Physical and microstructural properties of biodegradable films based on pea starch and PVA

Abstract

The effect of storage time on the physical properties of pea starch (PS) and polyvinyl alcohol 17 (PVA) films and their blend was studied to develop biodegradable packaging materials for 18 food applications. To this end, an analysis was performed of the microstructural and physical 19 properties (solubility, moisture content, barrier, mechanical and optical properties) of PS, 20 PVA and PS:PVA films stored for five weeks (25ºC-53%RH). Whereas SEM micrographs 21 showed a homogenous appearance for PS films, PVA presented irregularities typical of 22 semi-crystalline structures. Blend films showed a structure which was more similar to PVA 23 films. After 5 weeks, the physical properties of PVA films did not change; in the case of PS, 24 however, the elastic modulus and tensile strength increased markedly but the stretchability 25 and gloss significantly decreased, which was associated with water loss in the starch matrix. 26All the physical properties of blend films remained unchanged throughout time, except the 27 elastic modulus and the tensile strength, which slightly increased. Therefore, the 28 incorporation of PVA into pea starch films improved their physical properties and inhibited the 29 changes that occurred in the starch matrix caused by ageing. 30

Different strategies to improve the functionality of biodegradable films based on starch and other polymers

“…At the beginning of the process, all films exhibited a continuous structure with no visible holes. It is also possible to observe that the PVA films were more transparent than S films, in agreement with that previously reported (Cano et al, 2015a). The incorporation of antimicrobial oils conferred opacity and yellowness colour to the films, meanwhile the AgNPs, led to brownish films as a consequence of the silver reduction to form silver nanoparticles.…”

“…It is well known, that starch biopolymer such as starch and PVA are suitable biodegradable materials which are able to form blend films with proper physical properties (Cano et al, 2015a). In addition, their blends form interpenetrated polymer networks with beneficial effects on the film properties, mainly enhancing the water vapour barrier and mechanical properties, the films becoming much more stretchable and stable during storage (Cano et al, 2015a).…”

“…In addition, their blends form interpenetrated polymer networks with beneficial effects on the film properties, mainly enhancing the water vapour barrier and mechanical properties, the films becoming much more stretchable and stable during storage (Cano et al, 2015a). Both, pure and blend films, could act as carriers of bioactive substance such as antimicrobials.…”

The effects of the “green passive MAP” on the evolution of the gaseous and quality parameters in strawberries

“…The traditional post harvest techniques used until now need to be improved meeting the request of a greener supply chain system, consequently also the modified atmosphere packaging (MAP), that is well known to improve the shelf life of many fresh fruits and vegetables reducing their respiration rate (Kader and Barrett, 2005;Caner et al, 2008;Mangaraj et al, 2009;Soltani et al, 2015;Zang et al, 2015;Blanco-Diaz et al, 2016), must to be considered in this new prospective. The sustainability of the MAP technique to preserve fresh fruits is today mainly associated to the use on new materials (Almenar et al, 2008;Cagnon et al, 2013;Briano et al, 2015;Mistriotis et al, 2016) whose mechanical and chemical characteristics are well described (Cano et al, 2015), but more studies are necessary about their interaction with the contained fruits especially in terms of fermentative compounds, resulting by the post harvest maturity processes, that affect the acceptability of the consumers.…”

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“…Therefore, there are many environmentally friendly materials such as guar gum, xanthan gum, sodium alginate are used for synthesis of superabsorbent polymer due to good degradability and nontoxic properties (Cano et al, 2015;Murakami et al, 2010) and Kumar et al (2009) used xanthan gum and polyacrylamide to synthesis a kind of water-absorbing material with cerium as an initiator in a microwave-assisted environment. Yadav et al (2011) used carboxyl methyl guar to graft copolymerize.…”