快速评价红腐乳滋味的有效工具。

Analysis of Taste Compounds in Red Sufu during Fermentation and Discrimination with Electronic Tongue

In order to evaluate the taste compounds and taste characteristics of red sufu during its fermentation process, the samples collected at different fermentation stages were analyzed by ion chromatography, amino acid analyzer, and electronic tongue. The obtained data were analyzed by principal component analysis (PCA) and hierarchical cluster analysis (HCA). Results showed that a total of 17 free amino acids (FAAs), 6 organic acids and 8 taste attributes were identified and quantified in all samples. Total contents of FAAs increased significantly at pre-fermentation and post-fermentation stages, while total contents of organic acids showed a significant increase at the pre-fermentation stage and the middle stage of post-fermentation (P < 0.05). The levels of most FAAs and organic acids increased significantly at the pre-fermentation and post-fermentation stages (P < 0.05). Electronic tongue analysis showed that umami, saltiness, bitterness and richness were major taste attributes. Furthermore, correlation analysis between taste compounds and taste attributes showed that free amino acids (Glu, Asp, Ala, Gly, His, Cys, Phe, Met and Val), organic acids (lactic acid, acetic acid, succinic acid) and some other chemical components (reducing sugar, amino acid nitrogen and NaCl) played an important role in the taste characteristics of red sufu. The results of PCA and HCA showed that the taste compounds and taste attributes could be used to evaluate its maturity extent and that electronic tongue could be a rapid tool for the taste evaluation of red sufu.