Antimicrobial Effects of Spices1

There is a renewed interest in the antimicrobial properties of spices. In vitro activities of several ground spices, their water and alcohol extracts, and their essential oils have been demonstrated in culture media. Studies in the last decade confirm growth inhibition of gram positive and gram negative food borne bacteria, yeast and mold by garlic, onion, cinnamon, cloves, thyme, sage and other spices. Effects in foods are limited to observations in pickles, bread, rice, and meat products. In general, higher spice levels are required to effect inhibition in foods than in culture media. Fat, protein, and water contents in foods affect microbial resistance as does salt content. Very few studies report on the effect of spices on spores, and on microbial inhibition in conjunction with preservatives and food processes. Of the recognized antimicrobial components in spices, the majority are phenol compounds with a molecular weight of 150 to 160 containing a hydroxyl group. Eugenol, carvacrol and thymol have been identified as the major antimicrobial compounds in cloves, cinnamon, sage and oregano.