Examination of chemical irritation and textural influence on food preferences in two age cohorts using complex food systems

Factors Affecting Adherence, Intake, and Perceived Palatability of Oral Nutritional Supplements: A Literature Review

Oral nutritional supplements (ONS) are a clinically effective and relatively inexpensive way to supplement the diet of patients with, or at risk of, undernutrition. Good adherence is a primary determinant of the effectiveness of ONS. However adherence can be problematic for those with the greatest clinical need, such as undernourished older adults. This review aimed to appraise the available literature for the factors (contextual, personal and product related) affecting patient adherence and perceived palatability of ONS, identify areas requiring improvement and uncover gaps in the evidence to guide the focus of future research. Contextual factors identified were healthcare staff and the timing of administration. Personal factors included sensory changes and motivation which alter experience of and desire to consume ONS. The product's sensory characteristics determined palatability and intake, but undesirable attributes, such as off-flavours, can stem from nutritional ingredients. The contribution made by aroma to older adults' experience of ONS was a comparatively under-researched area. Further research should address this evidence gap to optimise the flavour, aroma profile and palatability for undernourished older consumers, thereby optimising intake. A combined multidisciplinary effort involving strategic expansion of research, industry development and clinical practice should simultaneously address the factors identified, to provide the best approach to improve adherence.

Pungency perception and liking for pasta filata cheeses in consumers from different Italian regions

We aimed to investigate whether the sensitivity to capsaicin had an effect on pungency perception of pasta filata cheeses. In addition, we assessed the effect of several individual variables (gender, age, consumer provenance, PROP status and personality traits) on both consumer liking and choice for pasta filata cheeses. Four pasta filata cheeses at two ripening times and 272 subjects from three different Italian locations were used. Based on sensory data, the PCA discriminated sweet (ripened at 2 months) from pungent cheeses (ripened at 12 months). Cheese pungency perception increased with increasing sensitivity to capsaicin (P < 0.001). There was no clear relationship between sensitivity to capsaicin or sensitivity to cheese pungency with cheese liking, whereas a number of other aspects, including sensory attributes and individual consumer characteristics, such as consumer provenance (P < 0.001), gender (P < 0.001) and food neophobia (P < 0.05), affected the liking for different pasta filata cheeses. Consumers who were younger (18-30 y.o.; P < 0.05), female (P < 0.001), unfamiliar with pungent foods (P < 0.0001) and consumers from Potenza (P = 0.001) more often declared to prefer sweet over pungent cheese, whereas in terms of real choice supertasters and neophobic subjects chose the sweet option more often (P = 0.01). In conclusion, sensitivity to capsaicin affected pungency perception in pasta filata cheese, whereas no clear relationship was observed between pungency perception and liking. The contribution of cheese and consumer characteristics on cheese liking and choice in addition to pungency, was confirmed by the differences in declared and real choice for sweet or pungent cheeses.

How addition of peach gel particles to yogurt affects oral behavior, sensory perception and liking of consumers differing in age

Addition of particles to foods, such as fruit pieces to dairy products or vegetable pieces to soup, is a convenient approach to alter nutritional composition, appearance, perception and acceptance. The aim of this study was to investigate the effect of addition of peach gel particles to yogurt on oral behavior, sensory perception and liking of consumers differing in age. One homogeneous yogurt and seven yogurts with peach gel particles were prepared. The added peach gel particles varied in size, fracture stress, or concentration. Oral behavior of n = 62 healthy Dutch, young adults (21 ± 2 years) and n = 62 healthy Dutch elderly (70 ± 5 years) participants was characterized by video recordings. Yogurts' sensory properties and liking were scored on nine-point scales. Elderly consumed yogurts with higher number of chews and longer consumption time leading to lower eating rate than young adults. Addition of particles, regardless of characteristics, increased number of chews, consumption time, and decreased eating rate up to 60% for both consumer groups, with an average decrement of 110 g/min for young and of 63 g/min for elderly consumers. With increasing peach gel hardness and concentration, the number of chews and consumption time increased while eating rate decreased. Peach gel particle size did not affect oral behavior. Sensory perception of yogurts with added peach gel particles was similar for healthy young adult and healthy elderly. Only small differences in sensory perception were observed between the young adults and elderly for flavor attributes, crumbliness, juiciness, and perceived particle size. Similarly, minor differences in liking of a few yogurts with peach pieces were observed between both consumer groups. Thus, healthy ageing seems to affect sensory perception of semi-solid foods to a limited extent only. We conclude that changes in food texture by addition of particles can be used as a strategy to steer eating rate and potentially impact food intake of young adult and elderly consumers while maintaining or enhancing food palatability. Additionally, particle characteristics can be modified to target specific consumer groups that might differ in eating capabilities.

How sensory sensitivity to graininess could be measured?

Considering the lack of the literature and the need for developing a valid method to measure the texture sensitivity, in this study, we investigated the individual sensitivity to discriminate among different levels of graininess. With this purpose, five samples of cocoa-based creams were prepared, by changing the refining time. Samples were first characterized in terms of particles size distribution, by means of laser diffraction. Then, 59 subjects evaluated the cream sample graininess intensity, by using gLM scales, and their liking, by using LAM scales. The graininess scores of each subject were fitted with a power model, already observed with the instrumental results, estimating both the power law exponent and the R² coefficient, and using them as clustering parameters. Subjects were then clustered into three groups: high sensitivity; moderate sensitivity; low sensitivity. First, as it was hypothesized, results showed a significant difference between the three groups in terms of perceived graininess. Second, even though results showed a significant difference between the three groups in terms of perceived graininess, only little differences were found in terms of liking scores. Indeed, all the samples were equally liked for both the moderate and low sensitivity groups, whereas a significant trend was observed for the highly sensitive subjects who liked more the most refined samples. No significant relationships were found with age, and only a little trend was observed with gender: females seemed to be more sensitive than males. Texture attributes discrimination ability, as for example sensitivity to graininess, could affect food rejection or preferences and choice, but it is poorly investigated. This exploratory study, proposes a method to cluster consumers, based on their sensitivity. A statistical methodology has been developed to discriminate among consumer sensitivity levels. The results provide useful information about graininess sensitivity suggesting that the used methodologies could be applied to other texture properties resulting in a valid tool for the industry in the development and optimization of tailored new products.

Altered Salivary Flow, Protein Composition, and Rheology Following Taste and TRP Stimulation in Older Adults

Taste and smell perceptions diminish in older age, impacting upon quality of life and nutrition, yet the causes of taste loss are largely unknown. Transient receptor potential channels (TRP) found on the oral mucosa are also involved in oral sensations including cooling and burning and may contribute to the eating experience of older people. Older adults often have reduced salivary flow and the physical properties of saliva may change, but the role of saliva in oral sensations of older adults is yet to be elucidated. Here, the effect of older age on subjective (perception) and objective (stimulated salivary response) measures of TRP stimulants, odors, and basic tastants was investigated. Whole mouth saliva was collected from younger (mean age 24 years) and older adults (mean age 72 years) following stimulation of taste [mono sodium glutamate (MSG) and caffeine], olfaction (menthol), and TRP receptors (capsaicin). Participants rated perceived intensity of each stimulus, and salivary properties were assessed. Older age was associated with 15% lower umami taste and 26% lower menthol odor perception, coupled with 17% lower salivary response to MSG. Interestingly, there were no differences for perception of TRP stimulants, so chemo-sensation was not affected by age. Younger adults had four times greater elasticity (Spinnbarkeit) with MUC7 levels almost double and 66% greater resting salivary flow rate. Stimulated salivary responses in the younger group were also higher compared to the older group, with changes in protein and viscoelasticity in response to taste and TRP stimulation. These results show the impact of older age upon taste and smell sensation which may lead to changes in the physical and compositional properties of saliva in response to taste/odor stimulation. Measurement of stimulated salivary flow and rheology provides an objective measure of taste in addition to subjective perceptions which can be influenced by participant bias. Chemo-sensation may be retained with age and trigeminal stimuli such as chili could be employed in future studies to enhance meals for an age group at risk of malnutrition. Alteration in salivary properties due to advanced age could impact on ability to taste due to poor diffusion of tastants and reduced oral surface protection.

Electronic Tongue and Consumer Sensory Evaluation of Spicy Paneer Cheese

Evaluating sensory properties of spicy foods can be challenging due to how quickly individuals experience fatigue. Analytical methods, such as HPLC quantification of capsaicin, are accurate. However, they may not always be interchangeable with perception of spiciness by consumers. The electronic tongue (e-tongue) offers a unique opportunity to simulate human perception of capsaicin pungency with an analytical method. This study evaluated consumer's and the e-tongue ability to discriminate among paneer cheese samples containing different levels of capsaicin (1.875, 3.75, 7.5, 15, and 30 ppm). Over 2 days, using a blocked design to minimize fatigue, consumers (n = 110) evaluated samples using a difference from control sensory test. Consumers distinguished the spicy paneer sample from the control (0 ppm) at 3.75, 7.5, 15, and 30 ppm (P < 0.05). Differences were found among sample 3.75, 7.5, and 15 ppm (P < 0.05). However, no significant differences were found between control and 1.875 ppm or between samples 15 and 30 ppm. Although these high and low concentrations were challenging for consumers, the e-tongue resulted in a high degree of discrimination of 93% among all samples. On the principal component analysis plot created by the e-tongue, PC1 explained 85.6% of the variability and was associated with spicy, sweet, salty, sour, and umami sensors. PC2 explained 7.96% and was associated with the bitter and metallic sensors. The 3.75 and 15 ppm samples were defined by PC1, while PC2 defined samples 1.875 and 30 ppm. These results conclude that the e-tongue may be useful in qualitative discrimination among spicy paneer along with sensory evaluation. PRACTICAL APPLICATION: As the market for spicy foods continues to grow, methods for rapid, accurate analysis of the sensory qualities of the food products is needed. As the electronic tongue discriminated effectively among spicy paneer cheese samples, the method could be used alongside sensory testing to evaluate spicy food samples without encountering the typical issues of fatigue common with evaluating spicy foods.

On Your Own: Older Adults' Food Choice and Dietary Habits

The United Kingdom, in common with many countries, has an ageing demographic. Changes accompanying ageing can influence food choice and dietary habits. This study explored older adults’ perceptions and practices related to dietary behaviour and the factors influencing their food choice in later life. Semi-structured focus-group discussions were conducted with 30 individuals (aged 63–90 years) in a UK city. An inductive thematic approach was adopted for data analysis, and 4 themes and 12 sub-themes emerged: age-related changes (lower appetite, food changes, declining physical function); food access (food cost, support with food, maintaining independence); on your own (cooking for one, eating alone, shopping for one); and relationship with food (food variety, eating what you want, dieting). These influenced participants’ food acquisition, food preparation and cooking, as well as eating habits. Living alone and its substantial influence, as well as associated social isolation and loneliness, were highlighted in many of the discussions. Given the possible implications for nutritional intake, further work is recommended in this area. Likewise, steps should be taken to improve food access, increase opportunities for commensal eating and, fundamentally, address social isolation and loneliness in the older population.

Association between Salivary Hypofunction and Food Consumption in the Elderlies. A Systematic Literature Review

OBJECTIVES

This systematic literature review aims to summarize the existing scientific evidence about the association between a reduced salivary function and food consumption in elderly people.

METHODS

A validated search strategy in two databases (PubMed and ISI Web of Knowledge) was carried out and retrieved papers together with their reference lists were screened by two independent reviewers. The quality of the included studies was critically appraised via the Quality Assessment Criteria for Evaluating Primary Research Papers.

RESULTS

From the originally identified studies (n=391), only 15 articles (all cross-sectional studies) met the pre-fixed inclusion/exclusion criteria. The methodological quality of the included studies was in general good, although only 3 from 15 obtained the maximum score. The control of confounding factors was the quality variable more poorly rated in the selected studies. Salivary hypofunction was associated with a decrease of the objective chewing and swallowing abilities and taste perception. Moreover, most of the selected studies showed a relationship between salivary hypofunction and food consumption (in terms of appetite loss, unbalanced dietary intake and malnutrition), although no causality could be established.

CONCLUSIONS

This study highlights the fact that salivary hypofunction definition and measurements are different across the studies. Therefore, future research efforts should focus on establishing a gold standard to define and identify salivary hypofunction throughout life and on performing longitudinal studies controlling for confounding factors to establish causality.

Fast or slow-foods? Describing natural variations in oral processing characteristics across a wide range of Asian foods

The structural properties of foods have a functional role to play in oral processing behaviours and sensory perception, and also impact on the meal size and the experience of fullness.

A Role for Identification in the Gradual Decline in the Pleasantness of Flavors With Age

OBJECTIVES

This study investigated a possible role for identification in the decline in flavor pleasantness with age.

METHODS

Two hundred sixty-four individuals aged from 16 to 85 years tasted 6 flavored drinks of varying identity and ease of identification, and rated each on pleasantness, a range of other characteristics and identified all flavors.

RESULTS

Using regression, firstly, pleasantness was inversely associated with age (β = -0.22, p < .01). Secondly, the decline in pleasantness with age was associated with poorer identification (β = 0.30, p < .01), lower perceptions of sweetness (β = 0.01, p < .01), lower strength of flavor (β = 0.00, p = .02), lower familiarity (β = 0.01, p < .01), and a lower frequency of usual drink consumption (β = 0.04, p < .01). Thirdly, improved identification with age was associated with increased drink familiarity (β =< 0.01, p < .01), coloration compared with no color (β = <0.06, p < .01), and correct compared with incorrect coloration (β = <0.27, p < .01).

DISCUSSION

These findings demonstrate a clear role for identification in the decline in flavor pleasantness with age. These findings thus provide clear evidence for a cognitive and perceptual element to these hedonic processes. Our findings suggest that likings for flavors in older individuals may be increased/maintained through the use of improved visual cues, easily recognizable foods, and/or identity labels.

Potential sources of mouth drying in beverages fortified with dairy proteins: A comparison of casein- and whey-rich ingredients

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.

Physiological and psychosocial age-related changes associated with reduced food intake in older persons

Dietary intake changes during the course of aging. Normally an increase in food intake is observed around 55 years of age, which is followed by a reduction in food intake in individuals over 65 years of age. This reduction in dietary intake results in lowered levels of body fat and body weight, a phenomenon known as anorexia of aging. Anorexia of aging has a variety of consequences, including a decline in functional status, impaired muscle function, decreased bone mass, micronutrient deficiencies, reduced cognitive functions, increased hospital admission and even premature death. Several changes during lifetime have been implicated to play a role in the reduction in food intake and the development of anorexia of aging. These changes are both physiological, involving peripheral hormones, senses and central brain regulation and non-physiological, with differences in psychological and social factors. In the present review, we will focus on age-related changes in physiological and especially non-physiological factors, that play a role in the age-related changes in food intake and in the etiology of anorexia of aging. At the end we conclude with suggestions for future nutritional research to gain greater understanding of the development of anorexia of aging which could lead to earlier detection and better prevention.

Compensation for age-associated chemosensory losses and its effect on the pleasantness of a custard dessert and a tomato drink

Differences between elderly subjects (n=52, 60-85 years) and young subjects (n=55, 18-35) in their food liking and their olfactory capability were investigated. Two food systems were used: custard desserts and tomato drinks. Flavor enhancement/enrichment, textural change, and/or irritant addition were incorporated as compensatory strategies into these foods. The addition of low concentrations of both cherry flavor and cream flavor to the custard desserts influenced their pleasantness for the majority of the elderly. The addition of cream topping increased the pleasantness of the custard desserts for both the elderly and the young. The elderly equally liked the tomato drinks with no or with low irritant addition, whereas the young generally disliked an irritant addition. However, the food liking of the elderly was not generally increased by these different compensatory strategies. Instead, subgroups were observed for each compensatory strategy, in which applied compensatory strategies led to an increase in product pleasantness. Age-associated losses in olfactory capabilities did not sufficiently explain differences in food liking, as only elderly with similar olfactory capabilities to the young demonstrated a liking of enhanced flavor. The present study does not support the assumption that age-associated impairment in olfactory capability will inevitably lead to changes in food liking.