Taste perception has been studied frequently in young and older adult groups. This paper systematically reviews these studies to determine the effect of ageing on taste perception and establish the reported extent of sensory decline. Five databases were searched from 1900 to April 2012. Articles relating to healthy ageing in human subjects were included, reviewed and rated (Downs and Black scoring system). Sixty-nine studies investigated the effect of ageing on taste perception; forty examined detection thresholds of which twenty-three provided sufficient data for meta-analysis, eighteen reported identification thresholds and twenty-five considered supra-threshold intensity perception. Researchers investigating detection thresholds considered between one and thirteen taste compounds per paper. Overall, the consensus was that taste detection thresholds increased with age (Hedges' g = 0 . 91, P < 0 . 001), across all taste modalities. Identification thresholds were reported to be higher for older adults in seventeen out of eighteen studies. Sixteen out of twenty-five studies reported perception of taste intensity at supra-threshold levels to be significantly lower for older adults. However, six out of nine studies concerning sucrose found perceived intensity of sweet taste not to diminish with age. The findings of this systematic review suggest taste perception declines during the healthy ageing process, although the extent of decline varies between studies. Overall, the studies reviewed had low Downs and Black scores (mean 16 (SD 2)) highlighting the need for more robust large scale and longitudinal studies monitoring the impact of ageing on the sensory system, and how this influences the perception of foods and beverages.Age: Taste: Threshold: Detection: IntensityOlder adults are at risk of under nutrition due to a multitude of physiological, psychological and socio-economic factors. Physiological factors are diverse, such as malabsorption of nutrients, infection, dysphagia, as well as loss of appetite and sensory decline. Older people frequently complain of blandness of foods or sensory changes that may influence their liking and subsequent consumption of food, further impacting on their risk of malnutrition (1) . Previous researchers have used taste enhancement, aiming to increase liking and consumption of meals by older adults, with conflicting results (2,3) . Therefore, in order to develop foods leading to improved liking and consumption by older adults, analysis of age-related changes in taste perception is essential. This paper systematically reviews the evidence for deterioration of taste perception within healthy ageing and discusses the extent of change.

Sensory perception has been found to change during ageing. The perception of mouthfeel by older adults, and the role of ageing on the sensory perception of texture attributes is uncertain. This study investigated perception of the textural attributes of thickness, mouth coating and mouth drying, in the context of dairy beverages, by older and younger adults. Just noticeable differences of a starch thickener and for cream concentration within milk were established for thickness and mouth-coating perception, finding no age-related differences between participant groups. Mouth drying was assessed through the directional paired comparison of a mouth-drying milk beverage to a skimmed milk sample. The older adults were found to be more sensitive to mouth drying (P = 0.03) than the younger adults. This study found no age-related decline in texture perception with older adults finding perception of some attributes such as mouth drying enhanced by ageing. PRACTICAL APPLICATIONSTexture is an important attribute of food and beverages at any age. The decline of olfaction, flavor and taste perception with age may force older adults to put more emphasis on texture attributes; therefore, understanding the perception of textural cues in the mouth is very important. This study found texture perception of thickness, mouth coating and mouth drying may not only be preserved but in the case of mouth drying enhanced during ageing. This may impact on the enjoyment and consumption of foods of older adults, especially during illness or when taking medication. This research study is essential in showing the impact of ageing on texture perception and highlight to the food industry, hospitals and care homes the importance of texture attributes when developing foods and meals for older adults and patients. bs_bs_banner Journal of Sensory Studies ISSN 0887-8250

This article is licensed under a Creative Commons Attribution 3.0 Unported LicenceHigh protein dairy beverages are considered to be mouth drying. The drying sensation may be due to the product protein content; however the mechanism of this mouth drying is uncertain. This study investigated the potential adhesion of milk proteins to porcine oral mucosa in vitro. Purified casein and ??-lactoglobulin were fluorescently labelled, placed on porcine oral mucosal tissues and their resistance to wash out with simulated saliva was monitored using fluorescence microscopy. Casein was found to be more adhesive to porcine mucosa than ??-lactoglobulin. Some investigation into the reason for this difference in mucoadhesion was conducted by thiol-content analysis, rheology and zeta-potential measurements. The higher viscosity of casein solution and smaller zeta-potential is believed to be responsible for its better retention on mucosal surfaces. These findings suggest that casein and whey protein are both capable of binding and eliciting mouth drying in high protein dairy beverages. ?? 2013 The Royal Society of Chemistry

Oral nutritional supplement drinks (ONS) are beverages high in dairy proteins that are prescribed to individuals at risk of malnutrition. Consumption of ONS is poor in elderly care facilities, with patients commenting that the sensory attributes of these drinks reduce their enjoyment and willingness to consume. Mouth drying is an attribute of ONS found to build with repeated consumption, which may further limit liking of these products. This study investigated the sources of drying sensations by sequential profiling, with a trained sensory panel rating a range of model milk systems and ONS over repeated sips and during after-effects. Sequential profiling found that fortification of milk with both caseinate and whey protein concentrate significantly increased the perception of mouth drying over repeated consumption, increasing by between 35 and 85% over consumption of 40mL. Enrichment of ONS with either whey protein concentrate or milk protein concentrate to a total protein content of 8.7% (wt/wt) resulted in whey and casein levels of 4.3:4.4% and 1.7:7.0% respectively. The product higher in whey protein was substantially more mouth drying, implying that whey proteins may be the most important contributor to mouth drying in ONS. However, efforts to mask mouth drying of protein-fortified milk by increasing sweetness or fat level were unsuccessful at the levels tested. Increasing the viscosity of protein-fortified milk led to a small but significant reduction in mouth drying. However, this approach was not successful when tested within complete ONS. Further analysis is required into the mechanism of protein-derived mouth drying to mask negative sensations and improve the enjoyment and consumption of protein-rich ONS.

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