By: Diane M. Schmitt
As a food scientist or foodie you probably have heard the term “supertaster” being thrown around. Individuals who are supertasters are generally thought to have superior taste, olfactory (smell), and tactile responses to foods and beverages. It is widely assumed that to be classified as a supertaster one must perceive the compound 6-n-propylthiouracil (PROP) to be intensely bitter. Non-supertasters perceive PROP to have lower bitterness intensity or do not taste the compound at all (non-tasters). However, this simple explanation is not the entire story of what the term “supertaster” originally meant and what the term has come to mean to the general population. A fact is that individuals who are supertasters for certain gustatory (taste-related)_sensations do exist, but the fiction is that they can be identified by or that their abilities can be attributed simply to their PROP taster status.
The term “supertaster” was first mentioned by Linda Bartoshuk in an article published by Food Technology in 1991 in reference to individuals’ PROP sensitivity. The chemical structure of PROP is shown below along with a similar compound, phenylthiocarbamide (PTC). In 1931 DuPont chemist Arthur Fox discovered, by accident, that PTC was perceived to be intensely bitter by some but not all individuals. PTC and PROP tasting ability are thought to be coded by the gene known as TAS2R38 . Individual variations in this gene correspond with different tasting abilities (Kim et al., 2003).
Originally, individuals who tasted PROP (or PTC) were classified as either non-tasters or tasters depending on whether or not they detected a taste in an aqueous solution of the compounds. Tasters, who were extremely sensitive to the taste of PROP, were further classified as supertasters. As a result, the initial use of the term “supertaster” only referred to individuals’ PROP tasting status (Hayes and Keast, 2011). Additional, aspects of being a supertaster such as increased overall bitterness, salt, and sweetness perception as well as heightened tactile sensations were later established via scientific findings and/or unscientific widespread generalizations. This confusion with the terminology has led some researchers to propose the term “hyperguesia” as an alternative to supertaster to describe a heightened gustatory response across stimuli (Hayes and Keast, 2011).
What does PROP tasting actually mean?
Fungiform papillae (FP) are taste-bud carrying structures on the tongue, and their density was once thought to be positively correlated to PROP sensitivity. Early experiments determined individuals’ FP density by coloring their tongues blue and then counting the number of FP in a specific area. However, the research supporting this claim has come into question recently as scientific methods and knowledge in the field have become more advanced. A study by Gameau et al. (2014), which tested 394 individuals, found no correlation between FP density and PROP tasting status. Unfortunately, this shift in the scientific thinking will have a long lag time before it is widely known and accepted by the general public, as is the case in many areas of science.
Research has shown that PROP tasting status and bitterness intensity ratings are correlated leading to the belief that supertasters will avoid bitter foods such as Brussels’ sprouts and coffee. However, PROP taster status has not been shown to be a good predictor of food preference. For example, some PROP supertasters enjoy Indian Pale Ale beers while others do not. Leading some researchers to hypothesize that cultural and environmental factors have at least as much or more influence on food preferences than genetics (Catanzaro et al., 2013). PROP tasting ability is not the only factor influencing eating behaviors. Individual food preferences are significantly influenced by cultural and environmental factors, particularly during gestation and the first couple of months after birth (Beauchamp and Mennella, 2011; Mennella et al., 2011). Cultural and environmental influences include the mother’s diet during gestation and lactation, the types of foods consumed by parents and other close individuals, as well as societal beliefs and practices, among other factors. If children are exposed to a large diversity of foods and beverages when they are very young they are more likely to be adventurous eaters throughout their lives. This occurrence follows the “mere exposure effect” which states that individuals prefer stimuli that they are familiar with and have been repeatedly exposed to. These repeated sensory stimuli may include your parents’ favorite foods or perhaps the Butterfinger BB’s, TMNT cereal, or Heinz EZ Squirt Ketchup that you used to eat (then again maybe not…).
It is proposed that PROP medium and supertasters are overrepresented in the wine expert population because individuals will self-select professions that they have a genetic advantage in. This assumption supports the proposition that an active gene-environment correlation (rGE) for gustation occurs. With a rGE a genetically influenced behavior, such as super-tasting, leads an individual to create, seek, or select and environment that matches their genotype, like wine-tasting, thus enhancing expression of a phenotype (PROP weak, medium, or supertaster) (Hayes and Pickering 2012). Unfortunately, this rGE effect with wine experts has not been observed with self-reported “foodies”, meaning that “foodies” as a group do not have a higher than normal percentage of supertasters (Pickering et al., 2013). However, don’t get too disappointed about these findings, innate abilities such PROP tasting status, cannot replace the need for training in wine tasting much like a naturally gifted athlete cannot succeed without practice. PROP tasters of all levels can improve their sensitivity to specific sensory stimuli through repeated exposure and other training methods. For example, repeated training and/ or exposure to specific aromatic compounds, such as linalool or diacetyl, has been found to increase the sensitivity of wine experts to these specific compounds (Tempere et al., 2012).
So whether or not you are classified as a supertaster with heightened gustatory sensitivities remember that PROP tasting status cannot account for all variations in food preference and food adventurousness. The TAS2R38 gene may not be the only marker that affects individuals gustatory abilities. Additionally, supertasting abilities may be determined by allelic variations of other genes or environmental factors as well as training. For now, enjoy the complex nature of food and sensory perception and stay tuned for upcoming discoveries in supertaster research!
What are your opinions on this topic? Have you been identified as a PROP supertaster? Are you a weak PROP taster but still identify as a supertaster? Please share your comments below!
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Catanzaro D, Chesbro EC, Velkey AJ. 2013 Relationship between food preferences and PROP taster status of college students. Appetite. 68: 124-131.
Garneau NL, Nuessle TM, Sloan MM, Santorico SA, Coughlin BC, Hayes JE. 2014. Crowdsourcing taste research: genetic and phenotypic predictors of bitter taste perception as a model. Frontiers in Integratibe Neuroscience. 8:Article 33.
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Hayes JE, and Pickering GJ. 2012. Wine expertise predicts taste phenotype. American Journal of Enology and Viticulture. 63(1): 80-84.
Kim UK, Jorgenson E, Coon H, Leppert M, Risch N, Drayna D. 2003. Positional cloning of the human quantitative trait locus underlying taste sensitivity to phenylthiocarbamide. Science. 299:1221–1225.
Mennella JA, Lukasewycz LD, Castor SM, Beauchamp GK. 2011. The timing and duration of a sensitive period in human flavor learning. A randomized trial. American Journal of Clinical Nutrition. 93:1019-1024.
Pickering GJ, Jain AK, Bezawada R. 2013. Super-tasting gastronomes? Taste phenotype characterization of foodies and wine experts. Food Quality and Preference. 28: 85-91.
Tempere S, Cuzange E, Bougeant JC, de Revel G, Sicard G. 2012. Explicit sensory training improves the olfactory sensitivity of wine experts. Chem. Percept. 5:205-2013.
Cover image (www.jordanwinery.com)