Spicy delights under the hot sun
People of hot, spicy cuisine can thank bad bacteria and other foodborne pathogens for recipes that, not entirely coincidentally, hail from countries with hot climates. Because the use of antimicrobial spices is associated with the risk that the food will spoil otherwise. Actually, the pungent-tasting substances of the plant serve to ward off predators. But long before the invention of deep-freeze storage, people were using them to protect their food from spoilage by microorganisms. This is reported by Jennifer Billing and Paul W. Sherman in the March issue of the Quarterly Review of Biology.
"The immediate cause of using spices is obviously for improved flavor," says Sherman, an evolutionary biologist and professor of neurobiology and behavior at Cornell University."But why do we like spices? Beneficial traits are passed down both culturally and genetically, including taste receptors in our mouths and our liking for certain aromas. People who enjoyed foods with antibacterial spices were likely to be he althier, especially in hotter climate. They lived longer and had more offspring. And they passed on their fondness for such foods to their children: 'This is how a mammoth is cooked.' In our opinion, the ultimate reason for using spices is to kill bacteria and fungi in food."
Sherman's student Jennifer Billing has painstakingly compiled much of the data needed to make the connection between microbes and spices: over 4,570 recipes from 93 cookbooks, representing traditional meat-based cuisine from 36 countries; each country's temperature and rainfall; the horticultural distributions of 43 herbs and the antibacterial properties of each herb.
According to her research, garlic, onion, allspice and oregano in particular act as the best bacteria killers. They really kill everything. Next come thyme, cinnamon, tarragon and cumin (they kill up to 80% of bacteria). Sweet peppers, which include chili and other hot peppers, are in the middle of the antimicrobial hit list (killing or inhibiting up to 75% of bacteria), while white or black pepper suppresses up to 25% of bacteria, as does ginger, anise and celery seeds and the juice of lemon and lime.
"In countries with hotter climates, spices are used more often than in those with colder climates. Yes, in hot countries almost every meat dish has at least one spice, but mostly many, especially the potent spices, while in cooler countries one large proportion of the dishes are prepared without seasoning, or with only a few seasonings." As a result, in the hot regions, a larger proportion of the food is protected from spoilage by seasoning.
Accordingly, Thailand, the Philippines, India and Malaysia are at the top of the list of countries where hot spices are used, while Sweden, Finland and Norway rank at the bottom. The United States and China fall somewhere in the middle, although Cornell University researchers studied the cuisines of these two countries by region and found large differences by latitude. This helps to understand why crayfish etoufée tastes spicier than New England clam chowder.
The biologists, however, also considered various alternative explanations for the use of spices, but rejected all of them with one exception. According to Sherman, the problem with the "eat-to-sweat" hypothesis, according to which people in hot regions eat spicy foods to keep themselves cool through the onset of perspiration, is that you don't have to sweat through all the spices. "And there are better ways to cool off. Like going into the shade." The idea of using spices to mask the taste of spoiled food "ignores the he alth hazards of ingesting spoiled food." Also, people probably don't eat spices because of their nutritional value, he said Biologist, because the same macronutrients are present in the same amounts in regular vegetables, which are eaten in much larger quantities.
However, the micronutrient hypothesis (that spices contain trace amounts of antioxidants or other chemicals that aid in digestion) may be true. But she doesn't rule out the antimicrobial explanation, according to Sherman. However, this hypothesis does not explain why people in hot climates need more micronutrients, the scientist adds. This is only made clear by the antimicrobial hypothesis.
The study of Darwinian gastronomy is a bit unfamiliar for an evolutionary biologist like Sherman, who normally focuses his research on the role of natural selection in animal social behavior. But eating, he argues, is clearly a part of the more social behavior of Homo sapiens, and his (Sherman's) recent activity would be a good way to see the interactions between cultural evolution and biological function. "I believe that cooking recipes are a history record of the co-evolutionary race between us and our parasites. The microbes compete with us for the same foods," explains Sherman. "Everything we do with our food - drying, cooking, smoking, s alting, seasoning - is an attempt to protect it from being poisoned by our microscopic competitors, who are constantly mutating and evolving to get ahead of us One way to reduce illness from spoiled food is to add another spice, which of course will make the dish taste different, and people who embrace the taste will be rewarded with better he alth."
Now that the link between bacteria and spices has been uncovered, some librarians may want to reindex their cookbooks under the "Food Safety" heading. And spice racks may be appearing in pharmacies soon.
Top 30 Spices with Antimicrobial Properties
(list from greatest to least antimicrobial effect)
|3. Allspice (Clove Pepper)|
|11. Bay Leaf|
|12. Sweet peppers|
|26. Pepper (white, black)|
|29. Celery Seed|
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