| Peanut,a scientific name as ground peanut(Arachis hypogaea Linn.), also known as longevity nut,is a kind of important nut oil crops,which is planted widely in China and is highly yielding. Every year,our country produces about 14 million tons of peanut per year,more than 40% of world total output,which is mainly distributed in Shandong, Henan,Hebei, Anhui provinces.Peanut is generally used for cooking oil and peanut protein production, besides consumption in a whole. Peanut skin is mostly thrown as waste in peanut processing, without any economic value, however,the content of resveratrol is high in peanut skin,just next to the roots.Peanut skin has great using value, while related studies is few, in this paper, response surface method was used to optimize resveratrol ultrasonic extraction from peanut skin.Resveratrol is a kind of natural active ingredient existed in giant knotweed,peanuts and grape, which produce when by the plants affected by adverse conditions. At present,the research mainly concentrated on the study of resveratrol’s extraction and purification, and little on its mechanism of action, This paper try to study its antioxidant capacity through vitro radical scavenging test and oil oxidation test and find out its reaction mechanism,to provide a reference for further use of resveratrol as a natural antioxidant properties.The main findings are as follows:Resveratrol extraction process in Peanut skin : response surface method is adopted to optimize the ultrasonic extraction of peanut resveratrol in peanut skin. Based on single factor experiment of extraction time, extraction temperature, liquid ratio and solvent concentration, resveratrol content as the response value, effects of the four factors on resveratrol content was discusses.optimal conditions was got: extraction time 63.60 min,extraction temperature 49.56 ℃, liquid ratio 14.96 mL/g and solvent concentration75 %.Under the above condition, the theoretical content value of resveratrol in the extract was 18.5111 μg/g, verified experiment with extraction temperature 50 ℃, liquid ratio 15mL/g, solvent concentration 75% confirmed that the extraction time was 64 min,,the average of three tests was 18.1785 μg/g, according with theoretical predictions.Research on resveratrol antioxidant activity : DPPH free radical clearance rate, total antioxidant capacity and reducing capacity of resveratrol were studied, compared with a commonly-used food antioxidant- butylated hydroxytoluene. The results show that resveratrol and BHT both have good scavenging effects on DPPH free radical,which increase with the increase of the concentration of antioxidants. Resveratrol does better on removing free radicals, total antioxidant activity and reducing capacity than BHT.Dynamics of resveratrol-DPPH free radical scavenging reaction: resveratrol-DPPH free radical scavenging reaction takes more than 6h to reach steady state, which is a slowreaction and the EC50 is 0.047±0.04 μmol antioxidant/μmol DPPH·, antiradical power is21.28±0.27, stoichiometric coefficient is 0.094±0.07, reaction rate constant is5.85×10-3±0.04 μM-1·s-1, then the possible reaction mechanism of resveratrol and DPPH· was guessed.two-sample t-test was used to compare the resveratrol group and control group in air oxidation test at different temperatures, which showed that resveratrol has certain antioxidant effect.Dynamic Analysis showed that oxidation process of peanut oil with or without resveratrol were in line with the first order reaction law, and the correlation coefficient is over 0.9000.Under different temperatures, the reaction rate constant of oil sample with resveratrol is less than those of blank samples, activation energy of oil significantly increased after adding resveratrol. |
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