The emulsion-filled gels with different fat contents exhibit various friction behavior and dynamic fat-related texture perception at different temperatures

Abstract

In vitro studies on the friction of emulsion systems often neglect the food dynamic temperature changes within the oral cavity. This study aims to establish the relationship between sensory attributes and tribological parameters under dynamic temperature to practically reflect the food perception change in different stages of oral processing. The impact of distinct temperatures (10, 25, and 35 °C) on the tribological attributes and temporal dominance of sensations (TDS) data of emulsion-filled gel containing different fat levels (0–10.5 %, w/w) under simulated oral processing conditions was evaluated. The results showed that as the temperature increased, the peak friction coefficient of the gel bolus decreased, and the difference in friction coefficient among gel boluses with different fat contents decreased. The sensory trajectory map revealed that high-fat gels exhibited a greater diversity of attributes perceived at particular moments and extended overall trajectory paths compared to their low-fat counterparts. A heat map and principal component analysis were conducted to elucidate the correlation between friction coefficients and TDS data. The strongest correlations with sensory attributes were identified in the friction coefficients recorded at sliding speeds of 1 mm s⁻¹ at 10 °C and 35 °C and 1–50 mm s⁻¹ at 25 °C. Notably, the sensory attributes spreadability, thickness, smoothness, and mouth-coating were found to be highly negatively correlated with these friction coefficients (P < 0.01). This study provides a basis for better characterizing the fat-related textural perception of emulsion-filled gels, and highlighting the critical role of fat content and temperature in optimizing sensory perception and product design.