The application of ozonated water to maintain the quality of tuna meat: The effect of contact time, contact temperature and ozone dosage

Tuna is one of the common fish consumed by Indonesian people. Tuna is highly perishable. Therefore, the handling technique is needed to maintain tuna's quality. This research brought about the application of ozonated water in controlling quality of tuna by observing the effect of contact time, contact temperature and ozone dosage. The standard quality of tuna is detected from the number of aerobic mesophyll bacteria, pH value, water content and the protein content. The study was conducted by testing the ozone solubility in water and contacting tuna to ozonated water. Tuna was contacted to ozonated water for 40, 80, 120 minutes' contact time at 8°C and ozone dosage of 0.3 mg/L; contacted at 37°C, 25°C and 8°C for 120 minutes and ozone dosage of 0.3 mg/L; and contacted at 8°C for 120 minutes with ozone dosage of 0.3 mg/L and 0.24 mg/L. After the treatment process, tuna was saved in 8°C chiller for 168 hours or seven days. The results show that the longer duration contact, the lower contact temperature, and the higher ozone dose, the lower the rate of quality degradation of tuna. Contacting tuna for 120 minutes can eliminate bacteria up to 66.7%, pH value decreases to 5.58 shortly after tuna was contacted to ozonated water; water content increases to 1.20% and protein decreases to 0.67% after 168 hours of storage. Contacting tuna at 8°C can eliminate bacteria up to 91.2%, pH value decreases to 5.48 shortly after tuna was contacted; water content increases to 1.14% and protein decreases to 0.22% after 168 hours. Meanwhile highest ozone dosage (0.3 mg/L) can eliminate bacteria up to 66.7%, pH value decreases to 5.58 after tuna was contacted; water content increases to 1.20% and protein decreases to 0.67% after 168 hours of storage.