| Summary: | Dissertação de mestrado integrado em Engenharia Biológica (área de especialização em Tecnologia Química e Alimentar) Fish consumption has gradually increased in recent years, mainly due to its unique nutritional characteristics and their benefits to the health of consumers. Glazing is a technique used in addition to freezing and is intended to retard the deterioration of fish. This work focuses in the study of the variables (fish temperature, coating temperature, dipping time) that affect the thickness of an edible coating (water glaze and 1.5% chitosan) applied on frozen fish. Samples of frozen Atlantic salmon (Salmo salar) at -15, -20, -25 °C were glazed with water at 0.5, 1.5, 2.5 °C and coated with chitosan at 2.5, 5, 8 °C during 10 to 60 seconds. For both water and chitosan lowering the salmon and coating temperature results in an increase of the thickness. The thickness of the coatings used was always higher for chitosan than for water, reaching a maximum thickness of (1.41±0.05) mm for chitosan and (0.84±0.03) mm in water. By DSC analysis it was found that both freezing temperature and cystallization heat are lower in 1.5% chitosan solution than in water, which favors the phase change. Salmon temperature profiles allowed confirming, for different dipping conditions, if the salmon temperature is within the limits of food safety for the growth of microorganisms pathogens. The maximum time salmon may be dipped in the coating (safe dipping time) for the tested conditions never exceeds 40 seconds. The average temperature of the coating that adhered to the salmon was determined experimentally, being important for future attempts to predict the coating thickness. O consumo de peixe tem aumentado progressivamente nos últimos anos, devido sobretudo às suas características nutricionais únicas e aos seus beneficios para a saúde dos consumidores. A vidragem é uma técnica usado como suplemento à congelação e a sua finalidade é retardar a deterioração do pescado. Este trabalho foca-se no estudo das variáveis ...
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