Linking Oral-Processing Capacity, Food Texture, and Bolus Readiness in Older Adults: An Asian Evidence Map and...

Age-related decline in oral function alters the ability of older adults to fracture, comminute, hydrate, lubricate, and transform foods into transportable boluses, increasing the need for texture-modified foods. Current food-texture standards provide a common language for classifying foods and liquids but do not determine whether a specific food texture is orally manageable for an individual. This systematic scoping review and evidence map synthesized Asian evidence on food oral processing, oral function, food-texture properties, bolus formation, texture-modified foods, and food-texture standards to evaluate the evidence supporting a Masticatory Texture Threshold (MTT) framework. Following PRISMA-ScR-informed methods, records from Web of Science, PubMed, and targeted Google Scholar searches were screened, resulting in 136 eligible studies from 5926 identified records. The evidence was concentrated in Japan, South Korea, and China and was dominated by studies on gel/model-food characterization, texture-modified food development, and oral-function assessment. Directional synthesis consistently linked greater texture demand with increased chewing effort, reduced occlusal support with impaired mastication, lower tongue pressure and saliva availability with compromised food handling and bolus formation, and multidimensional texture properties including hardness, adhesiveness, cohesiveness, lubrication, and viscosity with oral processing and swallowing-related outcomes. Existing standards effectively classify food textures but rarely integrate person-specific oral-processing capacity with texture selection, and no included study validated a complete person-level texture recommendation protocol. We therefore propose MTT as a framework for prospective validation of individual oral manageability of chewable foods, linking eating capability, oral-processing capacity, multidimensional texture demand, bolus readiness, and downstream nutrition-related outcomes. In this framework, oral-processing capacity is nested within the broader construct of eating capability, and nutrition-related outcomes serve as downstream validation endpoints rather than criteria defining the threshold. Future studies should prospectively validate MTT using standardized oral-processing endpoints, real-food translation, and existing texture standards.