Extraction of tannin from garlic skins by using microwave with ethanol as solvent

Tannins are phenolic compounds which have benefits as an anti-oxidant, anti-diarrhea, anti-bacterial and astringent. This study aims to determine the tannin content and antioxidant activity of garlic skins by microwave assisted extraction method. In this research, ethanol is used as solvent and the various experimental consist of 1:6 g/ml, 1:8 g/ml and 1:10 g/ml of garlic skin (solid) to ethanol (liquid) ratio; 30 s, 60 s, 120 s, 180 s and 240 s of extraction time; and 100 W and 180 W of microwave power. The tannin content of garlic skins is determined with Folin-Ciocalteu method. The antioxidant activity of garlic skins is evaluated with DPPH method. The results showed that extraction conditions had significant effect on the extraction content of tannin compounds, and the optimum condition is found at solid to liquid ratio of 1:8; extraction time of 180 s and microwave power of 100 W. Tannin content under this condition is about 1.77% and the antioxidant activity index of garlic skin extract is 1.994. The results showed that microwave-assisted extraction method is suitable and effective to extract tannin from garlic skin.