Relation between PROP taster status and fat perception, touch, and olfaction.

We tested the hypothesis that fat perception (sensitivity to and preferences for fat) may be linked to 6-n-propylthiouracil (PROP) taster status as a result of differences in trigeminal innervation of the oral cavity. In addition, we examined the relationship between taster status and sensitivity to other taste attributes, as well as tactile and olfactory sensitivities. Subjects (40 nontasters, 67 medium tasters, and 40 supertasters of PROP) rated samples (potato chips, chocolate drink, mashed potatoes, and vanilla pudding) varying in fat and flavor concentrations for the intensity of fattiness, saltiness, and sweetness, first without and then with nose clips, and for liking. Tactile sensitivity of the tongue was assessed according to responses to stimulation with Von Frey filaments (2.36, 2.44). Olfactory thresholds were determined for two odors (diacetyl and phenylethyl methyl ethyl carbinol). In general, taster status was not related to the perceptions of fat, saltiness, and sweetness. Subjects were able to accurately assess the fat content of the samples. Increasing the flavor levels in the potato chips and mashed potatoes enhanced the perception of fattiness for these systems. Supertasters were more sensitive to stimulation on the median of the tongue with the no. 2.36 Von Frey filament, and the olfactory thresholds for diacetyl were lower for PROP tasters and supertasters than for nontasters.

Relation between parotid saliva flow and composition and the perception of gustatory and trigeminal stimuli in foods.

The objective of this study was to investigate whether and how parotid saliva flow and composition correlated with the perception of gustatory and/or trigeminal stimuli in foods. Thirty (15 male and 15 female) subjects tasted seven foods or beverages (lemonade, beer, wine, soup, methyl cellulose, peanut butter, and crackers) with three levels each of a gustatory or trigeminal stimulus and rated the perceived intensity of the corresponding sensation over time using the time-intensity (TI) method while their parotid saliva was being collected. Salivary flow rates of males were significantly higher than those of females for all stimuli (p < 0.001). That did not translate, however, into consistent differences in perception of sensory attributes between males and females. Significant positive correlations were found between saliva flow and (1) TI parameters for adhesiveness of peanut butter and cohesiveness of mass of crackers (p < 0.05 or lower) and (2) time from intake to swallowing of crackers and peanut butter (p < 0.05). No correlations were found between saliva composition (e.g., sodium and total protein) and TI parameters. These results indicate that parotid saliva flow may correlate with the perception of some texture and mouthfeel attributes (presumably through oral work and bolus formation) but not with that of the taste attributes examined in this study (at the concentrations studied).

Relation between saliva flow and flavor release from chewing gum.

The objective of this study was to investigate whether or not parotid saliva flow is a significant determinant of flavor release from chewing gum. Cherry-flavored gum with 3 concentrations of citric acid (0.5, 1, and 2%) acting as a sialagogue was evaluated for sweetness and cherry flavor in duplicate by 13 subjects, using a computerized system for simultaneous time-intensity (TI) measurements and unilateral collection of parotid saliva. With increased acidity in the gum, maximum intensity of, and area under, the cherry flavor curve increased (p < 0.001), whereas total duration of sweetness decreased (p < 0.05). Large interindividual differences were found for parotid saliva flow in response to chewing gum. Mean unilateral parotid saliva flows in response to stimulation with water and gum with 0.5, 1, and 2% citric acid were 0.07, 0.30, 0.36, and 0.44 g/min, respectively. There was a significant positive correlation between saliva flow and time to reach maximum intensity of sweetness (p < 0.05) and of cherry flavor (p < 0.01), with "high-flow" subjects taking longer to reach maximum intensity than "low-flow" subjects for both attributes. We conclude that parotid saliva flow may affect the rate of flavor release, but not how much nor for how long flavor is released.

Does consumption of beer, alcohol, and bitter substances affect bitterness perception?

The relation between consumption of beer, alcohol, and bitter substances was investigated by comparing 20 each of male adults, low users ( < 720 ml/week) and high users ( > 3.61/week) of beer for sensitivity to and like/dislike for the bitterness of isohumulones. Intake of beer, alcohol, and bitter substances was measured with a food frequency questionnaire and a 14-day recall journal. Intake of alcohol (including alcohol from sources other than beer) and bitter substances was higher for high users of beer than for low users. The average bitterness units (BUs) in the beers consumed by the two groups did not differ, indicating that high users do not consume more bitter beers than low users. Detection thresholds for isohumulones in water did not differ between the two groups, but high users had higher difference thresholds for isohumulones in beer (p < 0.10). In time-intensity measurements of bitterness in beer, low users of beer recorded significantly higher maximum intensities (p < 0.001) and shorter total durations (p < 0.001) than high users, with no difference between the two groups for time to maximum intensity and area under the TI curve. There was no significant difference between the two groups for BUs of beers produced by ad lib mixing of low- and high-bitterness beers, or for mean hedonic ratings of various concentrations of isohumulones in beer. These results suggest that intakes of beer, alcohol, and bitter substances are not major determinants of taste responses to the bitterness of isohumulones.

Chemoreception and perception of the bitterness of isohumulones.

Psychophysical experiments were conducted to determine whether isohumulones share a common receptor mechanism with other bitter compounds, and whether parotid saliva flow affects perception of their bitterness. Findings from a study of inter-individual differences in sensitivity to 23 sweet and/or bitter compounds among 25 subjects using the time-intensity (TI) method suggest that isohumulone and tetrahydroisohumulone may share a common receptor mechanism with other bitter compounds except those with the thiourea moiety. Isohumulone and tetrahydroisohumulone displayed a unique dome-shaped TI profile. The bitterness of the two compounds took longer to develop, but it lasted as long as for other bitter stimuli. In a study of the relation between perception of bitterness in beer and parotid saliva flow in 20 young adults, no significant difference was found among the mean saliva flows triggered by 0, 15 and 30 mg/L of isohumulones added to beer, and no significant correlation was found between saliva flow and maximum intensity or total duration of bitterness.

Sensory responses to fat are not affected by varying dietary energy intake from fat and saturated fat over ranges common in the American diet.

OBJECTIVE: To examine the effects of manipulating dietary fat in foods on sensitivity and hedonic response to fat in selected foods. DESIGN: Twenty subjects were randomly assigned to a sequence of three 8-week experimental diets (average American diet, step 1 diet, low-saturated-fat diet) that varied in energy from fat (37%, 30%, and 26%, respectively) and saturated fat (17%, 10%, and 6%, respectively). Subjects participated in sensory tests designed to assess their sensitivity to and liking for fat in several foods, before the study (baseline), after consumption of each diet, and after the study (washout). SUBJECTS/SETTING: Subjects were participants in the Dietary Effects on Lipoprotein and Thrombogenic Activity (DELTA) study. RESULTS: No significant differences were found among diets for difference thresholds (i.e., just noticeable differences) for fat in milk and pudding, ad libitum mixing of low- and high-fat samples of milk and soup, and hedonic scaling of fat concentrations in milk and muffins and of cheese, mayonnaise, hot dog, and pastry samples. APPLICATIONS/CONCLUSIONS: Within the dietary fat ranges and for the fat stimuli tested in this study, dietary fat as percentage of energy from fat and saturated fat was not a significant determinant of sensitivity to and/or liking for fat. Sensory factors should not be a barrier to the implementation of low-fat diets such as the step 1 and low-saturated-fat diets.

Flavor-enhancing properties of mushrooms in meat-based dishes in which sodium has been reduced and meat has been partially substituted with mushrooms.

The effects of beef substitution with crimini or white mushrooms (Agaricus bisporus) on the flavor profiles of carne asada and beef taco blends were measured with a descriptive analysis panel. Sensory mitigation of sodium reduction through the incorporation of mushrooms was also investigated in the taco blends. The substitution of beef with mushrooms in the carne asada did not alter the overall flavor strength of the dish, but the incorporation of 50% or 80% ground mushroom in the beef taco blend did enhance its overall flavor as well as mushroom, veggie, onion, garlic and earthy flavors, and umami and sweet tastes. Overall flavor intensity of the 25% reduced-salt version of the 80% mushroom taco blend matched that of the full-salt versions of the 100% and 50% beef formulations, thus indicating that the substitution of 80% of the meat with mushrooms did mitigate the 25% sodium reduction in terms of the overall flavor impact of the dish, even if it did not quite compensate for the reduction in salty taste. This proof-of-concept study for the Healthy Flavors Research Initiative indicates that because of their flavor-enhancing umami principles, mushrooms can be used as a healthy substitute for meat and a mitigating agent for sodium reduction in meat-based dishes without loss of overall flavor.

Acceptability of complementary foods and breads prepared from zinc-fortified cereal flours among young children and adults in Senegal.

We completed a series of studies to assess the acceptability of zinc-fortified, cereal-based complementary foods and zinc-fortified wheat breads. Young children and their caregivers completed acceptability tests with complementary foods fortified with iron only (60 mg iron as ferrous fumarate per kilogram cereal flour), or the same level of iron and zinc (240 mg zinc as zinc oxide per kilogram cereal flour), and the caregivers completed triangle taste tests to compare the same products. A separate group of adult participants completed acceptability tests with wheat breads fortified with iron and folic acid (15 mg iron as ferrous fumarate per kilogram flour and 1.5 mg folic acid per kilogram flour) or the same levels of iron-folic acid and 2 levels of zinc (63 mg zinc or 126 mg zinc as zinc oxide per kilogram flour). Finally, a threshold test was administered to another group of adult participants to compare nonfortified wheat bread to breads fortified with zinc in 80 mg increments ranging from 80 to 400 mg zinc as zinc oxide per kilogram flour. All products were acceptable when compared to non-zinc-fortified equivalents, and were well liked by the respective participants. For the triangle tests, caregivers were not able to detect significant differences between products. For threshold tests, adult participants detected differences in breads prepared from fortified wheat flour at 80 mg, 160 mg, and 320 mg zinc per kilogram flour, but not at 240 mg and 400 mg zinc per kilogram flour, respectively, when compared to nonfortified bread equivalents. Zinc fortification of cereal flours in the ranges of fortification that were tested does not adversely affect the acceptability of complementary foods and breads prepared from these flours. Practical Application: Fortification of staple food products is a low-cost approach to deliver additional micronutrients (including zinc) to large segments of a population. Determining the acceptability of products fortified with zinc is an important step in the development of zinc fortification programs.

Sensory-specific satiety: comparison of taste and texture effects.

The respective contributions of taste (saltiness and sweetness) and texture (the hardness dimension) to sensory-specific satiety (SSS) were compared. Sixteen male and 16 female, young, normal-weight adults rated the pleasantness of taste, pleasantness of texture and desire to eat on visual analog scales for eight test foods, were then given one of the foods to eat ad libitum for lunch, and re-rated the same parameters for the eight foods 2 and 20 min after the end of the meal. The experimental sets of eight test foods and four lunch foods were balanced for taste quality (salty vs. sweet) and texture quality (hard vs. soft). Lunch foods were the hard and soft versions of a salty food (ham and cheese sandwich on baguette vs. white bread) or of a sweet food (apples vs. applesauce). Sensory-specific satiety was observed for both saltiness and sweetness (e.g. pleasantness of the taste of, and desire to eat sweet test foods decreased significantly after eating a sweet lunch food and similarly for salty foods), and to a lesser extent for texture (e.g. pleasantness of the texture of, and desire to eat hard test foods decreased after eating a hard lunch food and similarly for one of the soft foods). The authors conclude texture-specific satiety may be a significant component of satiety.

Effect of sugar and acid on the acceptability of frozen yogurt to a student population.

One hundred and forty-one college students tasted and rated on a nine-point hedonic scale their degree of liking for nine samples of vanilla frozen yogurt varying in sugar and lactic acid. Subjects were also asked to complete a questionnaire about consumption of frozen yogurt and other dairy products. Degree of liking differed significantly among samples, and the samples best liked were those with the lowest acidity, .23 to .29%, independent of sugar concentration. Degree of liking of frozen yogurt failed to correlate with dairy product consumption or hunger at the time of testing. No significant difference existed between male and female students for overall degree of liking of frozen yogurt or overall dairy product intake, yet the questionnaire revealed a significantly higher consumption of frozen yogurt among female students. The results of this study suggest that, for the student population tested, frozen yogurt should combine the sensory properties of ice cream (low acidity) with the nutritional properties of yogurt (low fat, active enzyme culture).

Determinants of the thirst-quenching character of beer.

The purpose of this study was to find which sensory characteristics are significant determinants of the thirst-quenching character of beer. The sensory attributes and thirst-quenching characteristics ("thirst quenching", "refreshing", "drinkability") of 18 beers were evaluated by a panel of 12 judges. The only significant positive determinants of the "thirst-quenching" character of the beers in the design were carbonation and bubble density. Significant negative determinants were foam, overall aroma and flavor, color, viscosity, malty, hoppy, burnt, bitterness, acidic, metallic, astringency and aftertaste. The same correlations (both in terms of direction and significance level) were observed between descriptive attributes and the "refreshing" and "drinkability" factors. A principal component analysis (PCA) of the mean ratings indicated that variability among beers was mostly along a thirst-quenching dimension (72% of the variance). Procrustes analysis performed on the individual ratings showed that, for one of the judges, the interpretation of the thirst-quenching concept differed from that shown by PCA for the overall panel.

Sensory acceptability of meat and dairy products and dietary fat in male collegiate swimmers.

This study was undertaken to determine whether high-level training alters food choice behavior with regard to meat and dairy products because of their high fat content. Twenty male collegiate swimmers were compared to 20 male sedentary students for dietary fat intake, nutrition knowledge, and liking of meat and dairy products. There was no significant difference between the two groups for restraint, energy intake, dietary fat intake, and energy derived from fat. Nutrition knowledge, energy derived from saturated fat, and cholesterol intake, however, were significantly higher in the athletes. The two groups did not differ in their hedonic ratings of flavor or in their overall degree of liking of the meat and dairy products, and the athletes actually liked the appearance and texture of the products significantly more than did the sedentary students. This study shows that the sensory appeal of fat-containing animal products is not affected in male swimmers by a high level of exercise.

Cheese acceptance and dairy product consumption in an older population.

This study examined the acceptability of cheese products in a population of older adults in relation to their consumption of dairy products. The majority of the subjects liked hard cheeses (Cheddar, Provolone and Swiss) more than soft, ripened cheeses (Brie and blue cheese), and showed no significant difference in preference between regular and lowfat or fat-free processed cheese. A positive correlation was found between hedonic ratings and frequency of consumption across the five cheeses evaluated in the study. Almost one-half of the participants considered cheese to be a high calorie, high fat and high cholesterol food. This study suggests that lowfat or fat-free cheese products in the form of mild, hard or processed cheeses could successfully be incorporated in the diet of older adults to implement current dietary guidelines for fat and calcium consumption.