Resistant Starch Type 5 Formation by High Amylopectin Starch–Lipid Interaction

The formation of resistant starch type 5 (RS5), primarily associated with amylose-lipid complexes, is typically attributed to starches with high-amylose content due to their affinity for lipid interactions. Recently, studies have also investigated the potential of amylopectin-rich starches to form amylopectin-lipid complexes (ALCs), expanding RS5 sources. This study explores the capacity of waxy corn starch (WS), which is rich in amylopectin, to develop ALCs with oleic acid (10% w/w) under different thermal and mechanical conditions. Specifically, WS was treated at temperatures of 80 °C, 85 °C, and boiling, with stirring times of 0 and 45 min. Results demonstrated significant ALC formation, reaching a peak complexation index (CI) of 59% under boiling conditions with 45 min of stirring. Differential scanning calorimetry (DSC) identified a notable endothermic transition at 110 °C, indicating strong ALC interactions. FTIR spectra further evidenced starch-lipid interactions through bands at 2970 cm^-1 and 2888 cm^-1. X-ray diffraction (XRD) analysis confirmed the presence of orthorhombic nanocrystals in native WS, with ALC samples exhibiting a V-type diffraction pattern, supporting effective complexation. This study advances knowledge on starch-lipid interactions, suggesting ALCs as a promising RS5 form with potential food industry applications due to its structural resilience and associated health benefits.