In 2001, Paul W. Sherman and Geoffrey A. Hash continued the examination of spices in human diet with a study entitled "Why Vegetable Recipes Are Not Very Spicy," published in Evolution and Human Behavior. They compiled information from 2,129 vegetable-only recipes from 107 traditional cookbooks of 36 countries. Then they examined the history of the spice trade and discovered that for thousands of years spices have been traded all over the world, resulting in their availability in most world cuisines. The most traded spices are black pepper and chile pepper, in that order.
Many studies have proven the antibacterial properties of spices, the fact that spices are more prevalent in warm climates than cool climates, and that the concentrations of spices in recipes are sufficient to kill bacteria. It is true that cooking eliminates the antimicrobial properties of some spices, such as cumin, but has no effect on others, such as chiles.
The researchers compared the vegetable-only recipes to the previous study of meat recipes according to the spices found in the recipes and discovered that vegetable recipes used far fewer spices than meat recipes. They attributed this to the fact that bacteria "do not survive or proliferate as well in vegetables, so adding spices is not as necessary." Interestingly, the four most common spices in both the meat and vegetable recipes were onion, black pepper, garlic, and chile peppers. Onion appeared in more than 60 percent of both types of recipes; black pepper in about 60 percent of the meat recipes and 48 percent of the vegetable recipes; garlic in 35 percent of the meat recipes and 20 percent of the vegetable recipes; and chile peppers in 22 percent of the meat recipes and 18 percent of the vegetable recipes.
Within countries, vegetable-based recipes called for fewer spices than meat recipes in all 36 countries. The countries using the most spices in both vegetable and meat recipes were, in order from the most used: India, Vietnam, Kenya, Morocco, Mexico, Korea, and The Philippines. Following were France, Israel, and South Africa.
In their second study, the researchers concluded: "By every measure, vegetable-based recipes were significant less spicy than meat-based recipes. Results thus strongly support the antimicrobial hypothesis."
Link to their earlier press release
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