ANTIMICROBIAL FUNCTIONS OF SPICES - WHY SOME LIKE IT HOT

Although spices have been important for centuries in food preparation throughout the world, patterns of spice use differ considerably among cultures and countries. What factors underlie these differences ? Why are spices used at all? To investigate these questions, we quantified the frequency of use of 43 spices in the meat-based cuisines of the 36 countries for which we could locate traditional cookbooks. A total of 4578 recipes from 93 cookbooks was analysed. We also compiled informa tion on the temperature and precipitation in each country, the ranges of spice plants, and the antibacterial properties of each spice. These data were used to investigate the hypothesis that spices inhibit or k ill food-spoilage microorganisms. In support of this is the fact that spice plant secondary compounds are powerful antimicrobial (i.e., anti bacterial and antifungal) agents. As mean annual temperatures (an indi cator of relative spoilage rates of unrefrigerated foods) increased th e proportion of recipes containing slices, number of spices per recipe , total number of spices used, and use of the most potent antibacteria l spices all increased, both within and among countries. Likewise the estimated fraction of bacterial species inhibited per recipe in each c ountry was positively correlated with annual temperature. Several alte rnative hypotheses were considered-that spices provide macronutrients, disguise the taste and smell of spoiled foods, or increase perspirati on and thus evaporative cooling; it also is conceivable that spice use provides no benefits. However, none of these four alternatives was we ll supported by our data. The proximate reason spices are used obvious ly is to enhance food palatability. But the ultimate reason is most li kely that spices help cleanse foods of pathogens and thereby contribut e to the health, longevity and reproductive success of people who find their flavors enjoyable.