Desenvolvimento de filmes biodegradáveis antioxidantes e antimicrobianos para preservação de carne bovina refrigerada

Abstract

The objective was to develop biodegradable antioxidant and antimicrobial films for the preservation of refrigerated beef. The execution of the research was divided into four distinct chapters: (Chapter 1)-General considerations; (Chapter 2)-Development and characterization of sweet potato and taioba leaf extracts; (Chapter 3)-Development and characterization of biodegradable films based on collagen from the skin of tilapia and cassava starch. (Chapter 4)-Was about the use of a collagen film based on extracts of sweet potato and taioba leaf in beef stored under refrigeration. The results showed that the two hydroalcoholic extracts had antioxidant potential, indicating greater effectiveness for the sweet potato leaf extract. Regarding antimicrobial activity, only the sweet potato leaf extract showed activity against Bacillus cereus (ATCC 11778) and Salmonella Tiphymurium (ATCC 14028). Both extracts showed a lethal dose (LD50) of less than 1000 µg / mL, showing to be toxic to Artemia salina Leach. Regarding the results of the characterization of the films, it was observed that the T1 and T4 treatments improved the film's resistance to water (p <0.05). The T3, T4 and T5 treatments provided higher values (p <0.05) of lightness (L *). Scanning electron micrographs (SEM) showed a more orderly, smooth and homogeneous structure for the T1 treatment, which resulted in greater mechanical properties (p <0.05) and greater thermal stability. Regarding the results of the physicalchemical analysis of beef, the main results showed that beef stored in packages containing 0.1% of plant extracts showed the lowest weight and color losses. The films containing extract also reduced lipid oxidation and the conversion of heme iron to nonheme iron, in addition to having the smallest accumulations of metmyoglobin. In this way, the data obtained for the characterization of sweet potato and taioba leaf extracts can be used for the development of bioactive ingredients with promising applications in the food area. For the characterization of the films, in general, the T1 and T4 treatments were considered the ideal formulations, as they alternated in the best mechanical, barrier and thermal properties. Regarding the application of the collagen film containing 0.1% of the extracts of sweet potato and taioba leaves in beef, they proved to be efficient in the quality control of chilled fresh beef, in comparison to the control treatment (PVC).