Cooking for Geeks: Real Science, Great Hacks, and Good Food (19 page)
Read Cooking for Geeks: Real Science, Great Hacks, and Good Food Online
Authors: Jeff Potter
Tags: #COOKING / Methods / General
You’ll have an easier time seasoning dishes if you understand the five primary tastes the tongue can detect, as well as how it responds to “other” things (for example, the chemicals that give hot peppers their kick, carbonated drinks their effervescence, and peppermint candies their cooling sensation).
When cooking, regardless of the recipe and technique, you
always
want to adjust and correct the primary tastes in a dish. There is just too much variability in any given product for a recipe to accurately prescribe how much of a taste modifier is necessary to achieve a balanced taste for most dishes: one apple might be sweeter than another, in which case you’ll need to adjust the amount of sugar in your applesauce, and today’s batch of fish might be slightly fresher than last week’s, changing the amount of lemon juice you’ll want. Because taste preferences vary among individuals, you can sometimes solve the balance problems by letting the diners adjust the taste themselves. This is why fish is so often served with a slice of lemon, why we have salt on the table (don’t take offense at someone “disagreeing” with your “perfectly seasoned” entrée), and why tea and coffee are served with sugar on the side. Still, you can’t serve a dish with every possible taste modifier, and you should adjust the seasonings so that it’s generally pleasing.
Bitter is the only taste that takes some learning to like. Some primitive part of our brain seems to reject bitter tastes by default, probably because many toxic plants taste bitter. This same primitive mechanism is why bitter foods are unappealing to kids: they haven’t learned to tolerate, let alone enjoy, the sensation of bitterness. Dandelion greens, rhubarb, and uncooked artichoke leaves all contain bitter oils that cause them to taste bitter; not surprisingly, I couldn’t stand those things as a kid.
Adding salt can neutralize bitterness, which is why a pinch of salt in a salad that contains bitter items such as dandelion greens helps balance the flavor. Sugar can also be used to mask bitterness. Try grilling or broiling Belgian endive lightly sprinkled with sugar. Quarter the endive down the center to get four identical wedges and place them on a baking sheet or oven-safe pan. Sprinkle with a small amount of sugar. You can also drizzle a small amount of melted butter or olive oil on top. Transfer the tray to a grill or place it under a broiler for a minute or two, until the endive becomes slightly soft and the edges of the leaves begin to turn brown. Serve with blue cheese or use the endive as a vegetable accompaniment to stronger-flavored fish.
Try this simple “bitter taste test” to demonstrate how salt interacts with bitter tastes. Modern tonic water (a much weaker version of the traditional medicinal drink of quinine and carbonated water that was then spiked with gin to make it palatable) uses quinine as a bittering agent and is easy to get at the grocery store. Pour tonic water into two drinking glasses. In one, add enough salt to neutralize the taste. Compare the taste of the tonic water in the two cups.
Bitterness seems to lend itself exceedingly well to drinks: unsweetened chocolate, raw coffee, tea, hops (used in making beer), and kola nuts (kola as in cola as in soft drinks) are all bitter. And many before-meal aperitifs are bitter, from the classic Campari to the simple parsley-dipped-in-salt-water customary during Passover. Conventional wisdom states that bitter foods increase the body’s production of bile and digestive enzymes, helping in digestion. The food science literature doesn’t seem to support the conventional wisdom, though.
Salt (sodium chloride) makes foods taste better by selectively filtering out the taste of bitterness, resulting in the other primary tastes and flavors coming through more strongly. The addition of a small quantity of salt (not too much!) enhances other foods, bringing a “fullness” to foods that might otherwise have what is described as a “flat” flavor. This is why so many sweet dishes — cookies, chocolate cake, even hot chocolate — call for a pinch of salt. How much salt is in a pinch? Enough that it amps up the food’s flavor, but not so much that the salt becomes a distinct flavor in itself. A “pinch” isn’t an exact measurement — traditionally, it’s literally the amount of salt you can pinch between your thumb and index finger — but if you need to start somewhere, try using ¼ teaspoon or 1.5 grams.
In larger quantities, salt acts as an ingredient as much as a flavor enhancer. Mussels liberally sprinkled with salt, bagels topped with coarse salt, salty lassi (an Indian yogurt drink), even chocolate ice cream or brownies with sea salt sprinkled on top all taste inherently different without the salt. When using salt as a topping, use a coarse, flaky variety, not rock/kosher salt or table salt. (I happen to use Maldon sea salt flakes.)
In larger quantities, salt brings a distinct taste to a dish. Try cooking mussels sprinkled with copious amounts of sea salt. Place a cast iron pan over high heat until the pan is screaming hot, and drop in the mussels. After two to three minutes, they’ll have opened up and cooked; sprinkle with salt. You can optionally add in diced shallots or crushed garlic, cooking another minute or so until done. Serve with forks and a small bowl of melted butter for dipping the mussels. You should rinse the mussels before cooking, discarding any that have broken shells or that aren’t closed tightly.
Imagine you’re slaving over the stove, cooking dinner with your girlfriend or boyfriend, and you get into a heated discussion about the dish needing more salt. To you it’s not salty enough, while to her (or him), it’s already way too salty. What’s going on? Why can’t you
ever
agree on the seasoning?
As it turns out, some of us really do taste things differently. Just like variations in eye color, there are variations in our taste buds. What one person senses and perceives can differ from what another person experiences. In terms of taste, there are a number of known differences, one of the most prominent being
supertasting
.
Supertasting was accidentally discovered in the 1930s when a DuPont chemist, Arthur Fox, unwittingly spilled phenylthiocarbamide (PTC) powder. He didn’t notice, but a colleague complained of a bitter sensation from the dust kicked up in the air. Curious, Fox started testing on friends and family (this was clearly in the days before internal review boards) and found that about one in four couldn’t discern any bitterness.
More recent research by Dr. Linda Bartoshuk has shown that those of us of who can sense PTC can be broken down into two groups: a
supertaster
group that detects these compounds as unbearably bitter (~25% of the general population of European heritage) and a second group of
medium tasters
who find the compounds bitter, but not overwhelmingly so (50%).
If you’re looking at the percentages and thinking “Mendelian trait?,” you’re right: you’re a supertaster if you’ve inherited both dominant alleles from your parents. As with other Mendelian traits, the percentage breakdowns do differ by ethnicity and gender. For example, white females have a 35% chance of being supertasters, while white males have only a 10% chance. Asians, Sub-Saharan Africans, and indigenous Americans have a much higher chance of being supertasters.
If you’re wondering if you’re a supertaster, there are a couple of ways to tell.
Method #1: PTC or PROP test strips
The best way to tell if you’re a supertaster is to see if you can taste the chemical directly. Two chemical compounds are commonly used to test for taste differences: phenylthiocarbamide (PTC) and 6-
n
-propylthiouracil (PROP). You’ll need to order paper strips impregnated with either chemical (search online for “supertaster test paper” or see
http://www.cookingforgeeks.com/book/supertaster/
for up-to-date sources).
Place the test strip on your tongue and let it rest there for 10 seconds. You’ll know if you’re a supertaster if you experience an extremely bitter taste. Supertasters will generally yank the piece of paper out of their mouths really fast. Medium tasters (individuals with only one dominant allele) will sense a mild but tolerable bitter taste, and
nontasters
will enjoy the pleasant sensation of, well, wet paper.
Method #2: Taste bud count
If you don’t have test strips, you’ll have to stick your tongue out (all in the name of science, of course). Because supertasters generally have more taste buds on their tongues than medium tasters, the low-tech (and low-accuracy, unfortunately) way of checking to see if you’re a supertaster is to count the fungiform papillae, which contain taste buds and are correlated to the number of taste buds you have.
You’ll need blue food coloring, a cotton swab or spoon, and a sheet of binder paper (i.e., three-hole punched paper that has a
5/16
” / 8mm–diameter hole).
Place a drop of the food coloring on the cotton swab, and then stain your tongue with it. Place the paper on top of your tongue such that you or a partner can see the tongue through one of the holes. Choose the area that is densest with spots, usually the front portion of the tongue. Count the number of pink dots visible (fungiform papillae aren’t stained by the food coloring). If you count more than 30 papillae, you’re probably a supertaster. Normal tasters tend to have between 15 and 30 papillae, while nontasters have fewer than 15, on average. These numbers are only broad generalizations, so it’s hard to say for sure which group you fall into based on the counts.
Counting the number of fungiform papillae visible in a three-hole-punch-sized area of the tongue takes a bit of dexterity and good lighting. Look for the densest area, the location of which varies among people. Count the lighter dots in the circle. This image shows approximately 12.
Being a supertaster or a nontaster isn’t necessarily good or bad. Supertasters might find some foods — especially dark-green leafy vegetables such as kale, cabbage, broccoli, and Brussels sprouts — to be overly bitter, because of phenylthiourea-like compounds that their tongues can sense. Supertasters generally also find astringent, acidic, and spicy foods to be stronger, due to the higher number of taste buds and thus larger number of cells experiencing oral irritation. Researchers have found that in addition to bitter tastes (tested using quinine), supertasters also experience sweet (sucrose), sour (citric acid), and salty (sodium chloride) tastes as being more intense. Nicotine is more bitter to supertasters, and sure enough, supertasters are less likely to smoke. Caffeine also tastes more bitter, and researchers have found that supertasters are more likely to add milk/cream or sugar to coffee and tea.
Keep in mind that supertasting is just one of many factors that impact our sense of taste and our food habits. Physiological factors and disease can affect our sense of taste, as can our experiences. Stress leads to an increase in the hormone cortisol, which, among other things, dampens the stimuli strength of taste buds. Our environment can also impact our taste buds. For example, drier conditions change the amount of saliva in the mouth, resulting in a decrease of taste sensitivity.
As we touched on earlier, temperature also impacts taste sensation, just as it impacts our sense of smell: foods served warmer (by some accounts, above 86°F / 30°C) will be detected as stronger by the taste buds than colder dishes, due to the heat sensitivity of at least one of the receptors (TRPM5) responsible for taste. Foods served below body temperature won’t register as warm, so if you want a dish — say, a spinach and bacon salad — to taste stronger, serve it on the warmer side (but below body temp). If you want a dish to carry milder tastes — e.g., to moderate the bitterness of beer or sweetness of ice cream — serve it colder.
Finally, if you’re a cilantro hater — if it tastes like dish soap and you can’t stand it — you’re not alone; even Julia Child hated cilantro. While there’s no known scientific mechanism or genetic marker for determining this reaction, preliminary research based on differences between identical and fraternal twins does suggest that a distaste for cilantro is genetic.
In some recipes, salt is used for its chemical properties, such as the osmosis of cellular fluids for food preservation. We’ll cover more uses for salt in
Chapter 7
.
As described in the sidebar “Differences in Taste and Supertasting,” there are known genetic differences in the way people taste some bitter compounds. Because salt masks bitterness, those of us who taste things like broccoli, Brussels sprouts, and kale as being bitter tend to add more salt to compensate.