Biodegradable chitosan coating for improving quality and controlling Alternaria alternata growth in figs

Abstract

The objective of this work was to evaluate the effect of a chitosan biodegradable coating (BC), functionalized with cinnamon essential oil and aqueous extract of Roselle calyces, on the quality, respiratory rate, anthocyanin content and antioxidant capacity using the ABTS radical. Figs ‘Black Mission’ of two maturity stages were used. The first maturity stage included purple fruits (14% SST), referred to as “ripe figs”. The second stage was unripe figs, which presented a green color in 25% of its surface (11% SST). Five treatments were applied for each fig maturity stage. 150 g of figs was kept into clamshells packaging at 5 °C for 0, 4, 10, 15 and 21 days, before being transferred to room temperature (20 °C) for 2 more days. The BC structure was evaluated with the use of SEM. Furthermore, quality of this fruits as a result of the use BC and the different storage conditions was determined. The incidence and severity of rotting caused by A. alternata was quantified. The matrix of the BC was porous and heterogeneous. The unripe figs treated with BC and preventive treatments showed a lower weight loss, color change, respiration rate, and anthocyanin content than the control group. Meanwhile, the ripe figs receiving the preventive, curative and coated treatments, only showed the smallest color changes compared to the remaining treatments, but the remaining variables were similar to those of the control group. Finally, A. alternata did not grow at 5 °C in unripe figs but only in the ripe ones. The BC preserved the physicochemical and microbiological quality of unripe figs at 5 °C for 21 days.