The effect of exposure time and water replacement in the application of ozonated water to maintain the quality of tuna

Fish was one of the common protein sources consumed by the Indonesian people. One type of fish that was widely consumed was tuna. Tuna contains protein as much as 18-30%. With high protein and water content, tuna was a highly perishable commodity. Therefore, the handling of tuna needs to be done to maintain its quality. The use of ozonated water for this issue was promising because ozone was a strong oxidant and does not produce toxic residues. This study used ozonated water to maintain the quality of tuna. The objective of this study was to evaluate the effect of exposure time and water replacement of the ozonated water on the quality of tuna, measured by the parameters of Total Mesophyll Aerobic Bacteria (TMAB), pH, water content, and protein content. Exposure time of 40, 80, and 120 minutes can deactivate the TMAB by 4.94, 60.99, and 65.43%, respectively. Meanwhile, water replacement every 60 and 40 minutes within 120 minutes can deactivate more TMAB, which values 82.59 and 89.38%. Exposure time of 120 minutes can also decrease the pH by 0.12, lower the water content by 0.63%, and decrease the protein content by 0.80%. Water replacement every 40 minutes within 120 minutes can decrease the pH by 0.08, lower the water content by 1.44%, and decrease the protein content by 2.20%.