Isoelectric solubilisation of animal matter

A method for recovery of protein from animal by-product by sequential isoelectric solubilisation of the animal by-product, the method comprising the steps of:

• isoelectric solubilisation of the animal by-product in one of an acid or alkali solution to provide a first solubilised protein fraction;
• separating the first solubilised protein fraction from unsolubilised animal by-product;
• isoelectric solubilisation of the unsolubilised animal by-product in another of the acid or alkali solution to provide a second solubilised protein fraction;
• separating the second solubilised protein fraction from unsolubilised animal by-product;
• and
• recovery of protein from the first and/or second solubilised protein fractions, wherein the protein from the first and second solubilised protein fractions are recovered by combining the first and second solubilised protein fractions in an amount to provide an acidic solubilised protein fraction having a pH of 5-6 to effect precipitation of the protein.