Effect of high-pressure processing on the physicochemical stability of yellowfin tuna (Thunnus albacares) during chilled storage

The effect of pressurisation on the physicochemical properties of yellowfin tuna (Thunnus albacares) during low-temperature storage was studied. Tuna chunks were vacuumsealed in EVOH multilayer pouches and subjected to pressure treatments of 100, 200, and 300 MPa at 25°C for 5 min. Unpressurised samples, which underwent no pressure treatment, were maintained as controls. All samples were stored at 2±1°C throughout the study for subsequent analysis. At regular intervals, all samples were evaluated for biochemical indicators, including pH, trimethylamine (TMA), total volatile base nitrogen (TVB-N), and thiobarbituric acid (TBA), and physical parameters such as hardness and hue.  pH in the samples increased slightly on storage. TBA content enhanced proportionally with the level of pressurisation of the samples and exhibited higher content in 300 MPa-treated samples. In contrast, TMA and TVB-N content in the tuna chunks showed an inverse relationship with pressurisation level, and lower levels of volatile base nitrogenous compounds were found in pressurised samples than in unpressurised samples. Application of pressure increased the hardness and lightness (L* values) of the samples. The control samples became unacceptable on the 20th day of storage, whereas all pressurised samples maintained better quality even up to 30 days. Among the samples, those treated with 200 MPa, exhibited the lowest lipid oxidation along with minimal changes in colour and texture. Keywords: Chilled Storage, High Pressure Processing, Physicochemical Changes, Tuna