中文摘要：

酵母抽提物（YE）是一种极佳的风味增强食品,具有极强的鲜味（umami）增强和浓厚味（kokumi）效果.对三种酵母抽提物（高纯YE,高I＋G YE,普通YE）的umami及kokumi滋味进行了评价和描述.通过超滤、凝胶层析对YE滋味组分进行了分离,初步得出分子质量处于200～1 000u的肽类,本身具有苦味及强烈刺舌滋味,对MSG-NaC1、I＋G＋NaC1、鸡汤-NaC1模型溶液具有增鲜,增加复杂口感及持续的满口感的kokumi效果.随后对三种YE的粗分质子量分布、肽分布、核苷酸含量、GSH含量进行了测定.结果得出,YE中＜1 000u分子量寡肽含量较高（约70％）,为其主要滋味物质,相对而言,YE中呈味核苷酸含量较低（3.530mg/g）,而不能与其中的kukumi活性物质起到协同效果.通过YE对MSG-NaCl、I＋G＋NaCl模型溶液的反馈感官鉴评实验,得出YE浓度分别达到0.25g/L、0.05g/L时开始体现出增鲜效果,而在两种模型溶液中YE分别达到2.5g/L,5g/L浓度时达到最大增鲜效果,超过这一浓度时,溶液开始呈现一定的苦味,鲜味也不再增强.此外,对于I＋G＋NaCl模型溶液,YE对其鲜味提升更为明显,增鲜阈值也较低.

英文摘要：

Yeast extract （YE） is a kind of excellent food flavor enhancer, which has a strong umami and kokumi taste. In this paper, the kokumi and u- mami taste of three types of YE （high purity YE, high I＋G YE, general YE） were evaluated. The taste-active components of YE were separated by the application of ultrafiltration and gel chromatography. A peptide arrays with molecular weight range of 200-1 000 u were obtained, which had a bitter taste and strongly barbed tongue effect and typical effect of umami-enhancing, complex, long-lasting and mouthfulness to the MSG-NaC1, I＋Cr＋NaC1 and chicken soup-NaCl taste model solutions. The molecular weight distribution, peptides distribution, nucleotides content and GSH content of three YE were determined subsequently. Result showed that the content ofYE with〈l 000 u was very high （about 70%）, which was the main flavor sub- stance of YE. However, the content of flavor nucleotide in YE was so low （3.530 mg/g） which did not exhibited a distribution effect on kokumi with such compounds. Application of response sensory evaluation on YE for MSG-NaC1, I＋Cr＋NaC1 model solution evaluated that the kokumi threshold of YE for MSG-NaC1, I＋Cr＋NaCI was 0.25g/L and 0.05g/L, respectively, while the maximum concentration used for kokumi enhancing were 2.Sg/L and 5g/L, respectively. Solution began to exhibit bitterness when reached this concentration. In addition, for the I＋Cr＋NaC1 solution model, the koku- mi effect of YE on umami improvement was more significant compared to others, and the kokumi threshold of YE was low.