Preparation and characterization of okara nanocellulose fabricated using sonication or high-pressure homogenization treatments

Nanocellulose was isolated from okara using either ultrasound or high-pressure homogenization treatments. Dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, swelling behavior, rheological properties, and thermal analysis were used to characterize the physical-chemical and structural properties of the cellulose obtained. Sonication at 600 W for 15 min led to a cellulose material with a small mean particle diameter (d =0.22 μm), narrow polydispersity index (PDI = 0.21), strong negative charge (ζ = −36 mV), high swelling ratio (SR = 7.6), high crystallinity index (CI = 72 %), and formed viscous solutions. The initial pyrolysis temperature of the cellulose increased from 212 to 225 ℃, while the pyrolysis residue decreased from 26 to 12 %, after the sonication/homogenization treatment. The cellulose material produced in this study may be applied in various food and non-food applications as a texture modifier, stabilizer, structural component, or digestion modifier.