Desenvolvimento e avaliação de embalagens ativas antimicrobianas a base de metil celulose e polpa de açaí

• Ano de defesa: 2013
• Autor(a) principal: Espitia, Paula Judith Perez
• Orientador(a): Soares, Nilda de Fatima Ferreira
• Banca de defesa: Teófilo, Reinaldo Francisco , Melo, Nathalia Ramos de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Nanotecnologia; Embalagens ativas; Peptídeos
• Palavras-chave em Inglês: Nanotecnology; Active packaging; Peptides
• Área do conhecimento CNPq: CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA::TECNOLOGIA QUIMICA::ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/469

Biopolymers have attracted the interest for the development of new packaging because of their biodegradability, wide availability in nature, low cost and easy of processing. These characteristics allow the use of biopolymers to elaborate biodegradable edible films. This study was divided into two parts. The first part aimed to study and optimize the sonication conditions of ZnO nanoparticles (nanoZnO), including power, time and the presence of a dispersing agent, as well as to evaluate the antimicrobial activity of NanoZnO at different concentrations (1 %, 5 % and 10 % w/w). Furthermore, this work aimed to develop nanocomposite films of methyl cellulose (MC) incorporated with pediocin and nanoZnO. Antimicrobial and physical-mechanical properties were evaluated using response surface methodology (RSM) with central composite design (CCD). The results indicated that the presence of dispersant had a significant effect on nanoZnO size and the optimal dispersion condition was achieved by sonication at 200 W for 45 min. NanoZnO dispersion had antimicrobial activity against Escherichia coli, Salmonella Choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae and Aspergillus niger. Moreoer, the incorporation of nanoZnO and pediocin affected the crystallinity, elongation at break, color, thermal stability and surface of MC nanocomposite films. Nanocomposite films exhibited antimicrobial activity against S. aureus and Listeria monocytogenes. Elongation at break and the colorimetric parameters L*, b*, opacity, yellowness and whiteness index of developed films were selected to perform the optimization by desirability function. The optimization was performed to obtain films with good mechanical and colorimetric properties. The optimization showed that films with desired characteristics can be obtained by incorporating 20 % (w/w) nanoZnO and 15 % (w/w) pediocin. The second part of this study aimed to develop and evaluate açaí edible films incorporated with apple skin polyphenol (ASP) and thyme essential oil (TEO), as well as their combination for food preservation. The optimal concentrations of these antimicrobials in açaí films were determined using RSM with CCD. The incorporation of ASP and TEO resulted in interaction against L. monocytogenes. Addition of ASP resulted in improved mechanical properties, while the incorporation of TEO decreased the mechanical strength of films. Antimicrobials had no influence on water vapor permeability of films. Açaí films tended to lightness and redness. Incorporation of ASP resulted in improved thermal stability of films. The presence of aggregates was observed on the surface of all açaí edible films. Antimicrobial activity, elastic modulus and colorimetric parameters L*, a* and b* were used in the evaluation criteria of desirability function, used for the multi-response optimization analysis. According to the desirability profile, açaí film with desired characteristics is obtained by incorporating 6.07 % (w/w) ASP and 3.1 % (w/w) TEO.