Adventures in Ethics and Science

As I was looking for a good sangria recipe some weeks ago, I came upon this article in Gourmet about how our understanding of the scientific basis for “flavor” as changed, not to mention what sorts of implications this might have for those who prepare — and sell — food.

One of the interesting bits is how different the science on taste is from what you probably think it is:

[N]early everything humans think they understand about taste is wrong. For generations, textbooks have trumpeted two universal truths about taste. Truth No. 1: There are four basic tastes–bitter, sweet, sour, and salty. Some have added a fifth basic taste, umami, from the Japanese umai, which refers to the savory, meaty taste first isolated in 1908 in Tokyo by Japanese chemist Kikunae Ikeda. Truth No. 2: Different tastes are detected on different parts of the tongue. This “taste map,” popularized by Harvard’s Edwin G. Boring in the 1940s, has been scoffed at by scientists for years. “That’s just hokum,” says Jeannine Delwiche, senior sensory and psychophysics scientist at Firmenich, another industry powerhouse. “You can taste everything everywhere.”

Recently, however, even the first truth has come into question. “There are no basic tastes,” says Michael O’Mahony, a sensory scientist at the University of California, Davis. “The notion was arbitrary, made up by a chap named Hans Henning in 1916.” The idea is misleading, O’Mahony continues. “The first question you should ask is, ‘What are basic tastes?’ Well, there are more than four types of taste receptors, so it can’t be that. There are more than four ways a chemical can react with a receptor. There are more than four types of neural codes those receptors can send to the brain. Lots of scientists felt they had to describe tastes using one of the four categories. It’s silly.”

Flavor is a result of what happens with taste-receptors in the mouth (including but not exclusively those on the tongue) and with olfactory receptors. The 40 or so kinds of taste-receptors interact with the chemicals in what you’re tasting (yes, all your food is made of chemicals!) and create a nerve impulse that sends a signal to the brain. Meanwhile, the 300 or so olfactory receptors send their own smell-signal based on the volatile components of your food. The taste-signal and the smell-signal are correlated in the brain to make the flavor you’re experiencing.

The science behind the whole process, needless to say, is both complicated and cool.

“Taste is like a chair with four legs,” explains [Cornell University flavor chemist Terry] Acree. “Before, we only had one leg–flavor chemistry. Now we’re building the other three: how a chemical reacts with the receptor; how that receptor communicates with the brain; and how the brain processes that information into behavior.” Once scientists have identified the chain of messages each chemical sends to the brain, they can begin to manipulate that conversation. The chemical gustducin, for example, is part of the signaling mechanism between receptor and brain. If you remove gustducin from mice, they drink bitter liquids as if they were water. If researchers can find less-invasive ways to stop taste receptors from telling the human brain, “Hey, this food is bitter,” suddenly those Brussels sprouts go down a lot easier. As does a child’s medicine.

Among other things, a better understanding of the receptors and of the various compounds that might interact with them (including in ways that block them from sending their usual signals) might allow food manufacturers to devise additives that block the unpleasant aftertaste of potassium chloride in low-sodium tomato juice. For the consumer who wants a V8 without racking up fully a fifth of her daily allowance of sodium (which is what you get in a serving of the regular version of V8), taking the tinny aftertaste out of the low sodium analogue seems like a good thing.

Assuming, of course, that that’s all the taste-blocking additive does when ingested. Indeed, for those who like to know what they’re ingesting, the article notes that such an additive “would be in such a tiny amount that it could be referenced in the ‘artificial flavors’ category and not be specifically listed on the label.”

In a world where manufacturers are trying to producing lower sodium (or lower fat, or higher fiber, etc.) foods — and to make these healthier foods taste good enough that consumers will buy them again — this is clearly a line of research with a constituency. The author of the article, though, sees farther reaching implications:

As scientists begin to home in on the biological foundation of different likes and dislikes, an even more tantalizing possibility arises: In the future, each of us will likely be able to identify our genetic predispositions to food. We might even have a food type, just as we have a blood type: I’m broccoli positive, you’re pumpernickel negative. To be sure, this does not necessarily equate to a like or dislike. As [CEO of Redpoint Bio Dr. Ray] Salemme cautions, we can learn to modify our responses. “There are many things you might not like the first time you taste them, such as single-malt Scotch, but you learn to like them. A lot.” The direction, though, is clear: Soon each of us will carry around our own periodic table of what food chemicals we respond to. You’ll no longer be able to ask dinner guests merely if they eat meat; you’ll have to send them a detailed questionnaire.

I think the prospective dinner guest questionnaire is probably going overboard. If someone offers you a meal in his home, it is a gesture of hospitality, one that is not usually undone if you’re served a dish that is not your favorite. Just as a gracious host does his best, so does a gracious guest. That this kind of worry even comes up points to the fact that for a great many humans, eating is not a simple matter of fulfilling a biological need. Rather, food has become a source of comfort — or of adventure.

To date, part of the adventure has been in exploring how various foodstuffs, prepared in different ways, tickle our taste buds. With more information on how to block (or enhance) certain of the signals traveling from palate to brain, the terrain of that adventure changes. Potentially, it could be used to widen our culinary horizons, but we could also use such information to narrow them, to keep us from tasting anything out of our comfort zone.

In some ways, that might be a horrible waste of arugula or Brussels sprouts.

There are other potential uses of flavor blockers that rub me the wrong way for what I think are reasons of style. The article brings us to the kitchen of a London restaurant:

“Lots of chefs have said they don’t care about this stuff,” says Chris Young, a chemist who worked as a food-research manager at The Fat Duck. “They just care how the food tastes on the plate. That’s fine. But this research will eventually trickle down to every level of cooking.” So can he imagine using a taste blocker at a high-end restaurant? “Sure. Savory ice cream. Sugar is inherently necessary to get the particular texture that ice cream has. You need it to depress the freezing point and give you enough solids. But for a true savory ice cream, you’d need to use sugar but block the sweet taste.”

Taste blockers present one solution to the problem of savory ice cream, but to me it doesn’t feel like a terribly inspiring one. It’s an engineered solution based on plentiful technological resources, not the kind of ingenuity you’d get from a chef who took more of a MAKE or MacGyver mindset to harnessing the qualities of her ingredients. Sugar is not the only edible substance that can lower a freezing point, and there may be other ways to boost the solids in one’s savory ice cream. (If it were me, I’d investigate avocado flesh as a potentially useful component.)

Part of the adventure of eating, after all, is in the artistry of the food’s preparation, and good art is often born of creative response to limitations.

Comments

  1. #1 Ian
    July 31, 2008

    “This food doesn’t taste right … or is it me?”

    Janet – we’re sure you taste right – it’s gotta be the food…!

  2. #2 mel
    July 31, 2008

    I love this post- thanks Janet. Some thoughts:

    -Molecular gastronomy has been exploiting and breaking down the long held misconceptions of taste properties with the aid of nifty techniques normally reserved for the laboratory.

    -Delving into the mechanisms of smell as it relates to taste the likes of Dr Andrew Horsfield and others create further excitement suggesting smell (and possibly taste) is distinguished by vibrations in the molecules which may present smell and taste as a spectrum similar to light and not just finite receptors.

    -The evolution of taste is best presented historically by Brillat-Savarin’s ‘Physiology of Taste’. A thoroughly entertaining read and account of all the fine aspects of taste and gastronomy including notes on that famous Ancient Roman delicacy ‘Dormouse dipped in honey and poppy seeds’- what flavor were they aiming for???

  3. #3 D
    August 4, 2008

    - Has anyone done Principle Component Analysis on these flavors to see if they do in fact cluster into four or five or three or whatever basic groups? While the four-based numerology is indeed suspicious, at least naively the idea that there are something like 40 x 300 or so flavors with no structure seems bizarre.

    - I agree that cooking has much to do with artistry, but don’t see why flavor blockers can’t be part of the the artistic toolkit. If nothing else, cooking with the possibility of using these chemicals is a strict superset of cooking without, and it seems scarcely credible that all the artistry is restricted to the smaller set

  4. #4 lonelyShoes
    August 4, 2008

    Thanks for this post. Something about there being only four basic tastes has never felt right to me, but I had no idea that scientists had rejected the idea years ago. That bit of info hadn’t trickled down to the schools when I was a young’un.
    Avocodo ice cream is a good idea. Here is Alton Brown’s take on it: Avocodo Ice Cream Recipe

  5. #5 Jonathan Vos Post
    August 4, 2008

    I was lucky enough to (simultaneously with a Math bachelor’s) earn my B.S. in English Literature (an odd degree) at Caltech at the same time as Harold McGee, whose breakthrough book “On Food and Cooking” merged the Laboratory and the Kitchen forever. The 2nd, expanded, edition has more on icecream, too. A New York Times bestseller for good reasons.

  6. #6 Toaster
    August 4, 2008

    Usually when we cook we use hydrophobic oils to lubricate the cooking process and carry flavors into the cells of the food we are cooking. Although much the same effect could be done with an electroporator and Triton-X, it makes me wonder if a completely hydrophic molecule, such as ethane, could be used to infuse, say, the taste of olives into brisket? Olives are rather oily, and as such should theoretically be relatively (to starches) soluble in ethane.
    Stupid idea or culinary genius?

  7. #7 Mary Parsons
    August 4, 2008

    That was a very illuminating overview of current thinking on taste.

    The Fat Duck is in Berkshire not London and you are flirting with criticising Heston Blumenthal who is lionised by science-minded types in the UK (OK, me and some colleagues). He published some research into taste in conjuction with the Uni. of Reading and it is one of the few, truly-earned honorary degrees that has ever been handed out (in 2006, Reading awarded Blumethal an honorary doctorate in science).

    If they ever show any of Blumenthal’s BBC series in the US then you might find it both interesting and entertaining. His book on Family Cooking has some simple and good experiments to do with children.

  8. #8 Methuselah
    August 5, 2008

    I see there being a distinct threat to our health from the exploration of taste for the purposes of deceiving our palates. We have been dabbling for years with this, resulting in the ubiquitous inclusion of pernicious additives like aspartame and monosodium glutamate in our foods.

    I appreciate that used sensibly, a greater understanding of taste mechanisms could bring benefits to mankind, but I just don’t trust the research community, driven as it is largely by corporate funding, to restrict itself to the beneficial applications.

    We have a tendency where diet is concerned, to seek shortcuts (The Professor Diet – Eat as Much Junk as you like) and find ways to avoid doing the one thing that would make us all healthy again – eating the diet we evolved to eat.

    Methuselah
    Pay Now Live Later

  9. #9 Tex
    August 5, 2008

    Only marginally OT:

    Sangria

    1.5 liter bottle of medium quality red wine, preferably Merlot (Cab is too harsh & pinot noir too soft)

    1 cup fresh squeezed orange juice
    ½ cup fresh squeezed lemon juice
    ½ cup fresh squeezed lime juice
    All of the syrup from a 10 oz. bottle of maraschino cherries
    ½ cup granulated sugar.

    Mix all ingredients until sugar dissolves. Taste for sweetness, and adjust, if necessary.

    Serve over a couple of ice cubes with a thin slice of lime and lemon and a couple of the cherries.

  10. #10 Theo Bromine
    August 5, 2008

    My sangria recipe is similar, but with the addition of an ounce or two of orange brandy, and some fresh or frozen fruit (strawberries, raspberries, peaches, plums) and without the added sugar or cherries (sorry, but I think maraschinos are an abomination against god and/or nature).

  11. #11 Methuselah
    August 8, 2008

    Hi – I posted a follow-up to the article I mention above, speculating about the mechanims by which science might one day make it possible to eat a food that looks and tastes like one thing but digests as another – if any readers are interested or have scientific knowledge that could confirm or refute my hypotheses, please come over and comment!

    Thanks,
    Methuselah
    Pay Now Live Later

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