Food Transport and Bolus Formation during Complete Feeding Sequences on Foods of Different Initial Consistency
TL;DR: A new model for bolus formation and deglutition is proposed because there was no predictable tongue–palate contact at any time in the sequence of complete feeding sequences on soft and hard foods.
Abstract: Food movements during complete feeding sequences on soft and hard foods (8 g of chicken spread, banana, and hard cookie) were investigated in 10 normal subjects; 6 of these subjects also ate 8 g peanuts. Foods were coated with barium sulfate. Lateral projection videofluorographic tapes were analyzed, and jaw and hyoid movements were established after digitization of records for 6 subjects. Sequences were divided into phases, each involving different food management behaviors. After ingestion, the bite was moved to the postcanines by a pull-back tongue movement (Stage I transport) and processed for different times depending on initial consistency. Stage II transport of chewed food through the fauces to the oropharyngeal surface of the tongue occurred intermittently during jaw motion cycles. This movement, squeeze-back, depended on tongue–palate contact. The bolus accumulated on the oropharyngeal surface of the tongue distal to the fauces, below the soft palate, but was cycled upward and forward on the tongue surface, returning through the fauces into the oral cavity. The accumulating bolus spread into the valleculae. The total oropharyngeal accumulation time differed with initial food consistency but could be as long as 8–10 sec for the hard foods. There was no predictable tongue–palate contact at any time in the sequence. A new model for bolus formation and deglutition is proposed.
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TL;DR: The goal of dysphagia rehabilitation is to identify and treat abnormalities of feeding and swallowing while maintaining safe and efficient alimentation and hydration.
521 citations
Cites background or methods from "Food Transport and Bolus Formation ..."
...The duration of bolus aggregation in the oropharynx ranges from a fraction of a second to about 10 seconds in normal individuals eating solid food [5]....
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...In contrast, during food processing, the tongue and soft palate move cyclically in association with jaw movement, permitting open communication between the oral cavity and pharynx [5,8]....
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...Therefore, the process model of feeding was established to describe the mechanism of eating and swallowing solid food [4,5]....
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TL;DR: The oral breakdown trajectory is mapped through 6 stages and a dynamic multi-scale approach is suggested to capture underlying physics to design new food and beverages that are healthy yet acceptable to consumers.
Abstract: Texture and mouthfeel arising from the consumption of food and beverages are critical to consumer choice and acceptability. While the food structure design rules for many existing products have been well established, although not necessarily understood, the current drive to produce healthy consumer acceptable food and beverages is pushing products into a formulation space whereby these design rules no longer apply. Both subtle and large scale alterations to formulations can result in significant changes in texture and mouthfeel, even when measurable texture-related quantities such as rheology are the same. However, we are only able to predict sensations at the initial stages of consumption from knowledge of material properties of intact food. Research is now on going to develop strategies to capture the dynamic aspects of oral processing, including: from a sensory perspective, the recent development of Temporal Dominance Sensation; from a material science perspective, development of new in vitro techniques in thin film rheology and tribology as well as consideration of the multifaceted effect of saliva. While in vivo, ex vivo, imitative and empirical approaches to studying oral processing are very insightful, they either do not lend themselves to routine use or are too complex to be able to ascertain the mechanism for an observed behaviour or correlation with sensory. For these reasons, we consider that fundamental in vitro techniques are vital for rational design of food, provided they are designed appropriately to capture the important physics taking place during oral processing. We map the oral breakdown trajectory through 6 stages and suggest a dynamic multi-scale approach to capture underlying physics. The ultimate goal is to use fundamental insights and techniques to design new food and beverages that are healthy yet acceptable to consumers.
416 citations
TL;DR: Oropharyngeal dysphagia should be given more importance and attention and thus be included in all standard screening protocols, treated, and regularly monitored to prevent its main complications.
Abstract: This position document has been developed by the Dysphagia Working Group, a committee of members from the European Society for Swallowing Disorders and the European Union Geriatric Medicine Society, and invited experts. It consists of 12 sections that cover all aspects of clinical management of oropharyngeal dysphagia (OD) related to geriatric medicine and discusses prevalence, quality of life, and legal and ethical issues, as well as health economics and social burden. OD constitutes impaired or uncomfortable transit of food or liquids from the oral cavity to the esophagus, and it is included in the World Health Organization’s classification of diseases. It can cause severe complications such as malnutrition, dehydration, respiratory infections, aspiration pneumonia, and increased readmissions, institutionalization, and morbimortality. OD is a prevalent and serious problem among all phenotypes of older patients as oropharyngeal swallow response is impaired in older people and can cause aspiration. Despite its prevalence and severity, OD is still underdiagnosed and untreated in many medical centers. There are several validated clinical and instrumental methods (videofluoroscopy and fiberoptic endoscopic evaluation of swallowing) to diagnose OD, and treatment is mainly based on compensatory measures, although new treatments to stimulate the oropharyngeal swallow response are under research. OD matches the definition of a geriatric syndrome as it is highly prevalent among older people, is caused by multiple factors, is associated with several comorbidities and poor prognosis, and needs a multidimensional approach to be treated. OD should be given more importance and attention and thus be included in all standard screening protocols, treated, and regularly monitored to prevent its main complications. More research is needed to develop and standardize new treatments and management protocols for older patients with OD, which is a challenging mission for our societies.
401 citations
Book•
28 Jun 2004TL;DR: In this article, the basic structure of the mammalian mouth is described and how the mouth operates, including the shape and size of the teeth, and how they fit in the mouth.
Abstract: Preface Flickart 1. How to get excited about teeth 2. The basic structure of the mammalian mouth 3. How the mouth operates 4. Tooth shape 5. Tooth size 6. Tooth wear 7. The evolution of the mammalian dentition Appendix A. Mechanical properties and their measurement: material properties made easy Appendix B. Properties of teeth and potential foods Notes References Index.
386 citations
University of Leeds1, Shaikh Khalifa Medical City2, University of Toronto3, Toronto Rehabilitation Institute4, Zhejiang Gongshang University5, University of Queensland6, University of São Paulo7, University College London8, University of British Columbia9, National Health Service10, Fayoum University11, University of KwaZulu-Natal12
TL;DR: The literature suggests a need to classify food and fluid behavior in the context of the physiological processes involved in oral transport and flow initiation, and pointed to properties of hardness, cohesiveness, and slipperiness as being relevant both for physiological behaviors and bolus flow patterns.
Abstract: Texture modification has become one of the most common forms of intervention for dysphagia, and is widely considered important for promoting safe and efficient swallowing. However, to date, there is no single convention with respect to the terminology used to describe levels of liquid thickening or food texture modification for clinical use. As a first step toward building a common taxonomy, a systematic review was undertaken to identify empirical evidence describing the impact of liquid consistency and food texture on swallowing behavior. A multi-engine search yielded 10,147 non-duplicate articles, which were screened for relevance. A team of ten international researchers collaborated to conduct full-text reviews for 488 of these articles, which met the study inclusion criteria. Of these, 36 articles were found to contain specific information comparing oral processing or swallowing behaviors for at least two liquid consistencies or food textures. Qualitative synthesis revealed two key trends with respect to the impact of thickening liquids on swallowing: thicker liquids reduce the risk of penetration–aspiration, but also increase the risk of post-swallow residue in the pharynx. The literature was insufficient to support the delineation of specific viscosity boundaries or other quantifiable material properties related to these clinical outcomes. With respect to food texture, the literature pointed to properties of hardness, cohesiveness, and slipperiness as being relevant both for physiological behaviors and bolus flow patterns. The literature suggests a need to classify food and fluid behavior in the context of the physiological processes involved in oral transport and flow initiation.
382 citations
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TL;DR: In this paper, a general three dimensional model applicable to foods is postulated with "Degree of Structure", ''degree of Lubrication'' and ''time'' as its axes, which is seen as the start of a general hypothesis for the physics and psychophysics of mastication.
Abstract: Many authors have drawn attention to the limitations of present texture testing methods. To a great extent this may be due to the assumption that the perception of the structural properties of foods is comprised of a series of single attributes. This philosophy may account for the failure of the single instrumental measurement as a reliable texture descriptor.
The present paper emphasises that texture perception is a dynamic sensory monitor of changes made to a food by processes occurring in the mouth. A general three dimensional model applicable to foods is postulated with “Degree of Structure”, “Degree of Lubrication” and “Time” as its axes. As each food is changed in the mouth, it describes its own “Breakdown Path” throughout the three dimensions. This approach is seen as the start of a general hypothesis for the physics and psychophysics of mastication.
479 citations
TL;DR: Alternation of jaw adductor and abductor activity during mastication provided a framework for integration of chewing, transport, and swallowing.
Abstract: The coordination of mastication, oral transport, and swallowing was examined during intake of solids and liquids in four normal subjects. Videofluorography (VFG) and electromyography (EMG) were recorded simultaneously while subjects consumed barium-impregnated foods. Intramuscular electrodes were inserted in the masseter, suprahyoid, and infrahyoid muscles. Ninety-four swallows were analyzed frame-by-frame for timing of bolus transport, swallowing, and phases of the masticatory gape cycle. Barium entered the pharynx a mean of 1.1 s (range −0.3 to 6.4 s) before swallow onset. This interval varied significantly among foods and was shortest for liquids. A bolus of food reached the valleculae prior to swallow onset in 37% of sequences, but most of the food was in the oral cavity at the onset of swallowing. Nearly all swallows started during the intercuspal (minimum gape) phase of the masticatory cycle. Selected sequences were analyzed further by computer, using an analog-to-digital convertor (for EMG) and frame grabber (for VFG). When subjects chewed solid food, there were loosely linked cycles of jaw and hyoid motion. A preswallow bolus of chewed food was transported from the oral cavity to the oropharynx by protraction (movement forward and upward) of the tongue and hyoid bone. The tongue compressed the food against the palate and squeezed a portion into the pharynx one or more cycles prior to swallowing. This protraction was produced by contraction of the geniohyoid and anterior digastric muscles, and occurred during the intercuspal (minimum gape) and opening phases of the masticatory cycle. The mechanism of preswallow transport was highly similar to the oral phase of swallowing. Alternation of jaw adductor and abductor activity during mastication provided a framework for integration of chewing, transport, and swallowing.
392 citations
TL;DR: The model suggests that there is an optimum moment for a mammal to swallow, defined in terms of a peak cohesive force between food particles, which is tested on human mastication with two foods, brazil nut and raw carrot, which have very different particle size breakdown rates.
Abstract: Mammalian mastication is a process combining simultaneous food comminution and lubrication. The initiation of swallowing, which is voluntary, has been thought to depend on separate thresholds for food particle size and for particle lubrication. Instead of this duality, we suggest that swallowing is initiated when it is sensed that a batch of food particles is binding together under viscous forces so as to form a bolus. Bolus formation ensures that when the food mass is swallowed, it will pass the pharyngeal region safely without risk of inhaling small particles into the lower respiratory tract. Crucial for bolus formation is food particle size reduction by mastication. This allows the tongue to pack particles together tightly by pressure against the hard palate. A major function of salivation is to fill the gradually reducing spaces between particles, so increasing viscous cohesion and promoting bolus formation. If swallowing is delayed, excessive saliva floods the bolus, separating particles and reducing cohesion. Swallowing then becomes more precarious. Our model suggests that there is an optimum moment for a mammal to swallow, defined in terms of a peak cohesive force between food particles. The model is tested on human mastication with two foods, brazil nut and raw carrot, which have very different particle size breakdown rates. The peak cohesive force is much greater with brazil nuts but both foods are predicted to be swallowed after similar numbers of chews despite the very different food particle size reductions achieved at that stage. The predicted number of chews to swallow is in broad agreement with published data.
329 citations
TL;DR: It is concluded that initial food consistency determines the number of chewing cycles before the first swallow and overall sequence duration and the change in the pattern of jaw movement in both the vertical and mediolateral directions cycle to cycle suggests continuous sensory modulation of the motor output to the mandibular musculature.
275 citations
"Food Transport and Bolus Formation ..." refers background or methods in this paper
...The mechanics of chewing have been extensively studied, with a primary focus on the interaction between the upper and lower occlusal surfaces of the teeth, the movements of the jaws, the cyclical nature of the chewing cycle, and the ‘‘efficiency’’ with which solid food is actually reduced to a ‘‘swallowable’’ condition [2]....
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...Regular cyclical jaw and tongue movements may be replaced by irregular jaw movements (clearance) for short periods before a swallow [2,9]....
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...Stage I transport: transport of ingested material from the incisal area to the molar region of the oral cavity; Processing: the reduction of food within the oral cavity to a ‘‘swallowable’’ condition; Stage II transport: movement of triturated food from the oral cavity through the pillars of the fauces to the oropharyngeal surface of the tongue; Pharyngeal swallow [2,8]....
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...As expected [2], total sequence durations differed with food type, with peanuts (mean 4 22....
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...This approach minimized the confounding factor of substantial interindividual variation in sequence behavior between subjects when feeding on the same foods [2]....
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TL;DR: In more than half of the instances, during normal eating, food enters the pharynx during the preparatory phase before a swallow is initiated, the path of pharyngeal transit of solid bolus is different from that of liquid bolus, and the epiglottal edge appears to be the most sensitive trigger zone for swallowing.
161 citations