Food Bolus Texture and Tongue Activity Just before Swallowing in Human Mastication (original) (raw)
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Journal of Texture Studies, 2012
The chewing process transforms food into bolus for a safe swallow. It is known that humans adapt their chewing behavior to food product characteristics. This study aimed at identifying individual chewing strategies of healthy consumers and determining the respective consequences on bolus properties. For that purpose, the chewing activity of 50 subjects was recorded during consumption of five model cheeses. Boluses were collected at the swallowing threshold for rheological analyses. We found that 30% of subjects showed only slight adaptation of chewing activity to product characteristics and thus produced boluses with different rheological properties. Among the 70% of subjects who adapted their chewing behavior, 57% adapted their behavior via chewing time and 40% adapted their behavior via chewing time and muscular contraction amplitude. Among the bolus rheological parameters, only consistency was not influenced by chewing strategies. Hence, it seemed to be a determinant factor of the swallowing threshold for these products.
Journal of Theoretical Biology, 2011
After swallowing a liquid or a semi-liquid food product, a thin film responsible for the dynamic profile of aroma release coats the pharyngeal mucosa. The objective of the present article was to understand and quantify physical mechanisms explaining pharyngeal mucosa coating. An elastohydrodynamic model of swallowing was developed for Newtonian liquids that focused on the most occluded region of the pharyngeal peristaltic wave. The model took lubrication by saliva film and mucosa deformability into account. Food bolus flow rate and generated load were predicted as functions of three dimensionless variables: the dimensionless saliva flow rate, the viscosity ratio between saliva and the food bolus, and the elasticity number. Considering physiological conditions, the results were applied to predict aroma release kinetics.
Role of Physical Bolus Properties as Sensory Inputs in the Trigger of Swallowing
PLoS ONE, 2011
Background: Swallowing is triggered when a food bolus being prepared by mastication has reached a defined state. However, although this view is consensual and well supported, the physical properties of the swallowable bolus have been under-researched. We tested the hypothesis that measuring bolus physical changes during the masticatory sequence to deglutition would reveal the bolus properties potentially involved in swallowing initiation. Methods: Twenty normo-dentate young adults were instructed to chew portions of cereal and spit out the boluses at different times in the masticatory sequence. The mechanical properties of the collected boluses were measured by a texture profile analysis test currently used in food science. The median particle size of the boluses was evaluated by sieving. In a simultaneous sensory study, twenty-five other subjects expressed their perception of bolus texture dominating at any mastication time. Findings: Several physical changes appeared in the food bolus as it was formed during mastication: (1) in rheological terms, bolus hardness rapidly decreased as the masticatory sequence progressed, (2) by contrast, adhesiveness, springiness and cohesiveness regularly increased until the time of swallowing, (3) median particle size, indicating the bolus particle size distribution, decreased mostly during the first third of the masticatory sequence, (4) except for hardness, the rheological changes still appeared in the boluses collected just before swallowing, and (5) physical changes occurred, with sensory stickiness being described by the subjects as a dominant perception of the bolus at the end of mastication. Conclusions: Although these physical and sensory changes progressed in the course of mastication, those observed just before swallowing seem to be involved in swallowing initiation. They can be considered as strong candidates for sensory inputs from the bolus that are probably crucially involved in the triggering of swallowing, since they appeared in boluses prepared in various mastication strategies by different subjects.
Physical and related sensory properties of a swallowable bolus
Physiology & Behavior, 2011
6 7 a b s t r a c t a r t i c l e i n f o 8 Rheology and water content properties of cereal boluses collected just before swallowing were investigated. 23 No specific physical markers for swallowing were found between subjects. Each subject had his own 24 mastication strategy leading to food bolus with different rheological and water content properties. However, 25 for most of the subjects, similar physical properties were found for food boluses obtained from consumption 26 of different cereals. Results showed that the food boluses from different cereals exhibited gel-like properties 27 being in a range from 14.1 kPa to 21.2 kPa (G′ (1 Hz, 0.4%) ), when swallowed. The food boluses had a static yield 28 stress varying from 1.3 kPa to 4.3 kPa. Another interesting finding was that the water content of food boluses 29 might be an important marker for swallowing since it was similar for different cereal food boluses (around 30 50%). This physical property might drive the fluid sensory perception, which could also be a sensory 31 swallowing threshold. 32
Food Quality and Preference, 2002
During chewing, a meat sample is mashed under compression and shear bite forces whilst saliva is incorporated. The resulting mixture is shaped into a cohesive bolus by agglomeration of small particles to trigger a swallow. This study aims to investigate the relationship between meat structure before chewing and texture after various chewing durations, according to the subject's chewing behavior. Twenty-five young adults participated. Electromyography activity (EMG) was recorded from surface electrodes on the elevator muscles during mastication of cold beef (5 g). Two different meat textures were obtained by varying aging and cooking temperature. Subjects were asked to chew and then to spit out the bolus either after a constant chewing duration (7 s) or when the bolus was ready to be swallowed. Boluses were then weighed to determine saliva incorporation. Cutting tests were applied to measure maximum shear force and to assess bolus structure homogeneity. From EMG recordings, temporal and amplitude parameters were analyzed. The mechanical shear force was maximal for meat before chewing and decreased for the bolus with the lengthening of the chewing duration. Significant texture differences were found for samples before chewing and for two types of bolus but differences were larger for the bolus after 7 s chewing than for the bolus when ready to be swallowed. The amount of saliva incorporated into the bolus increased with both chewing muscular activity and chewing duration. Finally, the more chewing cycles before swallowing, the more comminuted the meat bolus (lower shear force) and the more saliva was incorporated in it. These results fit with one of the major roles of the saliva, that is, to provide cohesion between particles [Nature 391 (1998) 329] and with the intra-oral management of meat during chewing as analyzed by videofluorography [Arch. Oral Biol. 47 (2002) 267].
BOLUS MOISTURE CONTENT OF SOLID FOODS DURING MASTICATION
Saliva addition plays an important role in bolus formation. During chewing, food breaks down, exposing food particles to saliva. The aim of this study was to explore and understand how bolus moisture content changes during the oral processing of solid foods. Twelve subjects chewed commercially produced solid foods; the boluses were collected at different stages of the mastication process, including the swallowing point, and all of the boluses produced were analyzed for their moisture content. The chewing sessions were recorded on video, enabling the number of chews to be assessed for each subject and food type. Results showed that moisture content of boluses during mastication increased linearly at a rate depending on the subject and food types studied. It was found that for the food types studied, an increase in initial food moisture content increased the bolus moisture content at the swallowing point.
The influence of product and oral characteristics on swallowing
Archives of oral biology, 2005
The urge to swallow food could be triggered by a threshold level in both food particle size and lubrication of the food bolus. Thus, both oral physiology and product characteristics may influence the swallowing threshold. We quantified the swallowing threshold in a group of 266 healthy adult subjects (age 42 +/- 12 years) by counting the number of chewing cycles needed to prepare food for swallowing. The influence of oral physiology on the swallowing threshold was determined by measuring salivary flow rate, maximum bite force and masticatory performance. We used about 10 cm(3) of bread, toast, melba toast, breakfast cake, peanuts and cheese to determine the influence on the swallowing threshold of various food characteristics, e.g. hardness, moisture and fat. Furthermore, we tested the effect of buttering the bread, toast, melba toast and breakfast cake on the swallowing threshold. Salivary flow rates were significantly and negatively correlated with the number of chewing cycles of ...
Tongue-Palate Interactions During Swallowing
Journal of Texture Studies, 2011
Investigating the sequence and magnitude of tongue movements against the hard palate during swallowing is basic to understanding the process by which the bolus is moved from the front of the mouth to the pharynx. Here we outline the basic muscular anatomy of the tongue, and we report on specific pressure patterns generated at three positions along the midline: at the front, middle and back of the hard palate. We show that there are sharp amplitudinal changes from positive to negative pressures at all three locations. While these pressure patterns show large interindividual variations, they appear to be consistent within individuals, irrespective of bolus size or consistency. Tentatively, we are able to identify three basic patterns; Type I, squeezer -a mostly positive pressure cascade from the front to the back of mouth; Type II, slider -characterized by an effortless and extended swallow, and Type III, slapper -large positive and negative pressure fluctuations during each swallow. Finally, we found that the most variability in pressure fluctuations occurred in the front of the mouth, from which we conclude that the front of the tongue has a predominant organisational role, whereas the back of the tongue is mostly propulsional.