原味肉味香精反应体系氧化脂肪作用于肉香风味形成的机制

The chicken fat is used as a representative. Other than the usual research train of thought that bases on the simple model reactions of cysteine and reducing sugars, real and complex Maillard reaction systems containing peptides and protein will be designed and utilized to study on the action mechanism of oxidized fat on the formation of meat flavor (aroma and taste) in a real meat flavoring preparation system, where oxidized fat, reducing sugars, and hydrolyzed animal protein are the main materials. The analysis of key aroma compounds and key taste components, and separation and identification of novel taste compounds generated by the reaction of oxidized fat with other components will be carried out through the research work. The influences of the reactants composition as well as the reaction conditions on the formation of meat aroma and taste, will be investigated to draw some regulatory rules from them. Contributions of free amino acids, and peptides and proteins in different range of molecular weights to the formation of meat flavor will be compared to reveal the key amino-containing flavor precursors in the hydrolyzed animal protein when the oxidized fat is present. The affect of the compounds from the oxidized fat with different structures and reaction activities on the formation of meat flavor (aroma and taste) are also to be researched to find out which one of the oxidized fat is a key reactive flavor precursor. Besides the interaction of lipid degradation with Maillard reaction, the interaction of lipid degradation products with amino acids, peptides and proteins, and the competitiveness of lipid degradation products with reducing sugars on carbonyl-amine reactions that have affects on the formation of thermal reaction flavor, are to be focused, where the chemical reaction routes that lead to the key aroma compounds, key taste components, and novel taste compounds, will be explored. Essentially, this proposal is intended for the formation mechanism of meat aroma and taste when lipid oxidization exists in a real and complex Maillard reaction system that consists of amino acids, peptides, proteins, and reducing sugars. As far as we know, there have been no reports concerning research contents as this proposal. It would not only provide guidance for the preparation of thermal reaction meat flavorings, but also provide references for quality control as well as toxic and hazardous factors (e.g. acryl amide) control in food processing.

区别以往“半胱氨酸-还原糖”简单模型反应，设计含“多肽、蛋白质”复杂模型反应，研究基于调控氧化脂肪的肉味香精制备反应中，氧化脂肪作用于肉香风味（香气及滋味）形成的机制。以关键香成分、重要呈味物质、脂质化新味感物质的分析分离为主线，研究原料组成及反应条件的影响规律，解析氧化脂肪存在下蛋白酶解物中对风味形成有重要贡献的氨基前体，明晰不同结构脂肪氧化成分的反应活性及氧化脂肪中的重要风味作用前体。除常关注的脂肪氧化与美拉德反应相互作用，还揭示脂肪氧化产物与氨基酸、多肽和蛋白质相互作用及与还原糖“羰-氨”反应竞争，对风味形成产生影响的化学本质与机制，探究关键香成分、重要呈味物质、新味感物质形成途径。项目实为研究脂肪氧化存在于含有氨基酸、多肽和蛋白质的复杂美拉德反应中，肉香气及滋味的形成机制。研究内容未见报道。研究结果为热反应肉味香精制备提供理论指导，还为食品加工及减少丙烯酰胺等有害因子生成提供参考。

研究基于调控氧化脂肪的肉味香精制备反应中，氧化脂肪作用于肉香风味（香气及滋味）形成的机制。以氧化脂肪、木糖、蛋白酶解液为原料设计模型反应，监测反应液420nm紫外吸光值及pH变化，发现脂肪氧化使还原糖与氨基化合物之间的美拉德反应减弱；并通过凝胶色谱、反相色谱、基质辅助激光解析-飞行时间质谱，分析鉴定出有增强滋味醇厚感和持续性的脂质化修饰肽2个。采用超滤及凝胶色谱分离鸡肉蛋白酶解液组分，基于分离后的不同分子量组分设计含有氧化鸡脂的模型反应，对产生的含硫、含氮杂环类香气物质及反应产物的呈鲜味或醇厚感特性分析评价，得出氧化脂肪存在下蛋白酶解液中对香气及滋味形成有重要贡献的氨基前体均为游离氨基酸和小于1Kd的肽，氨基组分的分子量越大贡献越小；烯醛和二烯醛为高反应活性脂肪氧化成分及氧化脂肪中的重要风味前体。以已醛、（E）-2-庚烯醛、(E,E)-2,4-癸二烯醛、葡萄糖和谷胱甘肽为原料设计模型反应，通过液-质联机分析及气-质联机分析，发现脂肪醛与氨基化合物结合形成可逆性中间体，从而使产生于美拉德反应的挥发性风味化合物减少；这些可逆性中间体受热反应后，可产生一些带烷基链的噻吩、吡啶、硫醇，从而对总体风味产生影响。以氧化鸡脂、谷胱甘肽、葡萄糖为原料设计模型反应，气-质联机、气相色谱-稀释嗅闻的分析结果再次表明，脂肪氧化产物一方面抑制美拉德反应，另一方面参与美拉德反应，表现为氧化鸡脂存在下产生于美拉德反应的含硫化合物的稀释因子及含量均降低，产生于脂肪氧化参与美拉德反应的带烷基链风味化合物的稀释因子及含量升高；并同位素标记法解析了双环噻吩、噻唑、烷基噻吩、2-酰基噻吩、苯类衍生物共26种物质的风味形成途径。总之，项目研究了脂肪氧化存在于含氨基酸、多肽和蛋白质的复杂体系中的肉香气及滋味形成机制，研究结果可为肉类食品加工及热反应肉味香精制备提供指导。