Psychophysics of Flavor Complexity

If I need evidence that we like complex flavors, I will quote this passage from The New Yorker:

“This sauce is really good,” she said. “It’s so Jean-Georges. He does this French-and-Asian thing.” She warned me that she would need a few seconds to figure out its precise ingredients. (She refused to divulge them, on the ground that Vongerichten would consider the recipe “a trade secret.” I later learned from one of the waiters that the ingredients include powdered English mustard and soy sauce.) “It’s so complex,” she said. “It makes me smile.”

The soy sauce is fermented. As any regular reader of this blog knows, I believe we evolved to like complex flavors so that we would eat more bacteria-rich food. So we have something in our brain that measures complexity of smell/flavor and translates that into pleasure: the more complexity, the more pleasure.

My experience of cooking is that it isn’t easy to produce a lot of complexity using spices and stuff like garlic and ginger. It’s possible but not easy. Ordinary recipes, such as in Saveur, aim for a low level, with 5-8 spices. Chinese Five Spice has 5 spices; spice mixtures might have 8; curry powders might have 10. At Whole Foods, the ready-to-eat soups have twenty-odd ingredients. Apparently their soup designers don’t find it easy, either.

Then I discovered that miso by itself produced sufficient complexity. Miso soup doesn’t feel “under-complex”. Finally I understood why wine is such a powerful flavoring agent; wine, like miso, is fermented. It makes sense that foods that our complexity detector  evolved to make us eat do a better job of setting off that detector than other foods.

Now consider how that detector works. Suppose you have two sources of sodium — two different salts, for example. You get the same saltiness from 2 g of Salt A as you do from 1 g of Salt A and 1 g of Salt B. I think complexity is quite different. I suspect that 2 g of Source A (e.g., miso) will produce a lot less complexity than 1 g of Source A and 1 g of Source B (e.g., wine).

I tried adding two fermented flavoring agents (miso and tsukudani) to soup. It worked! The result tasted clearly better than miso alone. Now I do this routinely. It’s very easy. The results have a level of deliciousness I can’t remember encountering before. Everything else I can eat (such as restaurant food) now seems less delicious. I think that three sources works better than two; whether four is noticeably better than three I don’t know.

The basic idea is there are strong sources of complexity (fermented foods) and weak ones (all other flavoring agents). One strong source = 10-20 weak sources. You get the best results by using several strong sources of complexity, perhaps three or more. Once you know this you no longer: 1. Obsess over recipe details (as in the New Yorker quote) because all complexity is alike and easily produced, just as no one worries about the source of saltiness. 2. Think traditional, time-honored recipes are better than what you can make yourself (e.g., Saveur). As far as I can tell food professionals (with one big exception) don’t understand this. I really enjoyed Top Chef Masters (a competition between 12 of the best chefs in America) but there was an almost total absence of fermented foods. Perhaps one chef used soy sauce. The winner, Rick Bayless, made a mole sauce. Mole sauces, which combine 20-odd weak sources of complexity, take hours. I think they produce less complexity than three fermented sources put together, which takes about a minute.

16 Replies to “Psychophysics of Flavor Complexity”

  1. very interesting. tsukudani is delicious also. i’ll have to try the combination. one question though, why when you write about this untested (untestable currently?) stuff do you write about it declaratively “So we have something in our brain… and not ‘so we might have..” ?

  2. Seth, you should enter cooking contests as a way to test your hypothesis which would be supported by high marks in such contests.

    Why do you think fermented foods produce such complex flavors and why do you think people enjoy them? For the first question, I’m wondering what the fermentation process does that produces complex flavors. Is it the production of rare compounds (rare in the sense that they’re not found in non-fermented foods)? If so, what is the nature of these compounds? And the second question then asks why do we enjoy these compounds (a question that should be addressed at both the functional level -why we are adapted to enjoy these flavors- as well as at the mechanistic level — what taste/odor receptors are being activated by the products of fermentation.).

  3. Another way to add complexity is with small amounts of smoked meats. For example, a couple of tablespoons of a strong sausage like spanish chorizo added to rice before cooking goes a long way towards making it a satisfying dish on it’s own. And it’s not because of the fat. Adding butter or olive oil only makes the flavor richer, not more complex.

    I don’t know anything about the process of smoking meats. Maybe there’s a bacterial component to it?

  4. Eric, if you find a way to get tsukudani in Beijing, let me know. The reason for such firm statements as “so we have something in our brain . . . ” is because I can’t think of a plausible alternative explanation.

    Todd, that’s a good poing. Burning stuff generally produces a large number of chemicals (more than 20?) so when you add smoke to something you are adding a lot of different chemicals. Maybe that is the reason it adds complexity. But smoking takes place at bacteria-friendliy temperatures so maybe some of the complexity comes from bacteria that grow and then die (killed by chemicals in the smoke).

    Aaron, bacteria produce many byproducts, in addition to the bacteria themselves, which probably fall apart when they die. And usually fermentation involves several different bacteria. So the chemical complexity of a food goes way up when it is fermented. As for why we enjoy these added compounds, see my posts on the umami hypothesis.

  5. I find this subject fascinating.

    In the past year, whenever I knew I’d be eating a boring supper, I would quickly stir together a sauce consisting of fermented foods, such as yogurt or sour cream, tamari, fermented pickle, and then flavor it with some combination of spices, herbs, garlic, tomato paste, or anchovy paste. (Besides making the food tastier, that kind of flavoring also satisfied some of the SLD tactics I use to lose weight.)

    When cooking a meat-based soup or stew, until now I have generally used a guideline of Three Meats (such as the one I made two days ago, which had bacon, beef, and chicken), with one of the meats having bone, and then add in some other glutamates, such as anchovy and tomato paste. I have also used red wine but I’ve been trending away from cooked wine because of the heartburn it gives me. Thinking about making a complex soup/stew using fermented foods gives me a new playground.

    As for miso, I have tried miso in various dishes, but the rest of the family objects to the taste. I probably need to pay more attention to the overall flavor and tweak before serving.

    As for your observation that professional cooks seem unaware of this subject, ‘The Flavor Bible’ has just a few entries for fermented foods, and for those fermented foods it does list, it rarely shows them combined with others (except for miso, which it says can combine with mirin, sake, and rice vinegar).

    I’d like to see a good list of tasty fermented food combinations. For example, I’m not a big fan of sauerkraut; I’d like to know if there is a way to combine it with other fermented foods to make it more palatable.

  6. Kirk, thanks for your comments. You might try putting sauerkraut in miso soup. In case you’ve been trying “dark” miso, you might also try “light” miso. A milder flavor. The way I use miso now (combined with substantial amounts of other fermented foods) it doesn’t taste like miso soup.

  7. Don’t mislead by overusing the term “bacteria”, I would suggest micro-organism is a better way to convey your meaning. Much fermentation is caused by yeasts and funghi.

    I made a vegetable soup today spiced by small amounts of vegetable stock, hoi sin sauce, angostura bitters, lea & perrins worcesteshire sauce, kikkomann soy sauce, maggi würze, marmite, maille mustard. I can honestly say it was the best tasting soup I, or any of my guests, can remember having been served.

  8. Thanks for the terminology correction. Yeah, maybe I should say “microbe”. And thanks for trying out my flavoring idea. I hadn’t heard of maggi wurze. And I now wonder why I keep worcestshire sauce in the refrigerator.

  9. Hi Seth,

    Very interesting observations.

    The “deliciousness” that you’re experiencing is called “umami.” It is the Japanese word for the flavor of glutamate. The complex flavors you note that are the result of fermentation also occur during aging (think parmesan and steaks) and cooking (think tomatoes and mushrooms). What’s happening is the breakdown of large protein molecules into smaller amino acid molecules. These amino acids have more flavor to us, and hence add to complexity.

    Keep tasting!

  10. Wow, you might have just solved a mystery for me. Recently, I had mentioned to my wife that I found the food at most of the restaurants — some we’ve been going to many years — suddenly to have a lot less flavor and to have a “cheaper” taste to them. I just didn’t enjoy them anymore, but I didn’t know why. And it wasn’t just one or two restaurants, it was most of them, pretty much almost across the board.

    My only theory was that food quality was going down.

    But it was about 6 months ago I started eating yogurt daily. I wrote to you in an earlier comment that it cured my seasonal allergies.

    So now this seems like the most logical explanation. (I hadn’t read your blog in several weeks before tonight, so my conclusion that restaurant food was less tasty could not have been subliminal.)

  11. Hi Seth,

    I am trying to think of a logical / evolutionary reason for why we would like “complex foods.” As Barb said, the complexity you refer to is Umami, and it’s basically just free amino acids (glutamate is the main one, aka MSG). Upon digesting food, our body breaks down the complex proteins into to their individual amino acids anyway, so ingesting them in an already free state would not be advantageous to us. And most of the complex foods that are created via microbes (predigesting proteins and lipids for our sensory enjoyment) contain very few if any living microbes (and whether or not the microbes or their enzymes would even survive a trip through our stomachs is totally up for debate).

    The only reason I can thing of is what I would call a boredom theory. It’s the same reason we love music or paintings or philosophy or even food blogs for that matter. As humans, we are both blessed and cursed with a great deal of intelligence and a lot of time on our hands. We need a way to entertain ourselves and take our minds off the burden of being alive. So much of what we love is simply here to entertain us, push our sensory envelopes further than what we would need to simply survive. If not for that, the 80+ years some people live would become an eternity of monotony.


  12. Dan and Barb, lots of complexity has nothing to do with umami. The complexity of wine, for example. In this case I have never heard anyone say miso or tsukudani tastes good because of umami (that is, glutamate). What makes you think that is what’s going on here?

    Let’s say miso has 1 unit of umami per tablespoon. Let’s say tsukudani has 1 unit of umami per tablespoon. Then 2 tablespoons of miso should taste as delicious as 1 tablespoon of miso plus 1 tablespoon of tsukudani. That isn’t true. This is why I doubt your explanation.

  13. Hi Seth,

    Just wanted to say that your blog has inspired me to start making my own yogurt, which is so much tastier than store bought yogurt. I make it by letting it incubate on a heating pad set to medium for 10-12 hours. I have also been making miso soup with mirin, soy sauce, sauerkraut and bacon, and it’s the most delicious soup ever. I agree with Mike that restaurant food is less tasty than before I started eating lots of fermented food.

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