Modelling and optimization of supercritical CO2 drying of tuna (Thunnus albacares) fillets: Unraveling physicochemical and structural changes

This study explores and optimises the innovative supercritical carbon dioxide (SC-CO2) drying process for tuna fillets (Thunnnus albacares), offering a sustainable alternative for food preservation. Using a central composite rotatable design (CCRD), we assessed the effect of drying time (120–360 min), temperature (35–45°C), and flow rate (15–25 kg/h) at 10 MPa on key quality attributes: moisture content, water activity (aw), rehydration capacity (RC), pH, and total colour difference (ΔE). Our findings indicated that drying time and CO2 flow rate are the main factors affecting the water content. Drying time and flow rate significantly reduced moisture content and aw, while RC improved with prolonged time and higher flow rates. Despite increases in pH (from 6.01 to 6.405) and ΔE (23.51) due to the treatment, these changes did not compromise the product’s overall quality. Optimal drying parameters were determined as 377.2 min, 39.7 °C, and 27.3 kg/h, with subsequent confirmatory experiments using three different conditions validating the moisture model. However, spectroscopy and microscopy analyses indicated potential lipid and protein oxidation related to the CO2 flow rate, highlighting avenues for future research to refine this promising drying technique.