Realizing Eco-Friendly Water-Resistant Sodium-Alginate-Based Films Blended with a Polyphenolic Aqueous Extract from Grape Pomace Waste for Potential Food Packaging Applications.

Water-resistant and environmentally friendly sodium-alginate-based films have been investigated to develop functional materials to extend the food's shelf-life. A water-stable alginate-based film was prepared, employing both the internal and external gelation approach in the presence of CaCl2. To apply this film to food packaging and thus preserve food quality, the aim of this work is to perform a chemical and physical characterization of the proposed materials, evidencing the main features and stability under different work conditions. Water contact angle measurements showed a value of 65°, suggesting an important reduced hydrophilic character of the obtained alginate films due to the novel CaCl2-induced compacted polymer network. The film's stability was thus checked through swelling measurements in water after varying pH, temperature, and ionic strength. The film was stable at high temperatures and not pH-responsive. Only highly concentrated salt-based solutions negatively affected the proposed packaging, causing a large swelling. Furthermore, a water-based polyphenolic extract from grape (Vitis vinifera L.) pomace waste was embedded inside the films in different amounts in order to confer additional properties. The extract's polyphenolic content (evaluated from HPLC/MS-MS measurements) endowed the films' UV-light screening and enhanced antioxidant properties. These important findings suggest the additional potential role of these films in protecting food from light deterioration. The stability of these hybrid films was also checked by observation, as the polyphenols' presence did not largely alter the alginate network that occurred yet was water-resistant under the described work conditions.

Antimicrobial wound dressing films containing essential oils and oleoresins of pepper encapsulated in sodium alginate films / Curativos medicamentosos antimicrobiano contendo óleos essenciais e oleoresinas de algumas pimentas encapsulados em filmes de alginato de sódio

ABSTRACT: Medicated wound dressings are important barriers to avoid contamination and, when they contain antimicrobial additives, can be used as treatment for infected wounds. There are several types of polysaccharide materials that serve as matrices for medicated wound dressings, among them, sodium alginate. For the preparation of the films studied in this paper, sodium alginate was employed in combination with essential oils/oleoresins (EO/OL) of six peppers that are commonly used in cooking. The EO/OL were incorporated at three different concentrations (low, intermediate and high). Most of the films prepared had better dispersion of the EO/OL at the intermediate concentration. All films studied in this research were dissolved in water at different rates. The antibacterial activity of the prepared films showed significant results against Escherichia coli, Staphylococcus aureus and Bacillus cereus, and demonstrated that the films studied may be a new alternative for medicated wound dressings.

RESUMO: Os curativos medicamentosos são importantes barreiras para se evitar contaminação e ainda, quando contém aditivos antimicrobianos, servem como tratamento para ferimentos infectados. Existem vários tipos de materiais polissacarídicos que servem como matrizes para curativos medicamentosos, dentre eles, destaca-se o alginato de sódio. Para a preparação dos filmes estudados neste trabalho, utilizou-se alginato de sódio e incorporou-se óleos essenciais/oleoresinas (OE/OL) de seis pimentas utilizadas na culinária, em três diferentes concentrações. A maioria dos filmes preparados apresentou melhor dispersão dos OE/OL na concentração intermediária destes. Todos os filmes estudados neste trabalho apresentam solubilidade em água, em uma certa extensão. A atividade antibacteriana dos filmes preparados mostra resultados significantes contra Escherichia coli, Staphylococcus aureus e Bacillus Cereus, mostrando que os filmes estudados podem ser uma nova alternativa como curativos medicamentos.