LIGNOCELLULOSE MICROPARTICLES OBTAINED FROM STEAM-EXPLODED AND MECHANICAL REFINING FROM SUGARCANE BAGASSE: STRUCTURAL CHARACTERISTICS AND TOTAL PHENOLICS CONTENT ASSESSMENT

In response to the global demand for sustainable materials, significant efforts have been made to explore natural, clean-label biopolymeric particles suitable for agro-industrial applications. Our work focuses on producing microparticles from sugarcane bagasse by deconstructing the lignin-polysaccharide structure using steam explosion (120°C/45 min) and mechanical refining (Rotor-Mill Fritsch). The following samples were analyzed: sugarcane bagasse (SB), steam-exploded sugarcane bagasse (SEB), mechanically refined sugarcane bagasse (MRB), and steam-exploded and then refined sugarcane bagasse (SERB). The MRB and SERB presented particle sizes of 0.65μm and 0.67μm, respectively. The samples were characterized for crystallinity by X-ray diffraction, thermogravimetric analysis (TGA), ss-¹³C-NMR, FEG-SEM, and total phenolics content. The crystallinity index was 44%, 41%, 41%, and 40% for SB, MRB, SEB, and SERB, respectively. The total phenolic content was 41, 90, 89, and 121 mg GAE/kg for the same samples, respectively. These values showed statistically significant differences (p<0.05) among the treatments. The decrease in crystallinity along to the increase in the total phenolic contents suggest a rise in the amorphous fraction of the biomass. Generally, the amorphous fraction is more reactive than the crystalline fraction due to the higher exposure of hydroxyl groups. TGA curves showed that the treatments changed the structure of the bagasse fibers, indicating degradation stages at slightly lower temperatures. Ss-¹³C-NMR analysis showed a small increase in the lignin region signal at δ 173ppm, suggesting that samples treated with steam explosion and micronization favored higher phenolic content, as lignin had been partially deconstructed. This lignin signal increased in SEB, MRB, and SERB samples, corroborating the other results. FEG-SEM images agreed with the overall characteristics of the microparticle surface. In conclusion, the steam explosion and mechanical refining deconstructed the structure of the bagasse fibers, resulting in the production of lignocellulose microparticles with the potential for agro-industrial applications achieved through an environmentally friendly process.