Recovery of Whey Proteins with Sodium Hexametaphosphate

Abstract

Interactions between proteins and anionic polyelectrolytes may be utilized to recover the protein of milk whey. Depending on the polyelectrolyte used, the protein content of the precipitates can be increased by gel filtration or by ion exchange. Under optimum conditions (pH 3), over 90% of the protein of whey was precipitated by sodium hexametaphosphate, provided the whey was decationized previously. On dry weight basis, the precipitates contained 70 to 85% protein, 10 to 20% sodium hexametaphosphate, and 10 to 15% lactose. Only a negligible amount of the precipitant remained in the supernatant.The protein content of the protein-hexametaphosphate complex was increased to 88 to 90% by either gel filtration or ion exchange. Ion exchange removed mainly the phosphate whereas gel filtration removed most of the lactose and part of the phosphate. Small amounts of residual sodium hexametaphosphate could be removed from the upgraded complex by neutralizing the solution with calcium hydroxide the centrifuging. The solubility curve of the product showed that the protein would not be denatured by this process. Gel filtration of the complex on Biogel P-10 at pH 8 to 10 yielded two protein fractions and the mineral-lactose fraction. The first fraction contained the immunoglobulins and blood serum albumin whereas the second fraction contained α-lactalbumin and β-lactoglobulin. © 1973, American Dairy Science Association. All rights reserved.