Investigation on digestibility differences of pea type III resistant starch induced by extrusion, frying and baking

Extrusion, frying, and baking are common high-temperature processing techniques in the food industry, which significantly accelerate the digestion rate of native starches. However, systematic investigations on the effects of these processing techniques on the digestibility and structural evolution of type III resistant starch (RS3) remain scarce. Compared with pea starch (PS) and high-amylose maize starch (HAMS) subjected to identical thermal processing conditions, the pea RS3 exhibited the smallest variation in molecular size distribution, the lowest content of damaged starch, the highest relative crystallinity and double-helix proportion, and largely retained its original micromorphology. This relatively ordered multi-scale structure contributes to the lowest digestibility of pea RS3. Notably, compared with frying and baking, extrusion induced the most extensive structural disruption and hydrolysis in all starch samples, which was mainly attributed to the harsh extrusion conditions involving high temperature, high pressure, and intense shear forces. Therefore, pea RS3, as a functional ingredient, is more suitable for application in fried or baked low-glycemic index (LGI) foods. This study provides key scientific support for the targeted development of heat-stable and digestion-resistant RS3 products.