Making taste and mouthfeel objectively measurable

An important step has been taken in better understanding taste and taste composition: the 'mouthfeel model' turns out to be a useful basis for measuring taste. This is an important conclusion from the thesis: 'Unraveling Mouthfeel. A novel approach to understanding taste' by Georgios Agorastos. 

The success rate of new food products and food reformulation is currently below 20%. "A major reason for that high failure rate is the mismatch between consumer expectations and preferences and the food’s sensorial properties," argues Georgios Agorastos. He successfully defended his dissertation in Maastricht on July 13, and may now call himself a doctor. "A better understanding of the sensory properties of foods and their origins can help to market more successful products. This requires methods that can capture sensory properties." 

"Understanding and being able to measure those properties of food is more difficult than it sounds," said the doctoral student. "The use of subjective evaluation methods, such as sensory analysis by taste panels, is influenced by psychological and physical factors. Moreover, the taste panel method is expensive, time-consuming, not very repeatable and reproducible. And there is still no well-defined lexicon between industry, food researchers/designers and consumers." 

The mouthfeel model

The hypothesis that flavor could be classified based on mouthfeel and flavor intensity was first supported scientifically by Peter Klosse (The Concept of Flavor Styles to classify flavors, Maastricht 2004). The TASTE Foundation spent the following years deepening research on taste and the role of saliva in tasting. The mouthfeel model unites the classical sensory taste approach and the molecular perspective of food technology. Georgios' doctoral research allowed physical-chemical analyses to be correlated with sensory observations from taste panels and the main parameters of the mouthfeel model. The analyses were performed in the university laboratories of Maastricht and Wageningen.

The research, made possible thanks to support from the Province of Limburg, first focused on increasing the understanding of the origin of oral sensations based on physical changes in human saliva. The new insights were used to improve chemical measurements. The agreement between sensory features with chemical measurements were evaluated by chemometric analysis (see box). Predicting or measuring "taste" based on chemical measurements is a valuable tool for the food industry and researchers. Quantifying taste objectively requires a good understanding of the various components and their properties. 

Understanding salivary lubrication

The findings from the study offer new insights into the role of saliva in tasting, and the mechanisms responsible for drying sensations during food consumption. The results show that applied chemical analyses related to sensory sensations are strongly correlated with sensory characteristics. These results suggest that oral sensations can be classified on the basis of tactile sensations and chemosensory sensations (the molecule-receptor interaction). Tactile sensations, such as coating and drying, are negatively associated with each other. Chemosensory sensations do not affect tactile sensations.

Measuring both polyphenols and cations concentration and their molecular characteristics could potentially be used to predict dryness perception. For example, changes in salivary composition appear to be very important for the perception of oral sensations. Cationic properties (such as valencies, or "the maximum number of bonds an atom of a given chemical element can form with other atoms") influence the salivation lubrication properties," the sliminess, of saliva. The interaction of polyphenols with salivary proteins decreases this lubricity, while larger molecular particles and lower pH increase friction. "Innovative chemical analyses and chemometric techniques can very likely be used in the future to predict oral sensations. This means that devices such as artificial tongues can potentially be used to replace the existing subjective sensory evaluations, i.e. taste panels, provided that these instruments are based on a useful model for taste classification."

Product development

Georgios concludes that assessing the influence of saliva on mouthfeel, taking into account age and medication effects, can optimize the development of personalized nutritional products and dietary interventions for diverse populations. "The model needs further investigation, but product developers in the food industry can already use the new strategies to increase the success rate of new products and product reformulations."

Chemometrics is an umbrella term for a number of tools for simplifying large sets of data and making variations visible. In the food industry, chemometrics is used to determine the gross composition of food with a measurement. NIR (Near-Infrared) spectroscopy can be used to determine, for example, the amount of moisture, and fat and protein content. Especially with food products, many components absorb near-infrared. This creates spectra consisting of overlapping absorptions. The naked eye often cannot detect correlations here. Chemometry helps to link the differences in the spectra to the varying compositions of the foods.

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