不同分子质量大豆蛋白和鸡肉酶解物的美拉德反应产物风味特征分析

为了研究不同分子质量的肽在美拉德反应后的风味特征,以大豆蛋白和鸡肉为原料酶解得到蛋白酶解物。对酶解物超滤分离得到小于1000Da、1000~5000Da和大于5000Da的不同分子质量肽组分,并对大豆蛋白和鸡肉酶解物完全酸水解得到复合氨基酸。在得到的肽段和氨基酸中添加一定量的木糖,构建美拉德反应模型。对美拉德反应产物感官特性进行评价,再采用气相色谱-质谱联用、高效液相色谱对挥发性和不挥发性化合物进行分析。结果表明:在2种不同蛋白来源的酶解物的美拉德反应产物中,共鉴定出挥发性化合物69种,其中吡嗪和呋喃硫醇等肉香味化合物的含量最高。统计分析表明:不同分子质量的肽和游离氨基酸的挥发性化合物存在明显差异。小于1000Da的肽在美拉德反应过程促进了吡嗪类化合物的生成,其中包括了吡嗪、5-甲基-2-乙基吡嗪、2,5-二甲基-3-乙基吡嗪、三甲基吡嗪、2-乙酰基吡咯等挥发性化合物。与肽相比,游离氨基酸有利于含硫化合物如呋喃硫醇类和噻吩类物质的生成。有29种挥发性化合物的相对气味活性值大于1。偏最小二乘回归研究了气味化合物与感官评价之间的相关性,发现小于1000Da的肽与基本的肉味和浓厚味密切相关,而大于5000Da的肽与苦味和焦煳味密切相关。在美拉德反应后,分子质量大于5000Da的肽数量显著减少;分子质量1000~5000Da的肽降解可以补充消耗的游离氨基酸;分子质量小于1000Da的肽容易发生交联和聚合现象而含量增加,其产物对风味的影响明显增强,能更好地体现基本的肉味、鲜味和浓厚味。希望研究可以为利用蛋白质酶解物生产美拉德反应产物的应用提供理论支撑和指导。

Flavor Characterizations of Maillard Reaction Products of Enzymatical Hydrolysates of Soybean and Chicken with Different Molecular Weights

In order to study the flavor characteristics of peptides with different molecular weights via Maillard reaction, the protein hydrolysates were obtained by enzymatic hydrolysis using soy protein and chicken as raw materials. Then the enzymatic hydrolysates were separated by ultrafiltration to obtain peptides with different molecular weights, less than 1000Da, 1000~5000Da and greater than 5000Da. In addition, the complex amino acids were obtained by complete acid hydrolysis of enzymatical hydrolysates of soybean and chicken. A certain amount of xylose was added in peptides and amino acids to build a Maillard reaction model. The sensory properties of Maillard reaction products were evaluated. Then the volatile and nonvolatile compounds were analyzed by gas chromatography-mass spectrometry and high-performance liquid chromatography. The results showed that in the Maillard product of enzymatical hydrolysates of two different protein sources, a total of 69 kinds of volatile compounds were identified, among which the contents of pyrazine, furanthiol and other meat flavor compounds were the highest. Statistical analysis showed that there were significant differences in volatile compounds of peptides with different molecular weights and free amino acids. The formation of pyrazine compounds was promoted by peptides less than 1000Da during the Maillard reaction, such as pyrazine, 5-methyl-2-ethylpyrazine, 2,5-methyl-3-ethylpyrazine, trimethylpyrazine, 2-acetylpyrrole, etc. Compared with peptides, free amino acids favored the formation of sulfur-containing compounds such as furanthiols and thiophenes. Only 29 volatile compounds had relative odorant activity values (rOAV) greater than 1. Partial least squares regression (PLSR) was used to investigate correlations between key odor compounds and sensory evaluations. Peptides less than 1000Da were found to be closely related to the basic meaty and kokumi, while peptides greater than 5000Da were closely related to bitter and burnt flavor. After Maillard reaction, the amount of peptides greater than 5000Da was significantly reduced. Degradation of peptides of 1000-5000Da could replenish the consumed free amino acids. The peptides less than 1000Da were prone to cross-link and polymerization and thus increased the content. The products had a significantly enhanced effect on the flavor, and could contribute well to the basic meaty, umami and kokumi. It was hoped that this study could provide theoretical support and guidance for the application of proteolysates to produce Maillard reaction products.