Hess, Mary Abbott. "Taste: the neglected nutritional factor. " Journal of the American Dietetic Association. 97.n10 (Oct 1997): S205(3). Academic OneFile. Gale. University of the Philippines - Diliman. 4 June 2011
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As soon as an edible body has been put into the mouth, it is seized upon - gases, moisture, and all - without possibility of retreat. Lips stop whatever might try to escape; the teeth bite and break it; saliva drenches it; the tongue mashes and churns it; a breathlike sucking pushes it toward the gullet; the tongue lifts up to make it slide and slip; the sense of smell appreciates it as it passes the nasal channel; and it is pulled down into the stomach to be submitted to sundry baser transformations without, in this whole metamorphosis, a single atom or drop or particle having been missed by the powers of appreciation of the taste sense (1). - J.A. Brillat-Savarin, 1825
Can you imagine the disappointment if, after all this, that edible body turns out to be limp, boring, or flavorless? Taste is one of the most satisfying and enduring bodily experiences. Except for pain, no other sensory system is as fully developed at birth. Throughout life, taste and its close companion, smell, are more resistant to destruction than other senses. In fact, among nerve cells, only olfactory and taste receptors develop, die, and regenerate (2). Human taste cells regenerate approximately every 10 days; olfactory cells are replaced every month or two (3,4).
"In the simplest possible system, we can see that taste and the pleasure and pain it delivers have been directly related to our success as an evolved species," suggests anthropologist Lionel Tiger in his informative, witty book The Pursuit of Pleasure (5). Taste triggers the salivary glands and stimulates the flow of gastric juices. In fact, someone who is fed directly into the stomach may not receive proper nourishment without the secretion of gastric juices (6).
In the evolutionary process, the primitive brain was programmed to seek out sweet-tasting substances. Mother's milk and ripe fruits are both sweet and good sources of nutrients and calories. Even single-cell protozoa in a petri dish will avoid bitter, poisonous alkaloids and head straight for the sucrose source. Some researchers theorize that sweet-tasting receptors relay a message to the brain that triggers the release of endorphins - the body's own opiate (7). Perhaps this is why, in times of stress, many multicelled creatures head straight for the sweet stuff too!
People's taste for salt also has an evolutionary origin. The need for salt may be tied to aquatic beginnings. A craving for salt is instinctive among herbivorous animals, but people who eat large amounts of animal protein need relatively little. Eskimos, for instance, abhor the taste of salt (8). Salt intake for almost all other Americans is far in excess of physiologic need.
In recent years, many health professionals (including dietitians) have focused on health and nutrition, often at the expense of pleasure and taste. This balance is changing. Today there is a new alliance of taste and health. The American institute of Wine and Food's ongoing program, "Resetting the American Table," says it well. "In matters of taste, consider nutrition, and in matters of nutrition, consider taste. And in all cases, consider individual needs and preferences" (9). This philosophy has far-reaching implications for nutrition counseling.
TASTE BASICS
The four primary tastes are sweet, salt, sour, and bitter. Oriental cultures identify a fifth taste called "umami," described as savory (10). Metallic may be yet another taste. Many textbooks and articles on taste include a map of the tongue showing the location of taste receptors for each of the four primary tastes. Scientists now think, however, that every taste bud has some degree of sensitivity to all the primary taste sensations. The brain detects the type of taste by the ratio of stimulation of different taste buds (11).
Much of what we call taste is actually smell. For example, a piece of apple and a piece of onion of equal crispness will taste the same if the nose is held while eating them. Humans actually can distinguish up to about 20,000 different odors and 10 intensities of each. Forty-four of these odors are particularly well understood and can be identified and described as a means of classification. When a cold results in our losing our sense of taste, what we really have lost is our sense of smell (6).
Cold food is not as odoriferous as hot or warm food because odor can be detected only if flavor molecules are in a vaporous state. Ice cream does not smell, but once it is in the mouth and slightly warmed, its flavor is more appreciated. Some restaurants vent odors outdoors to woo potential customers. When selling a home, a broker may advise the seller to bake cookies or bread to make the house smell like "home" to a potential buyer.
A person begins life with about 10,000 taste buds. Almost any ion will stimulate salt-sensitive taste buds. A person's sense of sodium saltiness depends on whether chloride or some other negatively charged ion is linked to the sodium. The potassium chloride in salt substitutes gives the perception of saltiness because the positive-negative ion balance it creates in taste buds is similar to that created by sodium chloride (12).
Sour-sensitive buds detect the degree of acidity in foods. Sweet-sensitive taste buds detect sugar and, through the course of history, have helped animals determine whether unknown foods are poison. Bitter-sensitive buds, on the other hand. have provided protection by detecting poisons in wild plants (11). In fact, bitter requires the weakest concentration of substances to be detected. For quinine sulphate, for example, 0.00003 g dissolved in 100 mL of water can be detected. For sugar, 0.7 g are required (6).
Working along with the taste buds and the sense of smell is the trigeminal system, branches of a nerve running between the brain, nose, and mouth. This system detects irritants such as hot chilies, pepper, mint, and carbonation (13). Add to all this texture, temperature, color, and appearance, and the result is, in the broadest sense, flavor.
Flavor enhancers like monosodium glutamate (MSG) and yeast extracts do not affect specific receptors on the tongue as sugar and spices do. Furthermore, flavor enhancers are not dependent upon the ability to smell; they are dispersed throughout the mouth (10). People with impaired smell can taste the difference between foods that have a flavor enhancer and those that do not.
Many different substances have flavor-enhancing capacity, including ingredients that represent the primary tastes. A pinch of salt can intensify the chicken flavor in soup and bring out the fruitiness in an apricot sauce. A spoonful of sugar will balance the acidity of tomato sauce or salad dressing. Sugar itself has the ability to increase the perception of fruit flavor, possibly contributing to the popularity of canned fruit in syrup. Vinegar or lemon juice may be added to a bland dish to sharpen its flavor.
Enhancers most often are used with processed foods to replace natural flavors and other characteristics lost during processing. "An appealing food product is more than the sum of its parts," reports Hegenbart (10). For example, the addition of flavor enhancer can make a canned food taste much fresher. In carbohydrate products, maltose can bring out sweetness while minimizing bitterness (10).
The number of taste buds and flavor discernment vary among persons. Even though taste and smell diminish more slowly than other senses, some researchers maintain that both decline considerably during the aging process.
"About half of those between the ages of 65 and 80 and three-quarters of those over 80 have major losses (of taste buds)," explained Dr Richard Doty of the Smell and Taste Center of the University of Pennsylvania in a May 3, 1990 Chicago Tribune article authored by Elaine Markoutsas. Thus, higher concentrations often are required for older people to perceive the presence of a particular flavor. Older people also perceive flavor mixtures differently than do younger tasters, according to Doty.
In contrast, Zallen (14) reports that in a study of adults 65 years of age and older, the ability to discern levels of salt in food was not impaired when compared to that of younger adults. The study showed, however, that older people appear to have more of a preference for higher salt concentrations than their younger test partners. The researchers theorized that this preference may be cultural or habitual rather than sensory. Salt was heavily used 40 years ago as a seasoning and preservative when older people were in their 20s (14). If Zallen's group is correct, differences may be due to memory loss and changes in the brain's perception of taste. In fact, odor perception is more vulnerable to aging than the sense of taste (13).
Medications, chronic disorders, and radiation therapy can alter taste perception, resulting in loss of appetite. Impaired taste perception can also lead to food poisoning because the ability to discern spoilage by taste is diminished (13). Certain endocrine dysfunctions, cystic fibrosis, Addison's disease, Cushing's syndrome, and hypertension have been reported to change the salt content of secreted saliva, thus affecting taste perception (13). People on sodium-restricted diets become more sensitive to salt. After a few months, they learn to prefer less salt on their food.
One way of classifying taste is to separate "tasters," who can distinguish the presence of the bitter chemical phenylthiocarbamide from "nontasters," who have apparently lost their bitter receptor sites. In some parts of the world, it is actually an advantage to be a taster or nontaster. In South America, for example, certain bitter-tasting plants can cause goiter. In this country, tasters - about two thirds of the population - are more likely to detect a bitterness in saccharine and salt substitutes (2). Tasters also have a more finely tuned perception of the nuances of wine and food.
The intensity of response to taste is greater at the beginning of eating, explaining why the first bite of food or the first sip of morning coffee is so satisfying. As the stimulus continues, both taste and smell fatigue set in. Consequently, some individuals add salt to their food halfway through a meal. Appreciation of food tends to be heightened when the sense of taste is challenged and surprised. Switching from food to food every few bites maximizes sensory impact and reduces sensory fatigue-another reason to eat a varied diet (13)!
TASTEFUL COUNSELING
A basic knowledge of how taste works is important to health professionals because taste is often the first determinant of what people purchase and eat. In fact, 88% of consumers rate taste as very important in shopping for food (15). If a food does not taste good, neither health professionals nor those they counsel are likely to eat it. As Food & Wine's Carole Lalli noted in her May 1992 editorial, "good to eat" means tasting good as well as being good for you (16).
By increasing attention to taste, the effectiveness of nutrition counseling can be increased. Following are some ways to focus on taste:
* When shopping, choose foods that are beautiful, fresh, and full-flavored. One perfect, ripe, juicy pear can be a glorious dessert or snack.
* In planning a menu, choose foods of different shapes, colors, and textures. Foods with eye appeal elicit more saliva. Visual appeal is essential in presenting modified diets and hospital trays. If food does not look appealing, it is less likely to be eaten. Food arrangements on the plate and garnishes can improve food intake and eating enjoyment.
* Recommend foods that are ethnically appropriate and that can be prepared with familiar seasonings. Build on client preferences as much as possible.
* Experiment with flavor enhancers and with balancing flavors.
* Encourage clients to take time to smell their food and to savor its flavor by holding it for a minute in a closed mouth like a fine wine.
* Advise clients to chew their food thoroughly to release its flavor molecules. Chewing also forces odors into the nasal cavity.
* Maximize flavor by providing a variety of foods within each meal. Switching from food to food throughout a meal reduces taste bud fatigue.
* Serve foods hot or warm to increase their volatile smells, especially if a client's appetite is poor.
* Choose foods with what flavor researcher Inglis Miller calls "flavor gestalt" (2). Garlic, onions, citrus, and ripe berries pack a lot of flavor. A little sharp cheese may be more satisfying than a greater amount of fat-free, low-sodium cheese. Reserve fat for maximum flavor impact, and use as little as possible to create the flavor effect. Experiments by flavor technologist Susan Schiffman of Duke University show that an extra blast of flavor helps people stick with a low-fat diet (2).
Looking critically at taste issues means taste-testing low-fat/salt/sugar foods in the supermarket to gain firsthand knowledge of what clients are being asked to eat. Simply advising people to omit all salt in recipes and to substitute yogurt for sour cream disregards consideration of taste. Instead, suggest step-by-step transitions that adjust ingredient ratios. A switch from whole to 2% milk for a few weeks before switching to 1% or skim milk may allow taste transitioning.
Taste is personal. Flavors are pleasing and displeasing based on physiologic, psychologic, and cultural variables. Effective nutrition counseling takes these variables into account. Recommended dietary changes are rarely black and white; more often, they are written in shades of gray. Printed lists of dietary "do's" and "don'ts" may reinforce instruction, but they seldom stand alone as tools to change eating habits. Compromise and adaptation are strategies for long-term success. Small changes that move the total diet in the right direction are sustainable and can be cumulative. Individualizing nutrition advice, with consideration of taste, health needs, and personal preferences, is a "signature dish" of quality dietetics practice.
References
1. Brillat-Savarin JA, Fisher MFG, trans. The Physiology of Taste. New York, NY: Harcourt Brace Jovanovich; 1978.
2. Cox M, Menagh M, Kunes E, Kaplan J, Goldberg J. A question of taste. OMNI. 1989;February:43-46, 78, 80, 81.
3. Boolootian RA. Elements of Human Anatomy and Physiology. St Paul, Minn: West Publishing Co; 1976.
4. McGee H. On Food and Cooking. New York, NY: Charles Scribner's Sons; 1984.
5. Tiger L. The Pursuit of Pleasure. Boston, Mass: Little, Brown and Co; 1992.
6. Lyman B. A Psychology of Food: More Than A Matter of Taste. New York, NY: Van Nostrand Reinhold; 1989.
7. Roach M. Accounting for taste. Hippocrates. 1989;November-December:49-54.
8. Trager J. Foodbook. New York, NY: Grossman Publishers; 1970.
9. American Institute of Wine and Food. Standards for Food and Diet Quality. San Francisco, Calif: AIWF; 1990.
10. Hegenbart S. Flavor enhancement: making the most of what's there. Food Product Design. 1992;February:56-58, 60, 65, 66, 69, 70.
11. Guyton AC. Physiology of the Human Body. Philadelphia, Penn: Saunders College Publishing; 1979.
12. Salt's techniques for tickling the taste buds. MenuNews. 1991;140:276.
13. Accounting for taste. University of California Berkeley Wellness Newsletter November 1990;7.
14. Zallen E, Hooks LB, O'Brien K. Salt taste preferences and perceptions of elderly and young adults. J Am Diet Assoc. 1990;90:947-950.
15. Food Marketing Institute. Trends: Consumer Attitudes and the Supermarket 1990. Washington DC: Food Marketing Institute; 1991.
16. Lalli C. Good to eat. Food & Wine. 1992;May:11.
M.A. Hess is president of Hess & Hunt, Inc, Nutrition Communications, 540 Frontage Rd, Suite 2025, Northfield, IL 60093.
Gale Document Number:A20343026
© 2011 Gale, Cengage Learning.
