key: cord-0835212-yzeythi8 authors: Chen, Jingguo; Ren, Xiaoyong; Yan, Huanhuan; Zhao, Bingjie; Chen, Jingyan; Zhu, Kang; Lyu, Hui; Li, Zhihui; Doty, Richard L. title: Comparison of Chinese and American subjects on the self‐administered Waterless Empirical Taste Test date: 2022-03-26 journal: J Sens Stud DOI: 10.1111/joss.12745 sha: b15daad33f453faa18cb3688e7e15a6f57287a1b doc_id: 835212 cord_uid: yzeythi8 Cultural differences have been reported between the taste sensitivity of persons of Asian and European ancestry, although findings have been mixed. This study sought to determine whether American and Chinese adults perform differently on a novel taste test that requires no water, can be self‐administered, and employs a representative of umami as one of its tastants. This 53‐trial test was administered to 113 Chinese and 214 Americans. The subjects orally sampled monomer cellulose pads containing one of four dried concentrations of sucrose, citric acid, NaCl, caffeine, and monosodium glutamate and indicated whether a sweet, sour, bitter, salty, brothy, or no taste sensation was perceived. Separate gender by culture analyses of covariance with age as the covariate were performed on the total score and the scores of each taste stimulus. For all taste qualities, women outperformed men and test scores declined with age. No difference between American and Chinese subjects was found for the total taste score (p = .129) or for the sucrose (p = .129) or NaCl (p = .368) scores. However, for monosodium glutamate, the scores were 28.40% higher for the Chinese than for the American subjects (p = .024), and for citric acid and caffeine, the scores were 24.12 and 21.79% higher for the American subjects (p's = .001 and .029). The basis for these differences is unclear, although both anatomical (e.g., differences in density or distribution of taste buds) and cultural factors may be involved. Future work is needed to determine the cause of these largely novel findings and whether they generalize to other Chinese and American samples. Practical applicationsIn this study, a practical self‐administered quantitative taste test that requires no water was found to be sensitive to quality‐specific differences in test scores between Chinese and American subjects, as well as to age and gender. The Chinese subjects outperformed the American subjects in correctly identifying the quality of monosodium glutamate (umami), whereas the American subjects outperformed Chinese subjects in correctly identifying the bitter and sour qualities of caffeine and citric acid, respectively. Experiential factors related to culture‐specific cuisines may explain some of these differences. This research indicates that a relatively rapid taste test, which can be sent through the mail and which requires no test administrator or source of water, can be used in cross‐cultural studies to elucidate individual differences in taste perception. . The American sample was comprised of 185 White Americans (87%), 11 Asian Americans (5%), 9 African Americans (4%), and 9 Hispanic Americans (4%). The backgrounds of the Asian Americans were Chinese (n = 5), Indian (n = 5), and Vietnamese (n = 1). Exclusion criteria were a history of past or current nasal disease (allergic rhinitis or chronic rhinosinusitis), COVID-19 disease, or smell or taste disorders. Informed written consent was obtained from all subjects. The study was approved by the ethics committee of the Second Affiliated Hospital of Xi'an Jiaotong University (No. 2021010) , China, and the New England Independent Review Board (www.mbl.edu/osp/neirb; #1279756). The Waterless Empirical Taste Test (WETT) (Sensonics International, Haddon Heights, NJ) consists of 53 plastic taste strips. Positioned on one side of each 1 Â 6 cm strip is a 1 Â 2.5 cm monomer cellulose pad containing a concentration of either dried sucrose (0.20, 0.10, 0.05, or 0.025 g/ml), citric acid (0.025, 0.05, 0.10, or 0.20 g/ml), sodium chloride (0.0313, 0.0625, 0.125, or 0.25 g/ml), caffeine (0.011, 0.022, 0.044, or 0.088 g/ml), monosodium glutamate (0.017, 0.034, 0.068, or 0.135 g/ml), or no stimulus. The version of the test which was used for the American element of the present study provides the taste strips in convenient packs where they can be removed for self-administration in a numbered order by the subject. The answers are filled into the response forms as the subject goes through the test (Figure 1 ). The version of the test which was used for the Chinese element of the study houses the taste strips in compartments of a portable box ( Figure 2 ). Each of the three drawers of the box is divided into nine compartments. These test strips are handed individually to each subject by a test administrator in an order denoted in each test drawer and the subject selfadministers the taste strips in the same manner as done in the American element of the study. In this case, the responses of the subjects are recorded by the examiner on the same test sheets pictured in Figure 1 . It should be noted that the WETT provides a general measure of the ability to identify various concentrations of taste stimuli with a minimum number of trials and without the calculation of thresholds, per se. Its presentation paradigm is operationally similar to that of a recognition threshold since ascending concentrations are presented in the first half of the test and descending concentrations in the second half of the test. However, the concentrations of a given tastant do not immediately follow one another, as normally occurs for a threshold test, but are interspersed among those of the other tastants. Such an approach maximizes efficiency, making it possible to test all five basic taste qualities in the same test session with short inter-stimulus intervals not confounded by adaptation. On a given trial, each subject was instructed to move a strip's cellulose pad around the mouth, particularly along the tongue's dorsal edges, for 5-10 s, and to then identify the taste quality or to indicate that no taste can be perceived. The test strip was then discarded into a waste container after each trial. A standardized protocol was followed according to the administration manuals of the tests and subject responses were recorded on the test sheets, as noted in Figure 1 . Within the test trial sequence, the four concentrations of each stimulus are presented twice. In the first half of the test (27 trials), which corresponds to the brief self-administered WETT (SA-WETT-27), the stimulus concentrations proceed from weak to strong in an ascending sequence, with the different tastants being counterbalanced in presentation order. No tastant (e.g., sucrose) immediately follows itself. The blanks are presented after each of the four caffeine presentations, the 0.25 g/ml sodium chloride presentation, and the 0.025 and 0.10 g/ml citric acid presentations. In the second half of the test, the reverse presentation order is made, that is, going from strong to weak concentrations. The blank that follows the 0.25 g/ml sodium chloride stimulus, which is the last trial of the first series, is not repeated at the beginning of the second series, resulting in 26 rather than 27 trials for the second half of the test. The total number of correct responses (sum of all correct responses) and the number of correct responses for each of the five taste stimuli were the dependent measures. Separate analyses of covariance were F I G U R E 1 The stimulus holders and taste strips used in the Waterless Empirical Taste Test (WETT-SA53) were employed in the American testing of this study. Each individual strip is pulled from the container by the subject in numbered order. The subject then moves its taste-laden cellulose pad around the surfaces of the tongue and discards it into a waste container after use. The subject's responses are indicated by filling in the answer on a given line of the pictured response sheet. A key is then used to count the number of correct resonses in each column. Courtesy of Sensonics International, Haddon Heights, NJ. Copyright © 2015, 2019, Sensonics International applied to each of these measures to compare the scores of the American and Chinese subjects and determine the influences of gender and age on such scores. The factors were gender and cultural group (Chinese, American); age was the covariate to examine age effects and to adjust for any age differences between the two groups. Pearson correlations were computed between the scores on the first and second halves of the test with p values Bonferroni corrected. Significance on all tests was set at the .05 alpha level. Statistical analyses were performed using SYSTAT 13.1 (Wilkinson, 1990) . The mean (SEM) age-adjusted total WETT scores are presented in Table 1 for the male and female Chinese and American subjects. Included are the test scores summed across all trials, as well as test scores for each of the subcomponent stimuli. The total test scores of the American and Chinese groups did not The average sour scores of the American subjects were 24.12% higher than those of the Chinese subjects ( η 2 = 0.00). The Pearson r between the sodium chloride scores of the first and second halves of the test was 0.48 (p < .0001). The bitter scores were 21.79% higher in the American than in the Chinese The brothy test scores were 28.40% higher in the Chinese than the (Rosenthal, 2000) . Our findings are congruent with those of Kobayashi and Kennedy (2002) , who found lower MSG thresholds in Japanese than in American or European subjects, and that Japanese subjects could better identify MSG in foods. In this same study, exposure of the non-Japanese subjects to shrimp crackers containing MSG for 11 to 12 days resulted in their ability to identify MSG at lower concentrations than non-exposed controls, stressing the role of experience in altering MSG sensitivity. and Japanese subjects are reported to be more sensitive than Caucasian subjects to the bitter taste of PROP, one of a number of wellstudied bitter substances (Guo & Reed, 2001) , perceived caffeine bitterness is related to daily caffeine intake (Lipchock et al., 2017) . Although sour-tasting citric acid is widely found in citrus fruits and is present in American food products, including soda, fruit-flavored beverages, candy, and flavored syrups and lemonade, grapefruit juice, and 0.48, and 0.42). When limitations on time are critical and a measure of overall function is needed, the first half of the test, that is, 27 items, can provide an accurate assessment of overall taste function. The sweet, sour, bitter, and salty coefficients were lower than those in the original validation study, which were 0.80, 0.77, 0.73, and 0.84, respectively. No value for MSG was presented in that study since its goal was to compare coefficients with other tests that did not employ MSG. The lower correlations of the present study likely reflect more attenuation of the range of the present test scores, since unlike the validation study, the subjects were non-clinical subjects with normal taste function and a narrower range of test scores. It is well established that correlation coefficients are extremely sensitive to restricted ranges of data (Bland & Altman, 2011) . The present study has both strengths and weaknesses. Its strengths are the use of a well-validated taste test and relatively large Chinese and American sample sizes. Its use of monosodium glutamate in addition to stimuli associated with the four classic taste qualities is also a strength, along with the fact that the test can be employed in settings where purified water is not available for rinsing. While the lower age of the Chinese sample would appear to be a limitation, the use of age as a covariate mitigated this problem. This study shares with most other taste studies the lack of random sampling of the population that was tested. Moreover, the present study did not assess regional taste differences despite the fact that these strips could be used for this purpose. While whole-mouth testing is the best reflection of overall taste perception, future studies are needed to evaluate whether and to what degree regional differences are found in crosscultural studies. 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