In-mouth breakdown behaviour and sensory perception of emulsion gels containing active or inactive filler particles loaded with capsaicinoids

Abstract

This work investigated the effects of active versus inactive filler particles on the structure, rheological properties, in vivo oral breakdown behaviour and sensory perception of emulsion gels containing capsaicinoids (CAPs). CAP-loaded Tween-80-coated emulsion droplets were not bound with the whey protein matrix (i.e. emulsion gels containing inactive filler particles) and appeared to be flocculated and inhomogeneously distributed in the gel matrix, which led to drastically decreased mechanical gel strength. CAP-loaded Tween 80 emulsion gels had significantly lower fracture stress and fracture stain than CAP-loaded whey protein emulsion gels (emulsion gels containing active filler particles), indicating that they were more easily broken down into small fragments in the mouth at small deformations with less chewing (i.e. lower fracture energy, fewer chewing cycles and shorter duration). During mastication, large amounts of oil droplets were released from the gel matrix of the CAP-loaded Tween 80 emulsion gels, which also contributed to their significantly smaller bolus particle size. The released oil droplets from the CAP-loaded Tween 80 emulsion gels facilitated bolus formation through lubrication and decreased the chewing cycles. A higher degree of fragmentation led to greater surface exposure (i.e. new surface area created) during mastication, and therefore to higher mouth burn perception. The large amounts of oil droplets released from the gel matrix during mastication and the inhomogeneous distribution of the oil droplets because of flocculation of the CAP-loaded Tween 80 emulsion gels also contributed to their higher mouth burn perception. The oral processing behaviour of the CAP-loaded emulsion gels and the sensory perception of capsaicinoids could be tuned by manipulating the droplet-matrix interactions and the gel structure.