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

Thursday, September 24, 2009


I will likely be sparse in posting for a couple of weeks. My wife and I are going on vacation to the Bay area in California to visit friends and eat at some wonderful places including Bouchon (Thomas Keller), Chez Panisse (Alice Waters), a private tasting menu at Orson (Elizabeth Falkner), Calafia (Charlie Ayers), and the Mi Lupita Taco Truck in Oakland. Its hard to tell what I'm the most excited about! You can be sure you'll receive a thorough analysis from a culinary and sensory perspective when I return.

A quick note about the widgets I've got on the right side of your screen.

First, the Google Voice gadget. This actually works, and it works through your home or cell phone. What it does when you click on it is call you first and then connect you directly to my voicemail. Please give it a try!

Next, the flagged stories gadget contains interesting stories I find mainly from one of my 90+ RSS feeds I pay (varying levels of) attention to.

Lower down, I just added a Sensory Book List, where I'm going to start building a book library list of Sensory and Culinary Science books that I personally have found interesting. Email (or call!) me if you have any suggestions - the ones listed are incomplete. I'll finish the library once I get to campus in the next coupla' days.

Finally, I have a list of Sensory Science Journals. This is all of the RSS feeds that I pay attention to related to the Sensory Science field. If you click on "View all" you can actually subscribe to this list all at once for your own purposes.

Wednesday, September 16, 2009

How do you measure up?

For each of us understanding our own taste and flavor sensory response is challenging. Do you detect a hint of cardamom in that curry? Or is that cumin? Does the rice have a hint of star anise, or allspice (or both)? Do I like my hamburger medium rare or well done (and does that preference change from day to day)?

Sensory scientists are constantly asking our panelists to answer these questions, which as you can see can become very challenging because we're trying to measure a response that is already ambiguous.

Enter scaling. We've all seen them, those little surveys that are left in hotel rooms or handed to us by our server at a restaurant.  Something like ----

How much do you agree with these statements: 
The flavor of the overall meal exceeded my expectations.
My food was served hot and fresh.
The quality of the food was excellent.

And then you check off one of the following for each statement:
Strongly disagree
Somewhat disagree
Neither agree nor disagree
Somewhat agree
Strongly agree
These surveys are mostly useless for many reasons.  First and foremost, surveys should provide objective information that is actionable, but instead surveys like this are designed by managers to stroke egos. 

Lets break my simple survey down.
"The flavor of the overall meal exceeded my expectations" is leading.  It encourages us to already think about how great the meal was, rather than rate the flavor objectively.  Second, if the soup was terrible but the entree sublime, how do you answer this question?  If you rate it based on the entree, then we mistakenly think the soup was perfect. 

"My food was served hot and fresh." 
This question is asking two things.  Food can be hot and not fresh, fresh and not hot, both hot and fresh, or neither.  Again, the answer is unactionable.  Second, what does fresh mean?  Fresh from the farm?  Fresh/raw?  Fresh-not-sitting-under-a-heatlamp-for-20-minutes?  Or are they asking if the food tasted stale and old and moldy?  Not sure here, but hopefully its not the latter.

"The quality of the foods is excellent."
Besides that this is another example of a leading question, the food is excellent compared to what?  The corn chowder I hypothetically just ate was excellent compared to a low fat frozen microwavable corn chowder, but was mediocre at best compared to the chowder I had last Christmas at Ashley's in Little Rock.  And what is quality?  Microbiological quality?  Color?  Taste?  Odor?  Cooking?  It is extremely ambiguous.

The rating doesn't have enough options, either.  I hate to break it to all of you, but no matter how much time you spend trying to decide whether or not you "Slightly Agree" or "Strongly Agree" with a statement, most restaurants lump these two categories together and determine that you were simply happy. 

Finally, you can't really average this scale together, at least not legitimately (sadly I'm sure some places do).  This is because if you assign the numbers 1 to 5 to the categories you're assuming an equal interval of "agreement" or liking between the numbers.  For example, is the distance between "strongly disagree - slightly disagree" the same as "neither agree nor disagree - slightly disagree"?  Probably not for most of you.   So it doesn't make sense to say that slightly agree is twice as much agreement as slightly disagree.

So what's the answer?   Well, I will spare you the lecture in psychophysics (for now), but I assure you it involves a lunatic/genious named Gustav Fechner.a nightmare, astronomy, and the fate of your soul (or at least Fechner's).  So simply trust me that this works:

This scale, the "Labeled Affective Magnitude" (LAM Scale) was developed by Howard Schutz, a legend in the sensory community who has been publishing non-stop since around 1950.  It happens to be for liking, so you'd have to rephrase your questions in the restaurant survey, but you could do it.  What is important here is to notice the top and bottom anchor - "greatest imaginable liking."  This helps to "center" everyone on the same scale, no matter their frame of reference.   If my greatest imaginable food liking is my grandmother's Thanksgiving dinners, then this scale works, and if it is a meal cooked in the greatest restaurants in the world, it also works.  Notice that the phrases aren't evenly distributed.  That psychophysics stuff taught us how to space these things so that we CAN apply a ruler to them and average them together from different people. There's other scales (i.e. the army quartermaster 9 point hedonic scale) that also work in similar fashion.  Your tax money via the army research labs developed both of these, btw.

My backup plan is to re-design restaurant surveys, because most are truly comical.  I hope that restaurants don't give them too much weight, and now you don't either, unless of course I designed it!  

Tuesday, September 8, 2009

What is Food Science?

The CIA lecture on Texture was a resounding success. The first part was geared towards helping students understand what Food Science was and was not - for example, when I asked them to tell me what their ideas of Food Science were they responded "Biotech," "Alton Brown," and "Molecular Gastronomy." Biotechnology and genetic engineering is a subfield of a subfield of Food Science. Alton Brown does a decent job covering the pop science aspects of food science, but he is an admitted anthropologist. And Molecular Gastronomy in its current incarnation is chemistry.

The second half of the lecture was based on a post I made here called The Tactile Symphony. I spurred a lot of conversation among students and got them thinking about the truly multidimensional nature of the culinary experience.

See a summary of my lecture and grab a pdf of the presentation here:

So, what is Food Science?

Food Science is a place for anyone who has a scientific inquiry about any aspect of food, from the taste and flavor, psychology, biology, chemistry, food safety, physics, nutrition, farming, fermentation, cheese making, enology, brewing, packaging, marketing and even protein structures and genetics. A food scientist learns a little about all of these things, and learns a lot and specializes in one or two aspects.

I think it is important that in this day and age to dispel myths about a field that have become increasingly harsh-toned. Food Science has been aligned with everything that is wrong with our food system, which admittedly could use improvement, but we don't go along damning the entire field of Doctors every time one incompetent surgeon leaves a scalpel in someone's abdomen. Its just that the field itself is relatively unknown, which thus makes it easy to create misconceptions about.

Thursday, September 3, 2009

out of your mind (and into a computer)

Some of the graduates of our lab go on to do varied things, because sensory science has a number of different aspects to it.  At Penn State, John Hayes studies the genetic basis of food perception, and is knee deep in gene sequencing.  If luck goes his way, he'll be contracting with NASA to work on relieving food boredom for astronauts next year.  Another graduate of our lab, Frank R., works for Symrise using sensory methodology to study flavor compounds.  Jeanine D. earned tenure at Ohio State as their sensory professor before being lured away by Firmenich, where she is a Senior Scientist in R&D.  And my wife, Effie, is a Food Scientist developing new food products at The International Food Network and their resident sensory science expert.

My own research, as I've alluded to from before, involves methods of creating Perceptual Maps.  So what are these?

Well, perceptual maps are a visual way to show relationships between sensory stimuli, which may be flavor samples, products, odors, pictures, or even texture samples.  The maps show the mental process of categorization.  Products that are mentally similar are represented close to one another, and products that are mentally dissimilar are further apart. There are many sensory methods to create these maps, and one I've studies quite a bit is called projective mapping.  Lets look at the apple picture again.

Ignore the arrows, for a moment, and focus on the labeled points.  At the bottom, you see the GS (Granny Smith) and AM (Acey Mac) located close to each other.  In a blind taste test, these apples were represented very similar.  Because they are pretty far away from the Red Delicious (RD) we conclude that these are more dissimilar. 

The arrows represent attributes of the apples and are statistically correlated with  the juices in the general direction of the arrow.  While we may have been able to guess that the Granny Smith was tart, I had no idea that a Pink Lady and Acey Mac were related on that attribute.  The arrows also tell us that the tart apples are negatively associated with the sweet arrow  because they are opposite of the sweet arrow.  Thus, there is a sweet/tart opposing axis.  Along the horizontal, there is also a crisp/mushy opposing axis.  Our conclusion is that texture and sweetness/tartness were the primary sensory dimensions for apples based on this test and these samples! 

For this test, I peeled and cut up the apples and treated all of them with citric acid to prevent browning ("Fruit Fresh" is the commercial name).  They were placed in plastic cups, which were labeled with random three digit codes.  We used red tinted lights in the room to even out any minor color variations in the apples, so that people could focus more on taste and wouldn't use color as criteria in their categorization.   The subjects sat in front of a 60cm square sheet of white paper, and tasted the apples and physically placed them on the paper such that apples that were close to each other were similar, and apples that were further were different.   In essence, each person is building their own personal perceptual map.  Then via the magic of fancy statistics (via R, the best statistics software out there) we combine the maps into an average map for the entire set of subjects.  The attribute arrows are added by asking the subjects to write down words next to the apples that help distinguish that apple.

The uses of these maps are numerous.  Food companies use them to see where their products sits compared to competitors.  They are used in cognitive research to evaluate peoples perception before and after some sort of intervening test condition, such as behavioral therapy treatment, to see if it was effective.  Anthropologists use perceptual maps to see how different cultures view relationships among kin. 

While I did not invent this method, I do hope to come up with new methods of creating perceptual maps.  I've been reading up on Graph Theory and have some ideas already that I'll be testing in the next week or two.

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!

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.

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

Thursday, July 30, 2009

Culinary Science and the Senses

Why are chilies "hot"? Why does salt make chocolate taste better? Why did that tragic spaghetti incident when I was four ruin spaghetti for me? Why is the taste map that we all learned in 9th grade biology HORRIBLY WRONG? Why does (did) airplane food taste so bland?

This blog is for foodies and scientists, because I am both. In fact, I belong to that field known ambiguously as Culinary Science and Molecular Gastronomy. I have previously studied both Culinary Arts and Food Science, and am currently working on a PhD in Sensory Evaluation.

Sensory Evaluation is the scientific discipline of evoking, measuring, analyzing, and interpreting people's responses to any sort of sensory stimulus, and in my case that stimulus is more often that not food. Sounds a lot like what a chef does, because it is.

The purpose of this blog is to bring to light sensory phenomenon surrounding everyday life. Those who study culinary arts already understand the importance of chemistry. It only follows that the mastery of the senses will help chefs and home cooks alike elevate the intended culinary experience.

I hope that those who work with food find this information interesting and applicable, from the home cook to the restaurant chef, and finally I hope those sensory scientists out there learn something about how sensory concepts can be applied outside of the large food companies and academic labs.