The effect of initial wash at acidic and alkaline pHs on the properties of protein concentrate (kamaboko) products from sardine (Sardina pilchardus) samples

Sardine samples were initially washed at acidic (2.50, 4.00 and 5.50) and alkaline (8.50, 10.00 and 11.50) pHs, followed by two washing cycles at pH 7.2 ± 0.15. Final recoveries for total solids were 77.5%, 71.5% and 63.1% at 4.00, 2.50 and 5.50 pHs and 48.3%, 43.3% and 29.3% at 8.50, 10.0 and 11.5 pHs, respectively. Consequently, similar were the results for protein recoveries (higher at acidic conditions) and lipid elimination (higher at alkaline conditions), indicating higher solubility of molecules in alkaline solutions. Lightness and whiteness index improved due to washing cycles, the thermal process further increased them and this was more evident in the samples washed at acidic conditions (p < 0.05). Kamaboko gels washed at acidic conditions showed higher values in firmness and more cohesive and elastic texture (p < 0.05). Evaluation analysis using sum scores revealed that initial wash at pH 5.50 is the most suitable treatment for kamaboko gels from sardine.