Effects of Marinating Time, Acetic Acid and Salt Concentrations on the Quality of Little Tunny Fish (Euthynnus alletteratus) Fillet

Abstract

Effects of marinating time, acetic acid and salt concentration of marinating solution on weight yield, shear force, omega-3 fatty acid content and sensory properties of marinated little tunny fish (Euthynnus alletteratus) were investigated using response surface methodology. Response variables including weight yield, shear force and overall acceptance scores were significantly affected by process variables. Acetic acid and salt concentration of marinating solution were significantly affected weight yield, shear force and overall acceptance scores, while marinating time had no significant effect. Decreasing of salt and acetic acid concentration at fixed marinating time (36 hours) increased the weight yield of marinated fish fillets. Decreasing of salt and acetic acid concentration slightly increased the omega-3 fatty acid ratio but it had no important effect on the omega-3 ratio of marinated fish fillets. Optimum conditions were as follows: marinating time, 30.28 hours; acetic acid concentration, 1.1 mL/100 mL; salt concentration, 6.2 g/100 mL. Under this condition, weight yield was 87.9 ± 0.8%, which well matches with the predicted value. Practical Applications Marinades are ready to eat fish products consisting of fresh, frozen or salted fish or portions of fish processed by treatment with edible acids and salt and put up in brines, sauces, creams or oil. Weight loss during marinating is main problem of the marinades industry since they primarily affect the cost of fish marinades. Together with acetic acid and water, proteins, lipids, free fatty acids and minerals diffuse into the brine, which decreases the quality and weight yield of the marinades. Response surface methodology was employed to study for improving weight yield without causing undesirable changes in the physical properties. The present study gives valuable information about effect of marinating time, salt and acetic acid concentrations on the quality of marinated fish fillet. The result of the study will be useful for the fish marinating industry to produce novel fish marinades with high yield and acceptable product quality characteristics.