Quality Changes and Microbial Load of Marinated Tilapia (Oreochromis niloticus) Stored at Refrigeration Temperature

Abstract

Tilapia is the main species farmed commercially in Egypt and is the most common for marketing as fresh fish. However, the usage of tilapia in marinade production is not common in Egyptian culture. The current investigation was aimed to produce tilapia (Oreochromis niloticus) marinade using different acetic acid concentrations with different methods, to determine its bacterial load and best sensory quality during storage at 4⁰C. The fish processing were headed, gutted, filleted, marinated and stored at 4°C until the end point, which was assessed by pH measuring, sensory, and microbiological analyses. Warm marinated was performed using solutions containing 2, 3% acetic acid and 3% NaCl then transferred into plastic jars, covered with 3% gelatin. Higher concentrations of acetic acid (5%) and NaCl (6%) were used for cold marinating process for 30 days then transferred into packaging solution of 2.5% acetic acid and 3% NaCl. Bacterial load has increased after 7 days with warm marinated fillets with best sensory scores in the first 3 days using 3% acetic acid solution, and best sensory scores in the first 7 days with 2% acetic acid. For cold marinated fillets, load of bacteria was reduced after 3 days from application of marinating solution until to the end of marinating process and after application of packaging solution with 2.5% acetic acid. The best sensory scores of cold marinated fillets were lower than the ones belong to warm marinated process. There is no significant change (p >0:05) in pH values during storage.