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The Science Behind Pumpkin Spice Lattes

Confession time - I absolutely love a pumpkin spice latte (PSL). I’m not a purist in terms of where that latte comes from and I don’t actually like pumpkin pie or that many other pumpkin pie flavored food items. But, when fall rolls around (and sometimes a little before), I consider a PSL the ultimate luxurious treat.

Despite the continually hot weather where we live, I have already indulged in my favorite fall beverage. As I was sipping the aromatic blend of coffee and spices, I naturally got to wondering about the origins of the ingredients and why this particular flavor blend has come to dominate fall here in the US.

Pumpkins are native to North America and the word describes a mature winter squash in the genus Cucurbita, usually Cucurbita argyrosperma, Cucurbita ficifolia, Cucurbita maxima, Cucurbita moschata and Cucurbita pepo (the one most people would identify as a pumpkin). Planted in the summer and harvested in the fall/winter, pumpkins are one of the most popular crops in the US, with over 1.5 billion pounds produced in 2017. Most of the plant is edible and is a good source of vitamin A and vitamin C, to a lesser extent. The fruit itself is a botanical berry known as a pepo (a simple fruit having seeds and a fleshy pulp produced from the ovary of a single flower).

There is evidence of pumpkin growing dating back to 7000 and 5500 BCE in Mexico and the etymology of the word can be either Greek in origin (from pepon which means melon) or from a Massachusett work pohpkun. This means ‘grows forth round’ and might have been used by the Wampanoag people to describe the fruit to English colonists.

But all this background about pumpkins is a little besides the point. The aroma and flavors of pumpkin spice don’t actually include pumpkin (which doesn’t really smell like much). The scent and flavor people crave comes from the spices that are associated with pumpkins, usually nutmeg, cinnamon and allspice (sometimes clove and ginger as well depending on the mix). These spices are found in different places around the world with some found exclusively in parts of Indonesia that became known as the Spice Islands. In the early 17th century the Dutch took control of the islands to control access to those spices, which were becoming popular in European cooking. The Dutch created spice blends that included some of the same spices found in pumpkin spice but also included cardamom and white pepper (sounds delicious).

In 1791, a blend of similar spices was found in The Practice of Cookery, written by a Scottish author and included nutmeg, clove and allspice and was recommended for use with fried flounder and mutton chops. By 1796, it was included in the first known cookbook to be written by an American and her mix included mace, nutmeg and ginger. (Of course, this is ignoring similar blends of spices that may have been used regionally by the people in areas where the spices were indigenously grown).

The spices themselves are fascinating. Cinnamon is the inner bark of several tree species from the genus Cinnamomum. There are several different spices that can be found in a range of geographies. Nutmeg is the seed of several tree species in the genus Myristica, which is a dark-leaved evergreen tree. Mace is from the seed covering of the same tree. Nutmeg and mace are native to the Moluccas (Spice) Islands in Indonesia. Cloves are as well. Cloves are actually flower buds from the tree, Syzgium aromaticum. Despite sounding like a spice mix itself, allspice is one spice made from the dried, unripe berry of the Pimenta dioica tree. This spice is native to the Greater Antilles, southern Mexico and Central America.

The common pumpkin pie spice or pumpkin spice was first commercialized by McCormick in 1934 to flavor pumpkin pie, a decidedly European invention using a crop native to North America. (The indigenous people of North America used pumpkin and other squashes in savory cooking). The introduction of the spice was in response to the introduction of canned pumpkin to easily make a pumpkin pie.

But why does it resonate so much? What in this particular blend keeps us hooked, even despite all the sarcastically comedic memes about our PSL addictions. Interestingly, we are not very good, as a species, in differentiating odors. The parts of our brain that process odor are not well connected to the parts responsible for language processing. What that means effectively is that any “warm spice” smell will likely evoke the same response as pumpkin spice, think apple cider or even apple pie or gingerbread. The popularity is likely linked to the fact that most of us have strong memories of something fall/winter related, of pumpkin pie or gingerbread or other “fall smells”. Our brains are powerful and they are constantly taking in information and building our individual realities. Part of the process is to fill “in the gaps between the scent of the spices and the memories associated with the smell”. The smell can trigger cozy fall memories such as family and Thanksgiving and walking in the fall leaves.

Add to this the fact that pumpkin spice is only available in the fall and comes back every year, well that creates the perfect set of circumstances for us to associate the smell with the seasons changing and all the cozy habits and rituals of the cooler months.

So next time you get a warm, fuzzy feeling from smelling pumpkin spice flavored, remember that you may not be smelling pumpkin spice at all (our brains are really good at filling in information so if we see a picture of a pumpkin the we’re likely to think of the pumpkin spice smell), but also be prepared for a warm, cozy feeling to wash over like your favorite blanket.

PS - Since publishing this post, I came across an enlightening article in the Washington Post about the violent history of the spices in pumpkin spice. One example being a Dutch invasion of the Banda Islands in Indonesia. The military action resulted in the decimation of the local population it what is thought to be the first instance of corporate genocide. Clove has a similar history with it nearly bringing England and the Netherlands to war. While we are a science-focused enterprise, we do believe in the importance of acknowledging and learning from history. This is especially true since all science is built on the historical work of others. If you can, please read this article in the Washington Post and learn a little bit about the history of these spices.



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