Fundamental Taste Research Articles

Predicting multiple taste sensations with a multiobjective machine learning method

Taste perception plays a pivotal role in guiding nutrient intake and aiding in the avoidance of potentially harmful substances through five basic tastes - sweet, bitter, umami, salty, and sour. Taste perception originates from molecular interactions in the oral cavity between taste receptors and chemical tastants. Hence, the recognition of taste receptors and the subsequent perception of taste heavily rely on the physicochemical properties of food ingredients. In recent years, several advances have been made towards the development of machine learning-based algorithms to classify chemical compounds’ tastes using their molecular structures. Despite the great efforts, there remains significant room for improvement in developing multi-class models to predict the entire spectrum of basic tastes. Here, we present a multi-class predictor aimed at distinguishing bitter, sweet, and umami, from other taste sensations. The development of a multi-class taste predictor paves the way for a comprehensive understanding of the chemical attributes associated with each fundamental taste. It also opens the potential for integration into the evolving realm of multi-sensory perception, which encompasses visual, tactile, and olfactory sensations to holistically characterize flavour perception. This concept holds promise for introducing innovative methodologies in the rational design of foods, including pre-determining specific tastes and engineering complementary diets to augment traditional pharmacological treatments.

The multi-modal sensory effect on sour taste perception during oral processing of starch-thickened fluids

Sour taste is one of the fundamental taste attributes and considered as a saliva secretion stimulant facilitating consumers with xerostomia and swallowing difficulties. The dynamic sour taste perception during oral processing of starch-thickened fluid was therefore investigated in this study. Recruited healthy subjects were divided into those with high (H_AMS) and low (L_AMS) salivary α-amylase activity groups and their temporal dominant sensory evaluation were analyzed while oral processing starch-thickened fluid samples with different concentration of citric acid. By simultaneously evaluating the physical and chemical properties of subjects' expectorated fluid/saliva mixtures, the complex and multi-modal interplay between fluid viscosity (tactile perception), citric acid concentration (taste perception), salivary α-amylase activity (binary taste interaction) was successfully demonstrated. The sour taste perception was found to be greatly affected by the continuous starch-thickened fluid hydrolysis by salivary α-amylase, resulting in a gradual production of sweet-tasting oligosaccharides and simultaneous decrease in fluid viscosity, and group variations (H_AMS vs. L_AMS) were pronouncedly observed in the hydrolyzed oligosaccharide concentrations (glucose, maltose, and maltotriose) which suitably corresponded to the selected dominant sensory attributes including perceived taste differences and taste dominant duration. These findings suggest that salivary biochemical properties and the thickened fluid type greatly influence consumers’ sensory perception. This could provide valuable insights for designing and optimizing thickened foods and beverages that are palatable in sensory properties and meet the needs of special consumers.

Umami in Wine: Impact of Glutamate Concentration and Contact with Lees on the Sensory Profile of Italian White Wines

Umami is a fundamental taste, associated with the molecules of monosodium glutamate and other amino acids and nucleotides present in many fermented foods and beverages, including wine. Umami also plays the role of flavor enhancer and prolongs the aftertaste. In this research, monosodium glutamate and aspartate, responsible for the umami taste, were quantified in Italian still and sparkling white wines aged through contact with yeasts. The wines were studied from a sensory point of view to quantify the perception of umami and relate it to other sensory parameters. The results show that monosodium glutamate and aspartate are present in the wines studied. However, sensory analysis shows that there is no clear relationship between the umami taste and the concentration of the two amino acids, but their presence plays a fundamental role in enhancing other gustatory and olfactory perceptions, making them even more persistent.

Effects of visual and aromatic stimulations on the perception of five fundamental tastes.

Taste perception is affected by various environmental factors. In the present study, we investigated the effects of visual and aromatic stimulations on stress responses and taste perception. Fourteen young healthy participants were assessed for stress levels and taste intensities under 5 different conditions: normal (no stimuli), watching an action scene, watching a forest scene, sniffing a rosemary aroma, and sniffing a lavender aroma. Compared to participants under the action scene condition, participants under the forest scene or under the rosemary aroma condition showed significantly lower stress levels. Furthermore, the forest scene condition significantly increased the saltiness intensity, whereas the rosemary aroma condition significantly increased the bitterness intensity. A positive or negative correlation was observed between the stress level and taste intensity of sourness and saltiness, respectively. These findings indicate that visual image and aroma have the potential to change taste perception as well as modulate stress conditions.

Mechanisms of Carboxylic Acid Attraction in Drosophila melanogaster.

Sour is one of the fundamental taste modalities that enable taste perception in animals. Chemoreceptors embedded in taste organs are pivotal to discriminate between different chemicals to ensure survival. Animals generally prefer slightly acidic food and avoid highly acidic alternatives. We recently proposed that all acids are aversive at high concentrations, a response that is mediated by low pH as well as specific anions in Drosophila melanogaster. Particularly, some carboxylic acids such as glycolic acid, citric acid, and lactic acid are highly attractive to Drosophila compared with acetic acid. The present study determined that attractive carboxylic acids were mediated by broadly expressed Ir25a and Ir76b, as demonstrated by a candidate mutant library screen. The mutant deficits were completely recovered via wild-type cDNA expression in sweet-sensing gustatory receptor neurons. Furthermore, sweet gustatory receptors such as Gr5a, Gr61a, and Gr64a-f modulate attractive responses. These genetic defects were confirmed using binary food choice assays as well as electrophysiology in the labellum. Taken together, our findings demonstrate that at least two different kinds of receptors are required to discriminate attractive carboxylic acids from other acids.

Epigenetic regulation of ion channels in the sense of taste

There are five fundamental tastes discovered so far: sweet, bitter, umami, sour and salty. Taste is mediated by the specialized neuroepithelial cells mainly located at the tongue papillae, namely taste receptor cells, which can be classified into type I, type II, type III and type IV. Ion channels are necessary for diverse cell physiological activities including taste sensing, smell experience and temperature perception. Existing evidences have demonstrated distinct structures and working models of ion channels. Epigenetic modifications regulate gene expression mainly through histone modifications, DNA methylation and non-coding RNA-mediated regulation, without altering DNA sequence. This review summarizes how ion channels work during the transduction of multiple tastes, as well as the recent progressions in the epigenetic regulation of ion channels.

Development of Miniaturized Interdigitated Electrode Sensors and Their Application in Taste Sensing

Interdigitated Electrodes (IDEs) or Interdigitated Arrays (IDAs) are frequently used in a variety of sensing mechanisms including electrochemical detection and have been subjected to extensive miniaturization in recent times. Multiple methods involving the fabrication of IDEs have been reported. However, these fabrication methods are often time consuming, multistep, skill intensive, expensive and require clean room conditions. This work reports on the fabrication and comparison of miniaturized IDEs fabricated using two inexpensive and clean room free approaches - inkjet-printing and direct laser writing (DLW) based photolithography. For inkjet-printing approach, a commercially available printed-circuit board (PCB) printer was used with a carbon ink to print the IDEs on a glass slide. For photolithography-based fabrication, a DLW system was used for the fabrication of IDEs on a copper-clad FR4 PCB board. Previously established, validated and reported models were employed for the design of IDEs. The design parameters were selected to optimize sensitivity while striking a balance with the overall size of the sensor. The application of the developed IDE sensors was demonstrated for its taste sensing capability. Sensing of five fundamental tastes, namely salty, sweet, sour, bitter, and umami, was established with electrochemical impedance spectroscopy (EIS). The chemicals which can simulate these fundamental tastes for experimental purposes were identified as sucrose (sweet), sodium chloride (salty), citric acid (sour), L-tryptophan (bitter) and guanosine monophosphate (GMP) (umami). EIS was performed on a benchtop electrochemical workstation with two electrode configurations and data was analysed in the frequency range of 1 Hz to 1 MHz. The obtained data was analyzed for different chemicals at varying concentrations and compared for changes in the response. DLW photolithography-based approach produces IDEs with excellent geometric dimensional repeatability. The IDEs produced on glass slides using Carbon ink-based printing were fabricated in under 2 minutes and cost less than US$ 0.3. Both approaches demonstrate the applications of IDEs with fairly reasonable and benchmarked taste sensing capabilities.Figure: a) Optimised Design b) Carbon ink-based printing c) IDE printed on glass slide d) Photlithography based DLW IDE fabrication e) IDE on a copper cladded FR4 PCR board. Figure 1

Artificial lipid membrane: surface modification and effect in taste sensing

In this work, an artificial lipid membrane was synthesized using tetra-dodecyl ammonium bromide (TDAB) and doped with gold nanoparticles (AuNP). The taste sensor designed using artificial lipid membrane is composed of tetradodecylammonium bromide (TDAB) as a lipid, dioctylphenyl phosphonate (DOPP) as a plasticizer, and polyvinyl chloride (PVC) as a supporting polymer in the ratio of 1:3:2. The lipid/polymer membrane acts as the recognition element which transforms the taste information generated by the chemical substances into an electric potential change. The fundamental taste analytes (like fructose for sweetness, HCl for sourness, NaCl for saltiness, MgCl2 for bitterness and MSG for umami) were used to study the effect of doping on taste sensing at different concentrations (10μM to 10mM). The study was based on the open circuit potential (OCP) change of the membrane with the analytes. The observations implicate that the doping increases the specificity of the artificially synthesized lipid membrane taste sensor for the sweet analytes, particularly for fructose.

Associations between human fungiform papillae and responsiveness to oral stimuli: effects of individual variability, population characteristics, and methods for papillae quantification.

Fungiform papillae (FP) on human tongue are the proxy structures designated to oral stimuli detection and transduction. However, the role of their density (fungiform papillae/cm2) in explaining oral sensitivity is still controversial. While early studies generally found that the responsiveness to oral stimuli increased as the number of papillae increased, recent large-scale studies failed to confirm this finding. The present paper reviews relevant studies dealing with the relationship between FP density and responsiveness to oral sensations including: fundamental tastes, 6-n-propyl-2-thiouracil (PROP), and sensations from trigeminal stimulation. Manual methods and automated methods for papillae detection and quantification are reviewed and their advantages and limitations highlighted. The main factors affecting FP density and functionality (age, gender, pathologic impairments) are also considered. Possible bias related to methodological issues in counting technique (equipment used, area and location of the tongue to count, procedures to validate the count), population sample (demographics), and sensory response collection (threshold or supra-threshold stimuli, intensity scaling) are illustrated. The lack of information related to the variability in taste pores density and the possible impairments due to nerve damages, may obscure the relationship between FPD and oral responsiveness.

Familiarity and Retronasal Aroma Alter Food Perception

Introduction When participants eat foods, they direct their attention to the particular taste quality that is the target of evaluation and subsequently perceive the intensity of the attended taste quality. We defined the ease with which participants pay attention to a particular taste quality as the “noticeability” of that quality. In our previous study, Japanese participants evaluated noticeability and intensity of five fundamental taste qualities (sweetness, umami, saltiness, sourness, and bitterness) under open- and closed-nostril conditions, using a popular traditional Japanese confection, yokan. The correlation between noticeability and intensity of sweetness was significantly reduced when participants were tested with open nostrils. Therefore, we hypothesized that high familiarity with a food and its olfactory information is necessary to decrease the correlation between these two scales.

Fabrication and implementation of printed sensors for taste sensing applications

This paper presents the design, fabrication, and implementation of low-cost taste sensors. A single-step procedure was performed using commercial polymer films to develop laser-induced graphene which was used as electrodes in sensor patches for taste sensing purposes. The cost of these sensor patches is less than two dollars based on the requirement for low-cost polymer films and Kapton tapes for developing the sensor patches. Five different chemicals corresponding to the five fundamental tastes of sour, sweet, salty, bitter and umami were tested with the developed sensors. The electrical parameters of the circuitry formed between the electrode-electrolyte interfaces during the experimental procedure were obtained by using the complex non-linear least square curve fitting technique by fitting a simulation curve to the Cole–Cole curve obtained from the experimental results. The sensor patches operating on a capacitive principle, exhibited significant differences in terms of their impedimetric responses for the kinetic processes taking place during the experiments, with different concentrations for each chemical. Four different concentrations were tested for each chemical to analyze the performance of the sensor for that particular chemical. A comparison between the responses of the five chemicals for each concentration was done to inspect the differences between their responses. An analysis of the differences in the conductivity response by the sensor patch for the five chemicals at a specific concentration was also done. The sensor patches did not show any hysteresis in their output responses, while obtaining significant repeatability when testing the chemicals with them. The response time of the sensor patches was around two seconds with the recovery time is 10min for the sensor being thoroughly washed and dried in between experiments The obtained experimental results from these sensor patches and their low cost, and easy fabrication process make them promising for their utilization in taste sensing purposes.

Comparative Study of Taste Substance Sensing by Liquid Membrane Oscillator and Electrochemical Systems With All-Solid-State Electrodes

In food industry, different types of sensors are used for characterizing and quantifying taste substances. Therefore, it is important to establish the principal advantages and disadvantages of these sensors for optimal application. In this paper, two possible systems are compared for sensing the four fundamental tastes: sour (citric acid), salty (sodium chloride), sweet (sucrose), and bitter (caffeine or quinine hydrochloride). One system is a bulk liquid membrane oscillator containing benzyldimethyltetradecylammonium chloride surfactant present during its transport in nitrobenzene membrane phase. The other system is based on all-solid–state electrode (ASSE) containing the same surfactant dissolved in polymer support. It was shown that the liquid membrane oscillator is significantly more sensitive to the presence of taste substances than the ASSE III system. Unfortunately, the functioning characteristics of this oscillator prevent it from steady, repetitive application in food quality control. On the other hand, ASSE III system shows remarkable stability on the long run. It was also found that a system composed of several ASSEs III, each containing different lipid compound, can distinguish successfully substances belonging to different taste classes. The obtained results suggest that such ASSEs III system can be used for food analysis.

Sucrose Octaacetate Chemical Kinetics and Shelf Lives at Various Formulation pHs.

Developing pediatric friendly dosage forms is a high priority worldwide. Sucrose octaacetate (SOA) has been recommended for use as a surrogate for bitter tasting active pharmaceutical ingredients. Even though SOA has found a number of human use applications and has been employed for decades, there are no rigorous chemical kinetic studies reported. A recently reported SOA stability-indicating method was used to perform SOA chemical kinetic and stability studies. As part of the chemical kinetic study, reaction order, activation energies, extrapolated rate constants, pH-rate profiles at 4 and 25°C, and estimated shelf lives at 4 and 25°C at different buffer pHs are provided. The estimated SOA shelf lives at 25°C and pHs 4.00, 5.20, and 6.00 were 25.3, 114, and 27.4days, respectively. At 4°C, SOA's estimated shelf lives were 0.478, 5.26, and 1.47years at pHs 4.00, 5.20, and 6.00, respectively. SOA can be formulated at pHs 4 to 6 and stored at 25°C for short-duration (less than 25days) uses such as a bitter tasting surrogate for fundamental taste mechanism studies or brief taste masking assessment clinical studies. For longer term solution studies, like being used as a bitter tasting control for blinded clinical trials, SOA should be formulated at the optimum pH of 5.40 and refrigerated at 4°C for maximum stability. The reported data can be used as a starting point for developing stable SOA formulations and estimating shelf life.

Lee Miller: A Woman’s War by Hilary Roberts

Reviewed by: Lee Miller: A Woman’s War by Hilary Roberts Beryl Pong Lee Miller: A Woman’s War. Imperial War Museum, London. October 15, 2015 – April 24, 2016. Lee Miller: A Woman’s War. Hilary Roberts, with an introduction by Antony Penrose. London: Thames & Hudson, 2015. Pp. 224. $55.00 (cloth). DELIGHTED YOUR WANTING TO JOIN US STOP YOUR INTELLIGENCE FUNDAMENTAL GOOD TASTE SENSITIVENESS ART VALUES MUST ULTIMATELY MAKE YOU GOOD PHOTOGRAPHER STOP SENDING CRITICISMS YOUR TRIAL PHOTOGRAPHS1 Condé Nast, the owner of Vogue who discovered Lee Miller in 1927 and turned her into a fashion model, had by 1940 begun to see her in a different light. As she transformed into a fashion photographer and then a wartime photojournalist, Miller joined Vogue in a different capacity. His telegram is nonetheless unambiguous about her being on “trial.” Indeed, one of Miller’s first photographs of World War II London was perhaps too inflected with those “art values” that Nast disdained. Focused on two young women posing coyly at the entrance to an air raid shelter in Hampstead, it portrays wartime fashion as oddly mechanical and macabre: the accouterments being modeled are not their dresses, but the black metal face masks and eye shields used for protecting against incendiary bombs. Their inhuman and robotic visages are presented with Miller’s characteristic mix of glamor and Surrealist humor. Unsurprisingly, Vogue did not publish the photograph. Not to be deterred, Miller eventually persevered and her insistence on the wartime setting, coupled with her idiosyncratic artistic signature, led to some of the most recognizable images of Blitzed London to appear in the magazine. Encompassing still life, fashion, portraiture, and documentary, her photographs by turns placed models in elegant suiting among bombsites, suggestively punned the shapes of shattered windowpanes with consumer trademarks, or chimed fresh with older ruins to suggest history’s recuperation of modern-day violence. [End Page 905] Click for larger view View full resolution Fig. 1. Self-portrait with sphinxes, London, England, 1940 © Lee Miller Archives, England 2016. All rights reserved. Miller’s photographs of Blitzed London are arguably her most well known, though they comprised a very limited section of the recent Imperial War Museum exhibition. In four rooms covering some 150 photographs, the focus instead is on images of Miller herself from her modeling days, and on her lesser-exhibited images of war-torn France, Germany, and Eastern Europe. These latter photos were made possible by her accreditation as an official U. S. Army war correspondent in 1942, which gave her access to military transport and to restricted theatres of war. It also enabled her to join the ranks of a small coterie of women correspondents like Martha Gellhorn, Mary Welsh, and Helen Kirkpatrick. Miller’s career in photography is complex and cannot be defined by her gender alone, but curator Hilary Roberts (who also put together the IWM’s 2012 exhibition of Miller’s arch-rival, Cecil Beaton) argues that Miller had a distinctively gendered approach to war journalism. As she notes in the exhibition catalogue, others often viewed Miller in terms of her gender and her femininity both before and after she became a war correspondent. The majority of her photographic subjects also continued to be women (17). There are a myriad of ways that men might not have been able to access the scenes Miller photographed: a group of socializing women in 1930s Egypt, for instance, whom she called the “black satin and white pearl set,” or a fresh laundry line with a nurse’s underwear hanging by a window (44). Yet, to understand her photography, one must also understand something of Miller as a person, especially her irreverent humor and interest in Surrealism. Both are evident in her documentation of the bizarre juxtapositions created by bomb blasts, and in her often-playful portraits of women in wartime. One photograph depicts an American nurse surrounded by a small wonderland of suspended surgical gloves; another, taken before a millinery show in liberated Paris, portrays fashion models resting against chairs, furniture legs protruding from their heads like rifle guns or unicorn horns. Where another recent exhibition of Miller’s work (in 2014 at Nottingham’s Djanogly Art...

Glucagon-like peptide-1 is specifically involved in sweet taste transmission.

Five fundamental taste qualities (sweet, bitter, salty, sour, umami) are sensed by dedicated taste cells (TCs) that relay quality information to gustatory nerve fibers. In peripheral taste signaling pathways, ATP has been identified as a functional neurotransmitter, but it remains to be determined how specificity of different taste qualities is maintained across synapses. Recent studies demonstrated that some gut peptides are released from taste buds by prolonged application of particular taste stimuli, suggesting their potential involvement in taste information coding. In this study, we focused on the function of glucagon-like peptide-1 (GLP-1) in initial responses to taste stimulation. GLP-1 receptor (GLP-1R) null mice had reduced neural and behavioral responses specifically to sweet compounds compared to wild-type (WT) mice. Some sweet responsive TCs expressed GLP-1 and its receptors were expressed in gustatory neurons. GLP-1 was released immediately from taste bud cells in response to sweet compounds but not to other taste stimuli. Intravenous administration of GLP-1 elicited transient responses in a subset of sweet-sensitive gustatory nerve fibers but did not affect other types of fibers, and this response was suppressed by pre-administration of the GLP-1R antagonist Exendin-4(3-39). Thus GLP-1 may be involved in normal sweet taste signal transmission in mice.

Retronasal aroma allows feature extraction from taste of a traditional Japanese confection

Abstract Background Common foods consist of several taste qualities. Consumers perceive intensity of a particular taste quality after noticing it among other taste qualities when they eat common foods. We supposed that while one is eating the facility for noticing a taste quality present in a common food will differ among taste qualities which compose the common food. We, therefore, proposed a new measurement scale for food perception named ‘noticeability’. Furthermore, we found that consumers’ food perceptions to common foods were modified by retronasal aroma. In this study, in order to examine whether retronasal aroma affects the relationship between noticeability and perceived intensity for taste, we evaluated participants for noticeability and perceived intensity of five fundamental taste qualities (sweetness, saltiness, sourness, bitterness, and umami) under open and closed nostril conditions using one of the most popular traditional Japanese confections called ‘yokan’. Results The taste quality showed that the highest noticeability and perceived intensity among five fundamental taste qualities for yokan was sweetness, independent of the nostril condition. For sweetness, a significant decrease of correlation between noticeability and perceived intensity was observed in response to retronasal aroma. On the other hand, for umami, correlation between noticeability and perceived intensity significantly increased with retronasal aroma. Conclusions As the retronasal aroma of yokan allowed feature extraction from taste by Japanese consumers, we reconfirmed that consumers’ food perceptions were modified by the retronasal aroma of a common food.

味覚定性定量検査 (濾紙Disc法) と電気味覚検査の相関性について

味覚定性定量検査 (濾紙Disc法) と電気味覚検査の相関性について

Flavor Lexicon for Sensory Descriptive Profiling of Different Rice Types

Rice flavor is a significant factor in determining quality and consumer acceptability as exemplified by scented rice, which is highly favored and commands a price premium. Sensory descriptive analysis has primarily been performed to assess rice flavor characteristics, but these studies feature only a limited lexicon for characterizing specific flavors or the range of flavor types is limited. This study was undertaken to establish a descriptive lexicon with reference standards for describing the flavor properties of a broad spectrum of rice types and use the developed lexicon to characterize which sensory attributes are most important in rice flavor quality. A rice flavor lexicon consisting of 24 descriptive notes was developed and expanded by 8 trained sensory panelists to characterize the flavor of cooked rice differing in terms of forms, types, and specialty (n = 36). Of these 24 descriptive terms, 19 were aromatic notes and 5 were fundamental tastes and oral feeling factors. Eighteen aromatic terms were significantly present in most rice samples whereas some descriptors exhibited unique characteristics of a specific-rice type. Subsequent multivariate analysis indicated that 18 descriptive terms were required to fully understand the characteristics of rice flavor in greater details. This lexicon covered a wider range of rice samples than in the previous studies and will facilitate targeting the characteristic notes important to rice processors as well as producers.

LEXICON TO DESCRIBE FLAVOR OF FRESH LEAFY VEGETABLES

ABSTRACT Trends such as organic farming and breeding to increase nutrition and functional health components have increased interest in understanding the flavor of vegetables, such as leafy greens. The main objective of this study was to select, define and reference a lexicon for describing the flavor of fresh leafy vegetables. A highly trained descriptive sensory panel determined a list of 32 sensory attributes that was able to describe the flavor of the fresh leafy greens studied. This lexicon includes five “green” attributes; mouthfeel characteristics such as pungent, bite, tooth‐etch and heat/burn; fundamental tastes including bitter and umami; seven terms that describe unique flavors related to specific vegetables such as cabbage, celery, lettuce, spinach, parsley, beet and radish leaves; and a group of other terms including citrus, piney, woody, water‐like, musty/earthy, floral, sulfur, metallic, soapy, petroleum‐like and overall sweet.PRACTICAL APPLICATIONSUnderstanding the effects that different breeding, growing, harvesting, shipping and storage technologies have on properties of leafy vegetables has increased the need for appropriate evaluation tools. Using this lexicon can guide researchers to a better understanding of differences in flavor among various fresh leafy vegetables and can help in understanding changes in flavors of those vegetables resulting from various alterations in the breeding and production systems. This project provides researchers with specific sensory terminology to track changes in fresh leafy greens instead of using generic terms such as “taste” or “typical flavor.”

Studies on a Taste-Recognition-Threshold Survey of Four Fundamental Tastes of Women's College Students in Tokyo

Studies on a Taste-Recognition-Threshold Survey of Four Fundamental Tastes of Women's College Students in Tokyo