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. ©     

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.     

Comparison of electromyographic pattern of sensory experts and untrained subjects during chewing of Mahon cheese

Use of electromyography (EMG) to monitor mastication is a relatively new concept in assessing food physical and sensory properties. Although expert assessment of cheese characteristics is widely used, the effect of training in sensory analysis on mastication patterns, as assessed using EMG is not well known. Nine samples of the same Mahon cheese (60 days ripening) were given to 24 subjects (8 experts, 16 untrained) and EMG recorded for each chewing sequence. Three samples were tested in a single session by each subject, and three sessions carried out on different days. EMG was recorded from four masticatory muscles for each subject. From EMG records the following was extracted: number of chews, chewing time, mean and maximum voltage of EMG bursts (i.e. chews) across chewing sequence, chewing work and chewing rate. No gender bias was found for the EMG parameters considered, therefore, as regards gender, each group was considered to be homogeneous. Variability within-subjects across samples was greater for experts than untrained subjects. Significant differences in chewing time, chewing work and chewing rate were found between the expert and untrained groups. Data analysis of the three sessions showed an influence of cognitive constructs, mediating states, on the chewing process. The experts were found to be goal driven as to their mastication process. Experts showed no significant differences between sessions, untrained subjects were found to vary their EMG output in successive sessions for number of chews, chewing time, mean voltage, and chewing work.     

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.     

Elucidation of the relationship between cooking temperature, water distribution and sensory attributes of pork - a combined NMR and sensory study

Low-field NMR T(2) relaxation was measured continuously during cooking of pork samples (m. longissimus dorsi) to a final temperature of 75 °C. Simultaneously the remaining muscle was cooked in an oven to a core temperature of either 62 or 75 °C and subsequently evaluated by a sensory panel. Highly significant effects of final cooking temperature on the sensory attributes juiciness (initial and final), hardness, tenderness, crumbliness and chewing time were found. Juiciness and tenderness decreased with increasing temperature, while hardness, crumbliness and chewing time increased with increasing temperature. Distributed T(2) relaxation data revealed marked effects of temperature (62 vs. 75 °C) on the water distribution within the meat. Partial least squares (PLS) regressions were used to examine a potential prediction of sensory attributes from the distributed T(2) relaxation data, and high correlations were obtained. Moreover, loadings from the PLS regressions were analysed to evaluate the alterations in the water distribution as a function of temperature that contribute to changes in juiciness. This analysis revealed that the reduction in juiciness at 75 °C can be ascribed to changes in the size of the pores confining the myofibrillar water together with an expulsion of water.     

Individuality of understanding and assessment of sensory attributes of foods, in particular, tenderness of meat

This study examines the extent to which variations in consumers' sensory assessments of food arise from the inability to report accurately sensory perceptions, from confusion regarding the criteria by which to assess samples, or from differences in their oral breakdown of the products.

Twenty consumers assessed the tenderness of a range of 8 hot, freshly roasted meat samples using Time Intensity (TI). Overall a significant correlation was found between the maximum recorded intensity (Imax) of their TI curves and single sensory scores given by a trained panel. Correlation was significant for only 42% of the consumers individually. Significant correlations were found between the amount of masticatory muscle activity undertaken during chewing (measured using electromyography) and Imax for all but 2 of the consumers. Thus subjects' perceptions were accurately described by their chewing work, suggesting between subject differences in perception arose from differences in the way chewing work was applied to break down the samples. The sensory input from the masticatory muscles may represent the major determinant of perceived tenderness of meat.     

Impact of Almond Form and Moisture Content on Texture Attributes and Acceptability

The objectives of this study were to measure sensory texture attributes of 5 types of almonds (blanched slivered, natural sliced, whole blanched, whole dry roasted, and natural whole) conditioned at 4 different moisture levels, to measure liking of a subset of these products, and to compare the sensory texture measurements with consumer liking ratings. Thirteen panelists trained to evaluate almond texture rated the texture attributes of the 20 almond samples. A panel of 113 almond consumers rated their liking of a subset of 8 of these almonds. Compared with the whole almonds, sliced and slivered almonds had less hardness, less crunchiness, less cohesiveness, less tooth packing, and required fewer chews and swallows to consume. Compared with slivered almonds, sliced almonds were more powdery, had more surface roughness, more loose particles, and were crisper. Compared with slivered almonds, sliced almonds were less hard, broke into fewer pieces, had less moistness and cohesiveness of mass, less fatty film, and required fewer chews and fewer swallows to consume. Dry roasted almonds were generally harder, more crisp, more crunchy, and produced more loose particles than natural almonds, which were, in turn, more hard, crisp, and crunchy than blanched almonds. As moisture content increased, moistness of mass and cohesiveness of mass increased. Crispness, number of pieces, hardness, crunchiness, persistence of crunch, and particulate mass decreased with increasing moisture content. Consumer texture liking ratings were highly positively correlated with the attributes crispness, crunchiness, and persistence of crunch.     

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.     

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.     

MICROSTRUCTURAL CHARACTERISTICS AND COMPRESSION RESISTANCE AS INDICES OF SENSORY TEXTURE IN A CRUNCHY SNACK PRODUCT

Identically formulated drum dried and cold formed half-products were puffed in hot air or by frying to determine microstructure-texture relationships. Structural attributes measured were cell size (CS), number of cells per unit area (CN), cell wall thickness (CW) and product specific volume (SV). Sensory attributes of crunchiness, hardness and density were also evaluated. Puffed product microstructure depended more on the half-product preparation process than the method of puffing. Similarly prepared half products had the same microstructural attributes whether fried or hot air puffed. Sensory scores for crunchiness were not significantly different among all samples but scores for hardness and density were significantly different between hot air puffed and fried products even when microstructural attributes were similar. Higher compression force values reflected lower sensory scores for crunchiness and hardness of puffed products. Compression force was significantly correlated with microstructural attributes of CS, CW and SV.     

Texture analysis of Red Delicious fruit: Towards multiple measurements on individual fruit

The sensory texture of Red Delicious apples was studied using single point and time–intensity (TI) methods together with penetrometers and in vivo techniques. Testing was performed in two trials on a per fruit basis, not with fruit batches. The standard penetrometer was significantly correlated (p < 0.05) to sensory hardness, juiciness, mealiness, crunchiness and degree of breakdown, but not to skin toughness. Facial muscle activity during chewing was collected with electromyography (EMG) together with spit outs for individuals. Parameters such as work done during chewing were extracted from the full EMG signals, and some were found to be related significantly (p < 0.05) to the penetrometer data and to sensory hardness. The aspect ratio of expectorated particles related significantly (p < 0.05) to sensory hardness and skin toughness.Principal component analysis shows that 76% of the variance in the combined data set was explained by seven components in Trial 1 and 73% by six components in Trial 2. The first component in both trials was described, principally by hardness, mealiness and the penetrometer value. The second component was described by the EMG signal parameters in Trial 1, and the apple skin properties in Trial 2. Sensory terms hardness, mealiness, crunchiness and juiciness were inter-correlated which may indicate that the texture of Red Delicious apples is perceived as mainly one-dimensional.     

STUDY OF FOOD TEXTURES BY RECORDING OF CHEWING AND SWALLOWING MOVEMENTS

Abstract Chewing and swallowing patterns were recorded in three subjects eating freely pieces of foods of various initial textures in an attempt to assess objectively these food textures as sensory stimuli in the mouth. In each phase of masticatory and swallowing movements corresponding to each piece of food, variations were noted differentiating the 16 textures tested. The number of masticatory movements, the time of mastication up to complete swallowing, the time course of the force of mastication and the number and distribution of swallowing movements were found to be the most discriminating parameters. In considering them, foods might be placed on a scale from hard and dry to soft and fluid textures. The results confirm the validity of recording chewing and swallowing movements as a new method for describing the true dimensions of oral sensory stimulations by food textures.     

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.     

INSTRUMENTAL AND SENSORY DETECTION OF SIMULTANEOUS BRITTLENESS LOSS AND MOISTURE TOUGHENING IN THREE PUFFED CEREALS1

The jaggedness of the compressive force-displacement relationship of cheese balls®, cocoa puffs® and peanut butter crunch® particles at various moisture contents was determined in terms of their apparent fractal dimension, and the mean magnitude of the power spectrum of their normalized residuals. The plots of these measures versus moisture contents had a characteristic sigmoid shape very similar to that of the corresponding sensory crispness and crunchiness vs moisture content relationships. This close similarity suggests that the jaggedness of the force-displacement relationship is a manifestation of the same failure events that produce the crispness or crunchiness sensation. (In the context of the tested products the two terms, crispness and crunchiness, were found to be synonymous.) In all three products moisture toughening could be clearly detected instrumentally but only in two there was an unambiguous corresponding increase in the sensory hardness scores. This indicates that at least in certain cereal products moisture toughening can be perceived simultaneously with brittleness loss.     

Effects of blade tenderization on some quality characteristics of the muscles of mature ewes

 The effects of blade tenderization (BT) on some of the quality characteristics of longissimus dorsi (LD) and semimembranosus (SM) muscles from the carcasses of mature ewes were evaluated in this research. Values describing panel tenderness (P<0.01) and residue after chewing (P<0.05) were significantly improved by BT. Also, the number of chews before swallowing was significantly reduced (P<0.01) in the tenderized samples. The LD muscle had a significantly better (P>0.01) panel tenderness score and number of chews value than the SM muscle. BT influenced significantly (P<0.05) the initial yield force values of the Instron Warner-Bratzler test, which were 5.42±0.40 kg and 6.45±0.42 kg for tenderized and non-tenderized samples, respectively. Peak force and work done values were also significantly (P<0.01) affected by BT. The LD muscle had a lower peak force value (5.88±0.39 kg vs 7.06±0.43 kg) than the SM muscle. However, other Instron Warner-Bratzler test parameters were not significantly (P>0.05) affected by muscle type. The chewiness, hardness, peak force 2 and work done 2 values determined by the Instron compression test were significantly affected by muscle type. Also, BT resulted in lower values for chewiness, hardness, peak force 1 and 2, and work done 1 and 2 values, but the differences between tenderized and non-tenderized samples were not statistically significant (P>0.05). Received: 16 July 1998 / Revised version: 14 October 1998     

INFLUENCE OF CHEWING EFFICIENCY ON TEXTURE AND FLAVOUR PERCEPTIONS OF FOOD

This study examined the effect of differences in chewing efficiency on selected panellists' perceptions of the stickiness and flavour of cooked pasta. Chewing efficiency was measured by the degree of breakdown of an almond, and weight loss of chewing gum after predetermined numbers of chews. Pasta was cooked for various lengths of time in tomato juice to provide a series of samples varying in texture and flavour. The attributes considered in this study were clearly understood and detected in all of the samples by all the subjects. Nevertheless the subjects differed in the time intensity representations of their perceptions of these attributes. Differences in the efficiencies with which subjects break down food in the mouth may account for the abilities of subjects to distinguish between samples in terms of texture and flavour.