Biodegradable films from dragon fruit (Hylocereus polyrhizus) peel pectin and potato starches crosslinked with glutaraldehyde

Abstract

This research aimed to fabricate and characterize the biodegradable films from pectin extracted from dragon fruit peel (Hylocereus polyrhizus) incorporated with native, heat-moisture treated, acetylated, or annealed potato starches with the aid of glycerol through the casting method and subsequently crosslinked with 20 % glutaraldehyde solution in ethanol. All achieved films were optically yellowish, semi-transparent to translucent, flexible, glossy, and effortlessly detached from the petri dish, while crosslinked ones were darker, more tenacious, and less glossy. Additionally, these products had smooth facades without any visible cracks or pores and moderate moisture content (11.87–15.50 %). Regarding without crosslinking, the blend films had lower solubility (68.49–71.71 %), transparency (3.79–9.26 %mm−1), and tensile strength (0.05–0.14 MPa), and higher thickness (225–384 µm), density (1.31–1.63 gcm−3), and water vapor permeability (2.95–4.70 ×10−10 gm−1s−1Pa−1) as compared to the pectin film (77.78 %, 22.00 %mm−1, 0.16 MPa, 158 µm, 1.22 gcm−3, and 2.81 ×10−10 gm−1s−1Pa−1, respectively). Particularly, glutaraldehyde-crosslinking could not only enhance the tensile strength (0.22–1.81 MPa) and elongation at break (30.38–46.09 %) of these films but also positively lessen their thickness (95–235 µm), solubility (21.54–54.36 %), density (1.02–1.32 g cm−3), and water vapor permeability (1.08–3.09 × 10−10 gm−1 s−1 Pa−1). Moreover, all products had good thermal stability. Among all products, the crosslinked film prepared from pectin and annealed starch had great properties in terms of thickness, moisture content, solubility, transparency, water vapor permeability, and thermal stability, which was acknowledged potential material applied in food packaging industries.