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Martinez I.,Research Center En Tecnologia Of Productos ocesos Quimicos | Partal P.,Research Center En Tecnologia Of Productos ocesos Quimicos | Garcia-Morales M.,Research Center En Tecnologia Of Productos ocesos Quimicos | Guerrero A.,University of Seville | Gallegos C.,Research Center En Tecnologia Of Productos ocesos Quimicos
Journal of Food Engineering | Year: 2013

This study focuses on the development of new bio-active protein-based bioplastics through a thermo-mechanical processing, which involves a first compounding step followed by compression-moulding of the resulting material into the desired shape. Two types of proteins, wheat gluten and egg-white albumen, and two different bioactive agents, formic acid and oregano essential oil, were selected. The effect of biocide addition on the material rheological response, its antimicrobial activity and biocide release behaviour have been assessed. Rheological tests demonstrated that formulation and processing may exert a notable effect on the material linear viscoelasticity. Kirby-Bauer tests carried out on four selected types of microorganisms revealed that oregano essential oil into a wheat gluten-based matrix may be suitable for applications where the active agent must be progressively delivered (for up to 7 days). Moreover, this biocide can inhibit microorganisms' growth even if the bioplastic is not in direct contact with the substrate. © 2013 Elsevier Ltd. All rights reserved.

Zarate-Ramirez L.S.,Pedagogical and Technological University of Colombia | Romero A.,University of Seville | Bengoechea C.,University of Seville | Partal P.,Research Center En Tecnologia Of Productos ocesos Quimicos | Guerrero A.,University of Seville
Carbohydrate Polymers | Year: 2014

The influence of adding different polysaccharides (locust bean gum, LBG; methyl cellulose, MC; and carboxymethyl cellulose, CMC) to gluten-based biodegradable polymeric materials was assessed in this work. Gluten/polysaccharide/plasticiser bioplastics were prepared at different polysaccharide concentrations (0-4.5%) and pH values by mixing in a two-blade counter-rotating batch mixer (at 25 °C under adiabatic conditions) and thermomoulding at 9 MPa and 130 °C. Bioplastic probes were evaluated through dynamic mechanical thermal analysis, tensile strength and water absorption capacity tests. Results pointed out that a moderate enhancement of the network structure may be achieved by adding polysaccharide at a pH close to the protein isoelectric point (pH 6), which also conferred a further thermosetting capacity to the system. Moreover, the addition of MC and CMC was found to significantly enhance material elongation properties. However, the presence of charges induced by pH leaded to a higher incompatibility between the polysaccharide and protein domains forming the composite. The pH value played a relevant role in the material water absorption, which significantly increased under acidic or basic conditions (particularly at pH 3). © 2014 Elsevier Ltd.

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