This study aimed to develop a noodle with slow digestibility by adding pullulanase-treated wheat flour (PF). PF was prepared from normal wheat flour (NF) by pullulanase treatment, then its characteristics were compared with NF. Varying proportions (0%, 3%, 6%, 9%, 12% and 15%) of PF were substituted for NF to produce white salted noodles (WSN). The rheological, digestive, cooking, color and textural properties of WSN were evaluated. This showed that the amylose content of PF (83 wt%, total starch) was 62% higher than that of NF. After pullulanase treatment, the pasting temperature increased from 62.7 to 75.0 °C and the crystal structure of the starch changed from a mixture of A- and V-types to one of B- and V-types. Microstructure graphs showed that the structure of PF was more compact than that of NF. PF substitution produced noodles of acceptable quality with increased water absorption, cooking loss, L* value, hardness, and resilience and decreased cooking yield compared with the control (100% NF). In vitro digestibility tests showed that k (the kinetic constant) for cooked WSN decreased from 0.405 to 0.168 as substitution levels of PF increased from 0% to 15%, indicating that PF still exhibited slow digestibility after cooking.
Keywords: In vitro digestibility; Pullulanase; White salted noodle.
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