Optimization of extracting proanthocyandins from red rice by response surface methodology

Response surface methodology was employed to optimize the extraction conditions of proanthocyanidins from red rice grown in Yanshou,Harbin. Based on single experiments,response surface methodology was employed to optimize the extraction conditions of the red rice,the optimum extractive conditions were ascertained as follows: acetone concentration 76%,extraction temperature 39 ℃,material- to- liquid ratio 1 ∶ 25( g / m L),extraction p H5,extraction twice,extraction time 40 min,the yield of proanthocyanidins of this optimized procedure was( 4.37 ± 0.02) mg / g,1.925 times than Sudu Heenati red rice of tradition Sri Lanka which was the highest procyanidins content of red rice reported. The result of infrared spectra showed that the proanthocyanidins of the red rice is mainly composed of structure unit of( epi)- catechin consisting of procyanidin polymers. The proanthocyanidins of red rice have stronger scavenging effects to DPPH radicals than VC,suggesting that the red rice reveals better antioxidant activity,and has the potential to be the source of proanthocyanidins.