The influence of chewing and oral lubrication on satiety using hydrogels

Certain oral processing strategies, such as slow eating, high number of chews and hard food textures, have been linked to lowering food intake in a systematic review and meta-analysis. Although oral lubrication is an important aspect of oral processing, its effects on satiation remain unclear. Therefore, this thesis aimed to study the effects of both chewing and oral lubrication on snack intake by developing model foods (non-fat hydrogels) with different textural properties. The methodology used in this thesis ranged from instrumental techniques to human trials. Instrumental (texture analysis, rheology, tribology) and sensory evaluations (descriptive analysis, n=11) were used to characterise simple and mixed hydrogels with/without inhomogeneity using different concentrations and ratios of biopolymers. Viscosity and friction coefficients (µ) of the hydrogel-boli were characterized after simulated oral processing. Results demonstrated that gel fracture properties were directly correlated to the chewing-related sensory attributes, such as ‘firm’, ‘elastic’ and ‘chewy’ (p < 0.05). On the other hand, µ at orally relevant speeds (3-50 mm/s) was inversely correlated to ‘pasty’ of the gel bolus fluid where the large bolus fragments were filtered out. In addition, it was questioned whether the eating capabilities (EC) of young healthy consumers can be a determining factor in oral processing. Using quantitative frame-by-frame video analysis (n=28), it was demonstrated that number of chews and oral residence time were mainly dictated by food material properties rather than EC of young panellists. The effects of these novel hydrogels on subjective appetite and objective intake of a salty snack were measured in a preload, between-subjects design (n=55). Results showed that oral lubrication rather than chewing resulted in a reduced snack intake after consuming a hydrogel preload (p < 0.05). In summary, manipulating oral lubrication is a promising new construct to reduce snack intake that merits future research in the oro-sensory satiety domain.