Capsaicin burn increases thickness discrimination thresholds independently of chronic chili intake

"Spicy Touch": Cross-modal associations between hand-feel touch and capsaicin-induced oral irritation

The influence of extrinsic hand-feel touch cues on consumer experiences in food and beverage consumption is well established. However, their impact on trigeminal perception, particularly the oral irritation caused by capsaicin or spicy foods, is less understood. This study aimed to determine the existence of cross-modal associations between hand-feel touch and capsaicin-induced oral irritation. This study investigated whether these potential associations were driven by the sensory contributions of the hand-feel tactile materials (measured by instrumental physical parameters) or by affective responses (evaluated through hedonic scales and the self-reported emotion questionnaire, EsSense Profile®, by consumers). In our study, 96 participants tasted a capsaicin solution while engaging with nine hand-feel tactile materials, i.e., cardboard, linen, rattan, silicone, stainless steel, sandpaper (fine), sandpaper (rough), sponge, and towel. They subsequently rated their liking and emotional responses, perceived intensity of oral irritation, and the congruency between hand-feel tactile sensation and oral irritation. Instrumental measurements characterized the surface texture of the hand-feel tactile materials, which were correlated with the collected sensory data. The results revealed that unique cross-modal associations between hand-feel touch and capsaicin-induced oral irritation. Specifically, while sandpapers demonstrated high congruence with the sensation of oral irritation, stainless steel was found to be least congruent. These associations were influenced by both the common emotional responses ("active," "aggressive," "daring," "energetic," "guilty," and "worried") evoked by the hand-feel tactile materials and the capsaicin, as well as by participants' liking for the hand-feel tactile materials and the characteristics of the surface textures. This study provides empirical evidence of the cross-modality between hand-feel tactile sensations and capsaicin-induced oral irritation, opening new avenues for future research in this area.

A review of assessment methods for measuring individual differences in oral somatosensory perception

While taste and smell perception have been thoroughly investigated, our understanding of oral somatosensory perception remains limited. Further, assessing and measuring individual differences in oral somatosensory perception pose notable challenges. This review aimed to evaluate the existing methods to assess oral somatosensory perception by examining and comparing the strengths and limitations of each method. The review highlighted the lack of standardized assessment methods and the various procedures within each method. Tactile sensitivity can be assessed using several methods, but each method measures different tactile dimensions. Further investigations are needed to confirm its correlation with texture sensitivity. In addition, measuring a single textural attribute may not provide an overall representation of texture sensitivity. Thermal sensitivity can be evaluated using thermal-change detection or temperature discrimination tests. The chemesthetic sensitivity tests involve either localized or whole-mouth stimulation tests. The choice of an appropriate method for assessing oral somatosensory sensitivity depends on several factors, including the specific research objectives and the target population. Each method has its unique intended purpose, strengths, and limitations, so no universally superior approach exists. To overcome some of the limitations associated with certain methods, the review offers alternative or complementary approaches that could be considered. Researchers can enhance the comprehensive assessment of oral somatosensory sensitivity by carefully selecting and potentially combining methods. In addition, a standardized protocol remains necessary for each method.

Effects of umami substances as taste enhancers on salt reduction in meat products: A review

Sodium is one of the essential additives in meat processing, but excessive sodium intake may increase risk of hypertension and cardiovascular disease. However, reducing salt content while preserving its preservative effect, organoleptic properties, and technological characteristics poses challenges. In this review, the mechanism of salt reduction of umami substances was introduced from the perspective of gustation-taste interaction, and the effects of the addition of traditional umami substances (amino acids, nucleotides, organic acids(OAs)) and natural umami ingredients (mushrooms, seaweeds, tomatoes, soybeans, tea, grains) on the sensory properties of the meat with reduced-salt contents were summarized. In addition, the impacts of taste enhancers on eating quality (color, sensory, textural characteristics, and water-holding capacity (WHC)), and processing quality (lipid oxidation, pH) of meat products (MP) and their related mechanisms were also discussed. Among them, natural umami ingredients exhibit distinct advantages over traditional umami substances in terms of enhancing quality and nutritional value. On the basis of salt reduction, natural umami ingredients improve the flavor, texture, WHC and antioxidant capacity. This comprehensive review may provide the food industry with a theoretical foundation for mitigating salt consumption through the utilization of umami substances and natural ingredients.

Methodological approaches to assess tactile sensitivity in the food context-A scoping review

In contrast to taste sensitivity, the assessment of texture or tactile sensitivity has received relatively little attention in the food context. Texture plays an important role in food preferences and food intake, and individual differences make it important to understand physiological drivers of perception as tactile sensitivity. The multi-dimensional and dynamic aspects of texture perception suggest there is not one single method that can explain individual differences. This scoping review aims to systematically map methods assessing tactile sensitivity, in the context of food, highlighting differences in approach and implementation. Eligibility criteria included papers describing methods to assess individual differences in tactile sensitivity, that involved human participants and the context was relevant to food behavior. Sources are peer-reviewed publications of original research in English. In mapping the methods, we assessed how they relate to food texture parameters (mechanical, geometrical, and surface) and the dynamics of breaking down (touch with hand, first bite/sip, oral processing, residual or after-swallowing sensations). We also review other parameters associated (oral processing, preference, diet and food intake behavior). The literature in this relatively young area is still very fragmented and it is difficult to have a clear picture regarding best practices or recommendations for the measurement of tactile sensitivity in the food context. Future studies should aim to methodological harmonization for application in the food behavior area, with a design of experiment combining different aspects of tactile sensitivity to food, focusing on the thresholds and perceived intensity of textural parameters as well as affective and behavioral responses, and covering the whole spectrum of tactile texture perception (mechanical, geometrics, and surface), including the dynamics of perception.

Saltiness enhancement by "má là" umami flavor in NaCl model aqueous and oil-added systems

The health concerns associated with high dietary sodium and the quest for a sensory experience have prompted the need for new strategies that can reduce the salt content of foods and have good acceptability. To investigate the cross-modal interaction effects of "má là" umami flavor (total of eight carriers) on the saltiness perception and effective sodium reduction in low-to-strong NaCl aqueous solutions (0.203 %-1.39 %) and oil-added systems (5 %, 10 %, 15 %, 20 %, 25 % canola oil, wt%), sixteen assessors were selected and two methods including saltiness intensity comparison with a category scale and rating with a generalized Labeled Magnitude Scale (gLMS) were used. The results showed PnSnUn carriers significantly enhance saltiness at moderate-to-strong NaCl solutions, and higher saltiness intensity with the addition of canola oil, especially at 25 % oil level. In addition, based on the developed Stevens' power function the sodium reduction was calculated, it was evident that two "má là" umami flavor combinations (one flavor combination was low "má", low "là" and moderate umami, and the other flavor combination with moderate "má", low "là" and moderate umami) were found to perform best with maximum sodium reduction of 18.88 % and 18 %, respectively, and when incorporating 25 % canola oil, the maximum sodium reduction raised by approximately 10 % (to 28.00 % and 28.42 %). This research not only confirmed the positive modulating effect of the "má là" umami flavor on saltiness perception in NaCl solutions, but also showed that the presence of oil further enhanced this effect. This work offered a new and promising insight into the development of foods with reduced sodium content while maintaining the saltiness properties.

More spice, less salt: How capsaicin affects liking for and perceived saltiness of foods in people with smell loss

People who lose their sense of smell self-report consuming more salt to compensate for a lack of flavor and enhance eating enjoyment. However, this may contribute to excess sodium intake. Capsaicin may help increase salt taste intensity and eating enjoyment in people with smell loss, but this has not been studied in this population. The purpose of this study was to determine 1) whether salt intake in those with smell loss differs from population averages, 2) whether capsaicin increases flavor and salt taste intensity, and 3) if adding spice to foods increases liking in individuals with smell loss. Thirty-three participants 18-65 years old with confirmed smell loss for at least 12 weeks completed two sets of replicate test sessions (four total). In two sessions participants rated overall flavor intensity, taste qualities' intensities, spicy intensity, and liking for model tomato soups with low or regular sodium content and three levels of capsaicin (none, low, or moderate). In the other two sessions, participants rated the same sensory attributes for model food samples with three levels of added spice (none, low, or moderate). 24-hour urine samples were collected to determine sodium intake. Results indicate that although sodium intake is higher than recommended (<2300 mg/day) in those with smell loss (2893 ± 258 mg/day), they do not consume more sodium than population averages (3039 ± 100 mg/day; p = 0.3). Adding low and moderate amounts of capsaicin to a model tomato soup increased the intensity of overall flavor (p < 0.001) and saltiness (p = 0.004) compared to a model tomato soup without capsaicin. However, capsaicin's effect on liking differed by food type. Thus, capsaicin can improve flavor, salt taste intensity, and eating enjoyment in people with smell loss.

Transient loss and recovery of oral chemesthesis, taste and smell with COVID-19: A small case-control series

Transient loss of smell is a common symptom of influenza and other upper respiratory infections. Loss of taste is possible but rare with these illnesses, and patient reports of 'taste loss' typically arise from a taste / flavor confusion. Thus, initial reports from COVID-19 patients of loss of taste and chemesthesis (i.e., chemical somatosensation like warming or cooling) were met with skepticism until multiple studies confirmed SARS-CoV-2 infections could disrupt these senses. Many studies have been based on self-report or on single time point assessments after acute illness was ended. Here, we describe intensive longitudinal data over 28 days from adults aged 18-45 years recruited in early 2021 (i.e., prior to the Delta and Omicron SARS-CoV-2 waves). These individuals were either COVID-19 positive or close contacts (per U.S. CDC criteria at the time of the study) in the first half of 2021. Upon enrollment, all participants were given nose clips, blinded samples of commercial jellybeans (Sour Cherry and Cinnamon), and scratch-n-sniff odor identification test cards (ScentCheckPro), which they used for daily assessments. In COVID-19 cases who enrolled on or before Day 10 of infection, Gaussian Process Regression showed two distinct measures of function - odor identification and odor intensity - declined relative to controls (exposed individuals who never developed COVID-19). Because enrollment began upon exposure, some participants became ill only after enrollment, which allowed us to capture baseline ratings, onset of loss, and recovery. Data from these four cases and four age- and sex- matched controls were plotted over 28 days to create panel plots. Variables included mean orthonasal intensity of four odors (ScentCheckPro), perceived nasal blockage, oral burn (Cinnamon jellybeans), and sourness and sweetness (Sour Cherry jellybeans). Controls exhibited stable ratings over time. By contrast, COVID-19 cases showed sharp deviations over time. Changes in odor intensity or odor identification were not explained by nasal blockage. No single pattern of taste loss or recovery was apparent, implying different taste qualities might recover at different rates. Oral burn was transiently reduced for some before recovering quickly, suggesting acute loss may be missed in datasets collected only after illness ends. Collectively, intensive daily testing shows orthonasal smell, oral chemesthesis and taste were each altered by acute SARS-CoV-2 infection. This disruption was dyssynchronous for different modalities, with variable loss and recovery rates across both modalities and individuals.

The heat is on: Consumers modify their oral processing behavior when eating spicy foods

Food texture properties and consumer characteristics influence oral processing behaviors. Little is known about oral processing behavior of pungent spicy foods. In two experiments, we investigated how adding ground dried chilies to tomato soup or beef patties and curried rice altered oral processing behaviors. In Experiment One, tomato soups differing in concentration of added ground dried chilies (0.01, 0.03, 0.20 or 0.40% w/w) were consumed (n = 23). In Experiment Two, lunch meals that differed in added ground dried chilies consisting of beef patties (0.0, 0.6 or 1.2% w/w) and curried rice (0.0, 0.4 or 1.0% w/w) were consumed (n = 49). Sip/bite sizes were determined using hidden balances. Oral processing behavior was quantified using video recordings followed by post hoc annotations of specific behaviors. When eating tomato soup, increasing oral burn was associated with increasing number of water sips, water intake and total time between sips. For the solid meals (beef patties and curried rice), increasing oral burn was associated with increased time between bites and total sips of water; conversely, total oral exposure time, total number of chews and number of chews per bite all decreased with greater burn. Saliva content and rate of saliva incorporation into the solid food bolus increased with added ground dried chilies while oral exposure time decreased. We conclude consumers adapt their oral processing behaviors to oral burn of solid foods by reducing oro-sensory exposure time, chewing bites less, increasing time between bites, and consuming more water, potentially to mitigate the discomfort associated with the burn imparted by ground dried chilies.

Transient loss and recovery of oral chemesthesis, taste and smell with COVID-19: a small case-control series

Anosmia is common with respiratory virus infections, but loss of taste or chemesthesis is rare. Reports of true taste loss with COVID-19 were viewed skeptically until confirmed by multiple studies. Nasal menthol thresholds are elevated in some with prior COVID-19 infections, but data on oral chemesthesis are lacking. Many patients recover quickly, but precise timing and synchrony of recovery are unclear. Here, we collected broad sensory measures over 28 days, recruiting adults (18-45 years) who were COVID-19 positive or recently exposed (close contacts per U.S. CDC criteria at the time of the study) in the first half of 2021. Participants received nose clips, red commercial jellybeans (Sour Cherry and Cinnamon), and scratch-n-sniff cards (ScentCheckPro). Among COVID-19 cases who entered the study on or before Day 10 of infection, Gaussian Process Regression showed odor identification and odor intensity (two distinct measures of function) each declined relative to controls (close contacts who never developed COVID-19), but effects were larger for intensity than identification. To assess changes during early onset, we identified four COVID-19 cases who enrolled on or prior to Day 1 of their illness â€" this allowed for visualization of baseline ratings, loss, and recovery of function over time. Four controls were matched for age, gender, and race. Variables included sourness and sweetness (Sour Cherry jellybeans), oral burn (Cinnamon jellybeans), mean orthonasal intensity of four odors (ScentCheckPro), and perceived nasal blockage. Data were plotted over 28 days, creating panel plots for the eight cases and controls. Controls exhibited stable ratings over time. By contrast, COVID-19 cases showed sharp deviations over time. No single pattern of taste loss or recovery was apparent, implying different taste qualities might recover at different rates. Oral burn was transiently reduced for some before recovering quickly, suggesting acute loss may be missed in data collected after acute illness ends. Changes in odor intensity or odor identification were not explained by nasal blockage. Collectively, intensive daily testing shows orthonasal smell, oral chemesthesis and taste were each altered by acute COVID-19 infection, and this disruption was dyssynchronous for different modalities, with variable loss and recovery rates across modalities and individuals.

Effect of Piperine on Saltiness Perception

Chemical irritants, like piperine, have the potential to increase human perception of tastes and odours, including saltiness. This cross-modal interaction could help the food industry develop new salt-reduced food products that maintain their salty taste. The objective of this study was: firstly, to determine the detection threshold of piperine (n = 72), secondly to evaluate piperine's influence on saltiness perception in model solutions (n = 78), and lastly to identify piperine's effect on sensory perception of low sodium soup using temporal check-all-that-apply (TCATA; n = 75). The group mean of the individual threshold was 0.55 ± 0.15 ppm. Piperine increased the saltiness perception of the model solutions, but it also increased the bitterness and decreased the sweetness of the solutions. The piperine significantly increased the saltiness intensity of the soups (evaluated using a generalized labelled magnitude), but during the TCATA task, the salty attribute was selected less for the soup with piperine than the control (based on the average proportion of selection). The TCATA indicated that the peppery attribute dominated the participants' perception of the soup with piperine. More studies are needed to assess piperine's cross-modal interactions.

Getting hot: Effect of chili pepper addition on sensory perception of liquid and solid foods

The impact of trigeminal oral burn and pungency on taste, flavor, and mouth-feel perception of commercially available foods is underexplored. This study aimed to determine the effect of oral burn sensations evoked by the addition of chili powder to tomato soup, beef burger patties, and curried rice on taste, flavor, and mouth-feel perception. Chili powder was added to tomato soups, beef burger patties, and curried rice at four concentrations. A consumer panel comprising n = 66 participants (49 women, 25.5 ± 5.8 years, BMI 22.9 ± 2.8 kg/m² ) assessed taste, flavor, trigeminal, and mouth-feel intensity of all samples using Rate-All-That-Apply methodology. Food matrix consistency strongly impacted oral burn sensations with solid food matrices (beef burger patties and curried rice) suppressing oral burn intensity compared to liquid food matrices (tomato soup). With increasing oral burn intensity, perceived intensity of beef flavor decreased significantly for beef burger patties. Tomato flavor, sweetness, and sourness intensity decreased significantly with increasing oral burn intensity for tomato soups. Perceived burn intensity of all food matrices and beef flavor intensity of beef burger patties differed between infrequent and frequent chili pepper consumers. We conclude that increasing oral burn intensity by the addition of chili pepper powder led to only small reductions in taste and flavor intensity of tomato soups and to little or no changes in flavor and mouth-feel perception of beef burger patties and curried rice. We suggest that reductions in taste, flavor, and mouth-feel intensity caused by oral burn might be more pronounced in liquid (tomato soup) than solid foods (beef burger patties and curried rice). PRACTICAL APPLICATION: There is a growing public and scientific interest in the development of strategies to increase the sensory appeal of healthy foods and beverages. Incorporation of trigeminal stimuli, such as chili peppers or capsaicin (pungent component of chili peppers), can be a strategy to increase sensory appeal of foods and beverages. Little is known about how trigeminal oral burn and pungency influence taste, flavor, and mouth-feel perception of commercially available foods, although it has been well established that taste, flavor, mouth-feel, and trigeminal sensations contribute to product acceptance. By investigating the sensory impact of oral burn on flavor and mouth-feel perception of foods, this study may help to better understand how trigeminal stimuli can be applied to moderate flavor and mouth-feel perception of foods to optimize sensory appeal.

Chili pepper preference development and its impact on dietary intake: A narrative review

A preference for chili pepper can be an acquired taste. The contrast between a chili lover and a hater illustrates the complexities involved in forming an appreciation for food that evokes a fiery pain sensation. This narrative review aims to understand the factors behind chili pepper preference formation across the life course and how individual chili pepper preferences can impact eating behaviors and dietary intake. This review was conducted using three databases, yielding 38 included articles. Results suggest five determinants of chili pepper preferences: culture, exposure, gender, genetics, and personality. Collective findings indicate that the strongest influences on preference acquisition include the individual environment from childhood to adulthood and repeated exposure to spicy flavors. With frequent exposure to spicy food, the perceived burn becomes less intense. Culture also influences exposure to chili peppers, with the highest consumption patterns seen within Mexico and some Asia countries. Additionally, males reported having a stronger preference for spicy foods than females. Twin studies illustrated that genetics influenced spicy taste preferences, underscoring the complexity of developing individual taste preferences. As for the impact of capsaicin-containing food on individual eating behaviors and dietary behaviors, appetite effects depend on the dose of capsaicin consumed, but three studies found a change in sensory desires for sweet and fatty foods after finishing a capsaicin-containing dish. Inconsistent results were reported for chili pepper's effects on hunger and satiety after consumption, but changes in specific food desires were observed. The impact of chili pepper on appetite and calories consumed was inconsistent, but the greater amount of capsaicin ingested, the greater the effect. Capsaicin's potential to be used for weight control needs to be further reviewed. In conclusion, evidence suggests that chili pepper preferences may be linked to innate and environmental aspects such as an individual's culture, gender, and genetics. Extrinsic factors like repeated exposure may increase the liking for spicy foods.

The effect of dairy proteins on the oral burn of capsaicin

This study focused on the effect of binding of capsaicin by milk proteins on oral burn. The concentration of free, unbound capsaicin in 5 ppm capsaicin solution containing 0-5% (w/w) micellar casein or whey protein isolate was measured by extraction into hexadecane. The concentration of free capsaicin decreased linearly with protein concentration and the decrease was greater for casein than for whey protein. The intensity of the capsaicin burn in similar solutions was assessed by a large cohort (n = 89) of untrained participants in a time-intensity study. The maximum burn intensity decreased with protein concentration and was lower for samples containing casein than for samples containing whey protein isolate. The maximum burn was linearly related to the free, unbound capsaicin concentration. When protein solutions (1-5% w/w) were used as rinses following exposure to a 5 ppm aqueous capsaicin solution, only the 5% (w/w) micellar casein solution was significantly more effective than the water rinse in reducing oral burn.