Abstract
Texture affects liking or rejection of many foods for clinically relevant populations and the general public. Phenotypic differences in chemosensation are well documented and influence food choices, but oral touch perception is less understood. Here, we used chocolate as a model food to explore texture perception, specifically grittiness perception. In Experiment 1, the Just Noticeable Difference (JND) for particle size in melted chocolate was ~5 μm in a particle size range commonly found in commercial chocolates; as expected, the JND increased with particle size, with a Weber Fraction of ~0.17. In Experiment 2, individual differences in touch perception were explored: detection and discrimination thresholds for oral point pressure were determined with Von Frey Hairs. Discrimination thresholds varied across individuals, allowing us to separate participants into high and low sensitivity groups. Across all participants, two solid commercial chocolates (with particle sizes of 19 and 26 μm; i.e., just above the JND) were successfully discriminated in a forced-choice task. However, this was driven entirely by individuals with better oral acuity: 17 of 20 of more acute individuals correctly identified the grittier chocolate versus 12 of 24 less acute individuals. This suggests phenotypic differences in oral somatosensation can influence texture perception of foods.
Highlights
Food texture is a perception[1], arising from the interaction of a food with mechanoreceptors in the oral cavity; it depends on the physical structure of the stimulus, and the neural impulses carried by multiple afferent nerves[2]
We describe two novel experiments on the ability of naïve chocolate consumers to discriminate between different particle sizes in dark chocolate
Individual differences in oral point-pressure sensitivity were assessed as measures of oral somatosensory function, and a significant relationship was observed between differences in clinical measures of oral somatosensory function at the tongue tip and texture perception of dark chocolate
Summary
Food texture is a perception[1], arising from the interaction of a food with mechanoreceptors in the oral cavity; it depends on the physical structure of the stimulus, and the neural impulses carried by multiple afferent nerves[2]. Physical force is applied to the cocoa paste to break down the cocoa and sugar particles into smaller sizes. This step is a common bottleneck in production, as finer particle sizes require more processing time and higher energy inputs[11]. When measured via laser diffraction, this value correlates with the sensory perception of the largest particles[9]. Another widely used parameter is the D(4,3) value, which refers to the volume or mass moment mean (i.e., the De Brouckere mean diameter). The closest we have been able to find is a 1967 report by Rostagno, who reported that chocolate was unacceptably coarse when 20% of the particles exceed 22 μm[13]
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