Edible Films Made of Dried Olive Leaf Extract and Chitosan: Characterization and Applications

Nowadays a possible strategy in food preservation consists of the use of active and functional packaging to improve safety and ensure a longer shelf life of food products. Many studies refer to chitosan-based films because of the already-known chitosan (CH) antibacterial and antifungal activity. In this work, we developed CH-based films containing Dried Olive Leaf Extract (DOLE) obtained by Naviglio extractor, with the aim to investigate the polyphenols yield and the antioxidant activity of this extract entrapped in CH-based-edible films. Olive tree cultivation produces a huge amount of byproducts that are usually simply burned. Phenolic compounds are already studied for their beneficial effects on human health. Some studies reported that phenols isolated from olive leaves have been shown to inhibit the growth of different strains of microorganisms. Thus, the antimicrobial effect of DOLE-containing films against bacterial strains (Salmonella enterica subsp. enterica serovar Typhimurium ATCC (R) 14028, Salmonella enteritidis RIVM 706, and Enterococcus faecalis ATCC (R) 29212) was tested in vitro. The DOLE component of the films is effective in inhibiting all the bacteria tested in a dose-dependent manner. Thus, it was demonstrated that these edible films can act as active bioplastics when used to wrap hamburgers in substitution for baking paper, which is normally used.

Automated summary

Nowadays, active and functional packaging is used to improve food product safety and shelf life. Chitosan-based films are studied due to their antibacterial and antifungal activity. This study developed CH-based films containing Dried Olive Leaf Extract (DOLE) and investigated their polyphenols yield and antioxidant activity. The results showed that DOLE-containing films exhibited antimicrobial effects against different bacterial strains in a dose-dependent manner.