Shireen: In today’s episode, we are in conversation with Dr. Guy Crosby as he provides us insights beyond the dining table and into the labs and kitchens where innovation meets tradition. More to come.

Several years ago, Dr. Guy Crosby, retired from teaching Food Science and Chemistry at both the Harvard School of Public Health and Framingham State University and now spends most of his time writing. His most recent book is “Cook, Taste, Learn: How the Evolution of Science Transformed the Art of Cooking”. Welcome, Dr. Crosby.

Dr. Guy Crosby: Well, thank you very much for inviting me to come and talk about my book and other things that I’m interested in, especially the science of cooking.

Shireen: Oh, we’re, we’re really delighted about this episode. This is a, this is a unique one for us. You know, first, just wanting to get to know you a little bit better, Dr. Crosby, you know, you, you play having an interest in chemistry when you were much, much younger. What inspired you to integrate your knowledge of organic chemistry with food science in particular?

Dr. Guy Crosby: Well, it was interesting, I guess when I was quite young, actually, I was very interested in art and painting because my my father was, he was an excellent but an amateur painter and I got into that into art and somehow the visual aspects of art translated into science for me, especially chemistry. I loved the shapes and sizes of molecules.

And I especially became interested in steroids like cholesterol, you know, the, the beauty of these molecules interested me a great deal. So when I was quite young, actually still in junior high school, high school again, with the help of my father, we built a little laboratory in the basement. One of these kids who hid out in the basement and worked with chemicals down there. And luckily I didn’t do anything to destroy the house, but I had a great time doing that. 

And so I, of course, I went off to college and majored in chemistry, organic chemistry because steroids are organic molecules. And then interestingly after I went to graduate school and then I went, after I got my PhD, went out to Stanford as a postdoc and did even more work in, in the area of steroid chemistry.

But from there, I took a job with a small company that was just starting up. We were developing a whole new concept of making what you might call polymeric food attitudes. So there were materials that when you ingested them, they wouldn’t be absorbed into your body. So you avoid all these toxic effects. So they were basically a very unique new class of food additives.

And that’s what got me going into food, food chemistry and a great deal of interest. And I headed up the chemistry group for this company for a number of years. We got a few things approved by the Food and Drug Administration and then, unfortunately, funding sort of ran dry on that. And I ended up moving to Princeton, New Jersey from California and, and worked for a food Machinery and Chemicals Corporation, and in the Food Ingredients division, so I continued to work with food ingredients and, and food chemistry. And I really have been involved with that ever since, even though my initial training was in organic chemistry and applied it to food and food ingredients.

Shireen: That’s quite fascinating. I do want to get into some of these components next. And first, I want to start out by, with just understanding, how has this integration of scientific principles because it sounds like science is a completely different thing, but it’s very related to food. So how has this integration of scientific principles really reshape the traditional techniques and methods in cooking and what are some examples of this transformation that you can share?

Dr. Guy Crosby: Well again, I kind of go through this in the book that you’d mentioned that I wrote in a chronological fashion. But if, if you go back to the various earliest days, there really was not a lot of science in in the early evolution of cooking, which is one of the reasons I got into writing this whole book was because I got fascinated with a book that I read by a professor at Harvard in anthropology called Richard Wrangham, his name is, and he wrote a book called “Catching Fire: How Cooking Made Us Human”. 

And he went through a lot of biological arguments in his book that claimed that the earliest that humans started to cook on this earth was about 2 million years ago. And so for millions of years, several million years, probably all they did was roast things over fire and flames. And, and there really was not a lot of unique applications of science to cooking until much, much later. Probably the first time that that started was with the evolution of agriculture, which was about 10,000 years ago. when early humans first learned to be able to collect seeds and sow them in the ground and grow crops, specifically wheat and barley and, and grow that and harvest that and then collect that.

And that was fairly the probably the first big evolution beyond the earliest stages of cooking. Because if you go back many thousands of years, it was really very little in the way of new developments in cooking. Maybe the first thing that they did about 30,000 years ago, they developed what they call these earth ovens where they would dig holes and plant hot stones or put stones around them and then build fires in there to heat the stones up and then they would cook their food on top of the hot stones. 

And this was probably the first unique development that humans had, but it was again, it was long after cooking was first discovered. And so there weren’t many, many developments until early science started and we can get into that unless you have any other questions. But I mean, really science did not come along in any formal way to affect cooking until till the 1600s.

So when you, when you go back to of the earliest science, the Greek philosophers, why they thought all the the four elements were, you know, earth, air, fire and water. And there wasn’t much you could do in terms of real science. If that was your basis for science was that those are the, those were the four elements. And it wasn’t until around 1650 that a scientist at Oxford University really got delved into what was combustion, you know, how did we create heat? And that was Robert Boyle at Oxford University. 

And so that was kind of the development of real science when we started to learn what was heat because heats involved in cooking, you’ve got to have heat to cook food. And, and that’s, that was the beginning. And, and at that point, we see some significant developments in how cooking changed.

There was one of the young French physicists who went and worked with Robert Boyle at the time in the, again, in the 1650s, 1670s, he developed a whole concept of pressure cooking and he developed the first pressure cooking about 1679 or so. And, and it was interesting, I guess he went through lots of exploded metal containers until he finally figured out that he needed a pressure relief valve.And so he invented the first pressure relief valve so that he could heat this thing up very, very high. And once he did that, he developed all kinds of wonderful recipes for cooking many different things in his pressure cooker. And it became very, very popular back then. 

So that was kind of the first step forward in the 1650s when we took real science that was beginning to be developed at that time and applied it to cooking. And then another another gentleman, Benjamin Thompson, who was also very interested, he was an American who went over to Europe. in fact, he was born right here and there in the area where I live in Massachusetts. And in the 1670s, he developed methods for cooking things in unusual ways. But if you look at what he developed, he was probably the first first one to develop sous vide cooking, very low control temperature cooking.

Back in, in 1679 I think it was, he developed a special cooker for doing this. Sous vide cooking, which we kind of think of as a modern method of cooking food. But really way back then, it was still understood and his knowledge of heat and cooking, he applied that to this new method. So there are these are some of the earliest developments when we really got into science and applied it to cooking.

Shireen: And this is helpful to get some context about the history of some of these items. I just want to talk about what role do advancements in food chemistry and physics really play in enhancing flavors textures and just the overall dining experience. Can you speak to that?

Dr. Guy Crosby: Well, you know, flavor is extremely important, Of course, in fact, it, the studies have been done around the world that show that flavor is probably the most important attribute of, of food that enable people to decide what foods they like and what foods they want to eat. So flavor becomes very, very important. 

But I just wanna say something about that because flavor is not something we taste, you know, we taste things, we smell things it with receptors in our mouth, but we don’t taste flavor, we don’t smell flavor. Flavor is actually created in your brain from your sense of taste and your sense of smell. And there’s a wonderful book that was written by a Doctor Gordon Shepherd in the Yale University School of Medicine called Neuro. What was it? I think? Well, and it was it had, he was a neurobiologist and he wrote the book all about how flavor is created in the brain.

So this is something that is is very important as a as a distinction from taste and smell. And it probably was extremely important in the evolution of the, of the human brain, which again, that’s something that Richard Raum goes into his book when people first started to cook and they develop new flavors. And he envisioned that as being extremely important for the development of the human brain and probably what set them apart from all other species on earth.

Because when you start to think about it, humans are the only species that cook food, cook their food. Nothing else developed this unique trait of cooking food and flavor is probably one of the major drivers, not only of wanting to cook food, but also since it’s a sensation that’s created in the human brain, it probably was a major factor in developing the human brain. So that, you know, many hundreds of thousands of years after early humans learned to cook, the human brain had developed and increased by about 60% in size over the very earliest brains of people who were the earliest cookers on earth. So, you know, it’s, it probably had a great deal in terms of the evolution and development of humans is flavor and how it impacts the brain and how it impacts, you know, the development of expansion of the brain and human evolution.

Shireen: You know, as science provides us with a deeper understanding of nutrition, now, how has this knowledge really been applied to create healthier yet delicious dishes? Right. So are there any challenges associated with this pursuit?

Dr. Guy Crosby: Well, that’s a good question because I get into that obviously in the last two chapters of the book because now one of the major applications, and I think the interest in cooking science and learning more about what happens during the science of cooking food, is being able to use this knowledge to create nutritious foods. 

We can of course, maybe learn to cook a steak so it’s the way we enjoy it or make a good pastry dough, pie dough or something like that. But the important thing is now is that we’re learning to apply the knowledge of cooking, to develop healthier foods, to know what nutrients are lost when we’re cooking by certain methods and what nutrients are actually increased by certain cooking methods.

It’s interesting. One of the probably the classic examples of this is the red pigment that’s in tomatoes called Lycopene and Lycopene is this material, the red pigment, it’s bound to a lot of the membrane polysaccharides and proteins and tomatoes. So if you eat a fresh tomato, you only absorb a certain amount of the Lycopene into your body. But if you cook the tomato, it gets released unbound from the being tied up with the polysaccharides and the proteins and you absorb about four times more lycopene in your body, then you from cooked tomatoes than you would from fresh tomatoes. 

So why is this important? Well, it’s been shown among other things that Lycopene is a very strong antioxidant and it actually has some very potent anticancer activities. And the studies have shown again here, this was at the Harvard School of Public Health that the Lycopene that’s released and absorbed into the body from cooked tomatoes has a significant reduction on prostate cancer in men. It reduces it by anywhere from 35 to 50% reduction in the incidence of prostate cancer by consuming the lycopene from cooked tomatoes. 

And in fact, if you cook the tomatoes with olive oil, the oil actually enhances the absorption of the lycopene and you absorb another 80% of lycopene relatives. Again, to what just the cooked tomato absorbs. So these are all important factors in, in cooking and in controlling some of these nutrients that are very important, both for our health and for and for avoiding certain diseases like cardiovascular disease and cancer. We need to get these very important components from the food we eat. And this is probably a good example of why that’s important and why cooking science helps us in this area.

Shireen: Another, are there any other examples you like to share? The tomato one is interesting. Anything else?

Dr. Guy Crosby: Well, there are, you know, as I say a number of compounds in food, there are lycopene, which I mentioned is classified as a carotenoid. It’s the kind of compound it is and they are very strong antioxidants which is again, why the lycopene has its properties, but they’re all oil soluble. So, of course, if, if you foods that have a lot of Lycopene in them, if you cook them and fry them in oil, you’re gonna draw out a lot of the, the carotenoids and destroy them and they’ll go away in the cooking oil. Whereas I, you know, they will, they will be retained if you steam them in water, for example. So knowing the right way to enhance the amount of these compounds. And, and there are good examples of carotenoids that I have other anticancer properties. 

And another type of compound that’s in cruciferous vegetables called the glucosinolates. There’s the name of them chemically, they tend to be water soluble. So if you boil them, unfortunately, you’re gonna remove a lot of them from the food. But if you steam the food, you’re going to enhance the property of these glucosinolates that are fairly strong, potent anticancer compounds. And I, I happen to have an interest in that, of course, since I have this form of cancer called multiple myeloma, a blood cancer. And so doing things with the food and with the diet that will help counteract that is very important to me and to many, many people. 

So, so these compounds, the things that you can do to enhance them when you cook them, you know, or avoid at least losing them as the important nutrients in the food, food and, and knowing this scientifically, which is based both on their chemistry and the science of cooking, I think is very important.

And it’s, it’s finally now that we see that there’s a whole branch of medicine being developed, fortunately called medicinal cuisine, or medicinal cooking, where doctors are beginning to learn more about nutrition and how food is impacting people and they can help to get, you know, improve their health when they go home after they’ve been treated in the hospital by learning the proper ways, which I go into my book a little bit, the proper ways of cooking food. So they can enhance the nutritional value, especially, you know, relative to whatever the chronic problem might be that these people have. But medicinal cuisine is becoming an important factor in medicine. And it, because it has been in nutrition for quite a long time.

Shireen: You know, when you, you mention medicinal cuisine, I also think about cultural and regional cuisines that really have deep roots, you know, for, in fact, when you talked about the tomato example and then cooking that in olive oil or any oil for that matter, I think to Indian foods that, that I cook. And within that one of the things that you do is you really, really saute. And that’s what gives that, that curry, that red color is because we’re looking at really sauteing and, you know, sort of cooking down the tomato. And so when you’re talking about the carotenoids and then it immediately my mind goes to man, we’re, we’re really butchering this thing. But having said that, how has the introduction of scientific techniques influenced the preservation and modernization of traditional recipes while also respecting heritage?

Dr. Guy Crosby: Well, I guess is one of the classic examples that I went through was the Lycopene and there’s so many nationalities cook tomatoes and make sauces out of them. And I suppose that one factor that I didn’t mention in this is that the study that I talked about in the effect on prostate cancer, it was shown that the reduction of the prostate cancer goes, is it significantly improved if you have basically around 3 to 4 servings of tomato sauce a week.

So if you’re consuming cooked tomatoes and so many different nationalities, as you say, Indian and Italian and even here in the United States, you know, we’re cooking the tomatoes and the idea that you cook it for a long period of time, the Italian sauces that you cook for hours is very, very important because it develops, a lot of the chemistry develops only very, very slowly when you cook it. And that’s one example. 

Another is, you know, when you’re cooking pieces of meat that have connective tissue in them, if you cook that for a long period of time, it takes generally three or four hours to cook the change the connective tissue into what’s called gelatin, the protein that then softens the meat and holds water and retains moisture. These factors of course, just improve what you’re cooking very much if you have this knowledge that you’ve got to cook it for a long period of time. 

So it may seem like you’re overdoing it, but when you, what you’re really doing is you’re enhancing the development of some of these nutritional components of food that you’re cooking by cooking it. Such a long period of time, it’s very important. And I guess traditionally, without even knowing this, we learned this over the years by just doing and trying and realizing we’ve got to cook something longer in order to improve this particular property that it has.

Shireen: And so, and so then coming back to my question, then how, how does it preserve sort of, how do you respect the heritage and still be able to sort of bring some of these influences around preservation?

Dr. Guy Crosby: Well, I suppose, you know, learning what the benefits are by, by cooking in a certain way, like cooking tomatoes long and slow or meat long and slow. It’s learning these things traditionally, we’ve just learned them by hit or miss methods, you know, now, finally, we’re beginning to understand the science of what’s behind this, what’s happening to food when we cook it low and slow and for a long period of time, you know, converting connective tissue to gelatin, for example, or extracting the important components. 

I think it’s something we’ve learned over the years that we didn’t know 100 years ago why we did it, but we did it through tradition and now through science, we’re learning why that was the right thing to do and how it’s beneficial and in some cases how it’s not beneficial. So, I, I guess it’s, you know, it’s only in recent years, we’ve learned a fair amount about this and, you know, you talked about flavor early. Well, one of the important flavor chemistries, it’s been known as the maillard reaction that was, was discovered by a French doctor back in 1912 in France. And it’s very, very important because it develops a tremendous amount of flavor in cooked and roasted foods and like coffee beans and chocolate and roasted meat and baked bread.

They all develop a lot of their chemistry and aroma and smell due to this particular chemistry called the maillard reaction: maillard. And, and it was really not until an African American chemist working for the USDA for many, many, many, many years, discovered the real attributes of the maillard reaction and published what’s become one of the most important papers ever published in the Journal of agriculture and food chemistry. And what really took the whole world of flavor chemistry and turned it upside down and so that we could learn how to manipulate flavor scientifically and improve what we’re doing. 

And I think chefs have have used this now ever since this knowledge that’s devolved since the 1950s, since Edward Hodge developed all this work with the maillard reaction. In fact, I, I have mentioned many times the things I’ve written, I think we should now call it the Maillard-Hodge reaction so that both of them get credit for not only the initial discovery but how it, how it can be applied through modern chemistry.

Shireen: As we, as we wrap up this episode, Dr. Cosby, just really looking ahead, what potential scientific advancements do you foresee having really the greatest impact on the art of cooking? And then how might these changes really shape the future of culinary innovation?

Dr. Guy Crosby: Wow, that’s a good all encompassing question. I mean, because here if you’re dealing with the art of cooking, you know that that’s really where the intersection occurs between science and art, which is what I I find most fascinating about cooking is there is this interaction between science and art. So there’s a science in knowing what’s going on chemically with the food and the various components, but there is of course, the art that’s involved in how you do it so that you develop, maximize the flavors, the aroma. 

And we know that that’s as I had mentioned earlier, extremely important in terms of deciding what foods people like to eat and want to eat. And you know, and especially if there are healthy attributes to these foods that becomes very important that you, you enjoy and appreciate eating something that is very healthy for you. That’s very good. And I think the art of preparing food becomes really important then so that you can get the maximum enjoyment out of the food that you eat and not only enjoyment, but also if it’s healthy for you, you know, it’s, it’s very important. So I think combining these attributes of the knowledge of science with the art of cooking and essentially maximizing the nutritional and, and health benefits of food is really where it’s all kind of coming together. 

Shireen: Lovely. At this point, we are toward the end of the episode. Dr Crosby, can you tell our listeners how they can connect with you and learn more about your work?

Dr. Guy Crosby: Well, I suppose they could certainly go to my website, which is cookingscienceguy.com, www.cookingscienceguy.com. I mean, it’s a website I’ve developed a number of years ago. I’m unfortunately, I am guilty of not updating it all that well, and I get, I get people contacting me on a fairly regular basis. Gee, you know, if we did this, you’d improve your website.

But if you want to find out a fair amount more about what I do and, you know, and things of that sort, I’d go to the website. That’s a good place to start. And, and I, and the reason I got into cooking science was way back in the early, I think it was 2003 I started teaching the food science course at the Harvard School of Public Health. But then around 2005, I started working as a science editor for America’s Test Kitchen. And now I work for Christopher Kimball’s Milk Street Kitchen as the editor. So there are things that I write and do for those magazines that people can learn more about me that’s in there. But, or by going to my website either way, 

Shireen: so what we’ll do is we’ll tag your website below

Dr. Guy Crosby: Right. And if people do want to write me questions, I’m happy to answer them to people, whether it has to do with food or food, food science, cooking, whatever nutrition, all of those areas.

Shireen: Ok. Well, appreciate that doctor. Thank you so much for being on this episode to our listeners. It is that time had a richer of social media and answer this one quick question: What are some of your favorite recipes that you’d like to learn the science behind? So again, a quick question for you, head over to our Facebook or Instagram, find this podcast post and comment below by telling us what are some of your favorite recipes that you’d like to learn the science behind? We’ll continue the conversation there, Dr. Crosby with that. Thank you so much for your time. It’s such a pleasure.

Dr. Guy Crosby: Thank you, Shireen, for inviting me. I enjoyed it very much. Thank you.

Connect with Dr. Guy Crosby:

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“Cook, Taste, Learn-How the Evolution of Science Transformed the Art of Cooking”