Chewing Stage Research Articles

Comparison of Child and Adult Mastication of a Sticky Processed Cream Cheese and Simulation with a Masticator.

An advantage of masticators is the calibration and possible standardization of intra- and inter-individual mastication variability. However, mastication of soft, sticky and melting products, such as processed cream cheeses, is challenging to reproduce with a masticator. The objectives of this work were, for the cheese studied: (1) to compare child and adult mastication and (2) to find in vitro parameters which best reproduce their in vivo chewing. Five parameters influencing mastication (mouth volume, quantity consumed, saliva volume, mastication time and number of tongue-palate compressions) were measured in 30 children (5-12 years old) and 30 adults (18-65 years old) and compared between the two populations. They were then transposed to a masticator (Oniris device patent). The initial cheese, a homogeneous white paste, was surface-colored to investigate its in-mouth destructuring. In vivo boli were collected at three chewing stages (33, 66 and 99% of mastication time) and in vitro boli were obtained by varying the number of tongue-palate compressions and the rotation speed. In vivo and in vitro boli were compared by both image and texture analysis. Child masticatory parameters were proportionally smaller than those of adults. The in vivo child boli were less homogeneous and harder than adult ones. Comparison of in vivo and in vitro bolus color and texture enabled the successful determination of two in vitro settings that closely represented the mastication of the two populations studied.

Study on saltiness sensing during oral processing of dry-cured pork base on salivary proteomics

Recently, the concept of low-salt and healthy diet has been widely accepted, while the market recognition of low-salt meat products is generally inferior due to their inability to satisfy the oral pleasure of consumers. Therefore, to investigate the role of saliva in saltiness during oral processing of chewing high-salt dry-cured pork, a subset of 3 male subjects with high salt-sensitivity were selected to partake this study. Cooked dry-cured pork (5% salt added) as chewed and held in the oral cavity without swallowing for four different chewing stages during oral processing. Saliva from the 3 subjects was collected and analyzed for salivary proteomics by Data Independent Acquisition (DIA) combined with food oral processing methods. According to the analysis of human proteome (H.sapiens, UP000005640), the abundance of RAC1(RAS-related C3 botulinum toxin substrate 1) and calmodulin-like 3 (CALML 3) was first found to be related to the change of saltiness sensing during oral processing. Moreover, oral chewing leads to upregulation of RAC1 protein, which leads to positive regulation of protein kinase B signaling, ultimately leading to increased serine-type endopeptidase activity and salt perception.

Flavor release from traditional dry-cured pork during oral processing

The rate of flavor release in the mouth from traditional dry-cured pork was evaluated in this study. It was hypothesized that a slow steady release of flavor would occur on chewing and hydration. To test this, high salt dry-cured pork was chewed and held in oral cavity without swallowing for 4 different chewing stages (B, NC30, C30, EC). Saliva and food bolus from 16 healthy subjects were collected during oral processing, and analyzed for saliva flow rate, total saliva protein content, saliva pH, conductivity, saliva and sodium, and taste components. Results show that oral processing behavior and salivary release have important effects on flavor release of dry-cured pork. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that oral processing has a certain effect on the protein composition and concentration in saliva. This study suggests that the interaction between food and saliva that accompanies chewing can lead to significant changes in sensory perception during oral processing.

Fragmentation of two soft cereal products during oral processing in the elderly: Impact of product properties and oral health status

This study investigated the mechanisms of fragmentation leading to bolus formation during chewing in the elderly population for two cereal foods of different compositions and cellular structure: sponge-cake (SC) and brioche (B). For both products, mechanical properties were characterized by uniaxial compression and 3D cellular structure was determined using x-ray micro-tomography. Stress-strain curves showed two distinct ductile-like behaviors: product B underwent plastic deformation, whereas product SC displayed a hyper-elastic behavior. Twenty subjects aged 65 years and over with two different oral health conditions (poor vs satisfactory dental status, variable stimulated salivary flow rate) were asked to consume both products. Bolus particle size was determined at three different chewing stages through image analysis, and the resulting particle size distribution (PSD) curves were fitted by Gompertz model. The model parameters were related to bolus particle heterogeneity and fragmentation, thanks to their correlations with median particle size diameter D50 and interquartile ratio (D75/D25), directly extracted from PSD curves. The use of model parameters allowed discriminating between chewing sequences for both products and revealed different fragmentation patterns: while SC boli exhibited a continuous particle size reduction during chewing, B displayed a combination of fragmentation and agglomeration. In addition, results showed that subjects with a satisfactory dental status produced significantly more degraded boli than those with a poor dental status. These results highlight distinct fragmentation mechanisms for these two soft products that were interpreted in relation to their differences in composition, structure and mechanical behavior.

Association between muscle activity and overjet in class II malocclusion with surface electromyography.

OBJECTIVES:The aim of the study was to assess the association and correlation between the overjet and muscle activity (the masseter and temporalis muscles) in patient with Class II malocclusion in different genders using surface electromyography (sEMG).MATERIALS AND METHODS:The overjet (measured clinically) and electromyographical activity (rest, chew, post chew rest, clench and post clench rest) of the masseter and temporalis muscle of class II malocclusion patient were assessed in 18 patients (3 males and 15 females) from the School of Dental Science, Hospital University Sains Malaysia.RESULTS:The results were compared by simple linear regression test to evaluate the association between overjet and muscle activity in different genders. Class II malocclusion patients with increased overjet group showed significant association with masseter muscle activity on chewing stage (P = 0.005, F = 6.081 and adj-R2 = 0.473). Left temporalis muscle in class II malocclusion showed a significant linear association (P = 0.014, F = 0.812 and adj-R2= −0.034) with gender during clench.CONCLUSION:In conclusion, class II malocclusion patient with increased overjet can affect masticatory muscle function and as well as clench force may differ in gender.

Relationships of oral comfort perception and bolus properties in the elderly with salivary flow rate and oral health status for two soft cereal foods

The aim of this study was to investigate food oral processing and bolus formation in the elderly population, and their relationship with the perception of oral comfort, for two soft cereal products of different composition: sponge-cake and brioche. Twenty subjects aged 65 and over participated in the study. They were classified in two groups according to dental status (poor vs. satisfactory) and presented various stimulated salivary flow rate (SSF) in each group. Food bolus properties (hydration ratio and apparent viscosity) were characterized after three chewing stages for both groups. Results showed that chewing duration did not depend on food product but rather on physiology: subjects with a poor dental status had a shorter chewing duration. For each chewing stage, sponge-cake boli showed a higher hydration ratio than brioche boli, which showed higher apparent viscosity. For sponge-cake, perception of oral comfort was primarily driven by SSF rate, irrespective of the dental status. In the case of brioche, oral comfort was also partially explained by SSF in the case of subjects with poor dental status. This result suggests that perception of oral comfort in brioche could be driven by product related attributes rather than oral health. For both foods, a phenomenological model of bolus viscosity as a function of stimulated salivary flow and chewing duration was proposed.

Structural Changes Within a Biscuit Bolus During Mastication

AbstractSolid food undergoes drastic structural changes during its transformation into a cohesive bolus, which play a key role in the perception of different textures during mastication. This article describes the structural changes in biscuits during mastication through particle agglomeration. Apparent particle size and bolus moisture content were measured at different chewing stages by image and gravimetric analyses. The microstructure of the ready‐to‐swallow bolus was also examined with light microscopy and cryo‐scanning electron microscopy (cryo‐SEM). The results reveal that moisture content increased at a parabolic rate during mastication, and the absorbed saliva increased apparent particle size and decreased particle number through agglomeration. Furthermore, both cryo‐SEM and light microscopy indicate that a majority of the solid particles in the ready‐to‐swallow bolus were individual starch granules. The results from cryo‐SEM also suggest that saliva composition varied locally within the final bolus, thereby implying that laminar mixing governs bolus formation during mastication.Practical ApplicationsIn materials science it is well‐known that the properties of a material are related to its structure. This concept can also be applied to the food bolus: the structure of a bolus determines its mechanical and rheological properties. These properties are perceived by senses within our mouths during mastication and translate to the perception of food texture. Hence, texture perception cannot be fully understood without analyzing bolus structure. This article also suggests that bolus structure is related to the type of mixing that operates within the mouth. Identifying the mechanisms involved in mastication will contribute towards a better understanding of texture perception, and can be applied in computational models of food breakdown and flavor release. This knowledge will allow solid food structures to be designed to enhance sensory appeal or follow a particular breakdown path in health food applications.

Advanced biorefinery in lower termite-effect of combined pretreatment during the chewing process

BackgroundCurrently the major barrier in biomass utilization is the lack of an effective pretreatment of plant cell wall so that the carbohydrates can subsequently be hydrolyzed into sugars for fermentation into fuel or chemical molecules. Termites are highly effective in degrading lignocellulosics and thus can be used as model biological systems for studying plant cell wall degradation.ResultsWe discovered a combination of specific structural and compositional modification of the lignin framework and partial degradation of carbohydrates that occurs in softwood with physical chewing by the termite, Coptotermes formosanus, which are critical for efficient cell wall digestion. Comparative studies on the termite-chewed and native (control) softwood tissues at the same size were conducted with the aid of advanced analytical techniques such as pyrolysis gas chromatography mass spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy and thermogravimetry. The results strongly suggest a significant increase in the softwood cellulose enzymatic digestibility after termite chewing, accompanied with utilization of holocellulosic counterparts and an increase in the hydrolysable capacity of lignin collectively. In other words, the termite mechanical chewing process combines with specific biological pretreatment on the lignin counterpart in the plant cell wall, resulting in increased enzymatic cellulose digestibility in vitro. The specific lignin unlocking mechanism at this chewing stage comprises mainly of the cleavage of specific bonds from the lignin network and the modification and redistribution of functional groups in the resulting chewed plant tissue, which better expose the carbohydrate within the plant cell wall. Moreover, cleavage of the bond between the holocellulosic network and lignin molecule during the chewing process results in much better exposure of the biomass carbohydrate.ConclusionCollectively, these data indicate the participation of lignin-related enzyme(s) or polypeptide(s) and/or esterase(s), along with involvement of cellulases and hemicellulases in the chewing process of C. formosanus, resulting in an efficient pretreatment of biomass through a combination of mechanical and enzymatic processes. This pretreatment could be mimicked for industrial biomass conversion.

Influence of oro-facial sensory input on the output of the cortical masticatory area in the anesthetized rabbit.

In order to study the role of sensory inputs to the cortical masticatory area (CMA) and plasticity in the CMA, the representation of sensory inputs and the change of sensory inputs and motor outputs in the CMA 16 days after trigeminal deafferentation in the rabbit were examined. Neuronal activity was recorded in response to mechanical and electrical stimulation of the oro-facial region and cortically-induced rhythmical jaw movements (CIRJMs) were analyzed. Cortical neurons with receptive fields in the deafferented region were not found in the CMA. However, the projection area of the intact lingual nerve extended both antero-posteriorly and medio-laterally in the CMA and included neurons with long latency responses to lingual nerve stimulation. In a previous study in the rabbit, CIRJMs were classified into two groups according to their similarity to normal masticatory patterns: one pattern resembled that occurring during the food transport stage (T-pattern), and the other resembled that occurring during the chewing stage (C-pattern). These two patterns of CIRJMs were evoked from different stimulation sites: T-patterns were induced from the dorsal CMA and C-patterns were induced from the ventral CMA. The relationship between the patterns of CIRJMs and the site of stimulation in the deafferented rabbits was similar to that observed in normal rabbits. This finding suggests that sensory inputs to the CMA may not directly influence the CMA motor outputs controlling jaw movements, despite a close spatial relationship between the input and output of this area.

Modulation of jaw muscle spindle discharge during mastication in the rabbit.

Discharges of jaw muscle spindles were recorded during chewing carrot from mesencephalic trigeminal nucleus (Mes V) in the awake rabbit to evaluate contribution of the muscle spindles to the development of complete sequences of masticatory movements. The Mes V spindle units were divided into two types according to the maximum firing rates during mastication, with a dividing line at 200 Hz; high-frequency units and low-frequency units. Although both types of units fired maximally during the jaw-opening phase of chewing cycles, their firing rates and pattern varied according to three sequential stages of mastication (stages I, IIa, and IIb). The high-frequency units often increased firing before the start of mastication and built up firing in the first few chewing cycles. Their maximal firing rate was sometimes lower during stage IIa (chewing stage) than during stage I (ingestion stage) and stage IIb (preswallowing stage), although the jaw movements were greater in stage IIa than in other stages. The phase relationship of the firing to a jaw movement cycle in stage IIa was consistent in individual units. The low-frequency units did not build up activity before the onset of movements. They fired mostly during the jaw-opening phase, but the peak of firing did not necessarily coincide with the time of maximal opening. It was concluded that the difference in the firing pattern among masticatory stages may be ascribed to a stage-dependent modulation of both fusimotor activity and jaw movement pattern.

Morphologic, sinumetric and enamel investigations of the pliocene arvicolids (Rodentia) from the Karewas of Kashmir, India

The Karewa arvicolids, 2.4 Ma in age, are analysed quantitatively and qualitatively. By using various techniques such as the characteristics of all molars and the record of morphology of the chewing surface in connection with the ontogenetic chewing stages in their variability, Kilarcola, Kotlia (1985) is documented with a new sub-species. Kilarcola indicus sahnii nov. ssp. has slightly more derived characters than those in K. indicus Kotlia & Koenigswald (1992) . The interpretation of the sinuous line (sinumetry) has resulted in understanding the increase of hypsodonty from K. indicus to K. indicus sahnii nov. ssp. Additional material of K. indicus is also described.