| Perilla frutescens, one of medicinal and edible plants, has a cultivation history of more than 2000 years in China. In recent years the perilla leaves have got more and more attention at home and abroad, because its have abundant nutrients and bioactive ingredients. In this research, the rosmarinic acid extraction technology with ultrasonic assisted and purification with macroporous resin and silica gel from perilla leaves were studied, and the oxidation resistance of rosmarinic acid were analysized. Furtherly, rosmarinic acid was used in mildew corrosion protection in the bread and cake. The main results as follows:Firstly, based on the single factor tests, the ultrasonic assisted extraction technique of rosmarinic acid in perilla leaves was optimized by response surface methodology. The optimal process parameters were ultrasonic temperature 40 ℃, liquid-solid ratio 25:1, ultrasonic time 30 min, and the yield of rosmarinic acid was 19.66 mg/g.Secondly, the optimal macroporous resin was obtained by static adsorption and desorption tests, which the best resin was XDA-8. Under these conditions, the adsorption rate and desorption rate were 91.81% and 95.36%. The optimal dynamic process parameters were obtained by dynamic adsorption and desorption tests, which included flow rate for sample of 2 BV/h, the amount for water elution of 2 BV, an ethanol desorption solution concentration of 70%(v/v), flow rate for elution of 1 BV/h and its amount for elution of 12 BV; The developing solvent was obtained by thin layer chromatography, which the best system was V(ethyl acetate) : V(methanol) = 20:1. These selected system was used in silica gel column chromatography to purify perilla rosmarinic acid. The content of perilla rosmarinic acid increased from 0.41% to 29.70% after macroporous resin purification, and from 29.70% to 50.96% after silica gel column chromatography.Thirdly, the antioxidant capacity of perilla rosmarinic acid was determined by using DPPH, hydroxyl radical and FRAP assay. The results showed that IC50 value of scavenging DPPH radicals were 538.02, 318.47 and 473.91 mg/L for crude rosmarinic acid, purified rosmarinic acid and Vc(control) respectively, and their hydroxyl radicals were 651.86、296.39 and 193.99 mg/L, FRAP value were 341.26 、 887.38 and 1054.72 mmol Fe2+/100 g respectively。Finally, perilla rosmarinic with different concentrations was added in the process of bread and cake as a food preservative, to test the mildew corrosion protection effect during their storage periods. The results showed that the number of fungi and bacteria growth speed was slower in the bread and cake added rosmarinic acid than control whether at room temperature(temperature 28-32 ℃, relative humidity 65%) or refrigerator temperature 4 ℃, relative humidity(40%), and their shelf life were prolonged 2-3 days. |
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