白腐乳中呈味肽的分离与鉴定

目的:从白腐乳中寻找呈味肽,分析其氨基酸序列,人工合成肽样品,研究其滋味特性。方法:白腐乳提取液经过超滤、Sephedex G-15葡萄糖凝胶过滤层析,分离出3个呈味组分,通过感官评价筛选出呈鲜效果最优的组分,采用反相高效液相色谱对其进一步分离纯化,选择峰面积最大的组分,使用基质辅助激光解析电离-飞行时间质谱结合De Novo软件分析呈味肽的氨基酸序列,人工合成肽样品,对合成肽样品的呈味特性进行分析。结果:在白腐乳中发现并确定序列的肽链3条,其氨基酸序列分别为:Asp-Phe-Lys-Arg-Glu-Pro、Asp-Arg-Glu-Lys-Phe-AspGlu、Asp-Glu-Asp-Phe-Lys-Arg-Glu-Pro。其中肽Asp-Phe-Lys-Arg-Glu-Pro具有鲜味,肽Asp-Glu-Asp-Phe-Lys-ArgGlu-Pro兼具鲜味与酸味,肽Asp-Arg-Glu-Lys-Phe-Asp-Glu虽无明显特征滋味,但在味精溶液中则体现出较强的增鲜效果。结论:腐乳的鲜味不仅仅来自于谷氨酸等氨基酸成分,还与小分子肽类的呈鲜作用有关。

Isolation and Identification of Flavor Peptides from White Sufu (Fermented Tofu)

To identify the flavor peptides from white sufu, analyze their amino acid sequences, and evaluate the taste characteristics of their synthetic counterparts. Methods: Ultra-filtration and glucose gel Sephedex G-15 filtration chromatography were applied to separate flavor fractions from white sufu extracts. The fraction with the best sensory evaluation was further purified by reversed phase high performance liquid chromatography (RP-HPLC). The subfraction with the maximum chromatographic peak area was identified by using matrix-assisted laser analytical ionization timeof-flight/time-of-flight mass spectrometry/mass spectrometry (MALDI-TOF/TOF MS/MS) with De Novo software. The potential flavor peptides were also artificially synthesized and their sensory properties were evaluated. Results: Three flavor peptides were obtained from white sufu. Their amino acid sequences were identified as Asp-Phe-Lys-Arg-Glu-Pro, Asp-Arg-Glu-Lys-Phe-Asp-Glu, and Asp-Glu-Asp-Phe-Lys-Arg-Glu-Pro. The first peptide had obvious umami taste. The third one had both umami and sour tastes. The second had less obvious taste although it could enhance the umami flavor of sodium glutamate solution. Conclusion: The umami flavor of white sufu not only cames from amino acids such as glutamate, but also was related to small peptides.