Distribution of Recognition Times to Fruity Flavor of Gummy Candies in Healthy Adults.

Times for recognition of fruity flavors in six gummy candies were measured using an electromyography-based system in 23 young healthy participants. They were instructed to chew one of the gummy candies at a random order and to press a button as soon as possible when they recognized what flavor was. The measured 181 recognition times showed two distributions, normally ( n = 107) and non-normally ( n = 74). The overall average of the normal distribution was 7.5 seconds (±2.34 seconds; standard deviation), and there were no differences in the average ratios among the gummy candies. Eighteen of the participants reported 41 inconsistent reports with flavors that were provided by the manufacturer. The most frequently observed report was an apple-flavored gummy candy (14, 34.1%) mainly for a pear-flavored. However, there was no significant correlation between the numbers of recognition times and those of inconsistent flavors among the used gummy candies.

Test-Retest Reliability of Detection Time Data Measured Using a Masseter Electromyogram in Healthy Young Adults: Preliminary Analysis of Data.

Few studies have assessed test-retest reliability of flavor detection time in semisolid and solid foods. In this study, test-retest reliability was assessed in 16 healthy young adults (22.6 ± 5.5 years old) on the data collected using a masseter electromyography-based system between two experimental sessions approximately 35 days apart. The overall correlation coefficients were calculated across five test foods; the correlation coefficient for the entire sample was statistically significant. Five correlation coefficients were calculated for individual test foods, but only orange-flavored gummy candy was significantly correlated across the two sessions. These results suggested that flavor detection time measured by the electromyography-based system is basically reliable over time, with considerable variation among flavors.

Synchronization of masseter activity patterns between the right and left sides during chewing in healthy young males.

Masseter activity patterns during chewing, which were quantitatively assessed using T50 values, were compared between the right and left sides of healthy young males. Surface electromyograms were recorded from both masseters, and each participant was asked to chew four different agar samples at his own pace across two separate sessions. The four agar samples, each possessing differing textural properties, consisted of two normal and two distinctive agar varieties. The Pearson's correlation coefficient was calculated for each pair of T50 values to evaluate the degree of synchronization of activity patterns between both masseters. A three-way analysis of variance revealed significant main effects of the 'participant' and 'experimental session' factors, but not of the 'test food'. The number of significant coefficients increased stepwise by increasing the number of chews per sequence. These results suggest the importance of the initial stages of chewing sequences in facilitating the synchronization of bilateral masseter activity patterns.

Differential sweetness of commercial sour liquids elicited by miracle fruit in healthy young adults.

Miracle fruit (Synsepalum dulcificum) contains the glycoprotein miraculin which turns a sour taste into a sweet one. Chemical analyses and sensory evaluation experiments were conducted to examine the sweetening effect of miracle fruit with regard to five different commercial sour liquids which were diluted until they were subjectively equally sour. HPLC-based analyses revealed that (1) the predominating acids in two and three of the liquids were citric acid and acetic acid, respectively and (2) all five liquids contained fructose and glucose. Healthy young adults (eight males and 10 females) in the sensory evaluation experiments were asked to chew a miracle fruit and apply their saliva to the oral mucosae. They were asked to score the sweetness elicited by the five liquids relative to a sucrose standard at 0, 15, 25 and 35 min thereafter. The citric acid-based liquids were perceived as being sweeter than the acetic acid-based liquids at all timepoints. Thus, commercial sour liquids that mainly contain citric acid are more effective than acetic acid-based liquids in eliciting a perception of sweetness after the miracle fruit application, while the sugars in the liquids seemed to play a minimal role as determinants of sweetness.

Sequential analysis of masseter activity patterns during chewing in healthy males.

The present study examined sequential changes in masseter activity patterns observed during chewing of four different agar samples in eight healthy young males. Two parameters, T(50) and D(50), were specifically used for evaluation of the activity patterns of individual bursts. Statistical significances were detected in regression coefficients (21.9% of 32 trials) and Spearman's rank correlation coefficients (28.1%) between the calculated T(50) values and chewing cycles, whereas no significant differences among the four agar samples were found. Three (I-III) types of activity patterns of masseter bursts during chewing sequences were classified by the D(50) values, which were derived from the T(50) values. The three types physiologically corresponded to incrementing (Type I), decrementing (Type III) and mixed discharge patterns (Type II). The classification of activity patterns suggested the usefulness of D(50) values in the sequential analysis of masseter activity patterns.

Sensory and motor responses of normal young adults during swallowing of foods with different properties and volumes.

We examined the influence of rheological/textural properties and volumes of test foods on the sensory and motor aspects of swallowing in healthy young adults. Three test foods differing in thickening agent concentration (0.0, 1.5, and 3.0%) were prepared and delivered in different volumes (approximately 3, approximately 5, and approximately 7 ml) to subjects seated on a chair. Viscosity analyses of the 1.5 and 3.0% test foods revealed that they behaved as non-Newtonian fluids and were thixotropic. The 1.5% test food differed from the 3.0% test food in its textural properties (hardness, cohesiveness, and adhesiveness). As determined by a linear model equation method, the thickening agent concentration affected the scores of all six sensory evaluation questions that were answered by the subjects, which suggests that the concentration affected the food properties being evaluated. Consistent with previous reports, thickening agent concentration and test food volume also affected some durational parameters of laryngeal (recorded by a piezoelectric sensor) and suprahyoid muscle (recorded on an electromyogram) motor activity. However, thickening agent concentration and test food volume did not affect the single amplitude parameter of the electromyogram that was measured. The thixotropic property of foods can affect the motor aspect of oropharyngeal swallowing as well as the sensory aspect.

Constancy of head turning recorded in healthy young humans.

This study evaluated the 'constancy' of head turning as recorded two-dimensionally by accelerometers. Fourteen healthy participants turned the head with his/her natural and comfortable speed. Maximum inclination angles (MIA) during head turning were measured in four (anterior, posterior, right, and left) directions of clockwise (CW) and counter-clockwise (CCW) conditions. Three indices were used for the evaluation: (1) standard deviations of MIA as an index of 'spatial constancy,' (2) anterior/posterior and right/left ratios from intervals among four MIA as indices of 'temporal constancy,' and (3) first derivatives from head turning trajectories as an index of 'angular velocity.' The spatial index varied from 0.15 degrees to 9.96 degrees (CW condition) and from 0.56 degrees to 10.6 degrees (CCW condition). The temporal index in the anterior-posterior direction varied from 0.711 to 1.103 (CW condition) and from 1.071 to 1.905 (CCW condition). The index in the right-left direction varied from 0.773 to 2.081 (CW condition) and from 0.842 to 1.226 (CCW condition). Characteristic hollows or protrusions were detected from the first derivatives of head turning trajectories and were regarded as abrupt changes in angular velocity during head turning. The results suggest that these three indices are appropriate tools for evaluation of the constancy of head turning.

Oral perception of bolus in healthy young women.

This study was designed to characterize oral perception of both weight and volume of boluses. A total of 80 healthy young female subjects was recruited and divided into bolus weight (n = 40) and bolus volume (n = 40) conditions. Tap water (25 degrees C) was the experimental material, and seven reference stimulus amounts ranging from 10 to 40 (grams and mL) were prepared. The reference stimuli, including a modulus of 20 (grams and mL), were delivered to the subjects in randomized order. The estimated magnitudes (psi) conformed to both the Fechner's and Stevens' psychophysical laws by the following equations: (1) psi(W) = 314.3 log (S+1) - 300.2 where S is stimulus intensity or weight, and psi(V) = 249.7 log (S+1) - 222.3 (volume) on logarithmic (log)-linear scales, and (2) psi(W) = 1.908 S1.297 and psi(V) = 4.097 S1.032 on log-log scales, respectively. The results indicate that oral perception of bolus weight and bolus volume conforms to the representative psychophysical laws.

Influences of thermal and gustatory characteristics on sensory and motor aspects of swallowing.

Two sets of experiments were conducted to examine the effects of two sensory modalities, temperature and taste, of foods on perceptual and motor aspects of swallowing in 20 young, healthy subjects (10 subjects for each experiment). A tasteless and odorless thickening agent was the basic testing material. The first experiment compared the swallowing of foods at four temperatures ranging from 5 degrees C to 50 degrees C. Food at 50 degrees C was more acceptable for swallowing than at 5 degrees C, 20 degrees C, or 35 degrees C. The suprahyoid muscles were less active during swallowing food at 50 degrees C compared with swallowing food at the other three temperatures. The second experiment compared foods with the five basic taste qualities (sweetness, saltiness, sourness, bitterness, and umami) with a tasteless food (dissolved in distilled water) to examine the influence of gustatory sensation. The sweet and tasteless foods were somewhat more acceptable for swallowing than the sour and bitter foods. However, none of the foods differentially altered the motor parameters of swallowing. Interactive influences of temperature and gustatory sensations of foods on swallowing are discussed.