Elaboração, caracterização e estudo do congelamento de almôndega e fishburguer à base de polpa de tilápia em freezer convencional com função de congelamento rápido

Abstract

The present study aimed to produce meatball and fish burger made from tilapia (Oreochromis sp.) pulp. Besides this, the physicochemical analyses, the freezing process and shelf life were evaluated. First, a formulation using by-products from tilapia filleting, such as pulp and mechanically separated meat (CMS) was produced. The proximate composition, pH, water activity (Aw) and microbiological analysis of the raw materials (tilapia pulp and CMS) and formulation were conducted. Additionally, the weight loss during cooking (PPC) was determined for the fish burger. A conventional freezer with a quick freezing function was used for obtaining the freezing curves. It was determined the initial freezing temperature (Tf), the times and rates to freeze the product in the critical zone (0 to -5°C) and to complete freezing (0 to -18°C). Finally, we carried out the study of the fish burger shelf life for nine weeks in frozen storage at -18°C. Analyses of pH, Aw, expressible water (EW), color of the crude and grilled fish burger, and sensory were performed. Tilapia pulp showed higher protein content (14.5%) and lowest percentage (4%) of lipids than CMS. The raw materials and the formulation had high Aw and pH near the neutrality. The microbiological results showed that they were in agreement with the current specifications. The use of thermocouples and a data acquisition system proved to be an efficient and easily performed method for obtaining the freezing curves and process parameters for the final products. The average freezer temperature was approximately -30°C. The fishburguer freezing time was longer than for the meatball, as it remained twice the time in the critical zone. Freezing rates between the two products differed, being higher for the meatball, thereby contributing to the reduction in freezing time. The fish burger PPC was approximately 20%, due to the low water holding capacity (high EW). There were no significant changes in the quality parameters evaluated during the frozen storage for 9 weeks, except for the color of the raw fish burger. It became more yellow and less red after the 6th week.