Color Control of Fish Sauce during Fermentation and Storage

为了控制鱼露的色泽，研究了鱼露和酱油在发酵过程中色泽的变化。并对影响其呈色的化合物及其作用机理进行了评价。鱼露的褐色度高于酱油。酱油中多酚氧化酶活性和多酚类物质含量均高于鱼露。这一结果表明，鱼露在发酵和储存过程中的褐变很小，这是由于多酚氧化酶的酶反应所致。在此基础上，利用多种糖和氨基酸组成的模型体系，研究了鱼露的非酶褐变反应(氨甲酰化反应)。氧气对葡萄糖-组氨酸体系的褐变反应有促进作用，而对其他氨基酸体系的褐变反应没有影响。在各种金属离子中，Fe~(2+)~(2-)对褐变反应有刺激作用，且在有氧条件下对褐变反应的刺激作用较大。此外，与特定氨基酸的反应产生了不同于棕色(蓝色、黄色、淡粉色)的独特颜色，这些结果为鱼露在发酵和储存过程中的颜色控制提供了有用的信息。

In order to control color of fish sauce, change in a color of various moromi mashes (of fish sauce and soy sauce) during fermentation process was investigated. Compounds affecting to their coloration and its mechanism were also evaluated. Brown color intensity of the mashes of fish sauce was higher than that of soy sauce. The polyphenol oxidase activity and the content of polyphenols in soy sauce were higher than those in fish sauce. This result suggests that brown coloration of fish sauce during its fermentation and storage is little due to the enzymatic reaction by polyphenol oxidase. Accordingly, non-enzymatic browning reaction (amino-carbonyl reaction) of fish sauce was investigated using a model system of various sugers and amino acids. The browning reaction in glucose-histidine system was stimulated in the presence of oxygen, but the reaction in the system of other amino acids was not affected. Of various metal ions, Fe^<2+> stimulated the browning reaction and its stimulation was extensive in the presence of oxygen. Furthermore, the reaction between and specific amino acids produced unique colors different from brown (blue, yellow, light pink).These results offer a usefull infromation for color control of fish sauce during its fermentation and storage.