The Science of Taste

Table of contents

  1. The Science of Taste. This page. Work in progress.
  2. Flavor wheels comparison. Work in progress.

Abstract

Purpose of this research is to layout scientific basis for rigorous approach to sensory lexicon, instead of previously used intuitive approach. See also: tastescience.com, 2015

Taste, flavor, smell and aftertaste

Taste

In the common language, the word “taste” is often used to describe sensations arising from the oral cavity. However, the biological definition of taste, or gustation, is narrower and includes only sensations mediated by a specialized anatomically and physiologically defined chemosensory gustatory system. Along with taste sensations, food usually simultaneously evokes other sensations, e.g., odor, touch, temperature, and irritation. Although it is not always easy to separate all these sensations perceptually, the nongustatory components are sensed by different systems, olfaction and somatosensation. Source: Taste Receptor Genes, 2007

Flavour

Complex combination of the olfactory, gustatory and trigeminaleditor note: somatosensation sensations perceived during tasting. The flavor may be influenced by tactile, thermal, painful and/or kinaesthetic effects. Source: Delwiche, 2004, p. 137; see also Green, 2004; Lundström et al., 2011; Spence, 2012b; Tournier et al., 2007

Orthonasal vs Retronasal Olfaction

Odors often produce different sensations when presented in front of the nose or intraorally, when eaten. It is a long-standing question whether these differences in sensations are due, for example, to the additional mechanical sensations elicited by the food in the mouth or additional odor release during mastication. ... The differences between ortho- and retronasal perception of odors are thought to be, at least partly, due to absorption of odors to the olfactory epithelium, which appears to differ in relation to the direction of the airflow across the olfactory epithelium. Source: Retronasal Perception of Odors, 2008

Aftertaste

Aftertaste is the taste intensity of a food or beverage that is perceived immediately after that food or beverage is removed from the mouth. The aftertastes of different foods and beverages can vary by intensity and over time, but the unifying feature of aftertaste is that it is perceived after a food or beverage is either swallowed or spat out. The neurobiological mechanisms of taste (and aftertaste) signal transduction from the taste receptors in the mouth to the brain have not yet been fully understood. Source: Aftertaste

Relationship between: taste, flavor, smell and aftertaste in time

Type of sensations and receptors

See also: List of gene receptors First parf of the table taken from: The receptors and cells for mammalian taste, 2006.

Tastant Receptor(s) Class of tastant Examples of tastants quality
Umami T1R1+T1R3 Amino acids l-Glutamate, L-AP4, glycine, l-amino acids
Nucleotide enhancers IMP, GMP, AMP
Sweet See more at: SuperSweet.
T1R2+T1R3 Sugars Sucrose, fructose, glucose, maltose
Artificial sweeteners Saccharin, acesulfame-K, cyclamate, aspartame
d-amino acids d-Phenylalanine, d-alanine, d-serine (also some selective l-amino acids)
Sweet proteins Monellin, thaumatin, curculin
Bitter See more at: BitterDB. BitterDB: A database of bitter compounds, 2011
T2R5 Cycloheximide
T2R8, T2R4, T2R44 Denatonium
T2R16 Salicin
T2R38 PTC
T2R43, T2R44 Saccharin
Sour See more at: The candidate sour taste receptor, PKD2L1, is expressed by type III taste cells in the mouse, 2007. The chemistry and physiology of sour taste — a review, 2007
PKD2L1 Acids Citric acid, tartaric acid, acetic acid, hydrochloric acid
Recent researches, which are still in progress
Calcium CaSR Source: T1R3: A human calcium taste receptor, 2012
Fattiness CD36 long-chain fatty acids Source: Reversible binding of long-chain fatty acids to purified FAT, the adipose CD36 homolog, 1996
GPR120 and GPR40 fatty acids linoleic acid and oleic acid. Source: Taste preference for fatty acids is mediated by GPR40 and GPR120, 2010
Heartiness (kokumi) Source: Glutathione. Hettiarachchy, Navam S.; Sato, Kenji; Marshall, Maurice R., eds. (2010). Food proteins and peptides: chemistry, functionality interactions, and commercialization. Boca Raton, Fla.: CRC. ISBN 9781420093414. Retrieved 26 June 2014.
Carbonation Source: The Taste of Carbonation, 2009
Starchiness Glucose Oligomers Source: Humans Can Taste Glucose Oligomers Independent of the hT1R2/hT1R3 Sweet Taste Receptor, 2016
Alkaline Source: The Alkaline Taste, 1956
Metallicness TODO: find research
Somatosensory system
Hotness TRPV1 and TRPA1 ethanol, capsaicin, piperine. TODO: find research
Coolness TRPM8 ion channels spearmint, menthol, ethanol, and camphor. TODO: find research
Numbness Sichuan pepper. Source: Challenges in taste research: present knowledge and future implications, 2003
Astringency Source: Astringency: A More Stringent Definition, 2014. Astringency: Mechanisms and Perception, 2008
Texture TODO: find research
Temperature TODO: find research
Olfactory system — everything else what we are sensing suppose to go in this category. See online databases for aromas: MetaChemiBio: Flavor, aroma and taste enhancing compounds, flavornet, SuperScent — a database of flavors and scents, FooDB, Zinc
Aftertaste - taste sensation to be researched yet. TODO: find research

Prominent researches on taste science

Challenges in taste research: present knowledge and future implications, 2003
Abstract: This chapter gives a brief survey on the chemistry of gustatory taste sensations, i.e. the perception of the basic tastes modalities sour, sweet, salty, bitter as well as umami, and lingual somatosensory sensitivity resulting from temperature and tactile stimulation as well as chemical activation of chemosensory receptors. Some of the present challenges facing researchers in taste chemistry and biochemistry are presented and future perspectives are discussed.

A study of the science of taste: On the origins and influence of the core ideas, 2008
Abstract: Our understanding of the sense of taste is largely based on research designed and interpreted in terms of the traditional four “basic” tastes: sweet, sour, salty, and bitter, and now a few more. This concept of basic tastes has no rational definition to test, and thus it has not been tested. As a demonstration, a preliminary attempt to test one common but arbitrary psychophysical definition of basic tastes is included in this article; that the basic tastes are unique in being able to account for other tastes. This definition was falsified in that other stimuli do about as well as the basic words and stimuli. To the extent that this finding might show analogies with other studies of receptor, neural, and psychophysical phenomena, the validity of the century-long literature of the science of taste based on a few “basics” is called into question. The possible origins, meaning, and influence of this concept are discussed. Tests of the model with control studies are suggested in all areas of taste related to basic tastes. As a stronger alternative to the basic tradition, the advantages of the across-fiber pattern model are discussed; it is based on a rational data-based hypothesis, and has survived attempts at falsification. Such “population coding” has found broad acceptance in many neural systems.

The science of taste, 2014
Abstract: An understanding and description of our sensory perception of food requires input from many different scientific disciplines: in addition to the natural and life sciences, human sciences, social sciences, as well as the arts each contributes their perspective on what we call taste. For the natural sciences, the key concept is flavor encompassing all physical, chemical, and neurophysiological aspects. For researchers in human sciences, psychology, anthropology, and social sciences, taste is a broader concept related to tradition, geography, culture, as well as social relations. For cooks and practitioners, taste is a multimodal facet of food and the way we perceive and enjoy it. An interdisciplinary symposium on The Science of Taste brought together in August 2014 researchers and practitioners who deal with taste from many different perspectives with an aim to provide a composite mosaic of our current understanding of taste.

Confusing tastes with flavors, 2015
Taste, flavour, trigeminal, and odours descriptors. Taste, flavour, trigeminal, and odours descriptors. Note that the only flavour that cannot also be smelled orthonasally is, apparently, ferrous sulphate (see Lawless et al., 2004). Abstract: People’s use of the terms ‘taste’ and ‘flavor’ is often confusing, both in everyday use and in the academic literature. Failure to distinguish these ‘basic’ terms is likely to slow the development of our understanding of the chemical senses, currently a rapidly growing area of study in perception science. Our aim here is to defend the idea that, ultimately, it doesn’t make sense to treat experiences of the putative basic tastes, such as ‘sweetness’ and ‘sourness’ in our everyday experience as tastes. Rather, we suggest, the evidence supports the view that they should be treated as flavors, just like ‘fruity’ or ‘meaty’. Here we highlight the pervasive nature of the confusion between tastes and flavors, and outline a number of reasons for its occurrence, linked to the topics of attention and oral referral. We then provide psychological, physiological, and philosophical reasons to support the stance that tastes should be classified as a sub-component of flavors and show how doing so helps to dissolve certain debates.

Figure taken from: The beer aroma wheel, 2009 Overview of the olfactory and gustatory overall impression

History of sensory lexicon development

First flavor wheel: beer

References: Beer flavor terminology, 1979.
Reference standards for beer flavor terminology system, 1982.
Sensory evaluation of the mouthfeel of beer, 1991. The beer flavor wheel was developed in the 1970s by Morten Meilgaard. It was subsequently jointly adopted as the flavor analysis standard by the European Brewery Convention, the American Society of Brewing Chemists, and the Master Brewers Association of the Americas.

Reference: The beer aroma wheel, 2009. In 2009 A. Schmelzle produced updated version of beer flavor wheel.

Wine Aroma Wheel

References: Modification of a Standardized System of Wine Aroma Terminology, 1987.
A ‘Mouth-feel Wheel’: terminology for communicating the mouth-feel characteristics of red wine. In 1984 Ann C. Noble invented the "Aroma Wheel" for wine tasting terminology.

Coffee flavor wheel

In 1995 SCAA created coffee flavor wheel. What coffee professionals may not know is that the flavor wheel was created as a visual tool to accompany The Coffee Cupper’s Handbook. Each term was very purposefully put in place to represent the weight of the molecules that they were meant to represent.

Reference: Coffee Taster’s Flavor Wheel — not a scientific research. In 2013 Counter Culture Coffee made own version of coffee flavor wheel.

References: Using Single Free Sorting and Multivariate Exploratory Methods to Design a New Coffee Taster's Flavor Wheel, 2016.
Development of a “living” lexicon for descriptive sensory analysis of brewed coffee, 2016. In 2016 SCAA and WBC produced updated version of coffee flavor wheel.

Cheese flavor wheel

References: Development of a descriptive language for Cheddar cheese, 2001.
Cross validation of a sensory language for cheddar cheese, 2001.
Cross validation of a sensory language for Cheddar cheese, 2002.
Flavor of Cheddar cheese: a chemical and sensory perspective, 2003.
Coupled stepwise PLS-VIP and ANN modeling for identifying and ranking aroma components contributing to the palatability of Cheddar cheese, 2015. In 1996 Mary Ann Drake PhD directs the North Carolina State University Sensory Service Center, which specializes in the sensory evaluation of dairy products. She and her colleagues produced cheese flavor wheel, as well as a more specific cheddar cheese lexicon.

Comparison and further development of sensory lexicons

Flavor Lexicons, 2003
Abstract: Flavor lexicons are a widely used tool for documenting and describing sensory perception of a selected food. Development of a representative flavor lexicon requires several steps, including appropriate product frame of reference collection, language generation, and designation of definitions and references before a final descriptor list can be determined. Once developed, flavor lexicons can be used to record and define product flavor, compare products, and determine storage stability, as well as interface with consumer liking and acceptability and chemical flavor data.

A System for Classifying Sensory Attributes
Abstract: Data from a descriptive analysis panel sometimes fails to detect differences between products for one or more sensory attributes. Results might nonetheless be consistent with the best possible data; lack of discrimination could be meaningful information if no true sensory difference exists between products for the attribute, which might occur when all products fall within one just-noticeabledifference (JND) interval (Castura et al., 2006).
A panel leader sometimes has prior knowledge of a product group and what level of performance is possible for particular sensory attributes within the product context. This information can help the panel leader to focus training in a relevant manner.
Systematic classification of sensory attributes based on the difficulty associated with identifying and scaling the attribute in specific product contexts can make this information available to the broader community of sensory practitioners.

Other

See also: Flavor wheels comparison