Abstract

The feasibility of a pH-shift process for protein recovery and salt removal from over-salted albumen was evaluated. The effects of albumen to water ratios (1:0, 1:1. 1:3 and 1:5, w/w) and pH-shift versions (acid and alkaline processes and direct pI precipitation) on protein yield and salt reduction were also studied. The higher the ratio of water added the lower the protein yield obtained for all pH driven methods. The highest protein yield (31%) was found using the acid-shift process without extra water. However, salt removal efficacy from the protein isolate was improved by increasing water added. To enhance the protein recovery, several flocculants were used with the acid process. Maximum protein yield of 36% was obtained when κ-carrageenan was used. Doubly washing the protein isolate with cold water with vacuum filtration further increased salt removal (49%) with the lowest protein loss. Therefore, an acid pH-shift process with the aid of κ-carrageenan and post-washing had the best potential for recovering protein and eliminating salt from over-salted albumen. The optimum process can recover protein up to 31% with 74% salt removal. The chemical structure of protein isolate was negligible change as seen using sodium dodecylsulfate-polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy.