Formulation of secondary compounds as additives of biopolymer-based food packaging: A review

Background: Biopolymers can be considered a valid alternative to synthetic polymers in the food packaging industry since their biodegradability, biocompatibility, easy renewability, and generally good mechanical properties, comparable with the ones of conventional polymers. Natural secondary metabolites derived from plants and fungi have attracted much attention in the food packaging industry because of their both antimicrobial and antioxidant activity and positive effect on biofilm mechanical performances. Scope and approach: Food packaging aims to preserve food quality and safety as well as to extend food shelf-life. Due to the environmental impact of synthetic polymers used in the food packaging industry, academic and industrial research focused the attention on the exploitation of biopolymer-based package systems. Active packaging is a new food packaging path, concentrating on generating a multifunctional system via formulating active agents into the packaging polymer matrices. Secondary compounds of plants and fungal are promising natural additives for active packaging since they can act as antioxidants, antimicrobial, and plasticizer agents. In this review, the antimicrobial, antioxidant, and plasticizing effect of secondary metabolites included in biopolymer-based food packaging materials are described, highlighting their main impact on bioplastics properties. Key findings and conclusions: Secondary metabolites (SMs) evidenced antimicrobial and antioxidant activity by inhibiting the growth of pathogenic microorganisms and protect food from oxidation. Besides, depending on the specific formulation, preparation methodology, and physical or chemical interaction occurring between the polymer and additive functional groups, they could provide peculiar effects on the mechanical performances of the biofilms.