Extraction and Characterization of Cellulose Obtained from Banana Plant Pseudostem

Each year, the amount of residue generated from food production increases, caused by the continuous population growth. Banana is one of the most consumed fruits in the world, with an annual production of 116.78 million tonnes. However, just 12 wt% of the plant, corresponding to the bunch, is effectively used. After the bunch is harvested, the rest of the plant is disposed of as residue, the pseudostem (PS) being the main constituent. Aiming to give an added-value application to the PS, this work is focused on the extraction of cellulose from this waste. For this, three different fractions of PS particles—a non-classified fraction (milled but without sieving), a fine fraction (≤180 μm), and a coarse fraction (≥2000 μm)—and three extraction methods—alkaline-acid hydrolysis, enzymatic hydrolysis, and TEMPO oxidation—were studied to determine the most promising method for the cellulose extraction from the PS. The alkaline-acid hydrolysis samples presented a higher number of amorphous compounds, resulting in lower crystallinity (13.50% for the non-classified fraction). The TEMPO-oxidation process, despite allowing the highest cellulose extraction yield (25.25 ± 0.08% on a dried basis), resulted in samples with lower thermal stability (up to 200 °C). The most promising extraction method was enzymatic, allowing the extraction of 14.58 ± 0.30% of cellulose (dried basis) and obtaining extracts with the highest crystallinity (68.98% for the non-classified fraction) and thermal stability (until 250 °C).