Improving the processability and digestion resistance of rice starch gel through linear chain-ferulic acid V-type complexation and branch-mediated crosslinking

Ferulic acid (FA) reduces starch digestibility but disrupts gel network, limiting its application in gel strength-reliant products. Rice starch was sequentially modified by pullulanase and transglucosidase to generate linear chains with a few branches (LCFBs), which were complexed with 0–2.0% FA to clarify how intermolecular interactions regulated the trade-off between gel strength and digestion resistance. At 0.5% FA, the hardness of modified starch gel remained at 98.2 g, whereas that of native starch gel decreased from 122.0 to 76.1 g. Moreover, the latter could not be shaped into blocks at 1.0% FA. Concurrently, compared with estimated glycemic index (76.6) of native starch gel, modified starch-0.5%FA complexation achieved an 11.10% reduction, while native starch-0.5%FA showed only a 5.61% decrease. The main chains of LCFBs favored V-type complexation with FA, while their branches promoted intermolecular crosslinking to preserve network integrity. This mode increased single helix from 5.92% to 9.40%, and relative crystallinity from 10.47% to 11.73%. In contrast, native starch-0.5%FA gel, despite exhibiting some V-type complex formation, suffered significant loss of ordered structures, which constituted the primary cause of reduced gel strength. Therefore, V-type complexation between LCFBs and 0.5% FA, coupled with branch-mediated crosslinking, effectively preserved gel strength and enhanced digestion resistance. Download: Download high-res image (441KB) Download: Download full-size image