Micro N₂-bubble-assisted esterification or crosslinking of corn starch by citric, lactic and malic acid: Facilitating...

This comparative study explores an innovative approach to enhance corn starch's resistant fraction through microbubble-assisted esterification. The modified starches showed reduced crystallinity and a higher degree of substitution (0.32 % to 0.49 %) in MAE compared to native esterified starches (0.24-0.37 %). FT-IR analysis identified a new absorption band at 1762 cm^-1, signaling the CO stretching vibration associated with ester bonds formed between starch and L-malic, L-lactic, and L-citric acids. The resistant starch pattern produced by lactic acid significantly differed from citric and malic acid; RS fragments exhibited smooth surfaces and a compact, fused structure, particularly notable in LNC and LMC samples. Lactic acid, through esterification, reacted with starch hydroxyl groups, boosting RS levels and lowering rapidly digestible starch compared to citric and malic acids, acting as crosslinkers. The lack of peaks in the RVA pasting profiles confirmed successful crosslinking or esterification, significantly altering the starch's pasting characteristics. Hydrodynamic cavitation provides multiple benefits for physically modifying starch and providing a reaction medium for esterification or cross-linking. These include minimizing chemical input, reducing processing duration, and offering high selectivity and product quality, further enhancing its environmental sustainability.