Abstract/Summary

Whey proteins are associated with numerous positive benefits and are commonly fortified into products. These products are often utilised in an ageing population to improve nutritional status. However, whey protein fortified products typically have negative mouthfeel attributes, likely to intensify with age, subsequently impacting compliance and acceptance. Accordingly, this thesis aimed to investigate mouthfeel perception (predominantly mouthdrying) in two whey models: liquid model (whey beverages) and solid model (cakes, biscuits, cupcakes and scones), with or without whey protein fortification, and the extent of modulation from individual differences. Consumer studies were carried out using healthy volunteers (18-30 and/or 65+ years) to: (a) rate individual liking and perception of products; (b) collect saliva samples post beverage consumption to measure mucoadhesion (oral retention) in the oral cavity; and/or (c) measure individual differences (saliva flow, dental status, mouth behaviour, appetite and sensory thresholds). Additionally, a sensory panel (n = 12) evaluated whey models via descriptive sensory profiling and determined a mouthdrying detection threshold in whey protein beverages (WPB). Results demonstrated whey protein causes mouthdrying regardless of food model. WPB mouthdrying was detected at low protein levels and mucoadhesion was a suggested causal mechanism. Fortified solid models were also associated with reduced liking and modulated mouthfeel (moistness, chewiness and hardness). Age-related differences were present where older adults had reduced unstimulated saliva flow and increased mucoadhesion (WPB), mouthdrying sensitivity (WPB thresholds) and chewiness (fortified scones). However, measured individual differences (saliva flow, dental status, mouth behaviour and appetite) were not significantly related to mouthdrying perception. Two mitigating strategies successfully reduced mouthdrying: increasing lactose levels in WPBs via cross-modal suppression and adding cream topping to scones by enhanced lubrication. In summary, all tested whey protein fortified products were mouthdrying and mouthfeel sensitivity altered with age. These products can help to alleviate malnutrition and impede sarcopenia; however, they need an acceptable mouthfeel.