Antibacterial/Antifungal Although thought to be less active than garlic, onions have been shown to possess antibacterial and antifungal properties (Hughes and Lawson, 1991; Augusti, 1996). Onion oil has been shown to be highly effective against gram positive bacteria, dermatophytic fungi, and growth and aflatoxin production of Aspergillus fungi genera (Zohri et al., 1995). In fact, Welsh onion extracts have been proven to be more inhibitory toward aflatoxin production than the preservatives sorbate and propionate at pH values near 6.5, even at concentrations 3-10 fold higher than maximum levels used in foods (Fan and Chen, 1999). Organosulfur compounds were cited as protective agents by researchers finding antibacterial effects of onion extract against oral pathogenic bacteria (Kim, 1997). The possibility arises for protection against dental caries. It should be noted that no protection was found in extracts obtained from grated onion kept at 37ºC for over two days. Enzymatic destabilization of thiosulfinates was proposed for the change in effectiveness. The organosulfur compounds of onions also have been credited with antiasthmatic effects (Dorsch and Wagner, 1991; Augusti, 1996). Thiosulfinates formed from onion tissue degradation (i.e. chopping) have been credited in inhibition of arachidonic acid metabolic pathways and subsequent anti-inflammatory and antiasthmatic effects (Wagner et al., 1990). In addition to inhibitory effects against pathogenic bacteria, onions have been found to promote beneficial microorganisms.