| Perilla is a traditionally medicinal and edible plants in China. It belongs to medicinal plant of Labiatae Perilla, meanwhile it is one of the first batch of the60homology of medicine and food species that Ministry of Health has announced. The leaves, stems and fruits of perilla are rich in flavonoids and terpenoid and have the functions of antioxidant, anti-aging, antibacterial, prevention and suppression of tumor, hypoglycemic and anti-allergy. To better develop of resources of perilla, taking perilla leaves as raw material in my research, using ultrasonic extraction and ultrafiltration methods combining with experimental designed to optimize the extraction and separation processes of perilla leaf antioxidant, and to study the antioxidant effects of the perilla leaf antioxidant in edible oil. The main results are as follow:Taking the clearance rate of DPPH·as the antioxidant activity evaluation, the L9(34) orthogonal was adopted in the experimental design to optimize the ultrasonic extraction conditions of perilla leaf antioxidant, and compared the effect on DPPH·of the ultrasonic extraction to traditional ethanol extraction scavenging. The results indicated that the optimum ultrasonic extraction conditions are the ethanol extraction solvent is75%, the solid-liquid ratio is1:25g/mL, the ultrasonic temperature is50℃, the ultrasonic power is270W, the ultrasound frequency is45KHz, the ultrasonic time is15min and the ultrasonic extraction times is once. Under these conditions, the extraction clearance rate of DPPH·is94.58%. Compared to the traditional ethanol extraction the clearance rate increased6.69%. And the UV-Vis scans shows that composition of the product derived by ultrasonic extraction or traditional ethanol extraction were basically consistent.Basing on the single-factor trial test, Box-Behnken model of response surface analysis was used to indicate the effect of UF pressure, UF temperature and stock ratio on the separation of perilla leaf’s crude extracts, and discussed the stability of the antioxidant extract. The results indicated that the optimum conditions for UF as follows:the MWCO is10000D, the UP pressure is0.35MPa, the UP temperature is 35℃, the stock ratio is1:1.8, the UF membrane flux under these conditions is24.24L/m2·h. And the UV-Vis scans shows that UF filter most of chlorophyll-a which is impurity. There is not obvious influence of temperature and light on the antioxidant activity of perilla leaf extraction. The activity of perilla leaf extraction basically inactivated beyond the alkaline conditions but higher under acidic conditions, and around pH6the antioxidant activity is quite stable, after storing25d the clearance rate of perilla leaf extraction on DPPH·remained around85%.Oven storage strengthen method was applied to research the anti-oxidation effect of the antioxidant (produced from perilla leaf) extract on the soybean oil and peanut oil. And the experiment also studied the effects of antioxidant the citric acid, glycine and VC compounded with the perilla leaf extract. The results indicated that the perilla leaf extract has a certain antioxidant effect on the soybean oil and peanut oil, and the antioxidant ability of the extract on peanut oil (PF=2.14) is stronger than that of soybean oil (PF=2.03). The extracts’antioxidant effect that add0.2%to soybean oil was stronger than that of BHT and the same to that of VE, while that add to peanut oil was stronger than the antioxidant BHT and VE. The complex antioxidant added citric acid of the soybean oil and peanut oil are a substantial increase in anti-oxidation, under20℃the shelf life of soybean oil is expected to be extended by2.14months to6.42months, and the peanut oil shelf life expectancy extended by3.07month to7.73months. |
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