Imagine a taste test that is based on genetics — on a person’s genotype — and how the results of that test could confirm or explain one’s taste perception, food choices, dietary behavior, or body weight. Well, little circles of filter paper embedded with 6-n-propylthiouracil (PROP) can actually do just that. 

PROP is a compound that for people with the TAS2R38 genotype tastes extremely bitter whereas for people who have a differing genotype, the compound goes unnoticed. As shown on a recent episode of Anderson Cooper’s daytime talk show, you can tell immediately who is genetically programmed to taste it and who is not. Those who are sensitive to the compound, classified as super-tasters — a term initially coined by Dr. Linda Bartoshuk — are absolutely disgusted by the overwhelmingly bitter flavor while people who are not sensitive to it, non-tasters, just taste the filter paper. Statistically, about 25 percent of the population are super-tasters, twenty-five percent are non-tasters, and fifty percent are somewhere in the middle, classified as medium tasters.  However, PROP seems to reveal much more about a person than how well they can perceive and bear bitterness. 

One of the focuses of the Rutgers University Sensory Laboratory, as well as other sensory research facilities across the country, is to examine just that: To further explore the link between taster status and dietary behavior. By grouping subjects into taster groups and offering them varieties of food ranging in fat and caloric content, definite conclusions can be made. See, super-tasters do not just only perceive the bitterness of PROP and the bitterness of other compounds more, they actually generally perceive sweetness more, hotness (like from a chili pepper) more, textural aspects of dairy products (like creaminess and mouthfeel) more, and consume higher fat foods less frequently than non-tasters. Super tasters seem to be overall more sensitive to multiple sensory characteristics in general and are generally satisfied with smaller quantities of food because of their attuned sensory perception (like being satisfied with less salad dressing on a salad). 

For example, one study conducted in the sensory lab exposed subjects to a buffet-style eating atmosphere. By tracking how many calories, and specifically, how many calories of fat each subject consumed, researchers looked at whether non-tasters consumed more food and more foods with higher fat contents in comparison to super-tasters and medium tasters.  They did.

Naturally there are always exceptions, and taste genetics is just part of the story. There are so many other factors affecting a person’s food choices, yet considering taste is so subjective, PROP does at least give scientists clear and concise results. With the growing fight against obesity, many researchers believe that PROP will prove to be very useful. Hundreds of studies, in fact, have examined PROP status. One actually found that heavy smokers are significantly more likely to be non-tasters because super-tasters are far more sensitive to the bitterness of nicotine. Super-tasters too perceive the bitterness of alcohol more strongly than non-tasters and thus generally consume fewer alcoholic beverages per year. So it makes sense, that connections between taster status and body weight are being examined. Perhaps one day, PROP could be used as a screening tool to help doctors identify individuals who could potentially be at risk for excessive weight gain.

Anxious to know your taster status? Unfortunately PROP discs cannot be ordered online, but an easy at home test does exist. First, using a cotton swab, dab a small amount of blue food coloring on the front of your tongue. Then, using a mirror or with the help of a friend, compare your tongue to the two photos above. The lighter blue bumps on the tongue are fungiform papillae (structures that contain taste buds) and supertasters have a higher concentration of these structures (top section of photo) in comparison to non-tasters (bottom section of the photo). Thus, supertasters taste more perceptively because they actually have more taste buds. 

Gluten is what makes bread dought elastic enough to risePhoto: Three Points KitchenIt’s clear that Americans have an obsession with gluten. Just begin typing the word into a search engine and “gluten-free” pops up immediately, followed by “gluten-free diet.” The next most popular term is “gluten-free beer.” So it seems the obsession with gluten is really about removing it from our diets. 

Make no mistake, celiac disease and gluten intolerance are very serious problems and pose real dietary constraints.  Considering the number of foods that contain wheat, rye, and barely, removing gluten from processed foods is very challenging. Recently, because of the growing prevalence of these forms of intolerance, the food industry has been working fiercely to develop gluten-free products to both meet the demand and optimize sales in response to a gluten-free trending market. 

And it’s true; the general public does now seem more aware of gluten, and many appear to be buying gluten-free products, regardless of their dietary constraints. But from a scientific perspective, it strikes me that most people probably don’t even know what gluten is, or how it functions in our food.

Let’s begin with gluten’s chemical composition; it is actually a complex protein created when gliadin and glutenin — two proteins found in several flours — are hydrated and mixed.  In the bread-making process, for instance, water is added to flour, where it hydrates proteins, causing them to swell and become stretchy and flexible. Kneading this mixture rearranges the proteins into what is called a “gluten complex.” As any bread aficionado knows, to make a good bread, the dough must be elastic enough to relax when it rests and expand and hold air when it rises — while still maintaining its shape. Gluten makes this behavior possible. 

And while wheat flour has high and nearly equal levels of gliadin and glutenin — those gluten building blocks I mentioned earlier — flours made from other grains that have insufficient amounts (or an imbalance in one or the other) will cause a limit to the structural matrix that can be formed in the final food product. Corn flour, for example, has high amounts of gliadin but low amounts of glutenin, rye has low amounts of glutenin, and oats have a very low amount of gliadin. This is also why gluten-free bread is so challenging to make and rarely tastes good. 

What many consumers don’t realize, however, is that there are many naturally occurring gluten-free foods that have been newly labeled as such, just to take advantage of the gluten-free trend. Anything made exclusively of rice flour (a grain which contains no gluten) for example — like mochi, rice noodles, or dumpling wrappers — has always been gluten free! The same goes for milk, chocolate, and potato chips.

Of course, there are also exceptions. You may have seen the new-gluten free Rice Krispies, for instance. Those came out this summer, and the new label is actually a legitimate claim.  The original Rice Krispies recipe, despite being based on rice, does actually contain gluten in the form of barley malt. And there are likely other examples.

For people with gluten sensitivity, these products are a necessity and will hopefully get better over time, as food scientists continue to make new breakthroughs (making bread without gluten is no easy task). But I think those of us who can eat gluten should appreciate what it does to our breads, pizza crusts, and bagels. After all, gluten isn’t evil, it’s just protein!

Photo: Mitchell MattesOne of the many reasons I enjoy food science courses is that they make all the abstract concepts I encountered in organic chemistry and biochemistry, semesters ago, suddenly seem quite down-to-earth, and extremely important.

For example, in most of the chemistry and biology courses, we’ve discussed water early in the semester. In chemistry, water is considered the universal solvent because of its molecular structure and interaction capabilities. In biology, we learn that water is vital for all known forms of life. Through the lens of a food scientist, however, water presents much more gripping topics of discussion — such as the crispy vs. chewy chocolate chip cookie debate.

Water is used in food processing as a medium for temperature exchange (boiling, blanching, steaming, etc.) and as a vehicle for transportation around a factory for foods that float (for example, apples). It’s also essential in any cleaning or soaking procedure, as when processing everything from potatoes to coffee beans. But the chocolate chip cookie conversation involves something that I learned in class just a few days ago: the idea of dealing with the water that is already inside of food.

Some of that water is bound or associated with various other molecules, and no longer behaves like pure water. Water activity is the term used by food scientists to express the amount of unbound water — water that still behaves like water — that is available for chemical and biological reactions.

Why is this important, you ask? Well, primarily because of the role water activity plays in a food’s shelf life. If a product is kept below a certain water activity level, microbial growth is inhibited, which results in a longer shelf life. Also, in mixtures of food types with drastically different water activities — say raisins (moderate water activity) and bran flakes (low water activity) in breakfast cereal — over time, the water from the raisins will travel to the bran flakes. So food scientists can use water activity to determine how much moisture migration will affect their product. 

As you might expect, water activity is very much related to overall moisture content. In class, we went into detail about every nuance in their somewhat complicated graphical relationship, but to generalize, a food that is dry, hard, and crisp has a low moisture content and low water activity, and a food that is moist, sticky, and soft, has a high moisture content and high water activity. Where things get really interesting is in thinking about how to transition a food from soft and sticky to dry and crispy, or vice versa.

Take chocolate chip cookies, for example. The range of possible moisture contents is vast. They can be cakey and chewy, or brittle and crumbly, or anything in between. Yet food scientists can actually account for a cookie’s textural attributes based on a scientific understanding of water activity and moisture content. It’s not just about adding more or less liquid to cookie dough to generate a moister or drier product — that’s only half of the story. It’s really all about adding more of another ingredient that will bind or trap more water!

That other ingredient — for cookies, at least — is most commonly a form of sweetener, such as white sugar, brown sugar, high-fructose corn syrup, or molasses. In other words, adding more sweetener to your cookie traps more moisture, which in turn creates a chewier texture. (At this point, you should feel free to replicate our classroom experiment, and verify for yourself that chewy chocolate chip cookies do indeed taste much sweeter than crunchy ones.)

Meanwhile, the same migration issue that occurs due to the varying moisture activities of raisins and bran flakes also applies to cookies and their interaction with the air. Chewy cookies are actually moister than the air and crunchy cookies are drier than the air. As in all scientific reactions, equilibrium is desired, so moisture from the chewy cookies will want to leave and enter the air, while some of the moisture from the air will want to enter a crunchy cookie. This is why things go stale — why chewy things become hard and crispy things become soft! Hence the need for all of that fancy resalable packaging comes in, to create a waterproof barrier between the cookie and the atmosphere. 

Now, imagine yourself working at a cookie factory or a bakery — or even making cookies from scratch at home — and realizing how this one little concept can affect your recipe design and the likelihood of achieving the final product you desire. I know that, personally, the search for a recipe that successfully creates my idea of the perfect chocolate chip cookie is still ongoing, but with this new knowledge in hand, I’ll be tweaking the amount of sugar and other water-binding molecules present in the standard Toll House recipe to create the texture and moisture content I have always dreamed of. 

I have always had a fascination with the idea of a food memory — a Proustian time capsule accessed through the smell and taste of a particular food. Sometimes just hearing the name of a dish can be enough to remind you exactly how it tastes and feels in your mouth, and can bring back the many associations you have with it.

My grandmother used to make a dish called, simply enough, spaghetti and breadcrumbs. As the name implies, she would toss spaghetti in a tomato sauce, pour it into a casserole dish, and top it with breadcrumbs.  She’d add a little bit of butter here and there (well, more like a lot of butter) and then bake it until the top was golden brown. The result was what is perhaps one of the simplest yet most delicious pasta dishes, in my opinion, to ever have been introduced to human taste buds. 

Growing up, I was a pretty picky eater, but this was a dish I wanted quite frequently. With my grandmother living in Florida and me in New Jersey, I would ask my mother time and time again to replicate the dish. My grandmother, of course, didn’t have any sort of written-down recipe, leaving my poor mother to take down vague directions from her over the phone. I ended up so frustrated by my mother’s mock spaghetti and breadcrumbs that I stopped wanting the dish.

Years later, as I was becoming more enamored with food, and, at the same time, getting into chemistry in high school, I began trying to work out the elusive spaghetti and breadcrumbs recipe myself.  I realized relatively quickly that the key ingredient was the canned sauce, and I conducted trial after trial until I finally found the flavor I was looking for. I knew it, too, as soon as I cracked open the can of that particular sauce. The smell of the dish baking in the oven, the cracking sound of the toasted breadcrumbs as my grandmother would scoop out a serving, and the experience of being in her kitchen, watching her cook, all came back to me in a rush.

It was then that I realized how important ingredients are, how important recipe formulation is, and how key it is to have the ability to replicate a recipe over and over again — to recreate the same exact product every time. 

Now that I’m a junior at Rutgers University and a food science major, I’m learning to think and understand at a chemical and biological level what food is, as well as how it is affected by processing and packaging. As many science professors have told me, the real validity of any experiment lies in the ability for anyone else, with no other information in front of them than the lab protocol, to be able to replicate the experiment and reach the exact same results. Recipe formulation relies on exactly the same concept. Food manufacturers can — and must — ensure that, whether a customer buys their product a week from now, a month from now, or a year from now, they will be purchasing the exact same product. That fact is the result of a scientific approach of dealing with food. In turn, it creates product loyalty — and more importantly —  food memories.

Over this fall, I will continue to broaden my scientific background, taking courses in microbiology, physics, and psychology and applying them to courses in food science as well as research in a sensory laboratory. I look forward to sharing my growing comprehension of the science behind food, and my appreciation of its usefulness. Meanwhile, though, here’s a piece of advice: next time you’re eating a delicious home cooked dish that you can’t imaging not being able to eat for the rest of your life, be sure to get the recipe — and if none exists, start working on developing one right away.