Sci Review: An overview of binary taste–taste interactions

Few words about of this science paper

Dr. Russell S.J. Keast

Current employment: Deakin University, AU

Research interests: Professor Keast’s research is primarily concerned with the sense of taste and it’s role with food choice. Using sensory evaluation techniques combined with nutritional assessment, the majority of Professor Keast’s published research has focused on understanding the taste system, in particular how knowledge of taste may be associated with dietary consumption and development of diet-related disease.

Awards: New Jersey Pharmaceutical Association Award for research on bitterness inhibition.

Deakin University

Dr. Paul Breslin

Current employment: Rutgers University, USA

Research interests: Professor Keast’s research is primarily focused on genetic basis of human oral perception and its impact on nutrient intake. on taste perception with an emphasis on taste discrimination, taste enhancement and suppression, and taste localization. He also studies oral irritation, mouthfeel, and astringency. The interactions among gustation, chemesthesis, and olfaction that comprise flavor are the topic of an ongoing research program that includes fMRI as a tool to understand regional brain involvement.

Awards: Over 17 awards. One of latest:

2016 Bill & Melinda Gates Award for Ameliorating Bitterness of Pharmaceuticals

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Paper abstract

The human gustatory system is capable of identifying five major taste qualities: sweet, sour, bitter, salty and savory (umami), and perhaps several sub-qualities. This is a relatively small number of qualities given the vast number and structural diversity of chemical compounds that elicit taste. When we consume a food, our taste receptor cells are activated by numerous stimuli via several transduction pathways. An important food-related taste question which remains largely unanswered is: How do taste perceptions change when multiple taste stimuli are presented together in a food or beverage rather than when presented alone? The interactions among taste compounds is a large research area that has interested electrophysiologists, psychophysicists, biochemists, and food scientists alike. On a practical level, taste interactions are important in the development and modification of foods, beverages or oral care products. Is there enhancement or suppression of intensity when adding stimuli of the same or different qualities together? Relevant psychophysical literature on taste–taste interactions along with selected psychophysical theory is reviewed. We suggest that the position of the individual taste stimuli on the concentration-intensity psychophysical curve (expansive, linear, or compressive phase of the curve) predicts important interactions when reporting enhancement or suppression of taste mixtures.

Main takeaways

There are four properties that make individual taste sensations unique, their:

  1. quality,
  2. intensity,
  3. temporal and
  4. spatial patterns

The attribute ‘‘quality’’ is a descriptive noun given to categorize sensations that taste compounds
elicit; there are five major taste quality descriptors:

  1. sweet,
  2. sour,
  3. salty,
  4. bitter and
  5. umami.

The attribute ‘‘intensity’’ is a measure of the magnitude of sensation(s) elicited by a compound at a given time. The ‘‘temporal’’ pattern of a compound is related to the time course of the intensities. And finally the ‘‘spatial’’ topography relates to the location of taste sensations on the tongue and oral cavity.

As a general heuristic, when two or more taste stimuli (above threshold) are mixed together the intensity is less than the sum of the individual taste intensities. This is called mixture suppression. Bartoshuk (1975) has proposed that all three phases (compressive, linear, expansive) exist for taste stimuli, although not for one stimulus.

Simple sigmoidally-shaped psychophysical (picture below) demonstrated that at very low concentrations of sapid compound the taste intensity can grow in exponential fashion, at medium concentration the perceived intensity can increase in linear fashion, at higher concentrations the perceived intensity may plateau. Three specific regions of a typical psychophysical concentration intensity function. Stevens power law (Stevens, 1969) can be applied to taste: I ¼ kCn where I is the perceived intensity, k is a constant related to the tastant, C is the concentration of the taste compound, and n is the exponential variable associated with the shape of the curve.

As a general heuristic, when two or more taste stimuli (above threshold) are mixed together the intensity is less than the sum of the individual taste intensities. This is called mixture suppression. Bartoshuk (1975) has proposed that all three phases (compressive, linear, expansive) exist for taste stimuli, although not for one stimulus.

Simple sigmoidally-shaped psychophysical (picture below) demonstrated that at very low concentrations of sapid compound the taste intensity can grow in exponential fashion, at medium concentration the perceived intensity can increase in linear fashion, at higher concentrations the perceived intensity may plateau. Three specific regions of a typical psychophysical concentration intensity function. Stevens power law (Stevens, 1969) can be applied to taste:

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where I is the perceived intensity, k is a constant related to the tastant, C is the concentration of the taste compound, and n is the exponential variable associated with the shape of the curve.

Based on a common understanding in the literature, enhancement equates to 1+1>2, additivity to 1+1=2, and suppression to 1+1<2.

Conclusions for same quality binary taste interactions show that in general, same quality interactions are often predicted by a sigmoidal shaped psychophysical function, with expansive, linear or compressive phases. The greater the intensity/concentration the more reports of suppressive interactions. For two qualities, sweet and umami/savory there is significant evidence of synergy of taste intensity (a peripheral effect) when two compounds eliciting the same quality are mixed together.

Conclusions for different quality binary taste interactions shows that at low intensity/concentration enhancement is reported more often, at moderate intensity/concentration there is a mix of enhancement, suppression and linear interactions, while at high intensity/concentration suppression is most common.

Schematic review of binary taste interactions. (a) represents a review of interactions of taste qualities from the expansive portion of the curve
Schematic review of binary taste interactions. (b) represents the linear phase
Schematic review of binary taste interactions. (c) the compressive phase.

Conclusions for Trinary or more complex taste mixtures have proven that when three or more (n) compounds around threshold (very low to low intensity) are mixed, their thresholds are mutually reduced by about 1/n x threshold. With the exception of sour, subsequent additions of taste eliciting substances caused a decrease in quality intensity.

Implementation

Implementation of information provided in this paper goes much beyond just commercial food chains and academic circles.  We can see awesome utilization of this information in every day cooking as well as in the professional culinary and gastronomic circles.

Overall review

This is  the best science paper that we have read in the long time. It is full of really utilizable theoretical and experimental content which is based on over 127 scientific sources and numerous experiments. Reading this paper you can gain insight into how taste compounds mutually interact. Extremely interesting material which can serve as foundation for future experimental research and implementation especially in food industiry & hospitality.

Overall rating:
5/5

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