Impact of varied oral processing on starch hydrolysis, bolus properties, and sensory texture attributes of mashed potatoes

BACKGROUND: Oral processing behavior influences starch bioavailability, yet the impact of chewing conditions on starch digestibility remains unclear. This study investigated how varied chewing behaviors affect starch digestibility in a mashed potato (MP) sample. Three chewing conditions were compared until individual swallowing readiness: slow-rate (SR) chewing, squeezing (tongue-palate compression without teeth), and free chewing. RESULTS: Instrumental texture analysis showed pure MP was too soft for chewing; κ-carrageenan (κ-Car) addition increased hardness, enabling mastication in MP-Car. A κ-Car-pectin blend (MP-CarP) exhibited intermediate mechanical properties, supporting both chewing and compression. SR chewing and squeezing extended oro-exposure by 31% and 26%, respectively, via longer cycles. Muscle patterns changed, resulting in suprahyoid dominance during squeezing and temporalis activation during SR chewing. Salivation decreased by 28% and 46% during SR chewing and squeezing. Boluses formed via habitual and SR chewing had similar texture, whereas squeezing produced a harder, less adhesive, cohesive, and less fragmented bolus, which corresponded to reduced starch digestibility. Lower salivation and diminished bolus breakdown during squeezing contributed to a 52% and 33% reduction in starch hydrolysis during the oral and gastrointestinal phases, respectively. Despite differences in oral manipulations, sensory ratings of hardness, homogeneity, moisture, adhesiveness, and cohesiveness for the MP-CarP sample remained similar across varied chewing conditions. CONCLUSIONS: These findings highlight the critical role of intraoral processing in starch digestion and suggest that modulating chewing behavior may optimize glycemic control, providing valuable implications for dietary interventions aimed at enhancing metabolic health. © 2026 Society of Chemical Industry.