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On Crispiness & Crunchiness

Reader Dan, who apparently made some fancy florentines over the weekend, asks me to speculate as to why crispy and/or crunchy foods are so darn delicious to human beings. Dan, you’ve positively made my day.

I’ve long been fascinated by the subject of crispy and/or crunchy food. Sure it’s an odd thing to take an interest in, but everybody needs a hobby. And anyway I get paid for it to some extent. As many of you who’ve read my bio know, I work quite a bit with food growers, packagers and sellers. And almost all of them — save for the beverage makers — are concerned with crispness or crunchiness to some degree, for the simple reason that it’s a highly valued attribute in food.

Every consumer group from health nuts to couch potatoes love it. And that of course creates huge markets for everything from bagged micro-greens to cheese balls. If one were to re-categorize foods in the supermarket based on their sensory characteristics, “crispy” would be the largest section by far, full of everything from apples to bacon, chips, pretzels, tater tots, pickles, granola, lettuces, candy, crackers, bell peppers, cookies, mini carrots, energy bars, nuts, microwave-ready edamame, frozen thin-crust pizzas, you name it. Producing, maintaining and delivering all that crispiness requires an army of food scientists, formulators, and packaging experts.

However for all that, very seldom is the question asked: why are human beings so terribly fond of the crispy/crunchy sensation in the first place?Food researchers theorize that a love of crispy foods is programmed into our DNA, a part of our brain’s food-quality-assessing hardware/software package. And indeed there’s some fascinating lab work that’s been done to validate those ideas. It turns out that humans are startlingly good at assessing the relative freshness of fruits and vegetables. We do this not so much by seeing or tasting as by feeling and listening. 

Everyone knows fresh fruits and vegetables are crispy and/or crunchy, but why? It’s a property of the cells within those foods known as turgidity. Basically, plumpness. The cells of very fresh carrots, for example, are under high pressure. Crush them between the teeth and they pop like balloons, creating vibrations in the mouth but also clearly audible sounds inside the head. We use both those inputs to judge the freshness of the carrot. And here you thought that potato chip deafness was just an accidental byproduct of the fact that our ears are located so close to our jaws. As software developers are so fond of saying: it’s not a bug, it’s a feature.

As fruits and vegetables get older, they lose their turgor. Which is to say their cells experience a loss in pressure. When you bite into an old carrot its cells don’t so much pop as just separate from one another. The result is the mushy/mealy mouthfeel that humans tend not to like (indeed my oldest daughter dislikes mushy textures so much that she can’t abide mashed potatoes or even pastry cream…it’s an inherited genetic trait which breaks my poor pastry-maker’s heart). Indeed, the degree to which human beings can discern fine shades of freshness using solely our senses of touch and hearing is truly startling. Blindfolded and with our tastebuds temporarily dulled, most of us can not only tell what kind of fruit, vegetable, or snack we’re eating, but also how fresh/old/stale those foods are. Our senses are that finely tuned. 

And while sensory labs continue to churn out data by the ream on the subject of food and texture — and sociobiologists continue to advance evolutionary explanations for their findings — there are still more than a few mysteries. Among them: why are human beings so passionate about foods with crispy crusts and soft, moist interiors? There seems to be no precedent for such foods in nature, yet people can’t seem to get enough of fresh-baked bread (which is extremely lean and has relatively little flavor of its own), fresh-fried doughnuts and chicken, “soft” pretzels, the list goes on. Ancient hunter-gatherers surely had no access to such foods, but if we could travel back in time and hand them bags of hot waffle fries, would they have gone, er…ape? The answer seems clear. But…why?

6 thoughts on “On Crispiness & Crunchiness”

  1. Crispy crunchy cookies are the best. Segue into discussion on baker’s ammonia. 🙂 (I know you’ve covered it in the past. But there’s always more to say.) Texture is a completely different animal than taste. It’s why I hate pancakes. I mean, yuck. No texture to speak of.

    On another note, I just read an article that might interest you and your readers: https://www.eater.com/2020/7/8/21271246/food-timeline-lynne-olver

    Maybe someone is interested in taking on the task?

    1. I’ve used the Food Timeline myself, and I think very highly of it. I also would hate to see it just disappear.

      Thanks Chana!

      – Joe

  2. What an interesting topic! Relating the last paragraph back to pastry, I’ve noticed that cookies with crispy edges with soft & chewy centers for some reason seems to be a mainly American characteristic.

    That’s not to say that texture combo doesn’t exist in cookies from other countries, but from my limited knowledge, cookies from other countries are usually crispy/crunchy entirely through (e.g. lebkuchen, wafers, biscotti, pizelles, crackers, British biscuits) or tender/crumbly (shortbread-esque types).

    But it seems cookies worldwide are usually dry, in comparison to American drop cookies with crispy exteriors yet moist interiors. As a wild guess, one explanation might be how historically cookies were made to keep better, hence being drier, while those drop cookies were invented more recently in America. What’s your take, Joe?

    1. Now that is a genius insight, Ken. I think you’re very right that European sweets — at least traditional sweets — are drier and crunchier than American sweets. Hands down their cookie-type confections are like that.

      This will be a fascinating idea to think about it. I shall have a great time cogitating over the next few days, Ken. Thank you very much!

      – Joe

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