Recovery Method for Surimi Wash-water Protein by pH Shift and Heat Treatment

Abstract

Surimi wash-water (SWW) contains a high concentration of protein resulting in a negative environmental impact and high disposal costs. Isoelectric point precipitation has been used for protein recovery from SWW. Here, we show an improved protein recovery method combining pH shift and heat treatment for Alaska pollock SWW. In a laboratory-scale experiment, a pH shift from neutral to pH 5 precipitated 63% of the SWW protein and subsequent heat treatment at 60°C precipitated almost all of the remaining protein. In a factory-scale experiment, the optimized pH shift and heat treatment yielded a 21% protein pellet with a 79% moisture content. The SWW protein gel thus obtained showed suitable quality as a surimi product as determined by the similar whiteness and strength as gel prepared from low-grade surimi. The optimized method combining pH shift with heat treatment improves the protein yield from SWW and prevents environmental pollution.