Mud crab （Scylla serrata） is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28℃, the temperature is suddenly...Mud crab （Scylla serrata） is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28℃, the temperature is suddenly reduced to 4℃. The crabs were sampled every 2 h for 10 h and dissected immediately to measure the enzyme activity. The crabs at room temperature （28℃） were used as the control group. The activity of superoxide dismutase （SOD）, catalase （CAT） and gkttathione peroxidase （GPX）, the content of malondialdehyde （MDA） and the activity of 4 ATPases （Na^＋, K^＋-ATPase, Mg^2＋-ATPase; Ca^2＋-ATPase; Ca^2＋, Mg^2＋-ATPase） were measured biochemically. In contrast to the control group, the SOD activity increased significantly from 2 to 6 h after the cold stress, and then decreased. The CAT and GPX activities increased in 2 h, and then decreased gradually. The content of MDA increased gradually in 4 h. The activity of Na^＋, K^＋-ATPase decreased in 2 h, increased up to the top value at Hour 6, then decreased again. The activities of Mg^2＋-ATPase, Ca^2＋-ATPase and Ca^2＋, Mg^2＋-ATPase increased significantly in 6 h, insignificantly in any other hours. Under cold stress, the activity of antioxidative enzymes in S, serrata was reduced at first then stabilized, ROS-scavenging weakened, and MDA accumulated gradually in the gill after 6 h. The activity of the 4 ATPases in the crab decreased after 6 h, suggesting that the ability to regulate ion concentration has been paralyzed. Therefore, the maximum period to sustain healthy meat in the crab under cold stress is 6 hours.展开更多
The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind...The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.展开更多
基金the National High-Tech Research and Development Program of China (863 Program) (No. 2002AA603013)
文摘Mud crab （Scylla serrata） is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28℃, the temperature is suddenly reduced to 4℃. The crabs were sampled every 2 h for 10 h and dissected immediately to measure the enzyme activity. The crabs at room temperature （28℃） were used as the control group. The activity of superoxide dismutase （SOD）, catalase （CAT） and gkttathione peroxidase （GPX）, the content of malondialdehyde （MDA） and the activity of 4 ATPases （Na^＋, K^＋-ATPase, Mg^2＋-ATPase; Ca^2＋-ATPase; Ca^2＋, Mg^2＋-ATPase） were measured biochemically. In contrast to the control group, the SOD activity increased significantly from 2 to 6 h after the cold stress, and then decreased. The CAT and GPX activities increased in 2 h, and then decreased gradually. The content of MDA increased gradually in 4 h. The activity of Na^＋, K^＋-ATPase decreased in 2 h, increased up to the top value at Hour 6, then decreased again. The activities of Mg^2＋-ATPase, Ca^2＋-ATPase and Ca^2＋, Mg^2＋-ATPase increased significantly in 6 h, insignificantly in any other hours. Under cold stress, the activity of antioxidative enzymes in S, serrata was reduced at first then stabilized, ROS-scavenging weakened, and MDA accumulated gradually in the gill after 6 h. The activity of the 4 ATPases in the crab decreased after 6 h, suggesting that the ability to regulate ion concentration has been paralyzed. Therefore, the maximum period to sustain healthy meat in the crab under cold stress is 6 hours.
文摘The aim of this work was to study the effect of essential oils as natural antioxidant for inhibition of peroxidase enzyme activity. Peroxidase enzyme is one of the most important enzymes in plant tissue which can bind to hydrogen peroxide and produce an activated complex that can react with a wide range of donor molecules. Therefore inactivation of the enzyme may increase the shelf life of raw and un-blanched frozen vegetables. In order to inactivate of the enzyme several physical and chemical treatments among them heating （blanching）, lowering pH or aw or adding chemical additives can be used, however each of the above mentioned methods has a kind of shortcoming. Our results indicated that crude extract of red cabbage and cabbage has the highest and potato and lettuce has the lowest peroxidase activity respectively （P〈0.05）. Although peroxidase resistance to essential oils varied among different vegetables but clove in all concentration had the best effects in decrease ofperoxidase activity （P〈0.05） whereas cumin and fennel were partially able to reduce the enzyme activity. （P〈0.05）.
