Deep eutectic solvent-assisted starch acetylation within stale bread particles to improve water resistance

TY - JOUR

T1 - Deep eutectic solvent-assisted starch acetylation within stale bread particles to improve water resistance

AU - Skov, Kasper B.

AU - Portillo-Perez, Guillermo A.

AU - Martinez, Mario M.

N1 - Publisher Copyright: © 2024 The Authors

PY - 2025/2

Y1 - 2025/2

N2 - Building up from our previous findings on deep eutectic solvents (DES) as reaction promoters for the acetylation of pure wheat starch, the current work explored combinations of reaction time, temperature and acetic anhydride: bread molar ratios to acetylate macromolecules within bread particles relying solely on macromolecule solvation and the slightly basic environment provided by the eutectic mixture. High degree of substitution with acyl groups (DSacyl, 0.73–1.09 as quantified by 1H NMR and confirmed by 13C NMR, and FTIR) was achieved within a short timeframe of 36 min and < 16 acetic anhydride:bread molar ratio. Spectroscopy discarded a major presence of side-reaction products starch carbamates and acetyl urea in reacted samples. Nevertheless, DES acetylation resulted in reacted samples with starch weight average molecular weight (Mw) ranging from 2.62 × 106 to 1.39 × 106 g/mol for the most degraded sample and the partial wash-off of starch and cell wall polysaccharides, which resulted in increased gluten content. Notably, TGA (coupled to real-time FTIR analysis of the evolved gases) suggested a potential enhancement in hydrophobicity and glass transition temperature (Tg) in the reacted samples, with a positive correlation between DSacyl and Tg. These findings emphasize the potential of DES as reaction promoters in complex starchy matrices for esterification reactions.

AB - Building up from our previous findings on deep eutectic solvents (DES) as reaction promoters for the acetylation of pure wheat starch, the current work explored combinations of reaction time, temperature and acetic anhydride: bread molar ratios to acetylate macromolecules within bread particles relying solely on macromolecule solvation and the slightly basic environment provided by the eutectic mixture. High degree of substitution with acyl groups (DSacyl, 0.73–1.09 as quantified by 1H NMR and confirmed by 13C NMR, and FTIR) was achieved within a short timeframe of 36 min and < 16 acetic anhydride:bread molar ratio. Spectroscopy discarded a major presence of side-reaction products starch carbamates and acetyl urea in reacted samples. Nevertheless, DES acetylation resulted in reacted samples with starch weight average molecular weight (Mw) ranging from 2.62 × 106 to 1.39 × 106 g/mol for the most degraded sample and the partial wash-off of starch and cell wall polysaccharides, which resulted in increased gluten content. Notably, TGA (coupled to real-time FTIR analysis of the evolved gases) suggested a potential enhancement in hydrophobicity and glass transition temperature (Tg) in the reacted samples, with a positive correlation between DSacyl and Tg. These findings emphasize the potential of DES as reaction promoters in complex starchy matrices for esterification reactions.

KW - Bioplastics

KW - Bread waste

KW - Green chemistry

KW - Polysaccharides

KW - Starch

UR - https://www.scopus.com/pages/publications/85211982119

U2 - 10.1016/j.ijbiomac.2024.138603

DO - 10.1016/j.ijbiomac.2024.138603

M3 - Journal article

C2 - 39662539

AN - SCOPUS:85211982119

SN - 0141-8130

VL - 288

JO - International Journal of Biological Macromolecules

JF - International Journal of Biological Macromolecules

M1 - 138603

ER -