Filmes e revestimentos comestíveis de quitosana e óleos essenciais na qualidade de camarão Litopenaeus vannamei congelado

Abstract

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. Keywords: Biopolymer. Volatile compounds. Antimicrobial activity. Freshness.