By-products of vegetables from organic cultivars as antioxidant foodstuff

摘要

Our study evaluate the influence of cropping systems (organic and conventional), polarities of solvents (aqueous water and ethanol: water) and the methods of sample preparation (dried and raw) on the ability of free radical scavenging of extracts prepared from cruciferous by-products including cauliflower, broccoli and white cabbage. Dried extracts had higher dry matter yield and a greater percentage of scavenging free radicals as compared with the raw extracts (P < 0.05). The amount of antioxidant substance required to reduce 50 % the initial concentration (IC_(50)) of 1,1 -diphenyl-2-picrylhydrazyi (DPPH) was variable and, following an increasing scale, it was demonstrated the greatest antioxidant capacity of the dried organic extracts was cauliflower by-product (IC_(50) = 0.33 mg/ml), followed by broccoli by-product (IC_(50) = 0.45 mg/ml) and by white cabbage by-product (IC_(50) = 0.52 mg/ml). Therefore, the organic vegetables have lower IC_(50) values as compared with the conventional crop system (P < 0.05). Regarding to the polarity of the solvent, the extracts solutions obtained by hydroalcoholic extraction had a higher antioxidant capacity compared to those that used aqueous water for extraction (P < 0.05). For hydroalcoholic extracts, themost potential antioxidant has been demonstrated by the cauliflower by-products (IC_(50) = 0.19 mg/ml), followed by broccoli by-products (IC_(50) = 0.40 mg/ml) and white cabbage by-products (IC60 = 0.51 mg/ml). It was concluded that (1) there is variation in antioxidant potential between species of cruciferous by-products; (2) the farming systems, the sample preparation methods and the type of solvent exert significant influence in the antioxidant property; (3) the antioxidant effect is dose-dependent.