Comparison of antimicrobial effects of chlorine and spice oleoresins on frozen Euthynnus affinis

The ability of natural antimicrobial preservatives to decontaminate tuna has been compared with that of chlorine in the present study. The physicochemical parameters and microbiological changes were monitored to understand the variation in quality of tuna after treatments. No difference between spice and chlorine treatments were observed in the electrophoresis patterns of thaw drip. Thus, the treatments did not have any observable effect on the fish proteins during frozen storage in the range of spice extract (0.2%) used. Drip loss from tuna samples after 6 months of frozen storage also did not show any significant difference from control except turmeric treated tuna. Protein leaching was also highest in turmeric treatment. The total plate count of the spice treated samples showed a marked decrease over the six month storage at-20°C. Statistical analysis showed significant difference in the bacterial count at all stages of storage (p<0.05) in the control as well as treated samples. The highest reduction of total plate count by clove treatment was also explained by its highest antimicrobial activity as compared to other spices. Thus, clove treatment may provide better microbial safety than chlorine with an added advantage of creating ‘green label ’for the tuna product