Biopreservation to Stabilize Euthynnus affinis Quality

Fishes are highly perishable and loose quality rapidly after catching due to enzymatic and bacterial spoilage. Plantderived antimicrobial compounds have activity against many bacteria. In this study the antimicrobial activity of spice oleoresins and their sensory impact with fresh cooked tuna were investigated. Clove (5μl) produced a 20mm inhibition zone against Escherichia coli (MTCC 45). Oregano, cardamom and rosemary (10mm) showed moderate activity whereas the activity of garlic (8mm) was weak. Significant differences (P<0.05) were found in the microbial numbers with spices compared to the control samples. There was an 88% reduction in the microbial load for clove whereas the chemical antimicrobial, chlorine killed only 54% of the bacteria. Samples treated with 0.2% concentration of spice oleoresins showed significantly higher values for instrumental hardness than those with 0.1%. However, all other texture profile analysis parameters like springiness, stiffness, chewiness, and cohesiveness did not show any significant differences (P≥0.05). The highest consumer acceptance was for cardamom (overall sensory score = 6 out of 7) followed by rosemary and clove (5.3 and 5.7, respectively). Garlic and oregano treated samples were poorly received by the panelists and were less acceptable than the control. A rosemary and cardamom blend was well received. The sensory scores of other combinations were also above the control. Although all the spices used for the experiment showed good antimicrobial properties, and did not have much effect on textural parameters except hardness. The experiment showed that spice combinations could play an important role in increasing the acceptability, safety and shelf-life of fresh tuna.