There is no conception in man's mind
which hath not at first, totally or in parts,
been begotten upon by the organs of sense.
---Thomas Hobbes, Leviathan, 1651

Monday, August 24, 2009

Suppress me and call me sweet

A loyal reader sent in a question that well illustrates a common sensory effect we encounter just about every day in one way or another. She noted that coffee makes chocolate taste better, and wondered why?

This effect is known as adaption and suppression. But that's getting ahead of ourselves. First, lets talk about basic tastes (sic) in chocolate and coffee. Chocolate primarily has bitter and sweet tastes (taste being what you perceive on the tongue). Black coffee has a strong bitter taste, and hardly any sweet. As an aside, the other compounds in both chocolate and coffee that give them the great flavors we all know and love are mostly "volatile" compounds that are perceived by the olfactory bulb in the upper reaches of the cavernous nasal cavity, which are unimportant for the illustration of this effect.

Adaptation occurs when we repeatedly perceive something over a short period of time. When this happens, our ability to perceive that particular thing becomes lessened. For example, how many of you notice right now that your saliva is salty? None of you, right. However, if we were to completely dry the saliva off of your tongue for a few minutes and then let it replenish, you could perceive the saltiness for a few seconds or minutes before you become "adapted." Another illustration - how many of you feel the texture of your clothes against your skin? Or hear the hum of the air conditioner? Adaptation is the body's way of filtering out sensory information so that we can pay attention to new events, which tend to be the most interesting or important.

Lets look at some (fake) data that illustrate adaptation and suppression with chocolate and coffee. Assume that on separate occasions you taste both pure coffee and chocolate and rate their bitter and sweet tastes on some scale. On the third tasting session, you take a big sip of coffee and swish it around in your mouth, and then immediately taste the chocolate. You've used the coffee to adapt your palate to the bitterness, thus suppressing the bitter level of the chocolate. The chocolate will taste sweeter, and most people like this.


This type of effect happens all of the time during meals, and chefs have to pay particular attention to it from one course to the next lest some adaptation effect causes a perfectly balanced dessert to taste extremely bitter because it was preceded by a too-sweet sorbet. Regular wines aren't paired with desserts because the overwhelming sweetness in most desserts would adapt your palate to sweet flavor, thus making the wine become bitter. Sweet dessert wines don't get overpowered as much. And the biggest challenge to chewing gum lasting forever is your palate becoming adapted to the constant flavor stimulus, not gum itself being unable to release flavor for a long period of time.

The dessert above is the "Chocolate and Coffee Sampler" from the Fall 2005 menu in the American Bounty Restaurant.

If you have any questions about sensory effects during meals or otherwise please feel free to email me and I'll do my best to address it in an upcoming entry!

Wednesday, August 19, 2009

The Chefs Palate

On Friday we're headed from Ithaca over to Hyde Park and my old Alma Mater, The Culinary Institute of America.  I'm giving a faculty workshop on why Sensory Science is important to chefs and teaching some basic techniques that chefs can use for their own taste tests or research.   The second seminar of the day will be to a group of students in the brand new Ecolab theater.  My goal is to help cheflings understand exactly what food science is, what sensory science is, and why there's an advantage to having a strong understanding of both.  The second half of the student lecture is loosely based on The Tactile Symphony, my last post here. 

 There's not a lot of research on Chefs, but there is some research on what's considered "experts" vs. "consumers" in taste vs. flavor perception.  An expert is someone who has had some sort of training, formal or not.  For example sommeliers and other wine professionals tend to be considered experts.  Their perception of wine is often vastly different than that of consumers, and, interestingly enough, is as much a practice in language learning as it is in flavor recognition. 

In 2006 I designed a taste test to compare the palates of Chefs vs. Consumers.  My specific question was to look at whether or not chefs, as a whole, had good agreement on how to classify 10 different fresh squeezed citrus juices (orange and grapefruit) compared to consumers' agreement.  I hypothesized that due to the training chefs had that they would agree better - I was completely wrong.  The chefs were all over the place and disagreed completely on how to classify the juices.  The consumers agreed well (published here).

So what was going on?  Our revised hypothesis is that consumers (i.e. the general population) have a rather simple look at orange juice.  They may recognized nuaced flavor differences between juices, but primary perceptions are "oranginess", sweet, and acidic.  Chefs, on the other hand, do recognize prominently nuaces in the juices.  And not only that, each chef attaches a different importance to the attributes they perceive.  Thus, in a classification task where prominent attributes prevail, chefs are all over the place, whereas consumers are not.

In the above picture, two chefs at the CIA are performing a brief survey on the juices to indicate the strength of 10 different attributes present in the juices.  In these simple "line scales," they rate how "sour" the juice is from 0 to 10, how "orangy," "pulpy," and so on.  I'll describe the details of this type of experiment in a subsequent post; the entire 2 part classification task is prominently featured in my dissertation research. 

What is the implication for the culinary world that chefs perceive foods in a different way than consumers?  On the plus side, it allows chefs to use their nuanced palates to illuminate to diners certain flavors and textures in food that consumers may not have noticed.  Thomas Keller, the chef at The French Laundry (among others)  famously presents multiple types of salt with his foie course, each with nuanced differences.  I think its beautiful, but my father wouldn't get it.  Wielded poorly, however, chefs can become too wrapped up in the concept of "The Chefs Palate," that "the diner just doesn't understand" and can even get angry if, perhaps, the diner requests salt for his soup while the chef believes that salty Parmesan cheese crouton counterbalance the delicately under-seasoned broth.

Tuesday, August 11, 2009

The tactile symphony

A couple of nights ago my wife and I cooked chicken picadillo tamales. Having not cooked picadillo since my stint as a Fellow for The American Bounty my memory was not one of taste, but of texture. In fact, I remember that I liked the flavor but couldn't even remember the primary flavor profile. My memory consisted of ground chicken with soft and juicy popping burts of sweet flavor from rehydrated raisins, crunch from almonds, stringy mozzarella cheese, soft masa dough, and a full mouth coating deliciousness from the butter and crisco. A tactile symphony, in tamale form.

Texture has long been the forgotten sensory property. Even so much, that a leader in the academic field (Szczesniak) recently wrote a peer-reviewed article titled "TEXTURE IS A SENSORY PROPERTY!!!!?!!!" (quotes and exclamation added for emphasis, I'm sure that's how she imagined herself saying it). Indeed, much of our perception of food relies on texture, but how much do we tune into that on a daily basis?

Have you ever asked yourself why is vanilla ice cream so popular? I guarantee its not the flavor (although sweet and vanilla-y IS delicious). Freezing is an expensive process and if it weren't necessary you'd hear kids chanting creme anglaise! creme anglaise! (which is frozen to make ice cream) in the back seat of your car rather than "ice cream! ice cream!" We might even be chasing down the "warm vanilla custard truck" down the street on hot summer days! It is the tactile feeling of cold, then the changes in texture as the ice cream melts from a hard-to-soft emulsion to a mouth coating smooth custard before finally swallowing the liquid remnants. This is what makes ice cream, ice cream. Add some pecans or dip it in magic shell (another terrible tasting but texturally wonderful product) and you're stacking the deck in your favor for something people will lose their minds over (not only children!).

A couple of years ago I ran a taste test on apples - specifically, I was interested in how people categorized overall perception of 10 different varieties (they were peeled and blinded, so that sight, color and names were not a factor). Only two primary attribute continuums came up, and the most important was texture, with soft and mealy at one end, and crisp at the other! How fascinating. The second most important was tart to sweet, which you can imagine had Empire at one end and Granny Smith at the other. Of all the differences in apple flavor, texture was most important in peoples' perception!

Szczesniak has spent a lot of time breaking down texture terms into definable properties. This is important, because if a chef or a food manufacturer wants to alter the "juiciness" of their product, she's determined that they should look at no less than six different properties (from Szczesniak, 2002).

1. force with which the juice squirts out of the product;
2. rate of juice release;
3. total amount released on chewing;
4. flow properties of the expressed fluid;
5. contrast in consistency between liquid and suspended
cell debris; and
6. effect on saliva production

That's something to ponder next time you pop a grape in your mouth!

Tonight when you're eating dinner think a little about texture. Maybe its the textural variation in salad (surely the flavor of the lettuce doesn't keep you that interested?), the layers of a sandwich, or the scoop of rocky road ice cream that really inform your overall perception of the meal.

I'd be remiss if I didn't occasionally include a recipe, although I don't intend this to be a recipe blog. Since chicken picadillo inspired me to write this entry here it is! This recipe was adapted from the CIA, which adapted it from the Bayless' Authentic Mexican. Use for tamales, enchildadas, as a side dish, in a soup, mix into some grits, top a poached egg with it - you get the idea!

CHICKEN PICADILLO TAMALE FILLING
Yield: 1lb
1lb Ground chicken
1 large Onion, coarse chopped
1 Tbsp. butter
2 Garlic cloves, chopped
1 tsp. Cinnamon
2 tsp. Salt
1 tsp. Black pepper, fresh ground
1/8 tsp. Anise seed, ground
1/8 tsp. Cloves, ground
2 Tomatoes, beefsteak, medium dice
¼ cup Raisins, golden
1 cup Water
¼ cup sliced Almonds, toasted
½ Tbsp. White vinegar
¼ tsp. Oregano, Mexican, dried

1 Combine chicken and onions and cook until onions are soft, about 8 minutes. Do not brown the chicken or onions. Stir in garlic, cinnamon, salt, pepper, anise, and cloves and sauté an additional 2 minutes.
2 Add tomatoes, raisins, and water. Cook until most of the liquid evaporates and the ingredients come together, about 25 minutes, stirring occasionally to prevent sticking. The chicken should be barely coated with liquid, but not completely dry. It shouldn't ooze liquid out if you put some on a plate.
3 Remove from heat and stir in almonds, Mexican oregano, and vinegar.

References:
Szczesniak, A. S. (2002). Texture is a sensory property. Food Quality and Preference, 13(4), 215-225.

Monday, August 3, 2009

The Bad Taste (Map)

A few weekends ago my wife and I took a trip to Hershey's Chocolate World in Hershey's, PA (recommended). We paid for their "Chocolate Tasting Adventure" because we are both Sensory Scientists and couldn't resist.

And then it came up. The tongue map. I couldn't believe it.

You've all seen it, because somehow it persists. Yet sensory scientists have known for years that it is not only false, but terribly false. The receptors for taste - tiny specialized structures that perceive different tastes when they come in contact with food, are located all over your tongue for all different tastes.

I challenge you to a simple experiment. Mix together some simple syrup (sugar + water, 10% by weight) and find an eye dropper. Test the different areas of your tongue and see if you can taste the sweetness where the drop falls, being sure to drink plain water between. Unsalted "Saltines" are great for cleansing the palate also. You can repeat with lemon juice if you can stand to continue the experiment. At best you'll noticed reduced sensation in different areas.

Back at the Culinary Institute of America in Introduction to Gastronomy, we were not (thankfully) treated to this map. The class does, however, simplify the tongue to "five basic tastes": sweet, salty, sour, bitter and the new kid, umami.

Umami is the full mouth feeling meaty sensation elicited by glutamate, an amino acid and a building block of protein. Because glutamate is naturally negatively charged, in its stable form it is bonded with sodium in a way very similar to table salt (sodium + chlorine), hence "Mono-Sodium Glutamate." It makes sense that we have developed a taste for meat because typically it signifies protein, and for most of human history protein was hard to come by. The Japanese company Ajinomoto patented the process for making MSG 1909. It is amazing to me that American's ignored this fundamental taste until the 70s or 80s. New kid, right.

The whole idea of basic tastes has been turned on its head recently. Gray Kunz, of Cafe Gray fame in NYC notes upwards of 23 basic tastes that him and his colleagues came up with (see Elements of Taste) in response to the inability of his staff to accurately describe taste sensations.  Wikipedia notes 7. So what are basic tastes, really? What distinguishes one sensation (say sweetness) being declared a basic taste, and another, such as "metallic", from not being elevated to one?

I think the concept of basic tastes in general is on its way out. It limits our own perception because we tend to default to "basic tastes" when describing flavor. Think beyond that. Texture, astringency, heat (from chilies), temperature, metallic, pungent, umami, electric and others. The tongue as a sense organ is way more magical and complex than that and we owe it to ourselves to think beyond such simplified perceptions when describing food.

"Essentially, all models are wrong, but some are useful." --George Box