Subreddit: r/NoStupidQuestions
User: u/stormyseraph
Original Post:
Why does food taste worse when it’s cold, but pizza is still good?
So, most food tastes way worse when it gets cold (like fries... ew), but somehow pizza is still good even when it’s cold? What’s the science behind this?
Does pizza have some magical ingredient that keeps it delicious at any temperature, or are we just programmed to like it no matter what? And why can’t other foods pull this off?
Imagine if cold fries were as good as cold pizza. The world would be a better place, honestly.
Any food scientists out there who can explain this pizza sorcery?
My Answer:
Hello, food scientist here.
There are two major categories that interact with the sensory aspects of food - taste and flavor. While similar, taste is governed by how taste receptors respond to non-volatile taste active compounds found in food. Flavor is governed by how odor receptors interact with volatile compounds that rise from consuming a food and vaporize retronasally in the back of your throat and up into our nasal passages.
Both taste and flavor are integrated by the brain to give you the sensory perception of food.
Most savory foods have very specific chemical profiles that are mainly amplified by the presence of salt, amino acids such as glutamic acid, peptides such as glutathione, and ribonucleotides.
Together, these compounds influence the saltiness, umami, and kokumi intensity of a food. Umami refers to a very specific savory/brothy taste brought on by amino acids and ribonucleotides. Kokumi refers to a sensation that increases the intensity and elongates the duration of savory sense perception. There is some effect of temperature on this, but for the most part, it is less tied to temperature due to the native solubility of these compounds in the water of the food and saliva.
However, the volatile compounds formed from the cooking process also play a role. These volatile compounds are mainly perceived when a food is hot, which increases the rate of evaporation and therefore intensity signal of our perception of these odor compounds.
Pizza, being made of mostly tomatoes, cheese, meats, and yeast-fermented dough, contains a high concentration of salt, umami, and kokumi compounds. Together, this combination is highly amplified - there’s a lot of math available to actually calculate this.
For example, tomatoes contain very high concentrations of glutamates, some of the highest of any vegetable. Cheese contains many peptides that elicit kokumi and umami, and also contains high amounts of salt. Yeast produce glutathione from dough, which is also a kokumi amplifier.
Essentially, many of these components still elicit savory flavor despite the pizza being cold; the only decrease is the savory notes. Other foods, like fries, rely heavily on aromatic compounds formed from the frying process to vaporize and have relatively low concentrations of umami compounds.
Once cooled, these aromatic compounds are not as well perceived - there is also a textural component as many foods that contain starches go through a process called retrogradation during cooling, which gives starches a very grainy, stale texture when cooled.
Pizza is less prone to this due to the way the dough is made and the presence of the sauce at the interface between the dough and the toppings.
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