Abstract:

Soybean oil was used to investigate the optimization of mixing ratio (m/m) for the water extract from Flos Sophorae Immaturus and the ethanol extract from Radix Glycyrrhizae for the protection of processed foods against lipid oxidation. Both the extracts were analyzed qualitatively by thin layer chromatography and IR spectroscopy and HPLC was employed for quantification. The antioxidant properties of a mixture of both the extracts having the best protective effect against lipid oxidation in soybean oil were evaluated by superoxide anion free radical scavenging assay and DPPH free radical scavenging assay and investigation of the protection of Cantonese-style moon cake against oxidation by the use of it was conducted. The optimum mixing ratio for both the extracts was 1:1. Rutin and glycyrrhizin were detected in the water extract from Flos Sophorae Immaturus and the ethanol extract from Radix Glycyrrhizae, respectively. IR spectroscopic analysis demonstrated that both the extracts contained molecules in which the phenolic hydroxyl group was associative type. The contents of rutin and glycyrrhizin in the mixture of both the extracts at 1:1 were determined by HPLC to be 76.8% and 0.46%, respectively. At a concentration of 1.5 g/L, the scavenging ratio of the mixture against superoxide anion free radicals was as high as 67.64%, and its DPPH free radical scavenging ratio at 10 mg/mL reached up to 62.88%. The shelf-life of Cantonese-style moon cake could be prolonged to around a month by the use of the mixture.

Key words: Flos Sophorae Immaturus, Radix Glycyrrhizae, antioxidant, antioxidation