The effect of post-brew holding time and carafe type on the sensory properties of drip brew coffee

BACKGROUND

Coffee quality is believed to degrade quickly after brewing, and retail establishments discard unsold brewed coffee after a specified holding time period, sometimes as short as 30 min. We used trained sensory panels to evaluate the flavor profiles of light, medium, and dark roast coffees held in three different carafe types (glass on hot plate, thermal jacket, and vacuum insulated) for times ranging from 15 min to 3 h. Furthermore, a panel of 93 coffee-industry professionals performed a blind evaluation of fresh (30 min) versus held (180 min) coffee for overall liking and attribute level adequacy.

RESULTS

Sourness increased over time, consistent with acidity increasing over time (i.e., higher titratable acidity, lower pH), but only for the light and medium roasts. Dark roasted coffee became significantly more acidic over 3 h post-brew but was not perceived as more sour over time by the sensory panel. Variations were observed between the thermal jacket and vacuum carafes for the light and dark roast, but few differences were observed with storage type in the medium roast. Surprisingly, the panel of coffee industry professionals showed no preference for fresh over held.

CONCLUSIONS

More sensory attributes decreased than increased over time, suggesting that the primary concern with loss of quality during coffee holding may be the loss of volatile aroma compounds. Hedonic ratings suggest that even if the changes over time are noticeable, they may not negatively impact overall liking. © 2022 Society of Chemical Industry.

A new Coffee Brewing Control Chart relating sensory properties and consumer liking to brew strength, extraction yield, and brew ratio

The classic Coffee Brewing Control Chart (BCC) was originally developed in the 1950s. It relates coffee quality to brew strength and extraction yield, and it is still widely used today by coffee industry professionals around the world to provide guidance on the brewing of coffee. Despite its popularity, recent experimental studies have revealed that sensory attributes and consumer preferences actually follow much more complicated trends than those indicated by the classic BCC. Here, we present a methodology to synthesize the results of these recent studies on drip-brewed coffee to generate new versions of the BCC: a new Sensory BCC that displays a broad array of statistically significant sensory attributes across typical total dissolved solids and percent extraction ranges, a new Consumer BCC that highlights the existence of two preference clusters with different likes and dislikes across those ranges, a new Sensory and Consumer BCC that combines both sensory descriptive and consumer preferences on the same chart, and a more streamlined BCC that omits consumer preferences and focuses on the overarching sensory descriptive trends. The new BCCs provide more accurate insight on how best to brew coffee to achieve desired sensory profiles. PRACTICAL APPLICATION: Through the manipulation of yield and extraction parameters, the new Sensory and Consumer Coffee Brewing Control Chart presented here can be used by brewers of drip coffee to design coffees with specific sensory profiles and match the preferences of different consumer types.

Sensory Analysis of Full Immersion Coffee: Cold Brew Is More Floral, and Less Bitter, Sour, and Rubbery Than Hot Brew

Cold brew coffee is often described as sweeter or less acidic than hot brew coffee. Such comparisons, however, are potentially confounded by two key effects: different brew temperatures necessarily change the extraction dynamics and potentially alter the resulting brew strength, and different consumption temperatures are well known to affect perceived flavor and taste. Here, we performed a systematic study of how extraction temperature affects the sensory qualities of full immersion coffee. The investigation used a 3 × 3 × 3 factorial design, with coffee from three different origins representing different post-harvest methods (washed, honey-processed, and wet-hulled), each roasted to three different levels (light, medium, and dark), and each brewed at three different temperatures (4 °C, 22 °C, and 92 °C). All coffees were brewed to equilibrium, then diluted to precisely 2% total dissolved solids (TDS) and served at the same cold temperature (4 °C). We find that four attributes exhibited statistically significant variations with brew temperature for all origins and roast levels tested, with bitter taste, sour taste, and rubber flavor all higher in hot brewed coffees, and floral flavor higher in cold brewed coffee. However, there were strong interactions with origin and roast, with several additional attributes significantly impacted by temperature for specific origins and roast levels. These results provide insight on how brew temperature can be used to modulate the flavor profile of full immersion coffee.

Acids in coffee: A review of sensory measurements and meta-analysis of chemical composition

Coffee contains a variety of organic acids (OAs) and chlorogenic acids (CGAs) that contribute to overall sensory properties. Large variations in preparation and measurement methodology across the literature complicate interpretation of general trends. Here, we perform a systematic review and meta-analysis of the published literature to elucidate the concentrations of OAs and CGAs in both Coffea arabica (arabica) and Coffea canephora (robusta), for both green coffee and roasted coffee at multiple roast levels. A total of 129 publications were found to report acid concentration measurements, yielding 8,634 distinct data points. Analysis of the full data set reveals several trends. First, roasted robusta has considerably more acidic compounds than arabica with 2 to 5 times as much total OAs, and much larger amounts of formic and acetic acid. As for CGAs, in both arabica and robusta 5-CQA is the major component, and progressive roasting decreases the concentration of all CGAs. The total amount of CGA present was more dependent on roast level than the type of coffee (arabica vs. robusta). Overall, this meta-analysis suggests that the increases in certain OAs with roast level might play more of a role in the sensory profile of dark roast coffees than previously suspected.

Food Choice and Waste in University Dining Commons-A Menus of Change University Research Collaborative Study

The purpose of this multi-campus research was to investigate the relationships of food type and personal factors with food choice, consumption, and waste behaviors of college students at all-you-care-to-eat dining facilities. The amount of food taken and wasted was indirectly measured in units relative to the plate size using before and after photos taken by the diners themselves. Animal protein and mixed dishes (e.g., stir fry, sandwich) took up more of diners’ plate space and these items were correlated to both greater hedonic appeal as well as a higher likelihood of the item being pre-plated. Greater confidence in liking an item before choosing it was correlated to a larger portion being taken. Finally, increased satisfaction with the meal and frequency of visiting the dining commons was correlated to less food waste. Understanding these potential food choice drivers can help dining facilities better target healthier meals to diners while reducing food waste.

Consumer preferences for black coffee are spread over a wide range of brew strengths and extraction yields

Brewing is the final and key step in the production of the coffee beverage. Extraction related metrics such as the total dissolved solids (TDS), percentage extraction yield (PE) of solutes, and brew temperature (BT) are widely believed to govern the flavor and corresponding consumer acceptance of the resulting brew, as summarized in the industry standard "Coffee Brewing Control Chart." In this study, we investigated how the three factors of TDS, PE, and BT affected consumer acceptance of a medium roast, single-origin coffee and whether consumer preference segmentation would be observed based on these variables. A cohort of 118 mostly college-age, self-reported consumers of black coffee tasted coffees that varied in BT, TDS, and PE. For each coffee, consumers rated overall acceptance on the 9-point hedonic scale; the adequacy of serving temperature, flavor intensity, acidity, and mouthfeel using 5-point just-about-right (JAR) scales; and described the flavor using a check-all-that-apply list of 17 attributes. Cluster analysis revealed two consumer segments whose preferences varied most strongly with TDS. Response surface methodology relating liking to TDS and PE produced dome- and saddle-shaped surfaces for the two segments, respectively. External preference mapping and penalty analysis indicated that overall flavor intensity as well as acidity heavily influenced the preferences of the two clusters. The Coffee Brewing Control Chart's "ideal" coffee should therefore be reconsidered to reflect consumer preference segmentation. PRACTICAL APPLICATION: This research informs the way coffee brewers manipulate brew strength and extraction of drip brew coffee for optimal consumer acceptance; and justifies a reform of the standard "Coffee Brewing Control Chart" in its representation of an "ideal" coffee as we uncovered two consumer preference segments with different positive and negative sensory drivers of liking.

The Dessert Flip: Consumer preference for desserts with a high proportion of fruit and nuts

American adults consume excess added sugar and saturated fat, and not enough fruit. A possible solution is the "Dessert Flip," a shift in which the proportions of more sustainable plant-based garnishes, such as fruit and nuts, are increased, while the proportion of conventional dessert is reduced. We hypothesized that the pleasing properties of fruits and nuts-color, variety, flavor, and texture-would allow the Dessert Flip to be liked as well or better than a conventional dessert by college-aged students in a dining hall. In a sensory test, participants (n = 118) significantly preferred plated flipped desserts-those containing 80% by weight fruit (strawberries, raspberries, blueberries, and mangoes) and nuts with 20% cake-over the conventional versions of those desserts with 80% cake and 20% fruit and nuts. No significant differences were found in overall liking. In a second experiment, after eating an entrée, participants (n = 150) chose pictures of multiple varieties of flipped cakes with 60% fruit and 40% cake significantly more than pictures of conventional 80% cake for dessert. Based on the U.S. average fruit prices, the Dessert Flip can be equal or lower in price per serving compared to an ungarnished typically sized cake. We conclude that the Dessert Flip offers a feasible option for increasing servings of fruits and nuts in desserts as well as reducing added sugar and saturated fat while maintaining sensory appeal. Future dietary guidelines could include this general strategy as a recommendation for helping adults include more fruits in their diets. PRACTICAL APPLICATION: The Dessert Flip offers an appetizing way for foodservice to promote healthier eating by increasing servings of fruits and nuts in their desserts while reducing added sugar and saturated fat. Consumers can try this strategy at home by cutting a smaller piece of cake and adding fruit on the side.

Effects of brew strength, brew yield, and roast on the sensory quality of drip brewed coffee

Drip brewed coffee is traditionally quantified in terms of its strength, also known as total dissolved solids (TDS), and its brewing yield, also known as percent extraction (PE). Early work in the 1950s yielded classifications of certain regimes of TDS and PE as "underdeveloped," "bitter," or "ideal," with the modifiers "weak" or "strong" simply correlated with TDS. Although this standard is still widely used today, it omits a rich variety of sensory attributes perceptible in coffee. In this work, we used response surface methodology to evaluate the influence of TDS and PE on the sensory profile of drip brewed coffee. A representative wet-washed Arabica coffee was roasted to three different levels (light, medium, or dark), with each roast then brewed to nine target brews that varied systematically by TDS and PE. Descriptive analysis found that 21 of the 30 evaluated attributes differed significantly across the brews for one or more experimental factors, yielding linear or second-order response surfaces versus TDS and PE. Seven attributes exhibited a significant response surface for all three roast levels tested: burnt wood/ash flavor, citrus flavor, sourness, bitterness, sweetness, thickness, and flavor persistence. An additional seven attributes also showed a significant response surface fit across some but not all roasts. Importantly, sweetness exhibited an inverse correlation with TDS irrespective of roast, while dark chocolate flavor and blueberry flavor decreased with TDS for medium roast. These results provide new insight on how to optimize brewing conditions to achieve desired sensory profiles in drip brewed coffee. PRACTICAL APPLICATION: This research provides guidance on how best to achieve specific flavor profiles in drip brewed coffee.

Sensory and monosaccharide analysis of drip brew coffee fractions versus brewing time

BACKGROUND

The composition of drip brew coffee versus brewing time has been chemically characterized in previous studies, and it is known that the total dissolved solids (TDS) systematically decreases with each fraction during the brew. Little information exists regarding the corresponding sensory attributes versus time, however, and it is unclear how TDS correlates with flavor profile.

RESULTS

Standard drip brews were fractionated into distinct samples by switching in an empty carafe every 30 s during the brew. Using a trained sensory descriptive panel, we found that most taste and flavor attributes decreased with brew time; for example, the earlier fractions were systematically more bitter and more sour than later fractions. Surprisingly, however, several flavor and taste attributes increased in time; for example, later fractions were systematically sweeter and more floral than earlier fractions. Since later fractions had lower TDS, these results indicate that perceived sweetness in drip brew coffee is negatively correlated with TDS. Mass spectrometry measurements of the monosaccharide content in the brews showed that none of the fractions had perceptible concentrations of any monosaccharide.

CONCLUSION

The results of the sensory analysis and the monosaccharide analysis suggest that perceptible sweetness in coffee is a consequence of masking effects and/or the presence of sweet-associated aromas and flavors. The results further suggest that unique flavor profiles could be obtained from the same coffee grounds by judicious combinations of specific fractions. © 2020 Society of Chemical Industry.

Evaluation of California-Grown Blood and Cara Cara Oranges Through Consumer Testing, Descriptive Analysis, and Targeted Chemical Profiling

The acceptability of Moro, Tarocco, Cara Cara, Shahani, Bream Tarocco, Boukhobza, and Sanguinelli oranges from both commercial and research orchards was tested with adult (n = 152) and child (n = 72) consumers. Qualitative focus groups were also conducted to understand consumer familiarity and thoughts about the fruit. Sensory descriptive and chemical analyses were carried out to identify drivers of liking. Overall, consumers preferred the lighter colored varieties consisting of Tarocco, Cara Cara, and Boukhobza. One cluster of adults (n = 80) showed preferences towards sweet and fruity flavors and away from sourness and citric acid. The second adult cluster (n = 72) was tolerant of the sour fruit but did not like fruit high in bitterness and flavonoid content. The largest child cluster (n = 42) showed preferences for samples higher in orange and tropical flavors (Cara Cara, Tarocco, and Boukhobza varieties). The appearance of the Cara Cara was strongly liked by the consumer population in both quantitative and qualitative settings. Hunter scale a color values strongly correlated to the higher berry/dried fruit flavors, and concentrations of naringenin. Focus group participants noted that they were relatively unfamiliar with blood oranges. Growers and producers may want to invest in the lighter colored varieties, such as Cara Cara, Tarocco, Boukhobza and Shahani, as these were liked by a majority of consumers and were low in less desirable sensory characteristics, such as bitterness and sourness. PRACTICAL APPLICATION: Through consumer tests, sensory evaluation, and chemical analyses, this research uncovered which sensory properties may drive consumer acceptance of blood and Cara Cara oranges, and informed potential production and marketing strategies for increasing their consumption. This information should benefit the citrus industry as a whole and may enhance the use of specialty oranges by the food, beverage, and food service industries.

Sensory Profiling and Consumer Acceptance of Pasta, Bread, and Granola Bar Fortified with Dried Olive Pomace (Pâté): A Byproduct from Virgin Olive Oil Production

An olive pomace (pâté) obtained from virgin olive oil production, was used for the fortification of pasta, bread, and granola bar. For each food, a control (without pâté) and a fortified sample (with pâté, 7% in pasta and 5% in bread and granola bar) were manufactured. Descriptive analysis showed that pâté strongly affected the appearance of pasta and bread and increased the bitterness of bread and granola bar but not pasta. Granola bar was less affected in general, likely because of its higher ingredient complexity. In a central location test with 175 Californian consumers, both the control and the fortified samples of all three foods were well accepted overall, with only the mean liking of the appearance of the fortified pasta falling below the "neither like nor dislike" mark. Approximately 30% of consumers preferred the fortified sample over the control for each food and 50% were willing to pay more for the fortified products. The percentage of phenols from pâté recovered in the prepared samples was such that 63 g of pasta, 18 g of bread, and 12 g of granola bar would be sufficient to meet the EFSA health claim for olive oil phenols. This study demonstrates that pâté can be used for fortification of foods for human consumption, thus adding potential economic value to the virgin olive oil production chain and allowing for a higher daily intake of phenols from Olea europaea L., whose beneficial health properties are well recognized. PRACTICAL APPLICATION: The dried olive oil pomace (pâté) that we developed and tested in this research can be used to fortify pasta, bread, and granola bars with health-beneficial phenols with only slight alterations of their sensory profiles and slight reduction in consumer acceptance. Virgin olive oil producers can use this byproduct and gain further economic value from olive oil production.

Sensory Properties and Consumer Acceptance of Cantaloupe Melon Cultivars

This research measured the sensory characteristics and consumer acceptance of 15 cultivars of cantaloupe. Eleven trained panelists assessed melons by descriptive analysis. Northern California consumers (n = 171) evaluated the melons for overall, appearance, flavor, and texture liking on the 9-point hedonic scale and the adequacy of ripeness, sweetness, and firmness on a 5-point just-about-right (JAR) scale. Twenty-two sensory attributes differed significantly among the melons. CaldeoDF, Caldeo, Globstar, RML0499, and Caribbean Gold showed higher firmness, crunchiness, and denser textures. Impac presented higher watermelon flavor, bitterness, and sourness. Caldeo, CaldeoDF, Globstar, Magellan, and Sol Real had higher overall intensity, sweetness and oversweet flavor, longer-lasting aftertaste, and salivating mouthfeel. Consumers liked Magellan, Acclaim, and Primo most, and Aphrodite and Impac least, and the harvesting period was not critical to consumer acceptance. Sweet, oversweet flavor, and intense orange and richness of color were drivers of overall liking. Preference clustering identified three groups of consumers with distinct sensory preferences and favorite cultivars. JAR data showed Acclaim, Magellan, Primo, and Saguaro were just right for ripeness and so was Acclaim for firmness. All melons were judged not sweet enough. Growers and distributors could use the information from this research to improve the quality and appeal of the cantaloupe melon offering in the United States. PRACTICAL APPLICATION: We profiled the sensory attributes and measured consumer liking of 15 cantaloupe cultivars. Our findings should benefit producers and consumers equally as they identified those cultivars with the most promising sensory traits and they uncovered preference segments among a population of Northern California consumers as well as drivers of liking for those segments.

Effect of Basket Geometry on the Sensory Quality and Consumer Acceptance of Drip Brewed Coffee

In this work, discrimination tests, descriptive analysis, consumer tests, and total dissolved solids (TDS) were used to evaluate the effects of brew basket geometry on the sensory quality and consumer acceptance of drip brewed coffee. Two basic geometries, semi-conical and flat-bottom, were evaluated in conjunction with coffee roast and particle size. Initial discrimination tests showed that small differences in median particle size were not discernable, but that coffees brewed using either semi-conical or flat-bottom filter baskets were significantly different (P < 0.05, N = 45). Additionally, coffee brewed in the semi-conical basket had significantly higher %TDS, and we estimated a sensory difference threshold of 0.24 %TDS. A subsequent descriptive analysis (DA) showed significant differences by roast for 11 attributes and by grind for six attributes. Although brewing geometry, as a single factor, was only significantly different for three independent attributes (smoke aroma, sweetness, and tobacco flavor), roast × geometry interactions were significant for six attributes (berry flavor, bitterness, burnt wood/ash, citrus flavor, earthy flavor, and sourness) and the grind × geometry interaction was significant for two attributes (bitterness and floral aroma). Attributes showing significant interactions with brewing geometry were also key drivers of consumer liking/disliking. Overall consumer liking (9-point hedonic scale) was analyzed by cluster analysis (N = 85), which revealed four distinct preference clusters. For each cluster, a particular basket geometry and/or roast level showed lesser acceptance. Overall, the results strongly corroborate the hypothesis that basket geometry affects the sensory quality of drip brewed coffee. PRACTICAL APPLICATION: Most Americans consume drip brewed coffee. Improving our understanding of the effects of basket geometry, roast level, and grind size on the total dissolved solids, sensory properties, and acceptability of drip brewed coffee gives producers and consumers alike an opportunity to optimize the sensory quality of their coffee.

Using Single Free Sorting and Multivariate Exploratory Methods to Design a New Coffee Taster's Flavor Wheel

The original Coffee Taster's Flavor Wheel was developed by the Specialty Coffee Assn. of America over 20 y ago, and needed an innovative revision. This study used a novel application of traditional sensory and statistical methods in order to reorganize the new coffee Sensory Lexicon developed by World Coffee Research and Kansas State Univ. into scientifically valid clusters and levels to prepare a new, updated flavor wheel. Seventy‐two experts participated in a modified online rapid free sorting activity (no tasting) to sort flavor attributes of the lexicon. The data from all participants were compiled and agglomeration hierarchical clustering was used to determine the clusters and levels of the flavor attributes, while multidimensional scaling was used to determine the positioning of the clusters around the Coffee Taster's Flavor Wheel. This resulted in a new flavor wheel for the coffee industry.

Exploration of flavor familiarity effect in Korean and US consumers' hot sauces perceptions

The present work explored how consumers' product perceptions differ when flavor familiarity with the product set varied. Half of the samples used in this study contained fermented ingredients (fermented red pepper or gochujang, a traditional Korean fermented soybean/red pepper paste), and the others were top selling hot sauce products in the US market. Free-choice profiling was performed by Korean and US consumers and was analyzed using GPA. Descriptive analysis was conducted and analyzed using PCA. While Korean and US consumers perceived product similarly along the first principal dimension which described distinctive sensory differences among the products, in the next principal dimension, it was found that these consumers perceived the products differently. Observations indicated that this discrepancy seemed to be originated from differences in flavor familiarity. This study showed flavor familiarity not only influences one's preference but also may influence perception of foods such as hot sauces.

Sensory properties of Californian and imported extra virgin olive oils

Production and consumption of extra-virgin olive has been increasing in the United States, particularly in California. The objective of this study was to compare the sensory characteristics of 22 extra virgin olive oils (EVOO) from California, Italy, Spain, Chile, and Australia using a generic descriptive analysis. A total of 22 sensory attributes were identified and defined by the descriptive panel. With the exception of thick and citrus, all sensory attributes were significantly different among the oils. Canonical Variate Analysis (CVA) showed that California oils differed from some imported EVOOs, mainly by their absence of defects. A second analysis, of only those attributes included in the International Olive Council (IOC) official scorecard, provided a less detailed description of the samples and did not allow for a full characterization of the oils. While the IOC attributes allowed for faster classification in terms of clean versus defective EVOOs, the more comprehensive descriptive analysis provided both more information and a more refined classification of the samples. Variety and region of origin were important factors in the classification of both Californian and imported EVOOs.

PRACTICAL APPLICATION

  Measuring olive oil sensory quality using the IOC method-positive attributes of fruitiness, bitterness, and pungency, and defects including fusty, musty, winey, and rancid-allows for the certification of oils as extra virgin but it provides limited information on the sensory characteristics of the oils. A full descriptive profile, on the other hand, provides information that can be used by producers in the processing and marketing of their oils, and is a useful tool in the education of consumers about the wide range of (positive) sensory attributes in EVOO and the various sensory styles of EVOO.

Yield effects on 2-methoxy-3-isobutylpyrazine concentration in cabernet sauvignon using a solid phase microextraction gas chromatography/mass spectrometry method

A rapid and automated solid phase microextraction (SPME) stable isotope dilution gas chromatography/mass spectrometry (GC-MS) method for 2-methoxy-3-isobutylpyrazine (MIBP) quantification in red wine was developed. Wines with 30% (w/v) NaCl and 2-methoxy-(2)H(3)-3-isobutylpyrazine internal standard were sampled with a 2 cm divinylbenzene/carboxen/poly(dimethylsiloxane) SPME fiber for 30 min at 40 degrees C and analyzed by GC-MS. The method was used to measure MIBP concentrations in Cabernet Sauvignon wines that were produced from six winter pruning treatments over two vintages. MIBP concentrations were significantly negatively correlated with buds per vine. In addition, the MIBP concentration was directly related to sensory vegetal intensity ratings obtained by descriptive analysis.

Novel approaches and application of contemporary sensory evaluation practices in iron fortification programs

Iron deficiency is the leading nutritional deficiency in the U.S. and the rest of the world, with its highest prevalences in the developing world. Iron fortification of food has been proposed as a strategy to reduce the high prevalence of iron deficiency. Poor consumer acceptance, unacceptable taste, and discoloration of the iron-fortified foods have been frequently listed as causes of unsuccessful iron fortification programs. An excellent prospect for improving consumer acceptance of iron-fortified foods is the incorporation of a thorough, organized, and unified approach to sensory evaluation practices into iron fortification programs for product optimization. The information gained from systematic sensory evaluation allows for the manipulation of the sensory attributes, and thus improvement of the sensory properties of the fortified food. However, iron fortification programs have not systematically measured the effect of fortification on the sensory quality of the food. Because sensory evaluation is an important criterion in successful iron fortification, an integrated approach is necessary. Therefore, nutritionists and sensory scientists should work closely with each other to select the most suitable sensory tests and methods. The objectives of this article are to: (1) critically review and discuss some traditional and contemporary approaches and applications of sensory evaluation practices in iron fortification programs, and (2) demonstrate the importance of incorporating a multidisciplinary, systematic sensory evaluation approach in iron fortification programs.

Relation between PROP (6-n-propylthiouracil) taster status, taste anatomy and dietary intake measures for young men and women

Previous studies have related 6-n-propylthiouracil (PROP) taster status to preference for, and consumption of various (bitter-tasting) foods recognized for their cancer-preventive properties. The aim of this study was to examine PROP taster status in relation to general measures of dietary intake as well as the consumption of specific food groups. College students (n=183) were classified as non-tasters (n=49), medium tasters (n=89) and supertasters (n=45) of PROP based on intensity ratings of NaCl and PROP solutions. Dietary intake measures were derived from a food frequency questionnaire and body mass indices (BMI) were derived from self-reported height and weight. Supertasters had higher fungiform papillae counts on the anterior tongue than tasters and non-tasters, yet the distributions of papillae counts overlapped across PROP taster groups. No significant differences were found for BMI values and energy intake among taster groups. PROP-tasting women derived a greater percentage of their dietary energy from fat, and consumed less fruit than non-tasters. PROP supertasters did not differ from tasters and non-tasters in intake of bitter fruits, vegetables or beverages except for a lesser intake of green salad. The hypothesis that PROP supertasters, through heightened sensitivity to, and avoidance of, bitter-tasting fruits, vegetables and other foods with antioxidant properties, may therefore be at increased risk for diet-linked diseases such as cancer, is not supported by these findings.

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.

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.

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.

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.

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.