For some, cooking is the necessary way to deliver food and nutrients. But for others –like me– it is a form of art. Probably it is because of my Italian heritage — yes, Italians indeed adore food. When people ask me how much salt to use for the perfect tomato sauce, I say that you just need to know. Experience makes a lot of difference in cooking. I learned how to pair flavors by watching my grandma and my mom cook every day for all my childhood. But are there objective rules that make food taste good and palatable?
A few months back, I watched Shokugeki no Soma (Food War!), a shonen manga and anime where eccentric teenagers battle each other through cooking. The show is hilarious, and the recipes are given with the highest level of details. They also give explanations about certain chemical tricks used in the kitchen (from Maillard reaction to the use of onion enzymes to predigest meat). All the explanations about taste boiled down (pun not intended?) to two simple rules: to reduce bitterness and to balance the remaining four taste components –that is, sweet, savory, salty and sour. This IS the essence of cooking.
Every time the dishes were judged in the show, there was one word that was repeated over and over: umami.
What is umami?
Umami is Japanese for delicious (umai) taste (mi). Chemist Kikunae Ikeda coined the term when first proposed to introduce it as a taste in 1908. It is the savory taste, and it was long debated if it was a taste like sweetness, saltiness, sourness, and bitterness. But it seems that tongues receptors are extremely sensitive to the umami flavor, typically described as “meaty” or “brothy”, thanks to the detection of glutamic acid and nucleotides as guanylate and inosinate. Foods like cheese, tomatoes, and mushrooms are rich in glutamate. Yeasts, fish, and meat are rich in guanylate. Finally, dried mushrooms are an example of inosinate-rich foods.
Many delicious recipes are umami-rich, but many are also sweetness-rich or sourness-rich. What makes umami special, then? While you might have had a soup that was too salty or a cake that was too sweet, I challenge you to think of something that was too savory/tasty. For example, we trained our tongue receptors for bitter and sour food (typical tastes of poisonous material to humans) to detect high concentrations of salt making the meal taste unpleasant (probably because too much salt is bad for us). But when it comes to umami, too much of it can be a good thing: when pairing ingredients that contain different types of umami, the flavor profile is more than the sum of the two. This takes the name of umami synergy.
Meat and mushroom in nordic cuisine, the yeast of bread paired with Parmiggiano Reggiano in Italian culture, Japanese dashi with dried fish and glutamate-rich seaweed are all example of perfect pairings where our ancestors have taken advantage of umami synergy.
Decomposition of the perfect food
The title was a bit of a clickbait: Pizza is not the tastiest food. But it is one of them, together with many other well-balanced dishes. But with more than 43 millions pizzas eaten every day in the US on average, with pizzas delivered in Space and Pizza Parties on the ISS being pretty fashionable these days, I decided to talk about this marvelous food. Specifically, we will be talking of the queen of pizza, pizza Margherita.
Let’s dive in and analyze what makes pizza a perfect dish. I already raised the point that the essence of cooking is balancing sweet, savory, salty and sour tastes. The ingredients of an original Margherita are dough, tomato sauce, buffalo mozzarella, a bit of salt, olive oil and basil — let’s see what tastes they are associated with.
Pizza dough is a combination of flour, water, yeast, salt and a small amount of oil. And while part of the flavour is given by salt, you will get a pretty boring pizza if you don’t give enough –yet controlled– time for the yeast to do its magic. Our tongue receptors are sensitive to small organic acids and amino acids, not long molecules of carbohydrates and proteins. Yeast breaks these long molecules down to their building blocks and uses smaller sugar molecules to produce carbon dioxide and make the dough rise. When fermenting for long times and at cold temperatures, there are a few things that happen: (1) the yeast has the time to produce flavorful byproducts, e.g. acetic acid; (2) some of the sugar remains undigested and it is used for a Maillard reaction during baking (the tasty brown of the crust comes from this reaction); (3) it allows natural bacteria present in the dough to consume some of those sugars into different sets of flavors. Not to forget, that the yeast itself has some umami taste, coming from guanylates.
Tomatoes are some of the foods richest in glutamic acid. That’s why tomato sauce is the bigger source of umami taste in pizza. All this tomato umami works in synergy with the yeast umami giving us an enhanced taste. But there is more to the story. Other major components of tomato sauce are malic and citric acids. They give a fresh and tangy taste but add too much of these acids and they overpower all the rest. Sometimes, a little bit of sugar or baking soda is added to the sauce to tone these acids down.
Many types of cheese are rich in umami. Not mozzarella, though. Mozzarella is on pizza for another reason: it brings a little bit more of sourness. This comes from the acetic acid used to make mozzarella, and from the lactic acid naturally present in the milk.
Salt… well, it adds the salty taste.
Olive oil is the only source of bitterness in pizza. It contains traces of phenolic compound, which give to olive oil a bitter and pungent taste. So, as far as we choose a tasty but not overwhelming olive oil, we won’t have a bitter taste to balance out.
Basil not only smell delicious, but it brings pure sweetness to the plate. It is composed of several essential oils, but the sweetness comes from its most abundant one: linalool.
To recap, dough and tomato sauce are the main carriers of flavor in pizza. The flavor comes from the glutamic acid of tomatoes and from the guanylate of yeast. They combine together to enhance the taste thanks to umami synergy. The dough brings also some sweetness from its sugars, while the tomato sauce adds sourness from malic and citric acid. Salt is added for saltiness, while olive oil, mozzarella, and basil are there to enhance flavor diversity — such as the linalool bringing a different type of sweetness and the acetic/lactic acid in mozzarella bringing a different type of sourness.
The Pineapple Conundrum
Pizza is good because it is balanced, but there is always the risk to make it leans toward acidity. We have different sources of sourness, with the tomato sauce being the greatest contributor. Do you know what else is acidic? Pineapple! So here is my science-inspired reasoning on why pineapple on pizza is wrong!
Disclaimer: I don’t like pineapple, not on pizza, not alone. So this post is biased by my own experience. Here you have it: your excuse to discard anything I am going to write next. Now, let’s go back to the facts.
Pineapple contains malic acid and citric acid. These are the same major acids components found in tomatoes. When you add pineapple on pizza, you are overdosing the pizza with sour tastes. The problem is not pineapple on pizza: the problem is pineapple and tomato sauce together on pizza!
Italians are not against using pineapple when cooking. The most popular Italian cooking website lists many savory recipes with pineapple. But none of the recipes contains tomatoes sauce. Humans have evolved a taste sense so that we can recognize a meal with balanced nutrients: that’s why too much acid shouldn’t be palatable to us!
“Hold up a minute! I love pineapple on pizza!” — That’s ok. Humans have acquired a taste for coffee and chilli peppers, even if they should taste like poison. Taste is a complex matter, and it is impossible to tell you are wrong if you like something. Moreover, I have omitted a lot of additional factors that contribute to taste, like food smell, texture, temperature, shape –just to name a few. But I wanted to explain why your Italian friends gag at the idea of pineapple on pizza: they are not food-religious, they act upon the cooking strategy of balancing tastes. Although, I am still convinced that every time someone orders a Hawaiian pizza, there is an Italian somewhere that falls down dead.
“Do I need all this chemistry when I cook?”
Short answer, no. When I cook I never think of balancing the chemicals involved, at what reactions are happening on the stove or at how enzymes/yeast/bacteria are contributing to breaking down flavors. Knowing a few things here and there, however, can help you figure out why a dish was a disaster, what taste was unbalanced and what ingredients you might use the next time to fix it. The rest comes with experience.
Time to leave your desk, get a stretch, wear your oven mittens and start practice science from the comfort of your kitchen. And remember that if you still decide to add pineapple on pizza, you are making my life at risk.
If you had fun reading about the chemistry and biology behind one of the most popular foods on the planet, then you will probably enjoy some of these resources:
- The Umami Information Centre, a website that explains umami, collects different research papers about the subject, stores a database of umami content in foods, and even offers some umami-rich recipes.
- The association of original Neapolitan pizza, with some interesting readings on the tradition of pizza and a list of official Neapolitan Pizzerias around the world.
- Chef VS Science, a hilarious kitchen challenge packed with science facts, not only from a chemistry and biology point of view but also on how to use physics techniques to cook (available on Netflix).
- Food – Delicious Science, another science of food show that I am binging now, and already got off on a great start (available on Netflix and Amazon Pri