Impact of pullulanase concentration on resistant starch formation in whole oat grain flour through dual extrusion-debranching.

Background: Resistant starch type 5, also known as amylose-lipid complex, is a functional component that offers recognized health benefits, particularly in preventing non-communicable diseases such as diabetes. This study examined the formation of type 5 resistant starch in whole oat grain flour using a dual-extrusion process with pullulanase-assisted debranching, leveraging its inherent lipids and starch content. Whole oat grains were first extruded to gelatinize the starch, followed by a second extrusion of the resulting flour with pullulanase to debranch the starch and promote amylose-lipid complex formation.

Results: Results showed amylose content increased from 21.20% to 32.53%, rapidly digestible starch decreased from 64.62% to 49.60% and resistant starch rose from 17.59% to 33.41% (peaking at 80 U g^-1). The starch relative crystallinity of the flour increased from 11.8% to 18.25% during enzymatic extrusion, reaching a peak at 80 U g^-1, with melting peaks observed between 115 and 125 °C. Moreover, the flour's ability to absorb water and expand decreased, whereas its solubility significantly increased.

Conclusion: The findings highlight the potential of pullulanase-assisted extrusion-debranching as an effective strategy for developing resistant starch in lipid-rich starchy foods, offering a promising approach to enhance health benefits and support scalable industrial applications. © 2025 Society of Chemical Industry.