Inhibition of Bacillus cereus by Garlic Extracts

Aqueous extract of garlic ( Allium sativum , L.) was prepared from a 1:2 (wt/vol) ratio of fresh garlic bulbs to sterilize distilled water. Garlic extracts of 3%, 5% and 10% inhibited the growth of Bacillus cereus on nutrient agar plates 31.3%, 58.2% and 100%, respectively. Extracts from garlic bulbs stored at -18°C are slightly more inhibitory to the growth of B. cereus than extracts from bulbs stored at 15-35°C for 6 months. The greatest extract activity was found when garlic bulbs were extracted and left at 30°C for 4 h before filtration. When the macerate was held at 4°C, 6 h of storage were needed for the extract to reach its greatest activity. Gamma irradiation, at the dose of 570 krads, of garlic bulbs with subsequent freezing before extraction decreased the extracts original activity up to 50%. Exposing the extracts to heat treatments of 80-90°C for a total heating time of 5 min completely destroyed the antibacterial activity of the extract.