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PEER-REVIEWED REVIEW ARTICLE
environmentally-friendly, and non-fossil-based packaging solutions (Talja et al. 2011). As a component of packaging materials, paperboard provides the necessary mechanical strength. However, it needs to be combined with other materials to promote the required barrier performance (Andersson 2008; Rastogi and Samyn 2015). For instance, traditionally, paperboard packaging materials are coated with synthetic polymers that enhance their resistance to water, moisture, grease, oxygen, and odor (Talja et al. 2011). In this review, we use the term “biobarriers” to refer to the main components of the system if they are bio-based, either in their pure, blended, or composite forms. So far, fossil-derived synthetic polymers have been the preferred choice, owing to their beneficial properties and the relatively low price (Siracusa et al. 2015). In stark contrast to paperboard, however, most petrochemical-based polymers exhibit poor biodegradability and represent a challenge for their disposal and subsequent landfilling (Johansson et al. 2012). In 2015, Europeans generated 84.5 million tons of packaging waste, equivalent to 166.3 kg per inhabitant. The share of plastic packaging waste was 19%, resulting in 31.6 kg plastic packaging waste per inhabitant and 15.9 million tons in total. The share of other packaging materials were 41% paper and cardboard, 19% glass, 16% wood, and 5% metal (Eurostat 2015). The food product packaging sector represents a minor share of the total environmental impact of packed food units (Johansson et al. 2012; Grönman et al. 2013). The adoption of biopolymer alternatives to petroleum-based plastics potentially reduce carbon dioxide emissions by 30% to 70% (Lackner 2015). The main objective of a package is to protect the product from the surrounding environment and to achieve this result in a sustainable manner (Gröndahl et al. 2004; Mikkonen and Tenkanen 2012). Packaging materials should provide mechanical, chemical, and biological protection (Khan et al. 2014). A suitable packaging should fulfill performance metrics and should be safe, enable long shelf life, reduce the loss of food (Khan et al. 2014; Sand 2016), and make the product more sustainable (Sand 2016). To fulfill these requirements, barrier materials should protect against oxygen, carbon dioxide, moisture (Gröndahl et al. 2004; Arora and Padua 2010; Johansson et al. 2012; Mikkonen and Tenkanen 2012), aromatic compounds (Arora and Padua 2010; Johansson et al. 2012; Mikkonen and Tenkanen 2012), water, micro-organisms (Mikkonen and Tenkanen 2012), and grease (Johansson et al. 2012). Some of the main functional properties of packaging materials are included in Fig. 1, relevant to the exposure to given agents. Generally, the most common challenges with biobarriers have been their low resistance to water, gases (Arora and Padua 2010), heat, and mechanical stress (Johansson et al. 2012), as well as their relatively high price (Song et al. 2009; Philp et al. 2013). In this review, wood- and microbial-derived polymers are considered as biobarrier materials. Wood-based materials are prominent for their high potential and availability (Vaca-Garcia et al. 1998; Gandini 2008; Edlund et al. 2010). Fermentation-based biodegradable barrier materials, such as polylactide (PLA), poly(butylene succinate) (PBS), and poly(hydroalkanoates) (PHAs), are synthesized from bio-based sources and are available at industrial scales (Fortunati et al. 2012; Rabu et al. 2013; Bugnicourt et al. 2014; Rastogi and Samyn 2015; Siracusa et al. 2015). Other options for bio-based barrier materials, which are not considered in this review, are proteins ( e.g. , whey, soy, gluten, collagen) and polysaccharides such as starch, alginate, and chitosan (Rastogi and Samyn 2015). While biopolymer processing is not covered in this review, we refer to the literature for discussion on the main technologies used to apply barrier coatings and films, including melt extrusion, dispersion, and solvent-based approaches, reported in
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Helanto et al. (2019). “ Bio-based barriers ,” B io R esources 14(2), Pg #s to be added.
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