Selected properties of chitosan-based films incorporated with Bidens pilosa extract for potential applications in food preservation

Edible films are known to have poor mechanical and limited functional properties. Plant extracts carry essential compounds that can be used to improve the characteristics of these films. Bidens pilosa is known for its antioxidant capacity that prevents the formation of free radicals. In this study, chitosan (Ch) was blended with 0.1 mg L^-1 of B. pilosa (BP) extract at 1, 3, and 5% to form Ch-1%BP, Ch-3%BP, and Ch-5%BP, respectively. Ch without plant extract was used as a control. The films were characterized and tested for antifungal properties in the agar diffusion method and antioxidant capacity in the DPPH assay. Chitosan-based films incorporated with BP extracts inhibited the growth of P. expansum with a 10-mm inhibition diameter compared to control films (3.33 mm). However, only chitosan films enriched with 1%BP (Ch-1%BP) inhibited the growth (10 mm) of Botrytis cinerea. The film thickness and density increased with an increase in BP concentration. The radical scavenging activity (RSA) of the films decreased with an increase in applied BP extract; Ch-1%BP exhibited the highest RSA (79.13%), and control films had the lowest RSA (50.97%). Control films also had the lowest film thickness and density (0.128 mm and 1.08 g cm^-3, respectively), while chitosan films enriched with 5% BP extract (Ch-5%BP) had the highest film thickness and density (0.291 mm, and 2.11 g cm^-3, respectively). The highest water vapour transmission rate (WVTR) and water content (17.15 g m^-1 24 h^-1 and 33.3%, respectively) were observed in control films, while CH-5%BP films had the lowest WVTR (8.92 g m^-1 24 h^-1) and water content (23.1%). Based on the principal component analysis, films made of CH-1%BP exhibited considerable antimicrobial properties, an attribute of high interest in the food industry and worth optimizing for controlling microbial spoilage in food preservation.