Starch extraction from avocado by-product and its use for encapsulation of ginger essential oil by electrospinning

Starches from alternative sources, such as avocado seed, have potential for application in the encapsulation of essential oils. This study aimed to extract starch from avocado seeds and its use as wall material to encapsulate ginger essential oil (GEO), at different concentrations. The fibers were produced by electrospinning and evaluated by morphology, size, infrared spectra, thermogravimetric properties, contact angle, loading capacity, and antibacterial activity. The major compounds in GEO were α-zingiberene, β-sesquiphellandrene, α-farnesene, and α-curcumene. The starch-GEO fibers presented a higher diameter (∼553 nm) than those without GEO (345 nm). Encapsulation of GEO in starch fibers increased their thermal degradation temperatures from 165.8 °C (free GEO) to 257.6 °C (40 % GEO fibers). The starch-GEO fibers presented characteristic bands of their constituents by infrared spectra. Loading capacity ranged from 44 to 54 %. The fibers showed hydrophilic character, with a contact angle of <90°. Free GEO and the fibers with 50 % of GEO displayed antibacterial activity against Escherichia coli, proving the bioactivity of the starch-GEO fibers and its possible applicability for food packaging. Avocado seed starch showed to be a great wall material for GEO encapsulation.