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Food oral processing includes all muscle activities, jaw movements, and tongue movements that contribute to preparing food for swallowing. Simultaneously, during the transformation of food structure to a bolus, a cognitive representation of food texture is formed. These physiological signals detected during oral processing are highly complex and dynamic in nature because food structure changes continuously due to mechanical and biochemical breakdown coupled with the lubricating action of saliva. Multiple and different sensations are perceived at different stages of the process. Although much work has focused on factors that determine mechanical (e.g., rheological and fracture) and sensory properties of foods, far less attention has been paid to linking food transformations that occur during oral processing with sensory perception of texture. Understanding how food structure influences specific patterns of oral processing and how these patterns relate to specific textural properties and their cognitive representations facilitates the design of foods that are nutritious, healthy, and enjoyable.

Replacement of ingredients or reformulating existing products can significantly change textural characteristics. Our aim was to investigate the effects of sensory input from different textures on adaptation of the chewing pattern. Jaw muscle activity and kinematic measures of mastication were collected by electromyography and a three‐dimensional jaw tracking system during chewing of Cheddar cheeses (varying fat content) and caramels (two levels of total fat and sweetened condensed milk). Reducing fat in cheese is associated with increased sensory firmness, springiness and decreased cohesiveness. Oral processing adjusted to decreased fat content with increased closing muscle (temporalis and masseter) activity, a shorter cycle duration and increased power stroke time. Increased adhesiveness in caramels was associated with increased closing and opening muscle activity, longer cycle duration and increased jaw movement. It was shown that changes in composition that produced changes in sensory texture change oral processing parameters of muscle activity and jaw movement. PRACTICAL APPLICATIONS Understanding the mechanisms of texture perception is essential when tailoring food to meet nutritional needs, while maintaining an acceptable level of quality. Textural characteristics change when ingredients are replaced or products are reformulated. In particular, the textures of low‐fat or low‐calorie products are perceived by consumers to be less pleasing compared with those of traditional foods. Understanding how oral processing is altered in response to changes in texture provides information on the physiology of texture perception that complements sensory analysis and mechanical tests. The aim of this study was to understand how the masticatory sequence adapts to textural variations in cheese and caramel of differing compositions. This information will enhance the understanding of the relationship between food structure and texture perception.

Hardness and rubberiness are distinct textural properties that are associated with extended oral processing times and therefore of interest to designing food structure for specific textural properties. Model food gels were developed with (1) increasing strength/hardness and constant deformability or (2) increasing deformability/rubberiness within a limited range of strength. Gel structures were characterized based on mechanical properties and the muscle activity (electromyography) and mandibular movements (three‐dimensional jaw tracking) required for oral processing. Increased strength or deformability required more chewing cycles and increased muscle activity to breakdown samples for swallowing. In contrast, jaw movement amplitude increased in all directions with increased strength and remained constant or decreased with increased deformability. Specific mechanical properties that were correlated with oral processing parameters changed as chewing progressed, possibly reflecting a change in dominate mechanical properties and sensory perception during oral processing. Practical Applications A fundamental understanding of how food structure determines sensory texture is essential to designing foods that are healthy and desirable to consumers. Oral processing, from first bite through swallowing, is the main physiological element of texture evaluation. Model soft solid foods with increasing strength/hardness or deformability/rubberiness were developed and characterized by mechanical tests and oral processing. Mastication of harder or more deformable structures required different chewing movements in bolus preparation. The specific mechanical properties relating to oral processing may change during the chewing sequence.

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