Differences in Taste Perception and Spicy Preference: A Thai–Japanese Cross-cultural Study

Chemical Senses, 2018, Vol 43, 65–74 doi:10.1093/chemse/bjx071 Original Article Advance Access publication November 9, 2017 Original Article Differences in Taste Perception and Spicy Preference: A Thai–Japanese Cross-cultural Study Dunyaporn Trachootham1, Shizuko Satoh-Kuriwada2, Aroonwan Lam-ubol3, Chadamas Promkam1, Nattida Chotechuang4, Takashi Sasano2 and Noriaki Shoji2 1 Institute of Nutrition, Mahidol University, 999 Phutthamonthon Rd., Salaya, Phutthamonthon, Nakhon Pathom, 73170, Thailand, 2Division of Oral Diagnosis, Department of Oral Medicine and Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, 3Faculty of Dentistry, Srinakharinwirot University, 114 Sukhumvit 23 Klongtoey Nua, Bangkok 10110, Thailand and 4Faculty of Science, Chulalongkorn University, Phyathai, Bangkok 10330, Thailand Correspondence to be sent to: Dunyaporn Trachootham, Institute of Nutrition, Mahidol University, 999 Phutthamonthon 4 Rd., Salaya, Phutthamonthon, Nakhon Pathom, 73170, Thailand. e-mail: Editorial Decision 5 November 2017. Abstract Taste perception is influenced by several factors. However, the relation between taste perception and food culture is unclear. This study compared taste thresholds between populations with different food culture, i.e.Thai and Japanese. A matched case–control study was conducted in 168 adults (84 for each; aged between 50 and 90 years). The age, sex, systemic disease, medication, smoking, xerostomia, and oral hygiene of both groups were not different. Recognition thresholds (RTs) of sweet, salty, sour, bitter, and umami were measured using filter paper disc (FPD). Detection taste thresholds were measured using electrogustometry. Spicy preference was measured by calibrated questionnaires. Higher RTs of all tastes and higher detection taste thresholds were found in Thai as compared to those of Japanese (P < 0.0001). Separate analyses of healthy and unhealthy persons confirmed the significant differences between 2 countries.The average thresholds for sweet, salty, sour, and bitter inThai and Japanese were 4 and 2, respectively. The average threshold for umami in Thai and Japanese was 5 and 3, respectively. Moreover, Thai population had stronger preference for spicy food (P < 0.0001) with 70% mild- or moderate and 10% strong lovers, compared to over 90% non- or mild-spicy lovers in Japanese. In addition, 70% of Thai consumed spicy food weekly, whilst 80% of Japanese consumed it monthly. Our findings suggested that population with stronger spicy preference such as Thai had much poorer taste sensitivity and perception than that with milder preference like Japanese. Extensive international survey is needed to conclude the influence of food culture on taste perception. Key words: cross-culture, electrogustometer threshold, older persons, spicy preference, taste recognition threshold, umami Introduction Enjoying taste is a great pleasure for older persons; however, taste alteration is a common worldwide complaint in those people (Schiffman 1997). Deteriorated taste sensitivity does lead to poor © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: appetite, decreased food intake, weight loss, malnutrition, and consequently poor quality of life (Murphy 2008). Furthermore, decreased taste perception can lead to unhealthy food choices (Rolls 1999; Lau 2008). For example, high threshold of salty or sweet taste increases 65 Chemical Senses, 2018, Vol. 43, No. 1 66 recognition thresholds (RTs) of 5 basic tastes i.e., sweet, salty, sour, bitter, and umami, in Thai and matched Japanese older persons. Spicy preference of participants from both nations was also compared. Materials and methods Materials A commercially available FPD taste kits, Taste Discs® were purchased from Sanwa Chemical. Laboratory Inc., Nagoya, Japan. The commercial FPD kit is composed of taste solutions (5 concentrations of each): sucrose, sodium chloride, tartaric acid and quinine hydrochloride for sweet, salty, sour, and bitter taste, respectively. For umami taste, 6 concentrations of monosodium glutamate (MSG) solution were prepared by dissolving MSG in distilled water and filtered through 0.2 μm pore prior to use. MSG was purchased from Ajinomoto Co, Inc., Japan. The concentrations of each taste solution as % (g/100 mL) and mM were depicted in Table 1a and b, respectively. Participants Thai participants were recruited from the dental clinic of Maha Chakri Sirindhorn Dental Hospital, Mahidol University. Japanese participants were recruited from the dental clinic of Tohoku University Hospital. Prior to the recruitment, all the participants were screened based on the following inclusion criteria: being 50–90 years old; born and resided either in Thailand or Japan for at least 5 continuous years; having no history of systemic diseases or having well-controlled systemic diseases. Exclusion criteria were as follows: having tongue cancer or history of tongue surgery; complete loss of all taste sensation; being critically ill or unconscious; disability to communicate; intolerance with FPD or electrogustometer test. All the participants signed their written informed consent prior to data collection. Their identities have been protected, following International Conference on Harmonization-Good Clinical Practice (ICH-GCP). In this study, we defined the participants aged 50 years old or above as older persons, according to a World Health Organization’s statement (WHO 2002). Table 1. Concentration of taste substance for FPD method a) %, g/100 mL Taste Sweet Salty Sour Bitter Umami Level Sucrose Sodium chloride Tartaric acid Quinine hydrochloride Monosodium glutamate 1 2 3 4 5 6 0.3 2.5 10 20 80 0.3 1.25 5 10 20 0.02 0.2 2 4 8 0.001 0.02 0.1 0.5 4 0.0187 0.0935 0.187 0.935 1.87 3.74 b) mM Taste Sweet Salty Sour Bitter Umami level Sucrose Sodium chloride Tartaric acid Quinine hydrochloride Monosodium glutamate 1 2 3 4 5 6 9 73 292 584 2337 51 214 856 1711 3422 1 13 133 267 533 0.03 0.55 3 14 111 1 5 10 50 100 200 more consumption of sodium or sugar, resulting in increased risk of heart disease, hypertension, and/or diabetes mellitus (Rolls 1999). Thus, a new strategy to improve taste threshold should have global impact on food intake, nutrition, and health for the older people. Previous studies demonstrated that several factors can influence taste thresholds including older age (Methven et al. 2012), systemic diseases (cancer, stroke), decreased salivary flow, side effects of radiation, medications, nutritional deficiency (Yoshinaka et al. 2007; Imoscopi et al. 2012), and oral hygiene (Solemdal et al. 2012). Besides those health-related factors, dietary intake and preference may also affect taste thresholds (Duffy 2007). Interestingly, a large-scale study in European children demonstrated that country of residence with different dietary (...truncated)