Changes of the antioxidative activity and isoflavone during processing of black soybean tofu and milk

• Main Authors: Shih-Jeong Kuo, 郭士榮
• Other Authors: Kai-Ts''''ung Yang Ph.D.
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/91620097521455907041

碩士 === 中國文化大學 === 生活應用科學研究所 === 87 === This research is to study the production efficiency, texture, antioxidative activity and isoflavone contents of tofu and soybean milk make from green-cotyledon black soybean and yellow-cotyledon black soybean. Also, the Ferric Thiocyanate Method and the Antioxidative Activity Test (A.O.A. Method) are both applied in this study to examine and compare the sensitivity in the linoleic acid model system. In terms of production efficiency, test results show that from the same weight ( per 1000 grains ) of two cultivars of soybean, the yellow-cotyledon black soybean generates greater amount of soybean milk and tofu than those of green-cotyledon black soybean. In terms of texture, test results show that tofu from yellow-cotyledon black soybean is softer than that from green-cotyledon black soybean. Therefore, we may conclude that yellow-cotyledon black soybean is more adaptive to tofu processing. In the antioxidative activity tests, results show a significant differene in using the Ferric Thiocyanate Method, but no difference in applying the A.O.A. method. When the Ferric Thiocyanate Method is applied, the greatest antioxidative activity occurs when the extract concentration of green-cotyledon black soybean is 1mg / ml in the linoleic acid model system; however, of yellow-cotyledon black soybean it is 4mg / ml. When the A.O.A. method is applied there is no significant difference between the two cultivars. Nevertheless, in terms of the relationship between antioxidative activity and repetition of grinding, we find that there exists a positive relationship in making soybean milk from yellow-cotyledon black soybean, which is not found in making soybean milk from green-cotyledon black soybean. This positive relationship in not found in the process of making tofu from either green-cotyledon black soybean or yellow-cotyledon black soybean. As to the contents of isoflavone, the results show that there exists a significant difference in the content of Genistein, however not in the content of Daidzein. The difference cannot be found in either tofu or soybean milk that made from green-cotyledon and yellow-cotyledon black soybean, either, when the grinding process of repetition is applied. In the color analysis we find that yellow-cotyledon black soybean shows significant differences in the a-value and the b-value. The analysis on the tofu made from repetition of the grinding process shows that there are significant differences in the L-value and the a-value. However, the analysis on the soybean milk made from repetition of the grinding process shows that there are significant differences only in the L-value. In this study we also find that after twice repeated grinding with grinding water tofu gel is easy to collapse. Also the hardness, the cohesiveness, the springiness, the gumminess, the chewiness, the adhesiveness result from repeated grinding with grinding water are significantly different from those without the repeated grinding process.