Effects Of Refining Process And Safflower Leaf Extract On Oxidation Stability Of Safflower Seed Oil

Safflower seed oil is a kind of edible oil with great nutritional value.The safflower seed oil（SSO）contains abundant essential unsatu-rated fatty acids.SSO is also rich in phenolic compounds,tocopherols,and phytosterols,as the main lipid concomitants,which endows it with great nutritional value and health-promoting functions.However,unsaturated fatty acids are prone to oxidative rancidity,which has a certain impact on oil quality,edible safety and oxidative stability.This paper starts from two aspects:one is to improve the refining deacidification process through ultrasonic assisted ethanol extraction technology,improve the oxidation stability of safflower seed oil by retaining endogenous antioxidant components to the greatest extent;The second is to optimize the phenolic extract of safflower leaves and add it to safflower seed oil to improve the oxidation stability of safflower seed oil from exogenous channels.The main research contents and results of this paper are as follows:（1）The effects of different refining processes（degumming,deacidification,decolorization and dewaxing） on the physical and chemical quality,fatty acid composition,main lipid companions and in vitro antioxidant capacity of safflower seed oil were analyzed in order to find the refining process that has the greatest impact on the quality of safflower seed oil.The results showed that the peroxide value and anisidine value of safflower seed oilsafflower seed oil increased significantly after alkaline refining and deacidification,The contents ofα-tocopherol,total phenol and total sterol decreased significantly,and the free radical scavenging ability of DPPH and ABTS decreased significantly.（2）The ultrasonic assisted ethanol extraction process has been optimized by random centroid optimization,and the effects of the two deacidification processes on the physical and chemical quality,main lipid chaperones and in vitro antioxidant capacity of safflower seed oil have been analyzed and compared.The results showed that the optimum process conditions for ultrasonic assisted ethanol extraction deacidification were as follows:ethanol concentration 100%,solid-liquid ratio 1:4,ultrasonic time 29 min,deacidification times 2 times,and the optimized safflower seed oil deacidification rate could reach 97.13%;Compared with the traditional alkali refining deacidification process,ultrasonic assisted ethanol extractiondeacidification process can effectively retain the beneficial lipid companions and unsaturated fatty acid content of safflower seed oil,significantly improve the acid value,peroxide value and anisidine,and improve the DPPH and ABTS radical scavenging ability of safflower seed oil.（3）With the safflower seed oil prepared by alkali refining and ultrasonic assisted ethanol extraction deacidification used as experimental materials and stored in the Schaal oven in dark for 30 days,the quality and oxidation stability of these two deacidificated safflower seed oil were investigated.The physicochemical property,main lipid companions and in vitro antioxidant capacity were took as indicators,and the corresponding shelf life model has been established.The results showed that the oxidation stability of ultrasonic assisted ethanol extraction deacidification safflower seed oil was better.During 30 days of storage in dark,ultrasonic assisted ethanol extraction deacidification safflower seed oil had better physical and chemical quality,higher content of lipid concomitants and stronger antioxidant capacity in vitro than alkali refining deacidification safflower seed oil;It is deduced that safflower seed oil at different temperatures conforms to the first-order kinetic equation.The oxidation rate constants‘k’at 30℃,40℃,50℃and 60℃are 0.08960,0.09117,0.09563 and 0.10805 respectively;Through the analysis of oxidation kinetics,the shelf-life models of ultrasonic assisted ethanol extraction deacidification oil and alkali refining deacidification oil are as follows:C=0.9639×e0.6506e_T^-608.5502t and C=1.4960×e0.5903e_T^-566.6638t.20°C and 25°C,the shelf life of ultrasonic assisted ethanol extraction deacidification safflower seed oil is about 28 days and27 days respectively,while that of alkali refining deacidification safflower seed oil is only 22 days and 21days.In conclusion,compared with traditional alkali refining deacidification,uaee deacidification safflower seed oil has better oxidation stability.（4）The total phenolic extracts from safflower stems,leaves and seed meal had been prepared.By measuring and evaluating the comprehensive antioxidant capacity of different extracts（including DPPH,ABTS and hydroxyl radical scavenging capacity）,the safflower extract with the best comprehensive antioxidant capacity was selected and added to safflower seed oil for oven accelerated storage experiment to explore its effect on the oxidative stability of safflower seed oil.The results showed that the comprehensive antioxidant capacity of safflower leaf extract was better than the other two extracts.In the Schaal accelerated oxidation experiment,adding 0.08%safflower leaf extract to safflower seed oil stored in the dark at 60℃for30 days could effectively improve the oxidation stability of safflower seed oil.Compared with the control group without extract,the acid value,peroxide value and anisidine value decreased by 24.24%,28.30%and21.33%respectively.Safflower leaves have the potential to be exploited as natural antioxidants.