Aplicação de extratos de gengibre e de alecrim em tirinhas empanadas de tilápia como agente antioxidante e antibacteriano

Abstract

Globally, about a third of the food produced annually for human consumption is lost, of which 35% are fish. Biological reactions such as lipid oxidation, enzymatic activity and the metabolic activity of microorganisms are the main causes of these losses. In this context, alternatives are sought to increase the shelf life of fish products. The addition of vegetable extracts with antioxidant and antimicrobial activity represents an alternative. Thus, this work evaluated the effects of ginger and rosemary extracts on tilapia fish fingers, as antioxidant and antimicrobial agents. For this, the fish fingers were prepared using mechanically separated meat (CMS) of carcass and the "V"-cut trimmings from tilapia, with addition of 2.5% of commercial extract and a control (2.5% distilled water). Initially, the CMS was microbiologically evaluated. Then, sensory analysis was conducted for the developed products and a similar commercial product by acceptance and purchase intention tests. Shelf life of tilapia fish fingers was evaluated monthly, during 120 days of frozen storage, through pH, instrumental color, peroxide determination, thiobarbituric acid reactive substances (TBA), sensory evaluation of the products with a trained panel and microbiological analyzes. The results of the microbiological analyzes indicated that the CMSs were produced under good hygienic-sanitary conditions. The sensorial analysis showed that the formulation containing rosemary extract had a higher average for all the evaluated parameters when compared to the other developed products. The formulation containing rosemary extract resembled the commercial product and was the most accepted among the developed formulations. There was no significant difference for pH results during the time evaluated, indicating that inhibition of bacterial growth could have occurred in the frozen storage. This information is consistent with the results of the microbiological analyzes for the total count of mesophilic bacteria and enterobacteria, which showed that there was no bacterial growth during the storage period. However, the growth was not reduced, showing that the commercial extracts had no antibacterial activity in tilapia fish fingers. The instrumental color showed that the formulation containing ginger extract was less bright after storage. At the end of the study, the three formulations showed a more yellowish and intense coloration. The results of the sensory analysis with a trained panel showed that the formulation containing ginger extract obtained the lower average for the flavor attribute. Additionally, it was the only formulation considered as unacceptable after 120 days of storage. The results of TBA and peroxides indicated that there was no significant difference among the formulations containing the extracts and the control, indicating that the extracts did not reduced the lipid oxidation reactions. However, through the sensorial analysis, it was noticed that the fish finger containing rosemary extract better maintained its sensory characteristics than the ginger extract formulation which presented more sensory alteration, becoming unacceptable at the end of the research study.