Soybean sprouts produced at physiological optimal temperature around 20℃ are placed or displayed for several days in market shelf of relatively cool temperature (ca. 13℃). During this period a number of changes occur including changes in color, smell, taste, nutritional quality, and etc. In order to know the changes, soybean sprouts packed in plastic film bag were stored at different temperature of 3℃and 13℃. Morphological characters, physicochemical changes and enzymes activity related to soybean quality (color) were examined. Although the number of fine roots and hypocotyl length were greater in sybean sprouts stored at 13℃, there was no significant difference in diameter, fresh weight and dry weight of hypocotyl between storage temperatures. Browning of hypocotyl known as typical deterioration in sprout quality was highly dependent on the activity of polyphenol oxidase (PPO) in hypocotyl. Considering the low level of soluble protein in hypocotyl, the relatively higher activity of PPO suggested a critical role of PPO in stored soybean sprout. PPO activity of sprouts stored at 13℃ was 2 times higher than that of sprouts stored at 3℃ after 4 days. The PPO activity was observed no longer than 6 day in sprouts stored at 13℃. Crude protein content was increased to 30.9～35.4% on a dry weight basis as storage period was extended. The changes in crude protein was more higher in sprouts stored at higher temperature (13℃). Total free amino acid content was increased in both temperatures. However, the changing rate was greater in sprouts stored at 13℃.

Chinese milk vetch (CMV) is a winter legume that is commonly used as cover crop in Korea. Kill date of cover crop for addition into soil affects N content in cover crop and N availability in soil. This study was conducted to evaluate the effect of CMV as green manure cover crop according to kill dates before growing corn without artificial fertilizer. Top of CMV cut three times on 13 April, 27 April, and 11 May were added into soil at a rate of 600 kg per 10a. Sugar content in CMV litter was persistently decreased from mid-April to late-May. The decrease of sugar content might be due to the transformation into starch and/or other storage or structural constituents. The decreased amount of sugars was greater than 12% and the increased amount of starch was less than 0.2%. Concentration of NH4+ in soil treated by CMV litter cut on May 11 was slightly higher than that in the treatment with early-cut (April 13) CMV, the concentration at 28 and 49 DAT (days after treatment) was higher in the treatment with late-cut CMV litter. Regardless of cut (kill) date of CMV, the phosphatase activity in the treatment of CMV litter was higher compared to the untreated control. Soil dehydrogenase activity was increased steadily by addition of CMV litter implying total microbial activities in the soil were increased. Our results demonstrate that the status of cover crop species at kill date is an important factor influencing soil enzyme activities derived from microorganisms. Therefore, the optimal kill date of cover crop should be examined to improve the efficiency of cover crop as green manure crop regarding the practical sequence in cropping system

Soybean quality is determined based on protein content, lipid content and fatty acid composition, and several functional components including isoflavones, anthocyanins and functional activity. Because the level of each component changes during seed development, it is necessary to know the concentration of quality-related components in developing seeds. Little is known of the pattern of changes in quality-related components. Seeds from field-grown soybean was harvest from the R6 stage to the R8 stage in 2004. Seed characteristics and the level of nutritional components were examined. Seed moisture content was dropped rapidly after the R7 stage in the tested varieties. Seed growth rate was the highest from the beginning of the R6 stage to the mid-R6 stage. Chlorophyll content was decreased rapidly in pods and seeds. However, seed growth period from the R6~;to~;R8 was 35 days. The crude protein content was. increased dramatically between 63 DAF and 70 DAF and then increased slightly. The pattern of isoflavone accumulation was nearly similar to that of seed weight increase. From the late R6 stage to the R7 , the accumulation rate was higher as compared to other stages. The angiotensin inhibitory activity was increased according to seed development from 63 (R6 ) to 84 DAF (R8 ). The difference of inhibitory activity in heated soybean powder, however, was not great among stages. The inhibitory activity was affected by heating treatment. The most effective heating time was 10 min. Excessive heating longer than 30 min resulted in a lowered inhibitory activity of soybean on ACE