Benjamin Le Révérend

Anatomical, functional, physiological and behavioural aspects of the development of mastication in early childhood

Mastication efficiency is defined as the efficiency of crushing food between the teeth and manipulating the resulting particles to form a swallowable food bolus. It is dependent on the orofacial anatomical features of the subject, the coordination of these anatomical features and the consistency of the food used during testing. Different measures have been used to indirectly quantify mastication efficiency as a function of childrens age such as observations, food bolus characterisation, muscle activity measurement and jaw movement tracking. In the present review, we aim to describe the changes in the oral physiology (e.g. bone and muscle structure, teeth and soft tissues) of children and how these changes are associated with mastication abilities. We also review previous work on the effect of food consistency on childrens mastication abilities and on their level of texture acceptance. The lack of reference foods and differences in testing methodologies across different studies do not allow us to draw conclusions about (1) the age at which mastication efficiency reaches maturity and (2) the effect of food consistency on the establishment of mature mastication efficiency. The effect of food consistency on the development of childrens mastication efficiency has not been tested widely. However, both human and animal studies have reported the effect of food consistency on orofacial development, suggesting that a diet with harder textures enhances bone and muscle growth, which could indirectly lead to better mastication efficiency. Finally, it was also reported that (1) children are more likely to accept textures that they are able to manipulate and (2) early exposure to a range of textures facilitates the acceptance of foods of various textures later on. Recommending products well adapted to childrens mastication during weaning could facilitate their acceptance of new textures and support the development of healthy eating habits.

Numerical modeling of human mastication, a simplistic view to design foods adapted to mastication abilities

The human diet contains a large variety of aromas, tastes and textures. The latter is particularly important since it determines whether foods are difficult to process orally and thus can be one source of food avoidance. It has also been reported in recent literature that food texture was a main driver for satiation processes and thus it is of interest for the food manufacturing industry to be able to control textural properties of food within the limits of acceptability for the consumer. For solid foods, fracture force is an important aspect of texture and we were interested in understanding the physiological drivers of this variable. We present a third order lever model of human bite force and the space between teeth based on data from the literature on human oral anatomy. Results from the model are compared with experimental data available in the literature. The model compares well with the experimental data(r2=0.95,p=0.0010,MPE=0.18), and can thus be used to derive a diagram of how food properties such as piece size or fracture force can be used to define whether foods are close to the limits of what the human jaw is capable of breaking. Such modelling tools can be used to define texture rules for tailor-made nutrition for specific populations based on their mastication abilities. The limitations of this modelling approach are also discussed, particularly the fact that tooth shape should also be considered, as this will ultimately define fracture stress, which is the deterministic factor of food fracture.

Biophysics of food perception

In this article, we present food perception across a range of time and length scales as well as across the disciplines of physics, chemistry and biology. We achieve the objective of the article by presenting food from a material science angle as well as presenting the physiology of food perception that enables humans to probe materials in terms of aroma, taste and texture. We highlight that by using simple physical concepts, one can also decipher the mechanisms of transport that link food structure with perception physiology and define the regime in which physiology operates. Most importantly, we emphasise the notion that food/consumer interaction operates across the biological fluid interface grouped under the terminology of mucus, acting as a transfer fluid for taste, aroma and pressure between food and dedicated receptors.

Advancement in Texture in Early Complementary Feeding and the Relevance to Developmental Outcomes

A childs transition to independent eating is a protracted process that progresses over the course of many years. Although major health agencies, such as the World Health Organization, now offer clear guidance when to begin introducing solids, advice about how to safely transition to progressively challenging foods is varied and comes from a staggering number of sources. The resulting conflicting views have promoted parental confusion and anxiety about what foods are appropriate and when to advance to new textures. Efforts to develop science-based recommendations for complementary feeding include research on the development of chewing motor skills. Chewing development is an essential aspect of feeding readiness that is often overlooked by agencies developing recommendations for complementary feeding, and little is known about the development of chewing motor skills and how children learn to accommodate foods with varying textures. Such information is essential for designing developmentally appropriate foods, minimizing food aversions, providing caregivers science-based guidance regarding the safety and appropriateness of new foods, and identifying children at risk for choking or feeding impairments.

Differing structural properties of foods affect the development of mandibular control and muscle coordination in infants and young children

The development of chewing is an essential motor skill that is continually refined throughout early childhood. From a motor control perspective, the advancement of textures is dependent upon the fit between a childs oral anatomic and motor system and food properties. The purpose of this exploratory study is to identify age-related changes in chewing motor coordination and control and to determine if these changes are associated with the differing structural properties of solid foods, as well as to explore the role of explanatory variables such as the emergence of teeth and bite force. The masticatory muscle coordination (i.e., coupling of synergistic and antagonistic muscle pairs) and control (i.e., speed, displacement, chewing rate, duration, and number of chews) of fifty children were assessed cross-sectionally at five ages: 9-, 12-, 18-, 24-, and 36-months using electromyography (EMG) and 3D optical motion capture while children ate three foods that had differing structural properties. The results of this study found that children made gains in their chewing motor control (decreased duration of chewing sequences and lateral jaw displacement) and coordination (improved jaw muscle coupling) throughout this period. The structural differences in foods also affected chewing performance at all ages. These preliminary findings suggest that some solid textures are better adapted for immature mandibular control than others and that the development of chewing is a protracted process that may be impacted by the emergence of teeth and changes to bite force.

Sensing in the Mouth: A Model for Filiform Papillae as Strain Amplifiers

Texture perception of foods is a common yet remarkably unstudied biophysical problem. Motivated by recent experiments reporting the presence of corpuscular endings in tongue filiform papillae, we develop in this work a mechanical model of the human tongue covered with filiform papillae in the form of elastic beams. Considering the typical flows that occur in the mouth during oral evaluation of Newtonian liquids, we suggest that filiform papillae may act either as direct strain sensors and/or as indirect strain amplifiers for the underlying mucosal tissue. Application of this model may also be valid for other biological appendages, such as primary cilliae and superficial neuromasts.

Frequency-Amplitude Cross Interaction during Pulsatile Taste Delivery Using Gustometers

In this article, we numerically resolve the flow profiles of tastant concentration in the pipe of a gustometer used to deliver alternative pulses in concentration, which is a typical case of Taylor dispersion. Using this model, we can define the cases where the experimenter will deliver to the assessors a concentration profile which is significantly different from that intended. This can be simply assessed a priori using a scaling argument which involves calculating a dimensionless frequency. This is a function of the pulses frequency, the dimensions of the pipe and the flow rate used. We show that unless this parameter is taken into account, modifying the pulse frequency will modify the pulse amplitude. This design criterion is absent from the literature but we suggest this is important for designing such experiments.