Exploring high-pressure carbon dioxide for demineralization of goldstripe sardinella scales

This study explored the use of HPCD for demineralizing goldstripe sardinella scales, using response surface methodology with an on-face central composite design to describe the effects of CO2 pressure (1.0 to 10.0 bar) and treatment time (1 to 5 h) on the demineralization efficiency (DM; %). Significant impacts from both parameters were observed (P < 0.05), with the highest DM of 16.13 ± 1.92% achieved at 10.0 bar for 5 h. Increased pressure enhanced DM more than strong acid treatment at comparable pH. However, further increases in pressure showed diminishing returns due to limited CO2 solubility and temporary buffering systems observed during the process. Scanning electron microscopy with and without energy dispersive X-ray spectroscopy revealed reduced calcium and phosphorus content, preserved collagen integrity, and altered scale structure of HPCD-treated samples.