Phase-specific adaptations in masticatory muscle activity in older adults during chewing of foods with different textural properties

Abstract Aging alters oral function and chewing behavior. This study employed surface electromyography to investigate age-related adaptations in muscle activity across chewing phases. Fifteen younger adults (22–28 years) and fifteen older adults (65–75 years) habitually chewed three foods differing in texture (soft candy, bread, and peanut). Bilateral masseter and temporalis activities were recorded and integrated to characterize neuromuscular coordination. Normalized integrated electromyography, normalized mean absolute value (MAV), chewing time, and chewing rate were analyzed phase-specifically across the chewing sequence. Texture analysis confirmed significant differences in hardness and cohesiveness among foods ( p < 0.01), with peanut showing the highest hardness (3176.93 ± 187.67 g) and soft candy the highest cohesiveness (0.91 ± 0.00). For soft candy, chewing time and rate were comparable between age groups, whereas normalized integrated electromyography was significantly lower in older adults ( p = 0.01). For bread and peanut, older adults showed phase-specific differences in chewing time and rate, particularly in the middle and late phases (all p < 0.05). In addition, significant age × phase interactions were observed for normalized MAV during bread chewing ( p < 0.01) and for both chewing time and rate during peanut consumption (both p < 0.05). These findings suggest that mastication in older adults is characterized by phase-specific adaptations that vary across different food textures. The results indicate that masticatory demand reflects multiple food-matrix properties beyond hardness alone, providing a phase-specific perspective for texture-oriented food design for aging populations.