Development of a novel resistant starch via synergistic triple modification strategy that enables lipid complexation under mild conditions

Abstract

To address the limitations of conventional resistant starches (RSs) cannot simultaneously inhibit the absorption of starch and lipids, a novel RS was synthesized via a synergistic enzymatic (combined branching and amylolysis) –physical–chemical triple modification strategy. After enzymatic modification to optimize the amylose content and average degree of polymerization, physical modification to create empty V-type helical cavities, and esterification to increase resistance, the final modified starch (E-P-C) exhibited both a high RS content of 69.7. X-ray diffraction and laser confocal microscopy–Raman analyses revealed that the short-range crystalline order of the E-P-C starch was improved despite disrupted long-range order crystallinity. It's confirmed that the E-P-C starch had the capacity for lipid complexation under mild conditions with complexing index (CI) of 43.4 %, followed the order of medium chain > long chain > short chain fatty acids. In vitro digestion experiments demonstrated that the E-P-C starch sequestered 19 % of the fatty acids in three phase noncomplexation → weak complexation → strong complexation, while retaining 67.23 % of the RS content in the digestive juice, indicating the potential prebiotic functionality. This work provides a scalable strategy to engineer starches that can modulate starch digestibility and lipid bioavailability concurrently to address key challenges in obesity management.