The study of improving GABA content in soybean sprouts, sprouts milk and sour dough.

• Main Authors: Yi-Shin Chen, 陳宜欣
• Other Authors: Yi-Chung Fu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/65928872667372252730

碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 97 === The GABA content in plant is minute, but some studies have pointed out that the vernalization of seeds is able to greatly increase GABA content. Therefore, for this experiment we chose to use soybean that is rich in protein, widely used in processing, and consumed daily by many people. The soybeans were germinated and then inspected to observe its effects upon GABA content under different environments and different germination conditions, in hope to find out the most productive potential of GABA in bean sprouts. In general, while exploring the processing of germinated bean sprouts and its resulting products, people tend to only emphasize GABA content, but ignore its possible negative substance-the purine content. Hence, this experiment also inspected the changes in purine during the germination process of soybeans, in hopes to lower the worries of general consumers towards germinated soybean products. In order to understand the glutamaic acid decarboxylase activities during the growing process of soybeans, we should use the Western blotting method to determine this enzyme. However, as a means to save cost and time, this experiment was carried out using the determination of GABA substrate- L-glutamic acid content to discover the activities changes in glutamaic acid decarboxylase, and later on, to utilize an optimal environment of glutamaic acid decarboxylase and the adding of a substance containing glutamaic acid decarboxylase in hopes to convert the L-glutamic acid into GABA from bean sprouts milk and sour dough. This is taken as an operation method to develop products with high GABA content. The results of analyzing GABA content in bean sprouts indicate that cultivating bean sprouts of up to 20cm high in the dark has shown the greatest potential in developing functional foods with high GABA content. However, considering the appearance and cultivating time of fresh bean sprouts, it is best to choose bean sprouts of a height around 12cm. An intake of 60g of bean sprouts is capable of resulting in the consumption of 18mg of GABA and the lowering of blood pressure. In regard to purine content, the total amount of purine contained in germinated soybean sprouts with a height less than 9cm is lower than non-germinated soybeans; and slightly higher than original beans when they have grown to a height exceeding 12cm. Therefore, the negative effect during germination on bean sprouts is non-significant. If we calculate germinated bean milk of dark-germinated sprouts with a height of 12-14cm to that of 480mL market-sold fresh soybean milk containing 48mg GABA, we can see that it is possible to take in 18mg of GABA content by merely drinking 0.4 bottles if it every day. Meanwhile, for 30g instant germinated bean powder drink, we only need to add 5g (only accounting for 16.7％) of bean sprout powder from sprout with a height of 18cm to achieve this dosage. These two processed foods are come with low purine content. The GABA content is slightly higher when the germinated bean milk is at an optimal environment or when it a substance containing glutamaic acid decarboxylase is added. However, the unapparent consumption of L-glutamic acid during the conversion process, and its incapability to upgrade GABA content to a desirable level are actually affected by the amount of glutamaic acid decarboxylase contained in germinated bean milk. While sour dough has to be added with large quantities of wheat germs and germinated bean milk, and coordinated with an appropriate fermentation time (＜18 hr) will then be able to increase GABA content significantly.