COMPARATIVE STUDY OF MECHANICAL, ENZYMATIC, AND PEF-ASSISTED ROUTES FOR THE PRODUCTION OF CELLULOSE NANOFIBRILS FROM PINEAPPLE POMACE

Cellulose nanofibrils and microfibrils (CNFs) have attracted attention as promising renewable materials due to their inherent properties, such as high aspect ratio, mechanical strength, biodegradability, and feedstock availability. They can be obtained via various methods, ranging from conventional mechanical and enzymatic treatments to emerging technologies such as pulsed electric field (PEF). This study aimed to compare the efficiency of extracting pineapple pomace CNFs (PNP-CNF) via three distinct routes: (1) an exclusively mechanical (M) process, (2) an enzymatically and mechanically assisted (EnzyM) method, and (3) a PEF-assisted enzymatic and mechanical extraction (PEF-EnzyM). For EnzyM (2), fibers underwent high-shear homogenization (HSH) followed by ultrasonication (US), before and after incubation with an enzyme cocktail (xylanase and cellulase) under controlled temperature and pH. The other routes followed a similar workflow: M (1) omitted the enzyme cocktail, while the PEF-EnzyM method (3) introduced a PEF pre-treatment prior to the enzymatic step. Additionally, a control sample (C) was prepared by undergoing all identical processing conditions, with the mechanical treatment applied only at the final stage. The efficiency of the extraction methods was evaluated in terms of gravimetric yield, zeta potential, and transmission electron microscopy (TEM). The results were analyzed by ANOVA and Tukey's test, 95% confidence level (ORIGIN® 2026). The PNP-CNF obtained by EnzyM (80.0±6.4%) and PEF-EnzyM (77.2±2.7%) exhibited the highest (p<0.05) yields, while M (31.9±0.78%) and C (37.3±0.14%) showed the lowest (p<0.05). In zeta potential, the C samples (-24.7±0.42 mV) and M (-23.6±1.98 mV) samples exhibited the most (p<0.05) negative values, while EnzyM (-14.7±2.5 mV) and PEF-EnzyM (-10.5±2.8 mV) revealed a lower (p<0.05) colloidal stability. This behavior can be attributed to the capability of the mechanical treatment to expose a greater number of surface hydroxyl groups compared to the enzymatic route. TEM analysis showed that the PNP-CNF samples obtained via the PEF-EnzyM route exhibited smaller dimensions than those produced by the other methods. This reveals that PEF pre-treatment was capable of enhancing fiber accessibility, thereby improving enzymatic defibrillation. Overall, integrating PEF with enzymatic hydrolysis represents a promising strategy to improve pineapple pomace defibrillation, leading to higher yields and reduced dimensions when compared to the mechanical route.