In this article, we are here with a beautiful compilation that looks at tasting, a field we enjoy very much, from the most realistic perspective. This article includes scientific publications, the oldest of which is from 2017 and the newest from 2023, and one summary article.
First, let's talk about our sense organs. We all memorized that there are 5 sense organs. The senses that are examined under 5 headings as hearing, taste, smell, touch and vision have been added to the senses, which are simply examined under 5 headings: vestibular sense (speed-movement-balance), interoceptive sense (internal organ sense) and proprioceptive sense (joint-muscle, action-reaction). It is quite exciting that the discovery of the human body is rediscovered despite the tons of budget allocated and new windows are opened every period. Here, as coffee lovers, we will start to examine the subject of language, which is the tool of the sense of taste, as much as possible and as current studies allow. Apart from these, we will also publish a detailed article, perhaps section by section, in a short time, regarding the taste-smell-flavor trilogy, where we have been examining both chemical and physical changes-interactions for a long time, as we wrote about water.
Now let's examine our main subject, the tongue organ, and see how it behaves in the act of tasting. Taste, above all, provides us with vital information that allows the body to prevent or at least reduce the effects that may occur after consuming harmful ingredients.
The tongue is a complex and multifunctional organ that interacts with and perceives both interoceptively (we can call it internal sensory perception) and exteroceptively (we can call it external sensory perception). Thus, the tongue perceives both internal and external sensory perceptions. A fully developed human tongue consists of two parts: the anterior two-thirds, the corpus linguae, called the body of the tongue or the body of the tongue; and the posterior third, known as the root of the tongue or the root of the tongue. The root of the tongue and the body of the tongue are structurally and developmentally different, supplied by separate nerves and provided with different vascularization and lymph drainage, and connected to the bony structure by the root of the tongue, formed by the tonsils. The human tongue is largely composed of muscles, and these muscles are covered by a layer of non-keratinized stratified squamous epithelial tissue containing the lingual papillae. As their name suggests, the circumvallate papillae (CVPs) are mushroom-shaped elevations surrounded by a deep circular valley where the taste buds come into contact. Filiform papillae, on the other hand, are papillae found to be 4-12 in number in humans, located on the tongue and generally not capable of tasting, and have the main function of mechanoreception. These papillae cover the part of the tongue from the back end to the sulcus terminalis, which is the head end. Unlike other taste papillae, filiform papillae have a greater height, a thinner epithelial layer, a flatter surface and a larger surface area. Filiform papillae are the sources of more tactile sensations on the tongue. These papillae, which give a feeling of relief to the texture of the tongue and enable the tongue to respond to external stimuli, also contribute to the function of pushing and manipulating food. Foliate papillae (FP) are small grooves located on the sides of the back of the tongue. The main function of these papillae is to contribute to the process of tasting. Some of the taste buds on the surface of the tongue are located in the foliate papillae and taste perception occurs here. These papillae contribute to the formation of the sense of taste and increase the sensitivity of the tongue. The cells that perceive taste substances are located in collections of taste receptor cells (TRCs) packaged as taste buds and embedded in taste papillae. Based on a recent literature meta-analysis on human taste papillae density, it was estimated that approximately 4,600 taste buds are distributed over three different types of taste papillae: 48% of these papillae are located in the CVP, 28% in the FLP, and 24% in the FP.
If we briefly and briefly explain the taste mechanism of the tongue, taste is perceived by taste buds located on the surface of the tongue. Taste buds contain special cells that recognize basic tastes. This information is transmitted to the brain via special taste nerve fibers. The taste information processed in the nucleus solitarius located in the brainstem is then sent to the gustatory cortex in the brain via the thalamus. Here, the recognition and evaluation of tastes occur. Finally, the processed taste information determines the person's taste experience, directing the ability to perceive sweet, sour, salty, bitter and umami.
The basic tastes that the tongue perceives, as mentioned above, are sour, bitter, sweet, salty and umami. But these are only the rough and basic outlines of perception. In the mid-20th century, it was widely accepted that the taste receptors that code for different basic taste characteristics (such as sweet, sour, bitter and salty) are distributed asymmetrically on the surface of the tongue. According to the tongue map that we have memorized for a long time but is no longer valid, sweet receptors are located at the front of the tongue, bitter receptors are at the back and receptors that can perceive salty and sour tastes are located on the sides. This study was first put forward in 1952 and for a long time everyone accepted this tongue-taste map. However, this tongue map idea was rejected by most scientists in 2006. The claim accepted in 52 is related to the spatial distribution (i.e. separation) of taste receptor cells in the tongue (for sweet, bitter, salty and sour), and neuroscience, which has developed greatly in recent years, has shown that the sensory receptors for different taste qualities are distributed in similar ways in different parts of the tongue and are certainly not neatly separated as the tongue map implies. The discovery that taste buds from all parts of the oral cavity, which were not taken into account in the fifties but are now an important part of the sense of taste, contain cells that respond to five basic modalities, is the most definitive answer to the lack of a spatial map. Stimulation of taste receptor cells in the oral cavity produces a conscious sense of taste.
The distribution of taste receptor cells on the tongue allows us to understand the complexity and diversity of the taste process. Scientific studies first show that taste receptors are spread all over the tongue and that taste perception is not limited to a specific area. This shows that the taste receptors necessary for taste perception are spread over a wide area, not just in certain parts of the tongue. Therefore, this means that the taste experience can be perceived in a similar way in different parts of the tongue.
The complexity of tastes is also an important factor in understanding the process of tasting. The complex interaction of taste receptors has shown that a food can trigger multiple taste perceptions simultaneously. For example, a food can cause both sweet and salty sensations. In this case, it appears that there is no single taste area and that tastes overlap and are processed in a complex way.
When we consider the complex structure of coffee, it spreads quite satisfactorily in every part of the tongue, palate and oral cavity where we perceive all basic tastes at the same time. At a point where specific tastes of foods cannot be indicated, making a mark on the tongue with thousands of papillae is a shortcut and far from reality. The rapid development of neuroscience and the growth of the gastronomy sector at the same rate at the molecular level have pushed scientific studies in this direction and there are quite extensive studies. At the same time, the fact that each individual's taste perception ability and preferences are different shows the complexity of the taste map. For example, while a certain food creates a sweet perception for one person, the same food may be perceived as more salty for another person. This shows that not everyone has the same taste map and that taste perception is completely personal and subjective. Finally, the flexibility of the tongue is also an important factor affecting the taste perception process. The tongue has a constantly changing structure and taste receptor cells are constantly moving within this structure. This shows that taste perception may not fit into a fixed map and may change over time.
So, let's talk about the answer to the questions of what bad taste is, how it is perceived and in what way, in one sentence.
Bad taste reactions originate from the inside of the taste bud, the tongue epithelium and the oral mucosa and are linked to complex behavioral response circuits, but we will not go into detail, stating that we have a separate article for the perception of "bad taste" and will publish it shortly.
One of the most important parts for coffee is the Oil (oleogustus). The perception of oil is not through the five prototypical taste mechanisms described above. The exact receptor that detects oil and the ligand components of oil are still very controversial issues within the chemosensory research community. In fact, it has been stated in studies that oil should also be considered as a taste and taken into account.
Here we would like to talk about the term that best describes this complex sense.
Gustatory means of or pertaining to taste. This term is used to refer to anything related to the sense of taste. The gustatory experience is not limited to the chemicals detected by the taste buds.
This beautifully illustrates the indescribable connection between our gustatory sense, our taste memories and the connection that occurs when we are given taste: the mouth-gastrointestinal system-brain-emotional connection introduced to us by Proust in the 14th century. In short, other sensory information, such as the smell and texture of food, also influences the taste experience. In addition, individuals' personal experiences and cultural backgrounds also influence the perception of taste. The description of the sense of taste in ordinary terms is rather dull and trivial, namely, that where you drink your coffee, as well as in what environment and with whom you drink it, are the elements that make the real differences and give meaning to the taste, and we conclude our article, which we have discussed in a broad scientific framework, with a romantic ending.
DUYGU KURTULUŞ
Co-Founder / Chemist / Nanotechnology Engineer / Hazardous Chemical Consultant / Chemical Evaluation Specialist