At SENSINGTech, research has focused on understanding how salivary alterations, common in neurological diseases and ageing, impact the oral processing of hard and soft foods. One of the major advancements includes the creation of world-first biomimetic systems featuring an artificial tongue. These innovative devices realistically reproduce the oral processing of both soft and hard foods, enabling the future design of safer and easier-to-consume foods, particularly for individuals with impaired oral functions. This work represents a significant breakthrough in personalised food design and research into healthy ageing.
The studies conducted have explored the role of saliva in the bolus formation of a hard and dry food such as bread, particularly in how its characteristics — such as quantity, composition, temperature, and enzymatic activity — affect particle size and cohesion. Using the Advanced Masticatory Machine (AM2), we have simulated various salivary conditions, ranging from xerostomia to hypersalivation. Results demonstrated that the absence of saliva leads to boli with dangerously large particles, while excessive saliva can overly break down food.
As a part of SENSINGTech, a biomimetic model, the Artificial Mouth, simulating tongue biomechanics during the oral processing of soft foods was developed, focusing on the interaction of food with the tongue and palate. We characterised foods with complex textures, such as gels and mousses, by evaluating their adhesive, cohesive, and viscosity properties. Bolus formation was analysed under in vitro conditions, and the results were validated against in vivo data.
Finally, a first-of-its-kind 3D biomimetic soft robotic masticator (SRM) was introduced, being capable of replicating intraoral events with unmatched realism, including food transport and chewing. The findings showed a close correlation between the properties of boli formed in vitro and those formed in vivo. Although the use of a salivary substitute provides some benefits, such as enhanced lubrication and reduced viscosity, under the studied conditions, it cannot fully replicate the intricate interactions and functions of natural saliva.
Overall, the combined findings emphasise the critical role of saliva in regulating hydration, cohesion, and physical and chemical breakdown, as well as its varying impact on solid and soft foods. For swallowing, solid foods require coordinated movements of the tongue, teeth, and saliva to achieve proper optimal bolus properties, while for soft foods depend on tongue shear and mixing.
