Desenvolvimento e caracterização de filmes de gelatina de peixe com carboximetilcelulose, álcool polivinílico e adição de nanopartículas de prata

Abstract

The general objective of this thesis was “To develop and characterize biodegradable films of fish gelatin combined with carboxymethyl cellulose and polyvinyl alcohol, added with silver nanoparticles” and is structured into three chapters. The first chapter presents a review article that serves as theoretical support for the research carried out, which is entitled “Biodegradable polymeric blends of fish gelatin, carboxymethylcellulose and polyvinyl alcohol used as active packaging: A review”. This manuscript provides an overview of the main features and shortcomings related to the application of fish gelatin in biodegradable films. It presents information that reports the production of films from the combination of biopolymers as a good strategy to overcome their limitations, highlights carboxymethylcellulose and polyvinyl alcohol as interesting polymers to form mixed films with gelatin with improved properties and considers the possibility of incorporating active compounds , particularly silver nanoparticles, to these polymeric matrices with the aim of providing antimicrobial properties to the films and extending the shelf life of packaged foods. The second chapter corresponds to the already published article entitled “Effect of polyvinyl alcohol and carboxymethyl cellulose on the technological properties of fish gelatin films”. In this study, biodegradable films were produced by mixing gelatin/carboxymethyl cellulose (FG/CMC) and gelatin/polyvinyl alcohol (FG/PVOH) in proportions 90/10, 80/20 and 70/30 with a total concentration of 3% (m/v) of solution and 10% (w/w polymers) of plasticizer, and the effect of adding these polymers on the performance of fish gelatin films was evaluated. The results showed that the mixture of gelatin with CMC and PVOH improved the mechanical strength, water vapor barrier capacity and solubility of the films. The maximum CMC concentration promoted the highest tensile strength, while the highest PVOH content produced a film with lower solubility. FG/PVOH films were more flexible and water resistant, but presented lower mechanical and thermal resistance compared to FG/CMC. The proposed mixing systems proved to be suitable for improving the properties of fish gelatin films. Chapter three presents the article “Optimization of the process for obtaining a biodegradable nanocomposite film based on fish gelatin and carboxymethylcellulose reinforced with silver nanoparticles”. The objective was to develop a biodegradable nanocomposite film from fish gelatin (FG), carboxymethylcellulose (CMC) and silver nanoparticles (NpAg). The formulation was optimized using response surface methodology to establish the best levels of FG (2–4%), CMC (0.5–1%) and NpAg(0.005–0.01%) in order to obtain a film nanocomposite (FG/CMC-NpAg) with better mechanical and barrier properties. The optimization was done based on the responses to water vapor permeability (PVA), tensile strength (RT) and elongation (E). The optimized conditions were: 3% FG, 0.54% CMC and 0.011% NpAg. The mechanical properties, PVA, solubility, optical properties and light transmission of the optimized and control films were analyzed. The optimized FG/CMC-NpAg film showed lower elongation and transparency, but on the other hand demonstrated greater tensile and water resistance, as well as improved barrier properties in relation to water vapor and ultraviolet light, when compared to the control film. Overall, the results indicated that the biodegradable nanocomposite film developed in this study may be suitable for use as packaging material.