Photo by Lepas
My Sicilian grandmother always tossed a bay leaf or two into her tomato sauce, and my mother does as well. But lately, I've found myself forgetting to add the bay leaf and wondering what purpose it really serves.
So, I was intrigued to find an article in the International Journal of Gastronomy and Food Science that addressed this very question.
I reached out to its author, Charles Spence, an experimental psychology professor at Oxford University and the author of Gastrophysics: The New Science of Eating, to discuss bay leaves, why they spark such debate, and how his own bay leaf use has changed since his research.
Why did you choose to research bay leaves?
It was initially a debate with my brother, who's a chef in Oxford, about what they do or what they add. I've got other papers on cinnamon and coriander. So, I am interested in the historical introduction and disappearance of different herbs and spices around the world over the decades, centuries, and millennia. What, exactly, are they doing in our food?
I've got a verdant bay tree just outside the window here, so I've got thousands of bay leaves, but for others, they can be extra expensive to purchase. My brother is convinced bay leaves add something, and I am, too. I always stick them in whatever I'm cooking. But what, exactly, does it add?
It's a curious question. It got me searching through the literature, and that brought up the fact that many chefs and others have a big debate about whether bay leaves have a taste/flavor or not. It's interesting to have an ingredient that could be reasonably expensive and for which lots of people don't know why they're using it.
Tell us about the work you do.
As a psychologist, I've always been interested in the senses and how they interact with and apply to the real world. For the first 15 years, I mostly worked on technology, talking window screens, mobile phones, car warning signals, and that kind of stuff. Then, Unilever funded me to help with their fruit teas. I'd never done anything on flavor at all, but they were paying the bill, so I said, "Okay, I'll do some experiments on that."
Suddenly, it got interesting. Flavors are probably the most multisensory thing we experience. They engage all our senses, but flavor is something that psychologists typically don't study.
Here in Oxford, we'd do experiments on how the senses contribute to flavor and how we can make things sweeter by coloring them pink or red or adding certain scents. But my experience was that the food company chefs could never make anything very exciting from the science.
Then, I was introduced to the world's top chef, Heston Blumenthal, and suddenly started doing experiments around the "sounds of the sea," which thereafter led to one of his most famous dishes. Diners wear headphones, and they hear the sounds of the sea while they eat sashimi plated to look like the seashore.
That got me more work in food, working with chefs, mixologists, and baristas rather than food companies. These latter creatives turned out to be very interested in trying to apply science and psychology to food as a multisensory object, always doing so in ways that ask how people today perceive these things and what they mean.
Over the years, I've had a few interdisciplinary grants with anthropologists, historians, art historians, philosophers, and a wide range of disciplines. And I guess through some of those workshops, which have been on other things like what aesthetics is, I keep coming up against the anthropologists who say, "You psychologists. When you try to understand sensation or flavor, you don't seem to understand the importance of culture and history."
I've come around to starting to be interested not just in how we perceive things but also in how we have perceived things in the past. Tracing the history of herbs, spices, and fruits allows me to do so.
Maybe bay is not an expensive or luxurious spice in the same way that saffron is. It's a ubiquitous spice or herb in this part of the world. I'm curious about the history of flavor and psychological history, which lets me better understand how we perceive from a broader social, historical, and cultural perspective.
What have you found interesting about the bay leaf?
Bay is the only herb I have encountered so far where some people say it tastes like nothing and don't know why they use it. That doesn't happen anywhere else, and this debate has even made it into the culinary and trade press; there's this debate going on about what bay is doing.
It could be that a third of people are unable to smell one of the chemical compounds, or it could be that it doesn't really have a perceptible flavor. It just does something to the flavor of everything else. It's like a flavor enhancer. I'm interested in other things like kokumi, the next thing after umami, or monosodium glutamate (MSG). Kokumi has no taste when you add it to food. But when it's added to things that have umami (e.g., mushrooms and Parmesan), it amplifies the other taste sensations.
Maybe bay leaves are doing that. So, is this difference genetic in what we can smell? Some people can, some can't. What the bay leaf does for everything else is interesting.
Maybe some people who say it doesn't do anything are focusing on what it smells like itself. They think it doesn't smell like anything; therefore, they think it does nothing. Others say, "I always add it to my cooking because of the end result and total flavor."
It may also depend on where you get your bay from, what part of the season it was grown in, whether it's California Bay or Laurel, how it's been stored, and whether it's been frozen, dried, or fresh.
What's also interesting about bay to me is the question of whether dry or fresh leaves are better. For most things, you think fresh is better than dried. And yet various people say, "No, dried bay is better than fresh."
So, which is right? How do you answer that when the thing itself doesn't taste very good?
I've been going to my tree here, picking them, and putting them in boiling water for a while, which, again, may not be the right thing to do. Maybe it needs fat to release all of what it can contribute to a dish.
I also have been putting them in a cup of bay leaf tea and then trying to almost do the blind taste test on myself with a cup of hot water that has bay leaves steeped in it and another one that's just hot water. Can I discriminate? I haven't done the official taste test because it's a bit too messy and time-consuming. But yeah, there is something there, a curious sensation.
How did your bay leaf use change as you were researching the topic?
Well, I never had bay leaf tea before, and then, through the research, I now think differently about picking them. Before, I just picked them whenever the bowl of dried ones ran out, and now I think there's no point in doing that just yet; I should wait till the end of the year.
I switch between the dried and the fresh, trying to decide which is better. Before writing the article, I probably would've only used the dried ones. But now I'm thinking back and forth. They say it makes a difference.
What do you hope people will take away from your bay leaf research?
My hope is that people will come away thinking, "Well, yeah, now that you mention it, I do wonder why I do that. Why do we add our herbs and spices to our food?"
I think there's a whole world that's not really been studied much. A few food historians are doing research on spices, but not anything from the psychology or sensory angle. Growing awareness and appreciation, perhaps particularly in the case of herbs, might be advantageous moving forward. These sorts of herbs can have interesting effects on taste and flavor and also maybe interesting impacts on our ability to absorb other nutrients.
Although I'm not sure bay necessarily serves that function, it is undoubtedly a culinary curiosity that I think gets people interested and thinking this is much more fascinating.
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