Individual Differences in Retronasal Odor Responsiveness: Effects of Aging and Concurrent Taste

Behavioural Nudges, Physico-Chemical Solutions, and Sensory Strategies to Reduce People’s Salt Consumption

This narrative historical review examines the wide range of approaches that has been trialled/suggested in order to reduce the consumption of salt. While sodium is an essential micronutrient, there is widespread evidence that high levels of consumption are leading to various negative health outcomes. This review summarises the evidence relating to the various approaches that have been put forward to date to help reduce salt consumption over the years, while also highlighting a number of important questions that remains for future research. Solutions to reducing salt consumption include everything from the gradual reduction in salt in foods through to the reduction in the number/size of holes in saltshakers (what one might consider a behavioural nudge). Physico-chemical solutions have included salt replacers, such as monosodium glutamate (MSG) through to the asymmetric distribution of salt in processed (e.g., layered) foods. A wide range of sensory approaches to modulating expected and perceived saltiness have also been suggested, including the use of salty aromas, as well as suggesting the use of colour cues, sonic seasoning, and even textural primes. It is currently unclear whether different salty aromas can be combined to increase odour-induced taste enhancement (OITE) effectiveness. In the years ahead, it will be interesting to assess how long such solutions remain effective, as well as whether different solutions can be combined to help reduce salt consumption without having to compromise on taste/flavour

Human Oral Sensitivity to and Taste Modulation by 3-Mercapto-2-Methylpentan-1-ol

Introduction

3-Mercapto-2-methylpentan-1-ol (3 M) is a key onion flavor (aroma), but past sensory work has focused primarily on ortho-nasal presentation. A series of experiments was conducted to characterize human sensitivity to oral 3 M solutions, then determine how 3 M impacts perception of basic tastes.

Methods

Detection thresholds were measured for a food grade, racemic mixture using a forced-choice staircase procedure (n = 19). Recognition was measured by presenting a single stimulus per trial (3 M, vanillin, or water), with "onion," "vanilla," or "water" as responses (n = 18). Supra-threshold intensity (n = 20) was measured for various concentrations using the general labeled magnitude scale (gLMS). Odor-taste interactions were studied using mixtures of 3 M and exemplars of basic tastes. Participants rated the intensity of basic tastes, or both taste and aroma, using the gLMS (n ranged from 10 to 15). All stimuli were in aqueous solution.

Results

Participants detected oral 3 M at about 0.90 ppb and recognized 3 M as "onion" at about 5 ppb. Supra-threshold intensity increased roughly as a cumulative logistic function of concentration. 3 M enhanced the rated savory intensity of monosodium glutamate, but did not enhance the dominant qualities of exemplars of the other four basic tastes. Under a response-context more favorable to an analytic approach, savory enhancement was reduced but not eliminated. Savory enhancement was eliminated with nose-clips.

Conclusions

Oral sensitivity was lower than previous retronasal studies would suggest, but roughly consistent with concentrations in cooked allium varieties. Oral 3 M selectively enhanced savory intensity, an effect likely due to retronasal aroma rather than taste or mouthfeel.

Implication

3 M is a promising candidate aroma to enhance or impart a savory flavor.

Food for the elderly based on sensory perception: A review

Background

The impairments of physiological functions caused by aging are common problems in the elderly, especially the impairments of sensory perception. Besides, close relationship between food sensory perception and nutritional status also suggests the importance of dietary management for the elderly population. The foods taking sensory perception into account are urgently needed by the elderly.

Scope and approach

This review analyzed sensory perception changes and their effects on food behaviors and nutritional status. Besides, sensory properties essential for aged-foods and acquisition methods, as well as current status of such foods were summarized.

Key findings and conclusions

Soft, smooth and moisty foods were more suitable for the elderly with chewing and swallowing dysfunction, which can be prepared by gelation, enzyme treatment, blade tenderization and other non-thermal technologies. Flavor enhancement/enrichment, irritant addition and packet sauces were recommended to compensate the impairment of chemical sensory. Molds, piping bag and 3D printing were suggested for refining appearance of pureed foods, and improving appetite of the elderly.

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Sensory perception changes of the elderly affect food behaviors and health.

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Soft, smooth, and moisty foods are more suitable for the elderly.

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Gelation and enzyme treatment are applied to modify the texture of aged food.

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Packet sauces may meet the heterogenetic flavor requirements of the elderly.

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Visually attractive food made by 3D printing can increase the appetite of elderly.

Food Neophobia, Odor and Taste Sensitivity, and Overall Flavor Perception in Food

Smell, which allows us to gather information about the hedonic value of an odor, is affected by many factors. This study aimed to assess the relationship among individual factors, odor sensitivity, and enjoyment, and to evaluate how overall flavor perception and liking in actual food samples are affected by odor sensitivity. A total of 749 subjects, from four different Italian regions, participated in the study. The olfactory capabilities test on four odors (anise, banana, mint, and pine), as well as PROP (6-n-prpyl-2-thiouracil) status and food neophobia were assessed. The subjects were clustered into three groups of odor sensitivity, based on the perceived intensity of anise. The liking and intensity of the overall flavor were evaluated for four chocolate puddings with increasing sweetness (C1, C2, C3, and C4). The individual variables significantly affected the perceived intensity and liking of the odors. Even if all of the odor sensitivity groups perceived the more intensely flavored samples as the C1 and C4 chocolate puddings, the high-sensitivity group scored the global flavor of all of the samples as more intense than the low-sensitivity group. The low-sensitive subjects evaluated the liking of the sweeter samples with higher scores than the moderate-sensitive subjects, whereas the high-sensitive subjects gave intermediate scores. In conclusion, odor sensitivity plays a pivotal role in the perception and liking of real food products; this has to be taken into account in the formulation of new products, suitable for particular categories with reduced olfactory abilities.

Mechanisms of umami taste perception: From molecular level to brain imaging

Due to unique characteristics, umami substances have gained much attention in the food industry during the past decade as potential replacers to sodium or fat to increase food palatability. Umami is not only known to increase appetite, but also to increase satiety, and hence could be used to control food intake. Therefore, it is important to understand the mechanism(s) involved in umami taste perception. This review discusses current knowledge of the mechanism(s) of umami perception from receptor level to human brain imaging. New findings regarding the molecular mechanisms for detecting umami tastes and their pathway(s), and the peripheral and central coding to umami taste are reviewed. The representation of umami in the human brain and the individual variation in detecting umami taste and associations with genotype are discussed. The presence of umami taste receptors in the gastrointestinal tract, and the interactions between the brain and gut are highlighted. The review concludes that more research is required into umami taste perception to include not only oral umami taste perception, but also the wider "whole body" signaling mechanisms, to explore the interaction between the brain and gut in response to umami perception and ingestion.

Aging and the (Chemical) Senses: Implications for Food Behaviour Amongst Elderly Consumers

The growing aging population are increasingly suffering from the negative health consequences of the age-related decline in their senses, especially their chemical senses. Unfortunately, however, unlike for the higher senses of vision and hearing, there is currently nothing that can be done to bring back the chemical senses once they are lost (or have started their inevitable decline). The evidence suggests that such chemosensory changes can result in a range of maladaptive food behaviours, including the addition of more salt and sugar to food and drink in order to experience the same taste intensity while, at the same time, reducing their overall consumption because food has lost its savour. Here, though, it is also important to stress the importance of the more social aspects of eating and drinking, given the evidence suggesting that a growing number of older individuals are consuming more of their meals alone than ever before. Various solutions have been put forward in order to try to enhance the food experience amongst the elderly, including everything from optimising the product-intrinsic food inputs provided to the remaining functional senses through to a variety of digital interventions. Ultimately, however, the aim has to be to encourage healthier patterns of food consumption amongst this rapidly-growing section of the population by optimising the sensory, nutritional, social, and emotional aspects of eating and drinking. An experimental dinner with the residents of one such home where nostalgic-flavoured healthy ice-creams were served is described.

Factors Contributing to Interindividual Variation in Retronasal Odor Perception from Aroma Glycosides: The Role of Odorant Sensory Detection Threshold, Oral Microbiota, and Hydrolysis in Saliva

Glycosides are sugar conjugates of aroma compounds that are found in many fruits and vegetables, and while glycosides are non-volatile, they can release flavor during eating, through enzyme hydrolysis from oral microbiota. Recently, a range of sensory phenotypes for glucoside perception have been observed, reflecting interindividual variation in response to precursors of floral and smoky flavors, geranyl glucoside and guaiacyl glucoside. To understand this variation and investigate the role of oral microbiota on in vitro hydrolysis of glucosides in saliva, metagenomic screening was conducted using individuals representing the range of sensory phenotypes for geranyl and guaiacyl glucosides. In parallel, sensory retronasal detection thresholds for geranyl glucoside, guaiacyl glucoside, and the volatile odorants geraniol and guaiacol were determined. Oral microbial communities correlated with hydrolysis of glucosides in saliva, but the relationship did not extend to sensory phenotypes. Overall, the retronasal detection threshold of the volatile odorants studied was the main factor determining sensory phenotype.