The effect of psyllium fiber on the in vitro starch digestion of steamed and roasted wheat based dough

Abstract

This study aimed to determine how the addition of psyllium fiber to steamed and roasted wheat-based flat dough pieces affected the in vitro starch digestibility. Wheat flour was replaced with 10% psyllium fiber in the preparation of fiber-enriched dough samples. Two distinct methods of heating were utilised: steaming (100 °C, 2 min & 10 min) and roasting (100 °C, 2 min & 250 °C, 2 min). Rapidly digestible starch (RDS) fractions reduced significantly in both steamed and roasted samples, whereas slowly digestible starch (SDS) fractions increased significantly only in samples roasted at 100 °C and steamed for 2 min. The roasted samples had a lower RDS fraction than the steamed samples only when fiber was added. This study demonstrated the effect of processing method, duration, temperature, formed structure, matrix and the addition of psyllium fiber on in vitro starch digestion by altering starch gelatinization, gluten network, and consequently enzyme access to substrates.

Keywords: Psyllium Fiber; Roasting; Starch Digestibility; Steaming.