Psyllium-enriched mashed potatoes: impact of texture, rheology, and oral processing on starch digestion

Psyllium, a dietary fiber known to improve glycemic control, holds potential for incorporation into potato dishes to lower their glycemic index. However, it is not clearly established how addition of psyllium impacts properties of potato products and starch digestibility. Starch digestion initiates during oral processing, critically affecting its bioavailability. This study aimed to evaluate how psyllium-induced changes in rheological properties, chewing duration, and bolus characteristics alter starch digestibility during habitual mastication in mashed potatoes (MP).

The incorporation of psyllium into an MP sample containing κ-carrageenan led to significant improvements in mechanical properties, including a 20% increase in hardness and a 15% increase in cohesiveness. Enhanced gel strength was further corroborated by elevated storage (G') and complex (G*) moduli values. These modifications necessitated prolonged chewing to achieve a swallowable bolus. Notably, the psyllium-containing bolus exhibited greater hardness and reduced fragmentation immediately prior to swallowing. Despite its enhanced rigidity, the MP-carrageenan- psyllium bolus was ingested without difficulty, likely attributable to psyllium's cohesiveness-enhancing effects. This combination of increased cohesiveness and diminished fragmentation contributed to a beneficial 20% reduction in starch digestion during mastication of psyllium-enriched MP samples.

This study demonstrates that psyllium incorporation into MP can beneficially modulate its textural properties and bolus characteristics, resulting in reduced starch digestion. This finding offers new opportunities for designing functional foods based on traditionally consumed starchy foods, which could be particularly beneficial for managing glycemic levels in diabetic populations. © 2025 Society of Chemical Industry.