CHEWING PATTERNS OF VARIOUS TEXTURE FOODS STUDIED BY ELECTROMYOGRAPHY IN YOUNG AND ELDERLY POPULATIONS

The effects of food texture on the chewing patterns of elderly and young people, masticatory recordings using electromyography (EMG) were carried out. Fourteen French adults (mean 29.4 years) and 23 elderly (mean 67.7 years) participated. Six food products (rice, beef, cheese, crispy bread, apple and peanuts) were tested. The chewing pattern of elderly subjects was characterized by a significant increase of number of chews and chewing duration for all foods except rice. Whatever the food type, muscle activity per chew (mean amplitude × burst duration) was lower for elderly than for young subjects. Single chews appeared less effective for food reduction in elderly than in young subjects. This can be partly compensated for by increasing the chewing duration and number of chews. No significant difference was found between both groups of subject for the total amount of EMG activity required prior to swallow whatever the food chewed.     

Electromyography of Eating Apples: Influences of Cooking, Cutting, and Peeling

ABSTRACT: The mastication of 7 differently prepared apple samples (raw pieces peeled and unpeeled, sliced, grated, cooked pieces with and without peel, and half-cooked pieces, 10 g each) was evaluated using electromyography (EMG). Eleven subjects participated in the EMG recording of both sides of the masseter and temporal muscles while eating samples normally. Only the grated sample reduced the number of chewing strokes and muscle activity before swallowing. In contrast, the thin apple slices produced significantly shorter contraction duration and cycle time only during the 1st 5 chewing strokes. The EMG duration and cycle in subsequent chews, as well as the other parameters, did not significantly differ between slices and pieces. Cooked apples exhibited significantly lower EMG amplitude and muscle activity per chew than their raw counterparts; however, there was no evidence of reduced total muscle activity required for swallowing. Raw and cooked apples with peel yielded significantly greater EMG amplitude and longer duration than those without peel. These findings suggest that appropriate preparation is necessary for people with various mastication abilities: grated for very low ability, cooked for those with weak chewing force, and unpeeled for mastication training.     

Training and Sensory Judgment Effects on Mastication as Studied by Electromyography

Electromyography recordings (EMG) were performed on 10 naive and 10 trained subjects during mastication of different samples of beef. For each group of subjects, ordinary mastication was compared to mastication accompanied by tenderness assessment of the chewed sample. Trained subjects showed a larger variation in muscle work than a naive group when chewing. Sensory assessment modified more the mastication profiles of trained subjects than those of naive ones and these variations occurred at the beginning of the masticatory sequence. EMG was useful for comparing mastication of different groups of panelists and appeared to be an interesting alternative for information about texture perception of naive subjects.     

ELECTROMYOGRAPHIC STUDY OF MASTICATION OF KELP SNACK

Electromyograms (EMGs) of mastication of kelp snack were compared with the physical properties measured by a tensile test and sensory assessment. The number of chewing strokes, masticatory time, total muscle activities and total duration for whole mastication agreed with the breaking force in the tensile test and with sensory difficulty of mastication. Amplitude, EMG activity, and duration per chew also showed the same tendency. In the masticatory cycle, significant differences among the samples were not observed. As mastication proceeded, the amplitude and EMG activity decreased, and the EMG-duration shortened. The EMG activity, amplitude, and masticatory rhythm changed significantly, and sample differences decreased from the middle to the late stage of mastication. Just before swallowing, the chewing cycle was lengthened, and no significant difference was observed among samples at the last chew.     

METHOD TO INVESTIGATE DIFFERENCES IN CHEWING BEHAVIOUR IN HUMANS

This study examines whether the patterns of muscle activity measured from the masticatory muscles during a chew are sufficiently reproducible to form the basis of a characterisation of chewing behaviour, and whether they express the degree of variation evident between individuals. Electromyograph (EMG) readings of the repetitive activity involved in chewing gum were analyzed for 10 subjects, each on three separate occasions. For each individual the temporal aspects of the chew cycle (duration of the activity burst, period between bursts of activity and duration of the complete cycle) were reproducible between EMG recording sessions. Consistency was also found for amplitude aspects of the EMG record: mean voltage within the activity burst, maximum voltage, and the area under the EMG trace. For all six parameters there was significant variation between subjects. The study showed that variations in the chewing pattern, as occur for chewing on opposite sides of the mouth, were reflected in the 6 EMG parameters examined, and that the changes elicited were different for each individual. Moreover, encouraging subjects to concentrate on the act of chewing caused them to modify their chewing pattern, highlighting the importance of avoiding such attention when assessing habitual chewing behaviour.     

TEXTURE ANALYSIS OF BEEF COOKED AT VARIOUS TEMPERATURES BY MECHANICAL MEASUREMENTS, SENSORY ASSESSMENTS AND ELECTROMYOGRAPHY

The potential of mechanical measurements, sensory assessments and electromyography (EMG) to detect the variation in texture properties of beef induced by cooking at temperatures of 45–80C was determined. The mechanical behaviour of meat, from two Semimembranosus muscles from one animal, was studied by compression and shear tests in destructive and nondestructive conditions. Electromyographs from the masticatory muscles of 14 trained subjects were recorded during mastication of the meat samples. Texture profiles were completed at the end of each masticatory sequence. Increase in cooking temperature produced an overall increase in shear and compression parameters as well as in meat elasticity. Sensory hardness and total muscle work developed during mastication also increased with cooking temperature. Mechanical measurements, EMG parameters and sensory assessment of texture were highly correlated. EMG, on which the influence of psychological factors is limited, can be used to characterise meat texture objectively.     

EMG assessment of chewing behaviour for food evaluation: Influence of personality characteristics

The aim of the present study was to evaluate the chewing behaviour stability over time and the influence of personality characteristics on chewing behaviour in order to assess the use of EMG for food assessment. From a set of eighty three subjects, thirty-two subjects were classified as personality type A or B (Jenkins Activity Survey questionnaire) and then recruited for the experimentation. Two types of assays were performed: Assay I: chewing gum for 10 chews and Assay II: chewing gum for 50 s. Only in two cases (6.3%) did the subject change his/her chewing behaviour; in the other cases, subjects’ chewing behaviour was stable over time (two months test). In both assays significant differences between the personality groups were found in terms of the EMG parameters. Discriminant and K-means cluster analysis confirmed the role of personality traits on the chewing behaviour of the subjects. Thus, personality traits should be considered for panel selection and/or data analysis.     

USE OF COMBINED ELECTROMYOGRAPHY AND KINESTHESIOLOGY DURING MASTICATION TO CHART THE ORAL BREAKDOWN OF FOODSTUFFS: RELEVANCE TO MEASUREMENT OF FOOD TEXTURE

This paper describes a method for obtaining detailed information about the velocities, directions and relative forces involved in mastication, and how these change throughout the chewing sequence, from combined electromyograph and kinematic records in human subjects. Differences in the temporal breakdown patterns of apple, carrot and biscuit are highlighted. Mastication of apple and carrot relied on vertical compression for each chew, with decreasing effort applied over the course of the chewing sequence. Differences between these products were related principally to the chewing effort exerted. For biscuit, compression was the predominant mechanism of breakdown in early chews but this was transferred to a shear action over the course of the sequence.     

DIVERSITY OF PERCEPTIONS OF MEAT TENDERNESS AND JUICINESS BY CONSUMERS: A TIME-INTENSITY STUDY

Seven judges, untrained in sensory assessment, were trained in the use of Time Intensity (TI) and asked to monitor the tenderness and juiciness of a range of cooked beef and pork samples. The subjects were given no definitions concerning sensory cues to monitor in their assessments, nor did they confer with each other. The shapes of the TI curves they recorded for tenderness and juiciness differed between individuals, although there were similarities in the curve shapes for the 2 attributes for each individual. Correlations between the intensity parameters of the curves (maximum intensity and area under curve) and the chewing time were not significant for the subjects as a group for tenderness, although significant correlations were found for some of the subjects when examined individually. The results indicate that subjects differ in their concepts of sensory tenderness and juiciness, and that perceived tenderness does not correlate with chewing time for all subjects. In more general terms the study supports the use of TI assessments for interpreting individual differences in sensory perceptions.     

Association between chewing efficiency and mastication patterns for meat, and influence on tenderness perception

The aim of this study was to investigate whether individuals' chewing patterns were related to their chewing efficiency, and influenced their perceptions of meat tenderness. Chewing efficiency was measured using two methods. Subjects continuously assessed the tenderness of a range of samples throughout the chewing sequence using Time Intensity. At the same time electromyographs (EMGs) were recorded from their masticatory muscles.

Subjects were subdivided into four groups with respect to their chewing efficiencies with the two methods. These subgroups differed significantly in the number of chews, total chewing time and chew work, both for the initial chews and the complete chewing sequence, for the meat samples. No significant difference was found in the dentition between the groups. Significant differences were found between the groups in their temporal perceptions of tenderness.     

ANALYSIS OF FOOD CRUSHING SOUNDS DURING MASTICATION: TOTAL SOUND LEVEL STUDIES 1

The total sound level of airborne noise was measured continuously during consecutive chews of fresh and stale samples of potato chips and tortilla chips. Sensory estimations of crispness were also made. Samples were evaluated using both an open mouth and a closed mouth procedure. Analysis showed that the total sound level decreased as chewing progressed. Significant differences were observed between open mouth and closed mouth chewing, with the former displaying higher sound levels. However, there were no statistical differences in the sound levels between fresh and stale samples. Sensory assessments ofcrispness showed decreasing crispness as chewing progressed. Statistical differences were observed in the sensory evaluations between fresh and stale samples. Openmouth sensory evaluations were significantly different from closed-mouth evaluations for potato chips but not for tortilla chips. Good correlations were observed between the acoustic measurements and the sensory estimations, in agreement with the work of other investigators.     

Oral processing behavior and dynamic sensory perception of composite foods: Toppings assist saliva in bolus formation

Composite foods consist of combinations of single foods, such as bread with toppings. Single foods can differ considerably in their mechanical and sensory properties. This study aimed to investigate the effect of toppings on oral processing behavior and dynamic sensory perception of carrier foods when consumed as composite foods. Two carriers (bread, crackers) and three toppings (firm cheese, cheese spread, mayonnaise) were selected and six carrier-topping combinations were prepared. Mastication behavior, bolus properties (33, 66 and 100% of total mastication time) and dynamic sensory perception were determined for single carriers and all carrier-topping combinations. Both carriers with cheese spread and mayonnaise were chewed shorter and with fewer chews than single bread and crackers, although twice the mass of food was consumed. These toppings contributed to a faster bolus formation by providing moisture, so that less saliva was incorporated into the bolus during mastication. As a result of the moisture incorporation, carrier boli with toppings were softened and perceived less firm and less dry than carrier boli alone. The largest effects of toppings on oral processing behavior and perception were found for liquid-like mayonnaise, and these effects were more pronounced in dry crackers than in moist bread. We conclude that toppings assist saliva in bolus formation of carriers. Carriers drive oral processing behavior and texture perception whereas toppings drive overall flavor perception. This knowledge contributes to food design tailored for specific consumer segments and future personalized nutrition.     

Mastication of heterogeneous foods: Peanuts inside two different food matrices

We investigated chewing behaviour and particle size outcome in the oral processing of heterogeneous foods using peanuts embedded within two types of food matrices. Eight subjects, selected according to strict dental and mastication criteria, were served four different model foods. Each model food comprised one of two matrices of different physical properties (chocolate and gelatine gel) which were embedded with one of two physically different particles (peanuts with low moisture or high moisture content). A standard volume of each model food was chewed to the point of swallowing and expectorated and the number of chews and chewing time was recorded. The matrix of the expectorated bolus was washed away to isolate the peanut fragments, and the particle size distributions of the peanut fragments were determined using image analysis. A Rosin-Rammler function was fitted to the cumulative distribution data of each bolus to derive particle size parameters (d₅₀ and broadness (b)).Results showed the properties of one food component (the matrix) can influence the breakdown of another food component (the peanuts) in a heterogeneous system. The properties of the matrix caused differences in mastication (measured in terms of the number of chews, chewing duration, and frequency) and broadness of the peanut particle size distribution, but did not influence the final d₅₀ of the peanut particle size distribution. Conversely the physical properties of the embedded peanut influenced the d₅₀ of the particle size distribution but had no effect on chewing behaviour. It is likely that properties of the matrix influenced the rate at which particles of various sizes were selected for chewing (known as the selection function), whereas the physical properties of the peanuts influenced extent of breakage when the teeth made contact with the particles (known as the breakage function).     

Dynamics of food breakdown during eating in relation to perceptions of texture and preference: a study on biscuits

Combined recording of masticatory muscle activity and jaw movement patterns during eating was used to examine the process of food breakdown in the mouth for a series of “Rich Tea”-type biscuits in 19 ordinary consumers. These data indicated an initial increase in chewing work from the masticatory muscles over the first 5–10 chews followed by a decline over the remainder of the chewing sequence. The work was concentrated in vertical closing of the jaw during the early chews but as this declined over the later chews there was an increase in the amount of work occurring with the teeth in near occlusion. The relative amount of work input into the chewing sequence, the duration of the sequence, and the degree of work undertaken at occlusion, differed among groups of the consumers who were classified according to their chewing efficiency (CE). Subjects from different CE groups appeared to have different understandings of the textural characteristics of the samples which they assessed as “hardness”, “crunchiness” and “crumbliness”. Differences in the oral breakdown patterns for different CE groups may provide an understanding of differences in consumer preferences for the samples. ©     

ELECTROMYOGRAPHIC STUDY ON COOKED RICE WITH DIFFERENT AMYLOSE CONTENTS

The texture of six varieties of cooked rice with different amylose contents was measured with a Texturometer. Masticatory behavior of the rice was evaluated using electromyography (EMG) of masticatory muscles. Differences in mastication patterns among the seven subjects examined were greater than between rice varieties. Masticatory behavior was more related to the adhesiveness and stickiness of rice as measured using a Texturometer than to the hardness. The number of chews and masticatory time, total duration of mastication and total muscle activities were highly correlated with each other, and were greater in cooked rice with a high amylose content, which showed low adhesiveness and stickiness values using a Texturometer. Cooked rice with a high amylose content was masticated with high masseter muscle activities. The ratio of jaw-opening muscle activity to the preceding jaw-closing muscle activity was low in high-amylose varieties, which corresponds to the ratio of stickiness to hardness using a Texturometer. Between-sample differences in mastication parameters were more apparent in the early stage of mastication, and no significant diference was observed in the late stage.     

The role of mechanical properties of brittle airy foods on the masticatory performance

This work investigates the mastication of two samples of typical cereal food products previously characterised by different sensory, textural and mechanical properties, by two complementary approaches. Electromyographic records and image analysis of chewed food particles first confirm the importance of the brittle behaviour of the products on human mastication. For both products, the fragmentation is followed by a significant agglomeration after less than 10 chewing cycles, both phenomena being correlated to the force magnitude and its evolution. Then, artificial mastication is undertaken to shed more light on the capability of the chewing simulator to discriminate both products under dry mastication conditions. The results depict a qualitative agreement with human mastication and texture properties.     

Interrelations among physical characteristics,sensory perception and oral processing of protein-based soft-solid structures

Oral processing is essential in breaking down the physicochemical structure of the food and thus important to the sensory perception of food in the mouth. To have an understanding of protein-based, soft-solid texture perception, a multidisciplinary approach was applied that combined studies of food microstructure with mechanical properties, sensory evaluation, and oral physiology. Model foods were developed by combining ion-induced micro-phase separation and protein-polysaccharide phase separation and inversion. Activities of masseter, anterior temporalis and anterior digastric muscles during oral processing were recorded by electromyography (EMG), while jaw movement amplitudes, durations, and velocities were simultaneously collected by a three-dimensional jaw tracking system (JT-3D). Changes in the microstructure of mixed gels significantly altered the characteristics of the chewing sequence, including the muscle activities, number of chews, chewing duration and chewing frequency. Mechanical attributes related to structural breakdown and sensory perception of firmness were highly correlated with the amount of muscle activity required to transform the initial structure into a bolus ready for swallowing. Chewing frequency was linked to mechanical properties such as recoverable energy, fracture strain and water holding capacity of the gels. Increased adhesiveness and moisture release also resulted in slower chewing frequency. Evaluation of oral processing parameters at various stages (i.e., first cycle, first 5 cycles, and last 3 cycles) was found to be a useful method to investigate the dynamic nature of sensory perception at first bite, during chewing and after swallowing. The study showed that muscle activity and jaw movement can be used to understand the links between physical properties of foods and sensory texture.     

Mastication efforts on block and finely cut foods studied by electromyography

To quantify the mastication effort for finely cut foods, mastication patterns were analyzed by electromyography (EMG) while normal subjects ate a mouthful size (7 g block, the same weight cut, and the same volume cut) of raw carrot, cucumber, roast pork, and surimi gels. Instrumental compression test revealed that raw carrot and cucumber exhibited high fracture stress and small relative deformation for fracture, while roast pork and surimi gels fracture at low stress and large deformation. For raw carrot and cucumber, the number of chews, masticatory time, total duration of mastication, and total muscle activities evaluated by EMGs were greater for cut samples than for same weight block samples. For roast pork and surimi gel, these factors were the same for equal-weight cut and block samples. Cut samples with the same volume, but of smaller weight, were often eaten with less total mastication effort until swallowing than a block sample. These results revealed that cutting food does not help reduce mastication effort for the same weight as a mouthful size block, although it may make easier mastication by decreasing the weight of one mouthful.