The Opitmization Of Peanut Lipase And Lipoxygenases Activity Detection Techniques And Their Effect On Storage Characteristics

Peanut is an important edible vegetable oil resources and cash crops, its annualproduction of edible vegetable oil accounted for nearly14%of the world’s, the totalproduction and yield of peanuts has always been the first of the oil crops in the country,about50%of the total oilseeds production. Peanut seeds, which content50%fat, especiallyunsaturated fatty acid content is high, accounting for more than80%of the grease, suitablefor manufacture of a variety of nutritious foods. It is an important reason for its qualitydeterioration in the process of fat metabolism that Peanuts can easily occur oxidation,rancidity, take the oil and other phenomenons during storage. Lipase and lipoxygenase is akey enzyme in the fat metabolic pathways, which can lead to free fatty acids hydrolysisfrom fat,as well as catalysis oxidation of unsaturated fatty acids, Lipase and lipoxygenaseplay a major impact duiring the process of peanut storage.Based on colorimetric determination method reported for rice lipase, we established anew method improving and optimizing the measurement for peanut seed lipase activity,with the optimum sampling amount of5mg and substrate concentration of30mg mL–1.The method was validated to be accurate, specific and well repeatable.The lipase activities of216peanut germplasm resources were detected, withsignificant difference (P<0.001) among them. Five with higher lipase activity and five withlower lipase activity were screened, and each two of which were selected to perform anaccelerated-aging experiment under42.5℃and87.5%moisture in humidity chamber. Theresults indicated that, with extension of storage time, the germination rate of peanut withlower lipase activity decreased slowly, while that of peanut with higher lipase decreasedrapidly, showing a negative correlation between seed vigor and peanut lipase activity(correlation coefficient was–0.8875).Lipoxygenases (LOXs；EC1.13.11.12), which effected the quality of soybean, riceand maize in storage processing, is the key enzyme in seed lipid metabolism ways, but israrely reported in peanut. Based on colorimetric determination method reported for plantLOX3β-carotene coupling, we established a new method improving and optimizing themeasurement for peanut seed LOX3activity, with the optimum sampling amount of8mgand detection period between10s and70s. The method was validated to be accurate,specific and well repeatable. The LOX3activities of214peanut germplasm resources weredetected, with significant difference (P<0.01) among them.24peanut germplasm resources which LOX3activity had significant differences were screened by the18months storagetest in normal state and expanded propagation. The results indicated that a highlysignificant correlation between seed vigor and peanut LOX3activity (correlationcoefficient was0.6984, P<0.01). The peanut with higher LOX3activity can be storagedlonger, The study provides a reference for the further research in the effect of LOX3onpeanut storage characteristics.