February 1, 1995
By: Scott Hegenbart
In the perennial holiday favorite "It's a Wonderful Life," George Bailey learns how influential his life has been by seeing what would have happened to Bedford Falls and its inhabitants if he had never been born. Flavor enhancers and other flavoring ingredients play a similar role in food products. They may seem insignificant because of their low use level, but they have a sizable effect on overall product quality.
Like George Bailey, these flavoring tools face obstacles of their own. Many consumer organizations have expanded their attack on monosodium glutamate to include other ingredients such as hydrolyzed vegetable protein, yeast-based flavor ingredients and even natural flavors. In some cases, the fervor is so strong that it has led some groups to demand a ban on the ingredient. (Many members mistakenly believe that food manufacturers mix MSG into other ingredients in an effort to "hide" it when, in fact, glutamate and other flavorful compounds occur naturally.)
If, for some reason, such a ban were to be put in place, what impact could it generate? Obviously, it would take away many of the tools designers rely on to create flavorful food products. Beyond this, however, these ingredients possess other capabilities that are as wide-reaching and surprising as the revelations of George Bailey.
Food products are continually being developed for ever more specialized markets, such as products targeted toward older consumers -- a population group experiencing tremendous growth. Researchers have predicted that 25% of the population of North America and 12% of the developing world will be 60 years of age or older by the year 2025. That's about 1.2 billion people worldwide.
As they age, many people experience a reduction in their senses of smell and taste. This does more than reduce the enjoyment of food. A 1993 survey of 750 physicians, nurses and health-care institution administrators specializing in elder care found that one in four elderly patients is malnourished. One-half of all elderly hospital patients and
40% of nursing home residents are believed to suffer from malnutrition.
Although many factors account for this, among the primary reasons many elderly become malnourished is the reduction of their sense of taste and smell. Susan Schiffman, Ph.D., professor of medical psychology at Duke University Medical Center, Durham, NC, has researched this subject extensively.
The decline of taste and smell usually begins at around 60 years of age and becomes more pronounced in persons over 70. This chemosensory impairment may be due to the normal aging process, but certain diseases and medications prescribed for such conditions also can contribute to chemosensory losses.
The losses can be great, and they can significantly elevate both the detection and recognition thresholds in older individuals. (A detection threshold is that concentration of a flavoring substance at which a transition from no sensation to sensation occurs. A recognition threshold is the lowest concentration at which a flavoring substance can be correctly identified.)
According to Schiffman's experiments, general flavor threshold levels average about 2.5 times higher for the elderly than for young college students. The increases in flavor threshold levels, however, are not uniform and tend to vary depending on the molecular structure of the compound being tasted. Fat, for example, has a detection threshold that is four times higher in the elderly. This would make it challenging to maintain the low-fat diets many senior citizens should follow. The greatest losses with age for taste sensitivity to amino acids are for glutamic and aspartic acids, which are flavor contributors in many foods.
Detection and recognition thresholds for odor can be as much as 11 times higher in the elderly than in the young. As with taste, the decreases in sensitivity are not uniform. Schiffman offers the example of substituted pyrazines, which commonly contribute to the odor of breads, vegetables and coffee. These show a significant threshold increase in the elderly. At the same time, older people retain their ability to differentiate the odor of 2-methoxy-3-isobutyl pyrazine, found in the aroma of green bell peppers.
Because decreases in flavor and aroma perception reduce the enjoyment of food, they can discourage proper intake and, consequently, impair the nutritional status of the elderly. But the effect of increased sensory thresholds is even more complex. Reduced taste and smell perception can actually interfere with the body's reflex reactions associated with food intake. Taste and smell stimulate salivation, gastric acid secretion, pancreatic secretions, and increases in blood plasma levels of insulin and pancreatic polypeptides -- all of which are necessary for proper digestion and use of food nutrients by the body.
Sensory stimulation by food also is accompanied by a decrease in plasma free-fatty acids, an increase in metabolic rate, and an increase in sympathetic nervous system activity. Impairment of these functions will further affect an individual's metabolism.
Correcting and preventing such nutritional and metabolic deficiencies is critical to maintaining good health. Schiffman has found that amplifying flavor and aroma by adding flavoring, and flavor-enhancing ingredients to foods increases the preference for and consumption of those foods among the elderly. Without access to these ingredients product designers wouldn't be able to create the specially formulated foods that could prevent, or even reverse, nutritional deficiencies.
Health in other segments
Besides aging and the afflictions of the elderly, the causes of chemosensory losses in other people can include certain disease states and/or their remedies, such as drugs, radiation therapy and surgery. As with the elderly, sensory reduction diminishes food enjoyment, consumption and metabolism.
Because proper nutrition is critical for patients undergoing medical procedures, malnourished individuals often are treated with liquid oral dietary supplements along with nasogastric and intravenous feeding. When medically appropriate, a nutrient-dense food with an amplified flavor profile can be a less costly alternative that also provides patients with the sensory pleasure of eating. In addition, obtaining nutrients from "regular" food can reduce or eliminate the nausea, diarrhea and abdominal distention associated with liquid diets, and lessen the risks associated with intravenous feeding.
Flavor ingredients also influence day-to-day healthful eating. One example is the area of sodium-reduced foods. Although not all research data agrees and marketers may think reduced-sodium claims have lost their edge, many health professionals believe adults in the United States consume too much sodium, often in the form of sodium chloride (salt). The body of evidence supporting the reduction of dietary sodium is significant enough for the U.S. Food and Drug Administration to allow specific claims regarding sodium content in the labeling regulations mandated by the Nutritional Labeling and Education Act of 1990 (NLEA).
Sensory analysis has shown, however, that food acceptability decreases as the salt level is reduced. This is one reason many people find it difficult to maintain a low-sodium diet. Applying flavor enhancers can improve the flavor -- and, subsequently, the acceptance -- of reduced-sodium foods.
Contrary to the misconceptions of certain consumers, monosodium glutamate contains only one-third the amount of sodium that is in sodium chloride. It also is used at much lower levels, so its overall contribution to sodium in the average diet is not significant.
MSG's enhancing capabilities can reduce the sense of flavor loss that occurs when the salt content of a food is reduced. For example, the addition of 0.38% monosodium glutamate combined with 0.4% sodium chloride can provide the same palatability as 0.75% sodium chloride alone, according to food scientists at Ajinomoto U.S.A., Teaneck, NJ (see chart).
Similar research has demonstrated that 5'-ribonucleotides also help enhance salty flavor and that they can replace 25% to 30% of a product's salt content. Comparable results are possible with other flavoring ingredients, too.
"Yeast extracts and yeast-based flavor ingredients are very effective at increasing salt perception without increasing sodium content," says J. Michael Hudson. Ph.D., technical director, Lallemand Bio-Ingredients, Montreal, Quebec. "It's possible to effectively achieve a reduction of from one-quarter up to one-third."
Such a reduction is realistic for starting salt levels ranging from 0.8% to 1.2%, according to Hudson. Other products that already are fairly low in salt are more challenging. In bakery products, on the other hand, yeast-based flavor ingredients can be used to reduce the sodium in pizza dough by 50% to 75%.
Ingredients such as soy sauce can be used in much the same way. Although it contains about 13.5% sodium chloride, soy sauce also contains many flavor-enhancing amino acids that reduce the sodium requirements of the formulation.
A dieter's dilemma
Reducing fat and calories also reduces the flavor and perceived quality of a food. When cutting fat, though, enhancers can help rebuild the flavor profile. Research into flavor enhancer function indicates that "feeling factors" are part of many flavor enhancers, and these can help build richness and fullness into a reduced-fat product.
When reducing sugar, flavor enhancers such as maltol and ethyl maltol can be used to enhance sweetness intensity. In fruit beverages, 15 ppm of maltol can allow a sugar reduction from 5% to 15% with no loss of apparent sweetness. Ethyl maltol is approximately four times as effective in this same application.
Flavor enhancers further help a formula when sugar reduction is accompanied by the use of a high-intensity sweetener. Many foods sweetened with high-intensity sweeteners have unbalanced flavor profiles that maltols can help correct. Certain sweeteners also may even have a bitter aftertaste which these enhancers can mask.
Every bit as surprising as Main Street in "Pottersville," the flavor of fat- and calorie-reduced foods affects more that sales. It can influence the overall effectiveness of a weight-reducing diet.
Many theories have been bandied about as to why most weight loss attempts by chronically overweight people fail. Physiologists suggest an excessive number of fat cells. Psychologists stress excessive oral needs due to unresolved dependency problems. Other research by Duke's Schiffman points to one characteristic that separates the overweight from their leaner counterparts: They want more intense and varied taste, odor and texture from food. In other words, an obese person has an exaggerated flavor and texture set point and overeats to satisfy the need.
"It would appear that each of us, whether thin or overweight, has a set point for flavor and texture," says Schiffman. "We must derive a certain level of sensation from food and beverages in order to feel satisfied with what we have eaten."
One cause for this phenomenon appears to be dieting itself. While consuming lower quantities of less flavorful food, a dieter experiences a degree of flavor deprivation. The deprivation of the diet is subsequently intensified during binges, where the dieter becomes acclimated to intense and varied flavor levels. This can drive the set point even higher and make subsequent dieting more difficult. This also explains why dieters crave strongly flavored foods like pepperoni pizza after several days of dry lettuce salads and cottage cheese.
At the same time, dieting is not a prerequisite for an increased need for flavor and texture. Overweight children and adults who have never dieted demonstrate the same phenomenon -- even as early as age four or five.
Schiffman also has studied whether increased food intake is due to a preference for a greater volume of food or for increased flavor. In several experiments, she intensified a food's flavor with a noncaloric flavor ingredient. When offered both enhanced and unenhanced foods, overweight individuals reduced their intake of the enhanced foods yet reported a degree of satisfaction that was not significantly different from the satisfaction they reported from consuming higher volumes of the unenhanced foods.
Making production feasible
People opposed to the use of flavoring ingredients often point to the fact that the home cook has no use for them, so processed foods should be easily prepared without them. Product designers, however, must consider such factors as stability, processing conditions and cost.
With respect to flavor, stability refers to maintaining the quality of a product's flavor profile over the length of its shelf life. Consumer perceptions that flavors and flavor enhancers "cover up" inferior quality are incorrect. Useful as many of the currently available flavoring ingredients are, they cannot compensate for inferior quality. These ingredients are building blocks in creating and maintaining the overall flavor profile.
"A large part of flavor ingredient use to bring back flavor lost in the processing," says Kathleen Rutledge, president, 21st Sensory Inc., Bartlesville, OK. "You may have had a flavor that was diminished in the retort process. You can restore some of this with a flavor-enhancing ingredient."
In one example, the natural glutamate content of various vegetables decreases during refrigerated storage of both raw and cooked product. This is believed to be one of the reasons freshly harvested product tastes better than stored. Another example is that roasted beef contains approximately 0.057% free glutamate, while juices recovered when the meat is sliced contain 0.088%. If the process separates the juice from the meat, it can significantly reduce the flavor of the meat. In both situations, adding monosodium glutamate would not be increasing the flavor profile as much as it would be restoring what had been lost to processing or storage.
Nucleotides are another flavoring component affected by processing. Mushroom flavor is associated with natural levels of 5'-nucleotides. When dried or canned, mushrooms have lower levels of this enhancing substance and, therefore, have weaker flavor.
Potatoes, on the other hand, become more flavorful with heat processing because the ribonucleic acid in the potato decomposes to 5'-nucleotides. The optimum enzymatic formation occurs at 50°C and a pH of 6.0. Higher temperatures favor the production of 3'-nucleotides, and lower temperatures and pH result in nucleoside formation -- both of which have weaker flavor-enhancing capabilities than the 5'-nucleotides.
Designers could determine the processing conditions for potato-containing products that would optimize flavor development. However, many processed foods undergo temperatures much higher than 50°C. (Retorted products often are subjected to temperatures above 100°C.)
For potatoes and mushrooms, added 5'-nucleotides can counteract the effects of processing.
Processing challenges aren't limited to the manufacturer. The way a product is prepared in the consumer's home may require flavor adjustments. In many microwave-prepared meals, results of the Maillard reaction are missing. Because maltol is one of the chemical products of this reaction, it and ethyl maltol can both improve the acceptability of foods formulated for microwave preparation.
Since the Maillard and other reactions don't occur in microwave ovens, products also don't develop a desirable brown color. "Some yeast extracts have dark colors that work well in products such as microwave entrees," says Gary Hayen. director research and development, Integrated Ingredients, Bartlesville, OK.
For such an application, Frances Hildabrand, Integrated Ingredient's manager of technical services, suggests formulating the ingredient into a glaze that can be deposited or sprayed onto a chicken breast. This approach can contribute "cooked" flavors and color to the outside of the piece.
Efficiency equals savings
In addition to making large-scale manufacture of quality food products feasible, flavor enhancers also contribute to cost-effectiveness. After all, the Bailey Building and Loan made a name for itself by being a more economic option.
Flavor enhancers help the bottom line in two primary ways. First. they improve production efficiency. In the production environment, throughput is king, so products are made as quickly as possible. Unfortunately, many desirable flavor compounds develop through slow reactions during cooking. One example is that the full, browned flavor of beef requires slow roasting. Many yeast-based and other flavor ingredients have been designed to compensate for this shortcoming.
"You're adding value by adding those flavor compounds that would normally be produced through Iong, intensive heating or simmering," says Lallemand's Hudson.
Meat roasted on an industrial scale tends to be kept in much larger pieces than would be prepared in the home. Because of this, many of the roasted flavors only develop in the outer portion of the meat -- even with slow roasting. A flavoring-ingredient solution could be injected into the meat to obtain uniform roasted beef flavor.
In other situations, it may be impractical to roast at all. Fast food outlets that serve roast beef sandwiches don't all have the capacity to handle and prepare beef roasts on-site. Instead, precooked meat could be sprayed or dipped in a flavoring solution that would contribute the missing roasted notes.
The importance of browning reaction flavor is not limited to meat. Years ago, researchers at the American Institute of Baking in Manhattan, KS, learned that the caramelized brown flavors in cookies require a certain amount of bake time to develop. Here, again, increasing bake time (and at the same time reducing throughput) to achieve the desired brown flavors is not always an acceptable option. The sweet, brown notes of maltols make them useful for contributing to the flavor of many baked goods.
The second way flavor enhancers provide economic benefits is by cutting ingredient costs. Flavor enhancers and yeast-based flavoring ingredients can allow product designers to reduce and replace more expensive ingredients such as meat extracts, cheese powders and spices while maintaining current flavor profiles. For example, a yeast-based flavoring ingredient designed to intensity cheese flavor might be used at only 0.25% to 3.0%, but would allow the cheese powder to be cut in half. This may not provide an overwhelming savings with ordinary cheeses, but with more expensive cheeses -- such as sharp, aged Italian cheese -- the difference can be significant.
"We've recently done a comparison of beef extracts to some of our natural beef flavors and, in many cases, you can get more beef flavor from a yeast-based flavor ingredient than you would using a beef extract," says Integrated Ingredient's Hildabrand. "Not only is this less expensive, but beef extract prices tend to go up and down, whereas yeast-based flavor ingredient prices tend to be more stable."
Flavor-enhancing ingredients indeed have many functions that reach beyond improving the appeal of food products. In both current and potential applications, they would be sorely missed if they were not available. While George Bailey learned that a person is truly rich if he has friends, designers must know that food products can have a wealth of success if they have flavor enhancers.
The Latest on Labeling
When Food Product Design last discussed flavor enhancers, in the February 1994 issue, the industry was anxiously awaiting a March 1994 decision on whether ingredients naturally containing glutamic acid would be subject to "contains glutamate" labeling. A year has passed, and still no decision has been reached. Does anybody know what's going on?
To avoid any fallout from the FDA, most people are reticent about commenting on the situation. Still, anonymous sources with both the FDA and the Federation of American Societies for Experimental Biology (FASEB) indicate that the issue seems to be on indefinite hold. Because of pressure from the food industry and consumer activists, the FDA probably will not act untiI it receives a final report from FASEB. On the other hand, FASEB is giving the project a low priority because the whole issue has outlasted its contract with the government to perform the work
Both FASEB and FDA sources agree that the February 1995 deadline for the report will most likely be put off until at least late spring or summer. Allowing time for FDA to review the files would make a decision possible no earlier than the fall of 1995.
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