Characterization of fibrous residues from agrowastes and the production of nanofibers

Oil palm trunk (OPT), oil palm frond (OPF), and okara are agrowastes generated abundantly by the palm oil and soy industries. There are vast potentials for these fibrous biomass rather than disposal at landfills or incineration. Fibrous materials (FM) and alkali-treated fibrous residues (FR) were produced from the selected wastes and subsequently characterized. Functional properties such as emulsifying properties, mineral-binding capacity, and free radical scavenging activity were also evaluated for possible development of functional products. Supernatants (FS) generated from the alkaline treatment contained soluble fractions of fibers and were also characterized and used for the production of nanofibers. Okara FM had the highest (P < 0.05) protein (31.5%) and fat (12.2%) contents, which were significantly reduced following alkali treatment. The treatment also increased total dietary fiber (TDF) in okara by 107.9%, in OPT by 67.2%, and in OPF by 25.1%. The increased fiber fractions in FR enhanced functional properties such as water-holding capacities and oil-holding capacities. Okara displayed the highest (P < 0.05) emulsifying properties compared to OPT and OPF. High IDF content of OPT and OPF contributed to high antioxidant activities (377.2 and 367.8% higher than that of okara, respectively; P < 0.05). The soluble fraction from alkali treatment of fibers was successfully electrospun into nanofibers, which can be further developed into nanoencapsulants for bioactive compound or drug delivery.