It’s fall, which means every other item at my local Trader Joe’s now has pumpkin in it. Or the essence of pumpkin, at least. You know, that lovely cis-3-Hexen-1-ol (C6H12O) that your nose senses after you slice into a big, orange gourd to carve a jack-o-lantern. Or the always nostalgic dash of sabinene (C10H16) that you taste in a good pumpkin pie, and naturally, pumpkin tortilla chips, which are also a thing… These products probably do have their fair share of pumpkin puree, but sometimes smushed pumpkin isn’t even what we really expect to taste when offered a “pumpkin flavor” product. This isn’t really a problem either way, since really what’s going on pumpkin and other flavors is just some refined manipulation of how we perceive flavor in the first place. And probably sugar.
Compounds that are convincing to your nose and brain
You might not have anything labeled cis-3-Hexen-1-ol on your spice rack, but it’s actually one of the various compounds you’re likely to notice when you cut into a ripe pumpkin. Alongside a few other alcohols and aldehydes, the right ratios of these molecules hitting the right smell receptors in your nose will get your brain working to identify what is causing the aroma. With a pumpkin in front of you, that particular blend gets labeled as “fresh pumpkin smell” in your memory, although none of those compounds are terribly unique. When you taste (and smell) the food you eat, your brain is simply referencing memories of other times you’ve had those particular smell receptors get activated in some particular proportion.
Now, cis-3-Hexen-1-ol is a decently large molecule, but only one portion of it is needed to activate a smell receptor. Rather than have a receptor that can accommodate the entire molecule at once, your nose only really cares about the OH at the end. This is very convenient for chemists, who can attach that smell signifier to other compounds that may be more stable, cheaper or somehow easier to work with than what the pumpkins make themselves. It’s a concept that gets used in tons of different foods, with these artificial flavors often being mixed back into the foods they originated in.
Close control over foods’ flavors
As food production shifted to industrial scales in the early 20th century, manufacturers needed food that could survive longer in transport and on shelves, bring down costs, and also taste consistent from one helping to the next. As with pumpkins, oranges have had their chemistry parsed to see which molecules trigger the experience of “orange flavor,” so that it could be used in other products, as well as orange juice itself. By adding something like ethyl butyrate to orange juice, manufactures can be sure that a crop of bland oranges won’t tank their sales for a season. Similarly, diacetyl was added to products to give them a buttery taste, but the flavor association was so successful that creameries now spike actual butter with the compound, so that butter tastes more like what our brains think of as butter.
In the case of the deluge of seasonal pumpkin products, we also have to accept that we’re not sure what we want to taste. While cis-3-Hexen-1-ol is found in actual pumpkins, that’s not a smell you’re really looking for in your coffee or pumpkin biscotti (which is also a thing.) In those cases, the target flavor is actually pumpkin pie, which is why recipes also include sabinene for nutmeg, eugenol for cloves, and cinnamaldehyde for cinnamon. As ubiquitous as this now seems, it’s not an easy batch of flavors to get right since one person’s perfect pie might not match the expectations of someone else. This led Jelly Belly candies to even temporarily abandon their attempt at pumpkin pie flavor, at least until they embraced the variability inherent in the task by billing the candies as their “family’s” own recipe. Fortunately for manufacturers, sugar helps smooth things out considerably, as it’s certainly a flavor that our brains remember as “yummy.”
Source: The Absurd History of Artificial Flavors by Alison Herman, First We Feast