Hot climates spawn hot cuisines (with recipe)
I grew up in a German-American community, just outside Chicago, where my family had farmed since the mid-19th century. Though part of the first generation off the farm, I was never far from farmstyle gardens—or cuisine.
Grandfather Henry and his mother Emma taking a break on the Raloff family farm, Blue Island, Ill., July 1918. Their cuisine, passed on to my generation, reserved spices for canning.
When Uncle Ed’s corn was ripe, we’d bop over just before dinner to pick a dozen ears from his three-quarter acre garden, the one he had retired to when the farm was sold. Most of the beefsteak, cherry, and Italian tomatoes that graced our table each summer—certainly the best of them—came from Ed’s farmlet on the south side of town.
Similarly, we never visited another uncle without coming home with armloads of cukes, beans, peppers, and berries—and admonitions to eat them in the next day or two, while they still tasted fresh. Neighbors and friends also had a habit of thanking Dad, the neighborhood’s Mr. Fix-it, with their garden-fresh produce.
It wasn’t until I went away to college that I realized most people routinely add more than salt or sugar when cooking fresh foods. Only during canning did Mom use spices, adding them to dill pickles and spiced peaches.
In our household, it was positively verboten to add garlic to anything. And no one we knew used rosemary, mint, or cardamom—fueling my suspicion that these were merely aromatic exotica marketed to fill spice racks and lend a worldly ambiance to prosaic all-American kitchens.
Once I left home, however, my nose and palate were continuously surprised by a world of foods that were not only peppered, but also laced with ginger, saffron, cilantro, and cumin. Friends relentlessly teased me about the blandness of any culture that could have evolved without spice.
In defense, I started ruminating on why we cooked so plainly. It couldn’t reflect my German heritage, because while spending a few months in Germany, I had found spicy vinaigrettes routinely pickling even in-season vegetables. I also recalled that much of the produce and meats in German groceries had looked past their peak, perhaps because many had arrived from far-off Italy, Spain, and Romania.
Eventually, I decided that my family’s long-standing spicefree diet must have evolved from a desire to let a food’s farm-fresh flavors emerge unchallenged.
A scholarly new study by Cornell University scientists now suggests my anecdotal assessment may not have been far off the mark. After analyzing the cuisines of 36 nations—based on 4,578 "traditional" recipes from 93 cookbooks—it finds that the hotter and wetter a country, the spicier its food. This suggests, Jennifer Billing and Paul W. Sherman conclude, that as the risk of food spoilage grows, so does a culinary reliance on spices—a natural source of antimicrobial compounds.
The two lay out their thesis and the science supporting it in a 46-page report, published this week, in the Quarterly Review of Biology.
What’s a spice?
Most cooks describe spices as those herbs or other botanical tidbits that make their recipes taste better. Billing and Sherman explain that because the term has been defined by use rather than biology, spice is a culinary rather than a botanical distinction. Over the years, food scientists have categorized these flavorings into four major groups: aromatic lichens; parts of trees or woody plants; roots, flowers, seeds, or fruits of herbaceous plants; and botanical extracts or essential oils.
Because many popular spices have an antimicrobial alter-ego, Billing and Sherman decided to probe whether the flavorings’ food-preservation properties might have initially driven their incorporation into local foods.
To test this, they sought out recipes that likely predated the advent of widespread home refrigeration—focusing exclusively on those featuring meat, fish, or shellfish (all of which tend to spoil more quickly than vegetables)—and noted the mention of spices. The recipes represent cuisines from every inhabited continent and 16 of the world’s 19 language families.
The scientists then pored over any and all published accounts of research on antimicrobial properties for each of the 43 spices mentioned in the recipes. Afterward, they scouted for any correlations between the frequency of a spice’s use and the physical climate in which these recipes evolved.
The hottest savor the hottest
Roughly 93 percent of all surveyed recipes used at least one spice. Every recipe from Ethiopia, Kenya, Greece, India, Indonesia, Iran, Malaysia, Morocco, Nigeria, and Thailand was spiced. At the other end of the culinary spectrum, Finnish and Norwegian cooks included spices in no more than one recipe in three.
Hot climates tended to use more spices and usually the more common ones, such as chilies, garlic, and onions. Climates with an average temperature over 62 °F proved especially likely to also use cinnamon, coriander, cumin, and ginger. Anise, lemongrass, and turmeric showed up almost exclusively in recipes that evolved where the mean temperature was around 78 °F. Much cooler climates tended to spawn recipes that relied on fewer spices—including some of the least common ones, such as savory, capers, juniper, and tarragon.
"We had assumed initially that most spice plants grow only in the tropics," the scientists note, "but this turned out to be untrue." Indeed, they found no relationship between climate and the number of indigenous spices. However, "although residents of hotter countries do not have more local spice plants to choose from . . . [they] use a greater fraction of those spice plants that are available (especially the potent antimicrobials)."
Overall, onions (including leaks, chives, and shallots) and pepper (primarily black) topped the spice list, required in more than 60 percent of all recipes. Rounding out the top 10 were: garlic (in 35 percent of recipes), chili peppers (24 percent), lemon and lime juice (23 percent), parsley (22 percent), ginger (16 percent), bay leaf (13 percent), coriander (about 8 percent), and cinnamon (around 7 percent).
Spicier is safer?
Of the 30 spices for which solid data exist, all inhibit at least some bacteria, and four—garlic, onion, allspice, and oregano—inhibit the growth of every species tested. Several spices are also reported to be powerful fungicides, the Cornell pair observe, "and can thus prevent production of deadly fungal metabolites (such as mycotoxin)." Though popular, lemon and lime juices were among the least effective spices in quelling the growth of microbial pathogens. However, as a source of acid, they appear to boost the antimicrobial performance of other flavorings.
Indeed, many of the spices performed proportionately better in the presence of other spices than when used alone. "This is interesting," the scientists note, "because recipes in our sample call for an average of four different spices."
Some occur so frequently in blends that they are often marketed that way—such as chili powder (usually a mix of red pepper, onion, paprika, garlic, cumin, and oregano), oriental five spice (pepper, cinnamon, anise, fennel, and cloves), or the French quatre epices (pepper, cloves, ginger, and nutmeg).
When Billing and Sherman tallied the amount of spices used in the typical recipe, between 0.25 to 3 grams per kilogram of food, they found it tended to fall within a range "sufficient to yield useful antibacterial effects." In fact, their data indicate that there "is a strong correlation" between regions having high average temperatures and the local cuisine’s reliance on spices possessing the most potent antimicrobial activity.
The scientists point to Japan and Korea’s different food-poisoning rates as anecdotal support for the value of these spices in food safety. Where almost 30 in every 100,000 Japanese diners experienced a food-poisoning incident between 1971 and 1990, the incidence was only one-tenth that high in Korea. While the climates of the two countries are quite similar, Koreans eat their food spicier. What’s more, Korean recipes were 50 percent more likely than their Japanese counterparts to call for at least one spice possessing especially potent antimicrobial activity. "As a result," Billing and Sherman observe, "the estimated proportion of foodborne bacteria inhibited by an average recipe is significantly higher in Korean (51 percent) than Japanese cuisine (12 percent)."
Speculating as to why this might have come about, the Cornell researchers suggest that when Japan could rely on locally caught fresh seafood, it had less need for antibacterial spices. Today, Japan imports much of its food, often from long distances, they note—potentially leaving traditional recipes too spice-deprived "to cope."
In sum, Billing and Sherman conclude, it appears that humans initially spiced foods to take advantage of the antimicrobial actions of the plant, especially in hot climates where food was more likely to spoil quickly. So "by cleansing foods of pathogens, spice users contribute to their health, survival, and reproduction."
From Chicago to D.C.
My career led me to settle in a dramatically warmer climate than the one in my home town. This southward odyssey paralleled a developing penchant for spicier fare. While far from fiery, my own family’s cuisine now places a heavy reliance on spices—especially cumin, garlic, and freshly ground black pepper.
Indeed, my customized variation of Moroccan carrot salad (see recipe below) has not only become a year-round household staple, but my most requested recipe. Now, I can also boast that it not only befits Washington’s beastly hot summers but also carries a healthy dose of antimicrobial flavorings. Dig in!
Chilies, which lend piquancy to the cuisine of many tropical and subtropical regions, may have initially become popular as a means of safeguarding local foods from spoilage.
Janet’s Carrot Salad
This can be hot or not, depending on the inclusion of a little Tabasco. Adults tend to appreciate the unexpected kick, kids don’t.
For each pound of peeled and grated carrots, mix in at least
1/2 to 1 cup of dried
Now add olive or canola oil (canola has less saturated fat)—about 1/3 cup. Also add at least 1/4 cup of lemon juice. Stir again.
It tastes best when prepared an hour ahead of time and left for the flavors to meld at room temperature. It will keep for 5 days in the refrigerator.
Billing, J., and P.W. Sherman. 1998. Antimicrobial functions of spices: Why some like it hot. The Quarterly Review of Biology 73(March):1.
Paul W. Sherman
Section of Neurobiology and Behavior
Ithaca, NY 14853
This week's Food for Thought has been prepared by Janet Raloff, senior editor of Science News.