Isolation Of Antioxidants From Glycyrrhiza Uralensis And Their Application In Palm Oil

The antioxidant effect of Chinese herbal medicine is a research hotspot.Glycyrrhiza uralensis is a potential natural antioxidant resource.In this experiment,the active ingredients of Glycyrrhiza antioxidants were determined,and the components of Glycyrrhiza antioxidants were separated to lay a foundation for the development of natural oil antioxidants.In this study,Glycyrrhiza antioxidant components were separated by macroporous resin,silica gel column chromatography and semi-preparative liquid chromatography.The antioxidant activity of the separated components was tested.The results of combined analysis with high performance liquid chromatography showed that the content of Glycyrrhiza antioxidant saponins was5.02 ± 0.32g/100g(glycyrrhizic acid),the content of total flavonoids was 38.5±0.38g/100g(in rutin),and the content of polyphenols was 70.68±0.26g/100g(in gallic acid).The main effective components of Glycyrrhiza antioxidants are polyphenols and flavonoids,which contain a small amount of saponins and no polysaccharides.The antioxidants of Glycyrrhiza are antioxidant through the synergistic action between the internal components.Taking palm oil as the main raw material and Glycyrrhiza antioxidant as the main research object,soybean lecithin,gallic acid,citric acid and ascorbic acid were selected as synergist components to study the synergistic effect between synergist combination schemes and antioxidants,and to explore the dose-effect relationship between them.The synergist was compounded with TBHQ,soybean lecithin,citric acid and ascorbic acid.Based on the comparison of the composite antioxidants,the natural antioxidants of frying oil were developed.The acid value,peroxide value,induction period and ultraviolet absorbance of oils and fats in each experimental group were determined and the antioxidant effect was evaluated according to the standard of 2 h and 4 h.The results showed that the acid value,peroxide value,induction period and ultraviolet absorbance of the samples with Glycyrrhiza antioxidant,soybean lecithin and gallic acid of 0.1 g/kg were better than those of the blank control group and the samples with Glycyrrhiza antioxidant and TBHQ alone under the same conditions.Taking the amount of Glycyrrhiza antioxidant,soybean lecithin and gallic acid as the factors,and the induction period as the index,the response surface optimization was carried out,and the maximum response value was obtained,that is,the amount of compound antioxidant was 0.2 g/kg of Glycyrrhiza antioxidant,0.16 g/kg of soybean lecithin and 0.14 g/kg of gallic acid,respectively.The results showed that the compound antioxidants optimized by response surface methodology were better than Glycyrrhiza antioxidants in high temperature frying oil,but slightly lower than TBHQ.