Dynamic texture perception, oral processing behaviour and bolus properties of emulsion-filled gels with and without contrasting mechanical properties

Abstract

Many highly palatable foods are composed of multiple components which can have considerably different mechanical properties leading to contrasting texture sensations. The aim of this study was to better understand the impact of contrasting mechanical properties in semi-solid gels on oral processing behaviour and dynamic texture perception. Four reference emulsion-filled gels without mechanical contrast were prepared using agar (1 or 2 wt%) or gelatine (2.5 or 5.5% wt). Six emulsion-filled gels with contrasting mechanical properties were obtained by combining two different gel layers. Agar reference gels displaying low fracture strain produced boli with many small particles and were perceived as grainy. Gelatine reference gels displaying high fracture strain produced boli with few large particles which melted in mouth and were perceived as creamy. Reference gels with large fracture stress were masticated for long times with a high chewing muscle activity and perceived as firm and grainy. Bolus properties, oral processing behaviour and dynamic sensory perception of the 6 contrasting gels were compared to the 4 reference gels using Principal Component Analysis. The presence of an agar layer in contrasting gels dominated bolus properties which contained many small particles and did not mix readily in mouth. The temporal sensory profiles and sensory trajectories of contrasting gels fell between the temporal sensory profiles and sensory trajectories of the two gel layers which they were composed of. We conclude that distinct features of dynamic texture perception in emulsion-filled gels with mechanical contrast are perceived separately in mouth.