Scavenging Activity of Different Garlic Extracts and Garlic Powder and their Antioxidant Effect on Heated Sunflower Oil

摘要

Seven garlic extracts were prepared in different solvents. The extract yield ranged from 0.36 (n-hexane) to 71.73% water (H20 at 50°C), total phenolic content from 11.16 methanol/water (MeOH/H20, 1:1) to 17.32 (H_2O) mg GAE g~(-1) extract and antioxidant activity (DPPH) from 27.25 (H20) to 16.39% (MeOH/H_2O, 1:1) at concentration of 150 ug uL~(-1), whereas IC_(50) ranged from 0.27 (H20) to 0.53 (MeOH/H_2O, 1:1) mg mL~(-1) DPPH. The efficiency of Garlic Extracts (GE) and Garlic Powder (GP) were studied as antioxidants, in comparison with BHT, to stabilize sunflower oil (SFO) heated at frying temperature. Each GE and GP was added to SFO (0.1 g mLr1 of oil) and heated in a draft oven at 180°C for 15 h (3 h day-1). Similar heating test was carried outusing legal limit of BHT at concentration of 200 ppm. The progress of lipid oxidation was measured in terms of Peroxide Value (PV), Acid Value (AV), Conjugated Dienes, (CD) and Conjugated Trienes (CT). The results of this study showed that GE and GP have inhibition effect on lipid oxidation. The reduction percent in peroxide values after using GE and GP as antioxidants ranged from 53.8 (SFO-H20) to 73.2 (SFO-MeOH) approximately and the reduction percent in acid value ranged from about 6.8 (SFO-H_2O) to24.1 (SFO-MeOH) in comparison to about 7.7 and 34.2%, after 15 h, respectively, for SFO-BHT. Whereas, the reduction percent in CD and CT, after 15 h, ranged from about 21.6 (SFO-MeOH/H_2O, 1:1) to 50.3 (SFO-GP) and from about 11.5 (SFO-MeOH/H20, 1:1) to22.2 (SFO-GP), respectively, in comparison to about 2.6 and 24.1, respectively, for SFO-BHT.