Biodegradable Poly (Butylene Succinate)-Based Composites for Food Packaging

Active packaging refers to packaging systems with active functions beyond the inert passive containment and protection of the product. It is commonly used with foods, as it helps extend shelf life, improve safety or sensory properties and maintain food quality [1]. Most diffused active packaging systems include the use of oxygen scavengers, carbon dioxide or ethylene emitters and scavengers, ethanol releaser, as well as antimicrobial and antioxidant agents. The active agent may be placed in the package with the food, within a small sachet or pad of permeable material, able to release volatile antimicrobial agents without allowing a direct contact with the food product. Incorporation of volatile active agents into polymers is a technological challenge, due to the need to avoid evaporation of the additive during melt processing of the polymer. Such challenge can be solved by incorporation of the volatile molecules within cyclodextrins (CD), as detailed in this contribution. Cyclodextrins are biocompatible, biodegradable cyclic oligosaccharides produced from a renewable natural material, starch [2]. Cyclodextrins can form inclusion complexes with various non-polar, aliphatic and aromatic compounds, including antibacterial molecules, whose release could enhance the quality of the packaged product and extend its shelf life [3]. In the research detailed below, b-CD was used as cage to include D-limonene (4-isopropenyl-1-methylcyclohexene), the major constituent in several citrus-derived essential oils, which is also a natural antimicrobial agent [4-6]. D-limonene is listed in the Code of Federal Regulations and generally recognized as safe flavoring agent and food preservative [7]. Its outstanding antimicrobial activities have already been tested with different species of food-related microorganisms, such as staphylococcus aureus, Listeria monocytogenes, Salmonella enterica, Saccharomyces bayanus [8, 9]. Unfortunately, D-limonene is susceptible to oxidative degradation, which directly results in its loss of activity [7, 10]. Moreover, similar to other volatile essential oils, limonene aroma could be easily released to the packaged food, thus contaminating it. In order to overcome to these drawbacks, D-limonene was included into CDs, and the inclusion complex CD-Lim thus obtained was dispersed into a biodegradable and bio-based polymer matrix, namely poly(butylene succinate) (PBS). PBS is a biodegradable and bio-based polyester, currently used for food packaging, and its use in this market area is expected to largely increase in the coming years [11]. The aim of this paper is to prepare a novel biodegradable polymeric-based system, as potential bioactive food packaging material, by dispersing CD-Lim inclusion complex into PBS polymeric matrix and to investigate the chemical-physical properties of the obtained blends.