Development of active biofilms of quinoa (Chenopodium quinoa W.) starch containing gold nanoparticles and evaluation of antimicrobial activity Carlos H. Pagno a , Tania M.H. Costa b , Eliana W. de Menezes b , Edilson V. Benvenutti b , Plinho F. Hertz a , Carla R. Matte a , Juliano V. Tosati c , Alcilene R. Monteiro c , Alessandro O. Rios a , Simone H. Flôres a,⇑ a Laboratório de Compostos Bioativos, Instituto de Ciência e Tecnologia dos Alimentos (ICTA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil b Instituto de Química, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil c Departamento de Engenharia de Alimentos, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil article info Article history: Received 4 June 2014 Received in revised form 9 October 2014 Accepted 14 October 2014 Available online 28 October 2014 Keywords: Nanocomposite Antibacterial Food packaging Metal nanoparticles Quinoa starch abstract Active biofilms of quinoa (Chenopodium quinoa, W.) starch were prepared by incorporating gold nanopar- ticles stabilised by an ionic silsesquioxane that contains the 1,4-diazoniabicyclo[2.2.2]octane chloride group. The biofilms were characterised and their antimicrobial activity was evaluated against Escherichia coli and Staphylococcus aureus. The presence of gold nanoparticles produces an improvement in the mechanical, optical and morphological properties, maintaining the thermal and barrier properties unchanged when compared to the standard biofilm. The active biofilms exhibited strong antibacterial activity against food-borne pathogens with inhibition percentages of 99% against E. coli and 98% against S. aureus. These quinoa starch biofilms containing gold nanoparticles are very promising to be used as active food packaging for the maintenance of food safety and extension of the shelf life of packaged foods. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Interest in the maintenance and/or improvement of the quality of packaged products and the reduction of waste packaging has encouraged the exploration of new packaging materials, such as biodegradable films formulated with raw materials derived from renewable sources, called biofilms. In recent years, many researchers focused on the production of edible films based on biopolymers, such as polysaccharides and proteins (Andreuccetti, Carvalho, Galicia-García, Martínez-Bustos, & Grosso, 2011; Kanmani & Rhim, 2014; Mei, Yuan, Wu, & Li, 2013; Nascimento, Calado, & Carvalho, 2012; Souza et al., 2012; Souza, Goto, Mainardi, Coelho, & Tadini, 2013). Starch, a renewable biopolymer consisting of amylose and amylopectin, is the most commonly used agricultural raw material for edible film manufac- turing because it is inexpensive, relatively easy to handle, totally biodegradable, and widely available in nature from various sources, such as cereals, roots, tubers (Nascimento et al., 2012), and more recently rediscovered pseudocereals, such as amaranth and quinoa (Araujo-Farro, Podadera, Sobral, & Menegalli, 2010). The quinoa seed (Chenopodium quinoa, Willdenow) is a grain typically found in the South American Andean highlands. It is com- posed of significant amounts of starch (up to 80%), has an amylose content of 10–21% (depending on the variety), and a small starch granule size (1 lm), which are characteristics that allow its easier dispersion and thus make this starch a promising material for film (Araujo-Farro et al., 2010). This starch may be able to form trans- parent biodegradable edible films without any prior chemical treatment. In order to maintain the quality of foods, it is necessary to select the correct materials and appropriate technologies for production of the packaging. Thus, current trends include the development of packaging that interacts with food. Many of these biofilms may be incorporated with different compounds aiming at provid- ing specific properties; as a result, the resulting biofilms are called active biofilms or active packaging. The promising biofilms include biofilms with antimicrobial activity (Kechichian, Ditchfield, Veiga- Santos, & Tadini, 2010). Nanocomposites with antimicrobial function are highly useful for the minimisation of the growth of contaminant microorgan- isms during the processing or storage of food and thereby the extension of shelf life and improvement of food safety (Rhim, Wang, & Hong, 2013). One of the most widely studied nanocom- posites used in antimicrobial food packaging is based on the http://dx.doi.org/10.1016/j.foodchem.2014.10.068 0308-8146/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +55 051 3308 9789. E-mail address: simone.flores@ufrgs.br (S.H. Flôres). Food Chemistry 173 (2015) 755–762 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem