Portal de Pesquisa da BVS Veterinária

Tese em Português | VETTESES | ID: vtt-216128

Resumo

As novas tendencias do mercado consumidor levaram o setor alimenticio a concentrar esforcos no desenvolvimento de filmes e revestimentos comestiveis a base de polimeros naturais em substituicao as embalagens plasticas convencionais. Os filmes e revestimentos comestiveis de quitosana e oleos essenciais podem ser uma excelente alternativa para manter a qualidade e frescor do camarao durante armazenamento. O presente estudo teve por objetivo avaliar as propriedades fisicas e mecanicas de filmes a base de quitosana e oleos essenciais (tangerina, limao, cravo, louro, manjericao, hortela), as potencialidades antimicrobianas dos revestimentos dos mesmos componentes dos filmes, alem de avaliar a eficacia de revestimentos de quitosana e oleos essenciais de limao e tangerina em camarao (Litopenaeus vannamei) congelado atraves de analises quimicas, fisico-quimicas e microbiologicas. Os filmes foram caracterizados quanto a solubilidade, permeabilidade ao vapor de agua (PVA), cor, opacidade, resistencia a tracao, elongacao na ruptura e modulo de elasticidade e apresentaram diferencas significativas (p<0,05) entre os tratamentos. A atividade antimicrobiana dos revestimentos foi testada frente a quatro cepas padroes de bacterias e todos os revestimentos apresentaram acao antimicrobiana. Foram realizadas analises de composicao quimica, pH, bases volateis totais (BVT), trimetilamina (TMA), substancias reativas ao acido tiobarbiturico (TBARS), e microbiologicas (contagem total de mesofilas e psicrotroficas, Vibrio spp e Staphylococus congulase positiva e coliformes termotolerantes) em amostras de camarao submetidas a cinco tratamentos: controle (C), glaciamento (G), revestimento de quitosana (Q), revestimento de quitosana + oleo essencial de tangerina (QT) e revestimento de quitosana + oleo essencial de limao (QL) durante 180 dias de armazenamento. Os valores de pH, TBARS, BVT e TMA das amostras de camarao apresentaram diferencas significativas (p>0,05) entre os tratamentos. As amostras revestidas (Q, QT e QL) apresentaram as menores contagens de bacterias mesofilas e psicrotroficas e os valores para coliformes termotolerantes, Staphylococcus coagulase positiva e Vibrio spp apresentaram-se dentro da legislacao vigente durante o periodo de armazenamento. Os filmes e revestimentos comestiveis a base de quitosana e oleos essenciais apresentaram excelentes propriedades fisicas e antimicrobianas e podem ser utilizados de forma promissora para manter a qualidade de camarao congelado devido a sua natureza nao toxica, biodegradavel e atividade antimicrobiana.

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New consumer market trends have led the food industry to focus on the development of natural polymer-based edible films and coatings instead of conventional plastic packaging. Thus the films and edible coatings of chitosan and essential oils can be an excellent alternative to maintain the quality and freshness of the shrimp during storage.The objective of this study was to evaluate the physical and properties of chitosan and essential oils (clove, Peppermint, lemon, laurel, basil and tangerine), the antimicrobial potential of coatings of the same components of the films, and to evaluate the efficacy of chitosan coatings and essential oils in shrimp (Litopenaeus vannamei) frozen through chemical, physicochemical and microbiological analyzes. The films were characterized in terms of solubility, water vapor permeability (WVP), color, opacity, tensile strength, elongation at break and elastic modulus and presented significant differences (p<0.05) between the treatments. The antimicrobial activity of the coatings was tested against four standard strains of bacteria and all the coatings presented antimicrobial action. Analyzes of chemical composition, pH, total volatile bases (TVB), trimethylamine (TMA), thiobarbituric acid reactive substances (TBARS), and microbiological (total mesophilic and psychrotrophic counts), Vibrio spp. and Staphylococus congulase positive and thermotolerant coliforms in shrimp samples submitted to five treatments: control (C), glazing (G), chitosan coating (Q), chitosan coating + tangerine essential oil (QT) and chitosan coating + lemon essential oil (QL) during 180 days of storage. The pH, TBARS, TVB and TMA values of the shrimp samples presented significant differences (p<0.05) Coated samples (Q, QT and QL) showed the counts lowest of mesophilic and psychrotrophic bacteria. Vibrio spp. in all the treatments presented counts under the current legislation. For thermotolerant coliforms and Staphylococcus coagulase positive the C and G treatments presented values above the legislation. Films and edible coatings of chitosan and essential oils have good physical and antimicrobial properties and can be used to maintain the quality of frozen shrimp because of their non-toxic, biodegradable nature and antimicrobial activity.

Biblioteca responsável: BR68.1