Feeling flavors and textural contrast in food

Michael Nestrud ('04) describes the "tactile symphony" that chefs compose in the kitchen, and how contrasting textures can impact flavor perception and preference.
Ecolab Theater, The CIA, Hyde Park NY, August 21, 2009.

As part of the Department of Menu R&D's Seminars in Culinary Arts and Science, Michael Nestrud, a former Teaching Fellow at the American Bounty, and currently a Ph.D. candidate studying sensory perception at Cornell University, shared his unique culinary science perspective on the role of texture on flavor perception to Bachelors and AOS students at the Hyde Park campus.

Michael began his talk titled "Food Science, Sensory Science, and the Tactile Symphony" by sharing his past and current career trajectory, which has taken him from computer programming, to the restaurant kitchen, and into Professor Harry Lawless' sensory evaluation laboratory in Cornell's Department of Food Science. Nestrud's overview of Food Science emphasized the inter-disciplinary nature of the field that incorporates principles of biology, physics, psychology, chemistry, statistics, and the culinary arts. "Food science is a cross-disciplinary field where you take a scientific approach to issues in food." Nestrud noted, and he highlighted a variety of career paths that combine aspects of Food Science and the Culinary Arts, including product development, research chef, journalism, food policy, education, and viticulture and enology.

Nestrud describes the fields of Food Science and Sensory Evaluation, and new career paths for culinary students.

The multifaceted field of Food Science presented Michael with the opportunity to take an evidence based approach to addressing questions that arose when he was working in kitchens. Michael joined the Lawless lab, at Cornell, where his dissertation studies include the sensory properties of chili peppers, and the differences between the flavor perception of chefs and consumers (amongst other topics). Nestrud described sensory evaluation as the process of "...evoking, measuring, analyzing, and interpreting sensory phenomenon" and made compelling comparisons to the objectives and methods of the culinary profession.

The student and faculty audience was rapped by Nestrud's description of how tactile sensations contribute to our overall perception and enjoyment of flavor. He divided texture into 4 major categories:

• Visual
• Tactile
• Thermodynamic (hot/cold)
• Chemical (AKA, "chemesthesis", which includes spicy, acidic, pungent, carbonated, and electric, amongst others)

Visual, auditory, thermal, and tactile cues all contribute to how we perceive food textures. Michael described how these sensory stimuli are essential for helping us identify our ingredients, distinguish degrees of freshness, and assess culinary excellence in our kitchen creations.

Nestrud used the example of a tangerine to explore the concept of "juiciness." The perception of juiciness, Michael explained, will depend upon a variety of factors including the force of juice release upon first bite, the rate and volume of release of liquid from the fruit sections, the thickness of the "expressed" liquid, and the contrast in physical properties of juices expressed and the particles of the fruit flesh in the mouth. The science behind "crisp" and crunch" was also covered. The high frequency snap sounds of "crisp" (think of breaking a piece of fresh celery) are distinct from the successive low frequency crunch sounds produced when you bite into rock candy, for example. These auditory cues are used by food scientists to assess freshness of fruits and vegetables (Lawless and Heymann, 1998), and develop new snack foods.

To illustrate the concept of chemesthsis - the response by the body to chemical stimulation on the surface of the skin or in the mouth - "sichuan buttons" were tasted. These flower buds created a unique chemestheic textural sensation on the tongue that students described as "carbonated", "mildly electrical", "citrusy", "cooling", and "salty like the ocean". Many pointed out that it was causing them to "hyper salivate", and one student described the flavor as "chaos in the mouth."

Flower buds from Acmella oleracea, AKA "Sichuan buttons", and the chemical structure of the active component, spilanthol, that causes a unique tingling flavor in the mouth.

The active compound in the buttons causing these unique percpeptions, Nestrud explained, is known as "spilanthol." This chemical is found naturally in the flower of the plant Acmella oleracea, and is similar in shape to capsaiacin, which might have something to do with its chemesthtic effects. However, little is know about this chemical, its underlying sensory mechanisms, or how it might be best used by culinary professionals. Nestrud noted that some restaurants have begun to incorporate it into their drink menu such as margaritas, or by rubbing it on the rim of glasses to create "electric cocktails". Students attending the seminar suggested that the Sichuan buttons might be used in confections, candies, and sorbets, and perhaps as a component of beer. Nestrud suggested that spilanthol might be used in products to counter drying caused by astringent compounds such as tannins found in grape skins.

(For details on spilanthol listen to Nestrud's NPR interview with Robert Smith that aired earlier this year

Michael's seminar generated a lot of interesting questions and discussion revolving around food industry applications of Sichuan buttons, molecular gastronomy, and the sensory science underlying the culinary creations of Grant Achatz ('02).

You can view the slides from Michael's presentation [PDF], and he can be contacted for questions at mike@ataraxis.org.

The next Culinary Arts and Science Seminar will be with psychophyciscist and sensory scientist, Jeannine Delwiche, Ph.D., who will focus on the "multi-modality" of flavor: how color, aroma, taste, audition, temperature, and texture, can impact flavor perception (Sept 25, 2:30 pm, Ecolab Theater).

References

LAWLESS, H.T. and HEYMANN, H. 1998. Sensory Evaluation of Food: Principles and Practices, Chapman & Hall.