Influence of Bitter Taste on Mastication Pattern

The Role of Bitter-Tasting Substances in Salivation and Swallowing: Results of the Pilot Study

The aim of this study was to investigate the effects of caffeine, vanillin, and epigallocatechin gallate on salivation and swallowing and to find ways to correct their negative effects. Solutions of these substances with an equivalent intensity of bitter taste were compared for this purpose. To compensate for their effect, solutions of adenosine monophosphate, saliva substitute, and their combination were used. The results of the sialometric and surface electromyographic analyses demonstrate that all of the bitter substances studied exert a significant influence on the physiology of salivation and swallowing while exhibiting distinct modes of action. Caffeine has been shown to increase the area under the swallowing electromyographic curve, which is indicative of an increase in maximal amplitude. Epigallocatechin gallate has been linked to a reduction in salivation rate, an increase in duration, and a decrease in maximal intensity of the sEMG curve. Vanillin is demonstrated to reduce the area under the swallowing electromyographic curve due to a decline in both duration and maximal intensity. The addition of adenosine monophosphate to solutions of all substances under study resulted in a convergence of the salivary secretion and swallowing profile toward a profile that is characteristic of water. The findings can be utilized to modify the physiological responses to bitter-tasting substances when developing novel food formulations.

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.

Oral processing behaviours of liquid, solid and composite foods are primarily driven by texture, mechanical and lubrication properties rather than by taste intensity

The aim of this study was to understand the influence of saltiness and sweetness intensity on oral processing behaviours of liquid, solid and composite foods. As salty foods, tomato sauce (liquid), penne pasta (solid) and their combination (composite food) were used at two levels of saltiness intensity (low/high). As sweet foods, strawberry sauce (liquid), milk gels (solid) and their combination (composite foods) were used at two levels of sweetness intensity (low/high). Saltiness, sweetness, hardness, chewiness, and liking were quantified using generalized labelled magnitude scales (gLMS). Oral processing behaviours were determined using video recordings (n = 39, mean age 25 ± 3 years) in a home-use-test (HUT) providing fixed bite sizes for all foods. As expected, taste intensity differed significantly between samples within the same food category. No significant effects of taste intensity on oral processing behaviours were found for sweet and salty foods. As expected, consistency strongly affected the consumption time per bite, number of chews per bite, number of chews per gram and eating rate. Solid foods were masticated for the longest time with the highest number of chews per bite, followed by composite foods as the liquid added to the solid foods enhanced lubrication. Liquid foods were masticated for the shortest time. We conclude that large differences in saltiness and sweetness intensity of liquid, solid and composite foods cause no differences in oral processing behaviours. We suggest that oral processing behaviours are primarily driven by texture, mechanical and lubrication properties of foods rather than by their taste intensity.

The association between a mixing ability test and patient reported chewing ability in patients treated for oral malignancies

INTRODUCTION

Mastication has been assessed in several ways in the past. Both patients reported and objective assessment methods have been developed. The University Medical Center (UMC) Utrecht has developed a mixing ability test (MAT) using a two-coloured wax tablet. The present study investigates the association between the mixing ability test and a chewing related questionnaire in patients treated for oral malignancies.

PATIENTS AND METHODS

In a cohort study, patients treated for oral malignancies were assessed 4-6 weeks before and 4-6 weeks after treatment, as well as 6 months, 1 year and 5 years after treatment. The mixing ability test was assessed using 10 and 20 chewing strokes and was compared to seven questions about several aspects of mastication. Regression analysis was performed and density plots were drawn for statistical analysis.

RESULTS

One hundred and twenty-three patients were included in this study. The questionnaire was less predictive for the 10-chewing stroke test and the test was less discriminatory for different food types than the 20-chewing stroke mixing ability test. Three questions about the ability to chew solid, soft and thickened liquid food types were found to be significantly predictive for the 20-chewing stroke test. Threshold values on the mixing ability index were around 20 for the ability to chew solid food types and 24 for soft food types.

CONCLUSION

The 10-chewing stroke mixing ability test is less suitable than 20-chewing strokes for patients with and treated for oral cancer. The 20-chewing stroke mixing ability test has a fair association with self-reported outcomes.

Impact of composition and texture of protein-added yogurts on oral activity

Understanding how oral processing is altered in response to changes in the composition and mechanical properties of food provides useful information to design food with improved satiating capacity which is largely influenced by oral exposure. In turn, this information deepens the knowledge about the physiology of texture perception. Six yogurts were formulated with different amounts of protein and protein sources and addition of apple cubes: control (C), extra skimmed milk powder-added (MP), whey protein isolate-added (WPI), and whey protein microgels-added (WPM). In addition, MP was also added with maltodextrin (MPMD) and with fresh apple cubes (MPF). Activities of masseter, anterior temporalis and anterior digastric muscles during oral processing of each sample were recorded (electromyography), and jaw movement amplitudes in three dimensions were determined (jaw tracking system). The jaw muscle activities were highly dependent on the type of yogurt. Addition of apple cubes (MPF) almost doubled the oral processing time, number of chews, and muscle activity of all samples. MP and MPMD required similar but lower values of oral processing than MPF attributed to their reinforced network of milk protein. The lowest values were found for WPI, C and WPM, indicating a weaker, more fluid material. These behavioral results, which clearly differentiate the samples, are discussed in connection to the rheological and sensory properties of the yogurts. This study suggests that adding apple cubes significantly alters the oral processing pattern, such that they may be a more effective way of increasing the oral processing time (time exposure) compared to more subtle changes in the protein amount or source. Nevertheless, changes in the protein amount and source also affected, although to a lesser extent, the behavioral, rheological, and sensory properties of yogurt.

Perception and measurement of food texture: Solid foods

There is still a gap between instrumental measurement and sensory evaluation because of the complexity of food texture in spite of many efforts. In sensory evaluation, the terms describing the texture should be well understood by panelists, which poses a problem of establishing lexicons and training panelists. In the instrumental measurement, more efforts are required to understand the large deformation and fracture behavior of foods. The texture profile analysis (TPA) proposed by Alina Szczesniak, Malcolm Bourne, and Sherman has been applied to many foods, and was useful to develop the understanding of textures. But sometimes confusion of the interpretation of TPA parameters appeared. Many new techniques have been introduced to quantify TPA parameters. Recent efforts to fill the gap between sensory evaluation and instrumental measurements, human measurements, or physiological measurements have been introduced. This endeavor is an effort of synthesizing the dentistry and biomedical approach, sensory and psychological approach, and material science approach, and therefore, the collaboration among these disciplines is necessary. This manuscript mainly discusses texture studies for solid foods.

PRACTICAL APPLICATIONS

To fill the gap between the sensory evaluation and the instrumental measurement of texture, it is necessary to examine the physical change of foods during the oral processing. This will give us the designing principle of palatable and safe foods.

Impact of oral processing on texture attributes and taste perception

Mastication is the first step of food digestion, where foods are broken down and simultaneously impregnated by saliva resulting in the formation of semi-fluids known as food boluses. This review focuses on the impact of oral processing on texture attributes and taste perception. The article describes the oral actions in which texture characteristic are measured for the critical conditions that trigger swallowing. Taste perception also plays a key role in oral processing and oral sensations. There are still challenges in terms of determining different oral physiological characteristics. These include individual chewing behavior regardless of the temporal aspects of dominant processes of comminution, insalivation, bolus formation and swallowing. A comprehensive approach is essential to process favorable foods with respect to the food properties of texture and taste.

Effect of the bitterness of food on muscular activity and masticatory movement

PURPOSE

The purpose of this study was to clarify the effect of the bitterness of food on muscular activity and masticatory movement.

METHODS

Twenty healthy subjects were asked to chew a non-bitter gummy jelly and a bitter gummy jelly on their habitual chewing side. The masseter muscular activity and the movement of mandibular incisal point were recorded simultaneously. For all cycles excluding the first cycle, parameters representing the muscular activity (total integral value and integral value per cycle) and masticatory movement (path, rhythm, and stability) were calculated and compared between the two types of gummy jellies.

RESULTS

The total integral value of masseter muscular activity during the chewing of bitter gummy jelly was significantly smaller than during the chewing of non-bitter gummy jelly, however, no definite trends in the integral value per cycle and the stability of movement were observed. The parameters representing the movement path tended to be small during the chewing of bitter gummy jelly than during the chewing of non-bitter gummy jelly. The masticatory width was significantly smaller during the chewing of bitter gummy jelly. The parameters representing the rhythm of movement were significantly longer during the chewing of bitter gummy jelly than during the chewing of non-bitter gummy jelly.

CONCLUSION

From these results it was suggested that the bitterness of food does not affect the integral value per cycle or the stability of the masticatory movement, but it does affect the movement path and rhythm, with narrowing of the path and slowing of the rhythm.

The influence of oral processing, food perception and social aspects on food consumption: a review

Eating is an essential activity to get energy and necessary nutrients for living. While chewing, the food is broken down by the teeth and dissolved by saliva. Taste, flavour and texture are perceived during chewing and will contribute to the appreciation of the food. The senses of taste and smell play an important role in selecting nutritive food instead of toxic substances. Also visual information of a food product is essential in the choice and the acceptance of food products, whereas auditory information obtained during the chewing of crispy products will provide information on whether a product is fresh or stale. Food perception does not just depend on one individual sense, but appears to be the result from multisensory integration of unimodal signals. Large differences in oral physiology parameters exist among individuals, which may lead to differences in food perception. Knowledge of the interplay between mastication and sensory experience for groups of individuals is important for the food industry to control quality and acceptability of their products. Environment factors during eating, like TV watching or electronic media use, may also play a role in food perception and the amount of food ingested. Distraction during eating a meal may lead to disregard about satiety and fullness feelings and thus to an increased risk of obesity. Genetic and social/cultural aspects seem to play an important role in taste sensitivity and food preference. Males generally show larger bite size, larger chewing power and a faster chewing rhythm than females. The size of swallowed particles seems to be larger for obese individuals, although there is no evidence until now of an 'obese chewing style'. Elderly people tend to have fewer teeth and consequently a less good masticatory performance, which may lead to lower intakes of raw food and dietary fibre. The influence of impaired mastication on food selection is still controversial, but it is likely that it may at least cause adaptation in food choice. Systemic conditions, such as high blood pressure, diabetes and cancer, with or without medicine use, tend to be associated with taste and chewing alterations. However, definite conclusions seem hard to reach, as research protocols vary largely.

Mastication and swallowing: influence of fluid addition to foods

Introduction:

The production of sufficient saliva is indispensable for good chewing. Recent research has demonstrated that salivary flow rate has little influence on the swallowing threshold.

Objectives:

The hypothesis examined in the present study was that adding fluids to foods will influence chewing physiology.

Materials and Methods:

Twenty subjects chewed on melba toast, cake, carrot, peanut and Gouda cheese. They also chewed on these foods after addition of different volumes of water or α-amylase solution. Jaw muscle activity, number of chewing cycles until swallowing and chewing cycle duration were measured. Repeated measures analysis of variance was applied to test the null hypothesis that there would be no statistically significant difference among the results obtained for the various food types and fluids. Subsequently, contrasts were determined to study the levels of intra-subjects factors (food type and fluid volume). Linear regression was used to determine the changes in muscle activity and cycle duration as a function of the chewing cycles.

Results:

Fluid addition significantly decreased muscle activity and swallowing threshold for melba, cake and peanut (p<0.05). The effect of α-amylase in the solutions was similar to that of water (p>0.05). Doubling the volume of tap water had a greater effect.

Conclusions:

Fluid addition facilitated chewing of dry foods (melba, cake), but did not influence the chewing of fatty (cheese) and wet products (carrot). This study is relevant to improve patients’ life quality and the management of chewing and feeding disorders caused by hyposalivation.

The effect of hardness of food on amygdalar histamine release in rats

When animals eat food, the oral cavity receives a variety of sensory information from food. The hardness of food, which elicits somatic sensation, is thought to affect feeding behavior, however, the details of neuronal mechanism are unclear. The histaminergic system is known to be involved in feeding behavior, and our previous studies indicated that gustatory information activates the histaminergic system, and that palatability of tastants influences its activity. From these findings, we hypothesized that the hardness of food may affect the histaminergic system. Thus, in the present study, we examined the effect of the hardness of food on histamine release in the central nucleus of amygdala when rats consumed either of two types of pellets composed of similar ingredients but having different degrees of hardness: hard and soft pellets. Histamine release was significantly increased in the rat fed with hard pellets. By contrast, histamine release was not enhanced in soft pellets-fed rats. There were no significant differences between the hard and soft pellet intakes during the experimental period. When rats acquired a conditioned aversion to soft pellets, histamine release was increased during feeding, in sharp contrast to no change of histamine release pattern seen during unconditioned soft pellet intake. These observations indicate that the amygdalar histaminergic system is modulated by oral somatic sensation from food, and by palatability of food texture.

The role of contact chemoreception in egg-laying behaviour of locusts

Following selection of an appropriate egg-laying site desert locusts lay their eggs at depths in soil by digging their abdomen into the substrate using rhythmic movements of their abdomen and hard, sclerotised ovipositor valves. We have analysed the role of contact chemoreception on egg-laying behaviour and on the rhythmic digging movements of the valves. All chemicals tested acted aversively and reduced both the duration spent egg-laying and the number of eggs laid, with the concentration at which they became aversive being dependent on whether the chemical was normally present in the diet. Chemicals such as sucrose and a lysine glutamate salt prevented egg-laying only at much higher concentrations than known anti-feedants such as nicotine hydrogen tartrate and hydroquinine. Similarly for animals in which fictive digging movements were induced all chemicals stopped the digging rhythm, with sucrose and sodium chloride inhibiting the rhythm at relatively high concentrations compared to NHT and hydroquinone. We conclude that for both egg-laying behaviour and rhythmic digging that the aversiveness of a chemical rather than its identity per se plays a major role in regulating behaviour.

Effect of bolus size on chewing, swallowing, oral soft tissue and tongue movement

Simultaneous 3D articulograph and ultrasonograph techniques were used to monitor the chewing, swallowing, oral soft tissue and tongue movements of six subjects whilst consuming varying numbers (1, 2 and 4) of a confectionery product. Modifying the number of confectionery units had a variable effect on chewing, swallowing and oral soft tissue movements during the start of the chewing sequence. The distance, range and velocity of chin movement were significantly lower when 1 confectionery unit was consumed compared with 2 and 4 during the middle stage of the chewing sequence. Significant differences in modioli movement were observed during the initial stages of chewing allowing the identification of a working and non-working side, whilst no differences in thyroid cartilage movement were noted over the whole chewing sequence. Increasing the number of confectionery units caused a significant increase in the index of tongue movement during the end of the eating sequence, although the mean index of tongue movement over the total chewing sequence remained constant. Jaw movement correlated with tongue movement, where for all samples, gape decreased linearly as the chewing sequence progressed, reflected in a similar decline in the index of tongue movement. The lack of differences in the index of tongue movement observed over the start and middle of the chewing sequence as a consequence of the number of confectionery units consumed suggested that the change in the physical properties of the bolus had a greater effect on the index of tongue movement than the change in bolus size.

Influence of oral characteristics and food products on masticatory function

Mastication is a complex process that involves activities of the facial muscles, the elevator and suprahyoidal muscles, and the tongue. These activities result in patterns of rhythmic mandibular movements, food manipulation, and the crushing of food between the teeth. Saliva facilitates mastication by moistening food particles, making a bolus, and assisting swallowing, whereas food consistency modifies masticatory forces, the mandibular jaw movements, the duration of the mastication cycle, and the number of cycles preceding the first swallow. Jaw elevator EMG activity research shows a clear relation between muscular activity and food properties. The teeth, masticatory muscles, and temporomandibular joints are also important because together they form the mechanism by which the food particles are fragmented. Hard and dry foods require more chewing cycles and a longer time in the mouth until swallowing for sufficient breakdown to take place and for enough saliva to be added to form a coherent bolus safe enough for swallowing. Product characteristics, the amount of saliva, dentition, and bite force affect the chewing performance. This study presents an update and synopsis of the effects of saliva, food, dentition, muscle force, and temporomandibular disorders on the masticatory process.

Adaptation of healthy mastication to factors pertaining to the individual or to the food

Mastication is a physiological process controlled by the central nervous system and modulated by inputs from the mouth. Both the intrinsic characteristics of the subject and the extrinsic characteristics of the chewed food are responsible for variations of the masticatory function. Age, gender and dental state constitute the most studied intrinsic factors whereas hardness, rheological characteristics such as plasticity or elasticity, and food size are the better known extrinsic factors. These factors cause physiological adaptations which can occur during individual cycles or the whole sequence of mastication. Electromyographic and jaw movements (kinematic) recordings are commonly used to study mastication, from which, several variables can be measured. Vertical and lateral amplitudes and, velocities of jaw movements, are only given by kinematic recordings. Bioelectrical activities per cycle or per sequence are closely linked to masticatory forces and are measured from electromyographic recordings. Number of cycles, sequence duration and masticatory frequency can be measured from both types of recordings. The objective of this review is to provide an overview of the variations of the measured masticatory variables that occur when mastication adapts to changes in characteristics of the individual or the food.