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<p>Chemical modifications such as acetylation and carboxymethylation significantly alter the physicochemical properties of biopolymers, including exopolysaccharides (EPS). In this study, glucan EPS from <i>Enterococcus hirae</i> OL616073 was chemically modified to acetylated glucan (AG) and carboxymethylated glucan (CG) via an affordable process. The structure and properties were investigated by <sup>1</sup>H NMR spectroscopy, Fourier transform infrared (FTIR), scanning electron microscope (SEM), contact angle, particle size, thermal analysis (TGA-DSC), and X-ray diffractometer (XRD). Lightness (L*) varied between 70.13 and 74.46 with a mild darkening effect in AG than CG, with a slight increase (70.24) in whiteness index (WI) for CG in comparison to AG (68.10). Decrease in bulk density (0.532 to 0.415&#xa0;g/mL), tapped density (0.756 to 0.531&#xa0;g/mL), Hausner ratio (1.42 to 1.27), and compressibility index (CI) (29.61 to 21.81%) from untreated glucan (UT) to CG. Micrographs showed AG formed agglomerates, while CG had rough, collapsed granules. Water activity (a<sub>w</sub>) decreased in AG (0.345) but increased in CG (0.380). Particle size increased with modification, reaching 365.8&#xa0;nm (AG) and 526.4&#xa0;nm (CG). Water contact angle enhanced in AG (66.28°) compared to CG (44.13°) though hydrophilic nature was maintained. Water holding capacity increased from 328.11% (UT) to 494.22% (CG). AG had better emulsion stability, while CG showed superior antitumor activity against HCT116 cells (47.04% reduction at 500&#xa0;µg/mL). These findings suggest that acetylation and carboxymethylation can tailor EPS properties for applications in functional foods and biomedical fields.</p> Graphical Abstract <p></p>

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Influence of acetylation and carboxymethylation on physicochemical characteristics of glucan exopolysaccharide isolated from Enterococcus hirae OL616073

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月1日

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  • Irshad Ahmad Shah,
  • Swati Tiwari,
  • Palanisamy Bruntha Devi,
  • Digambar Kavitake,
  • Prathapkumar Halady Shetty

摘要

Chemical modifications such as acetylation and carboxymethylation significantly alter the physicochemical properties of biopolymers, including exopolysaccharides (EPS). In this study, glucan EPS from Enterococcus hirae OL616073 was chemically modified to acetylated glucan (AG) and carboxymethylated glucan (CG) via an affordable process. The structure and properties were investigated by 1H NMR spectroscopy, Fourier transform infrared (FTIR), scanning electron microscope (SEM), contact angle, particle size, thermal analysis (TGA-DSC), and X-ray diffractometer (XRD). Lightness (L*) varied between 70.13 and 74.46 with a mild darkening effect in AG than CG, with a slight increase (70.24) in whiteness index (WI) for CG in comparison to AG (68.10). Decrease in bulk density (0.532 to 0.415 g/mL), tapped density (0.756 to 0.531 g/mL), Hausner ratio (1.42 to 1.27), and compressibility index (CI) (29.61 to 21.81%) from untreated glucan (UT) to CG. Micrographs showed AG formed agglomerates, while CG had rough, collapsed granules. Water activity (aw) decreased in AG (0.345) but increased in CG (0.380). Particle size increased with modification, reaching 365.8 nm (AG) and 526.4 nm (CG). Water contact angle enhanced in AG (66.28°) compared to CG (44.13°) though hydrophilic nature was maintained. Water holding capacity increased from 328.11% (UT) to 494.22% (CG). AG had better emulsion stability, while CG showed superior antitumor activity against HCT116 cells (47.04% reduction at 500 µg/mL). These findings suggest that acetylation and carboxymethylation can tailor EPS properties for applications in functional foods and biomedical fields.

Graphical Abstract