Oral processing and oral comfort appreciation of whey-enriched dairy products by older adults

Consuming proteins rich in leucine, such as whey, has documented benefits for muscle health in older adults. The objective of this study was to evaluate the sensory suitability for this population of whey protein-enriched dairy products prototypes, resembling respectively a yoghurt and a cream cheese. Prototypes and in vitro boli were characterized instrumentally (rheology and tribology) and in vivo data on oral processing (microscopical characterization of expectorated boli) and oral comfort (sensory questionnaire) were acquired on a panel of 80 older adults. The rheological properties of both prototypes were comparable to those of some commercial yoghurt and cream cheese. Based on tribological measurements and compared to the yoghurt prototype, the cheese prototype showed higher lubrication properties, which even increased in presence of model saliva. The in vitro boli of cheese were also characterized by a shift in size of small particles, presumably free fat globules, into bigger particles. Microscopical observations of boli produced in vivo confirmed that larger fat droplets were formed by coalescence during food oral processing of the cheese prototype. In-mouth time residency and insalivation rates suggested that both prototypes required very little oral manipulation before swallowing. The sensory attributes sticky, pasty and melting were those contributing most to the oral comfort, but both prototypes were judged as very comfortable to eat independently of the dental status and salivary flow of the subjects. To conclude, these whey-enriched dairy products would be suitable as part of a diet aiming at optimizing protein intake in older adults.