Qualitative and quantitative effect of marination on tuna (Euthynnus affinis) During frozen storage/cooking

The protein loss from fresh tuna, marinated + cooked tuna and marinated + frozen tuna was studied. The marination was done with spices (0.2%) viz., clove, cardamom, garlic, oregano, rosemary and turmeric. A positive control without any treatment and a negative control with chlorine (2 pmm) were also maintained. Quality of protein lost from tuna was analyzed using SDS-polyacrylamide gel electrophoresis. The protein band of the cook water in the range of 20.1 kDa remained intact in the control and clove treated samples. The protein band of 29 kDa remained intact only in the control. Additional bands were observed between the range of 29 to 43 kDa for cardamom and garlic treated cook water samples. The low molecular weight bands (20.1 to 3 kDa) present in all the other treatments, was absent in garlic treated cook water of tuna. The electrophoretic pattern of thaw-drip protein was very similar in all the spice treated samples and closely resembled to that of the control. Only low molecular weight proteins were present (< 29 kDa) in thaw-drip, whereas, a wide range of protein bands (66 kDa-3 kDa) were observed in cook-water. The study revealed that, freezing after marination of the fish does not have much effect on the quality compared to cooking fish after marination with spices. Marination caused loss of sarcoplasmic protein when compared to untreated sample, though no significant difference in their total amount was observed. Hence, value addition using spices in fish products can be done without contributing much to the yield loss. In addition, spices have both antimicrobial/antioxidant properties which promotes shelf life