The study, published in the Journal of Sensory Studies, investigated how the addition of a lipid emulsion affected the perception of the five human tastes, namely sweet, sour, salty, bitter and umami.
“These results suggest that, depending on the type of tastant used, the presence of a lipid phase in an emulsified form may alter the sensory perception of foods,” said the researchers.
The authors, led by Silvana Martini, assistant professor at the Department of Nutrition, Dietetics, and Food Sciences at Utah State University said that gaining a better understanding of the mechanisms associated with taste perception will help formulate new food products with improved sensory and health characteristics.
“Current tendencies of incorporating a healthy diet in consumers' everyday lives have challenged food manufacturers to produce foods with improved nutritional qualities while maintaining their sensory characteristics. Some of these improvements include the formulation of low-sodium, low-carbohydrate and/or low-fat products,” said the researchers.
Previous research has suggested that the composition of fats in an emulsion can have significant effects on the taste profiles and thresholds of the five tastes, said the authors.
They added that research suggesting certain lipids – such as cis-polyunsaturated fatty acids – can be detected by taste receptor cells in the mouth, and possibly influence the perceptions of other tastes, are becoming widely accepted.
They noted that linoleic acid has been shown to significantly raise the taste thresholds for citric acid, sodium chloride (NaCl) and caffeine in previous research, whilst tuna-soybean oil and high-oleic corn oil have been suggested to lengthen taste perception duration in previous studies.
“In spite of all of the research that has been performed, our understanding of how lipids are detected by taste receptor cells and of the effects of their detection on various physiological factors and sensory phenomena is still limited,” said Dr Martini and colleagues.
They said that questions related to how differing concentrations of fatty acids may affect taste thresholds and intensities, and whether these effects are strongly dependent upon the type of fatty acid or tastant involved, remain unanswered.
“The objective of this research was to systematically examine how lipid addition, in the form of emulsions, and lipid composition affect taste thresholds …of the five tastes (i.e., sour, umami, bitter, salty and sweet) in 20% oil-in-water emulsions,” said the researchers.
The researchers used specific tastants to represent the five tastes: citric acid, MSG, quinine hydrochloride, sodium chloride and sucrose, representing sour, umami, bitter, salty and sweet tastes, respectively.
They reported that the addition of emulsified lipids significantly increased taste thresholds for sour and bitter tastes produced by citric acid and quinine hydrochloride, respectively.
In comparison, they said that the presence of a lipid phase increased the perception of umami and saltiness, with higher intensity values observed in the emulsions.
The addition of lipid was seen to have no effect on the intensity of sweet flavours.
The authors said that it is important to note that the study was performed with three lipid systems with different chemical compositions and a specific emulsifier. They warned that caution must be taken if attempting to extrapolate their results “to the entire universe of fats, oils and emulsifiers.”
“In addition, tastant intensities tested in this research were “near-threshold” intensities,” said the researchers.
“Results obtained in real food systems, with other ingredients … might differ from the ones reported in this research,” they added.
Source: Journal of Sensory Studies
Volume 25, Issue 6, pages 861–875, doi: 10.1111/j.1745-459X.2010.00311.x
“Effects of three emulsion compositions on taste thresholds and intensity ratings of five taste compounds”
Authors: J.E. Thurgood, S. Martini