New Processes to Extract and Purify Phosvitin by Using Aqueous Salt Solutions, Precipitation and Ultrafiltration Techniques

Phosvitin is the most phosphorylated naturally occurring protein and it is concentrated in the granular fraction of egg yolk. It has interesting antioxidant and cation chelating properties that can be used to preserve food and cosmetics, but its industrial application is limited as its separation relies on the use of organic solvents and chromatographic techniques, which are expensive and difficult to assimilate in a continuous procedure. In this study, we propose a new phosvitin separation process using substances legally accepted for use in the food industry (NaCl and HCl), employing egg yolk granules as raw material. In this case, the NaCl concentration and the pH of the solution of granules were screened in order to obtain a phosvitin-rich supernatant after centrifugation. Additionally, two new processes were proposed to purify this phosvitin-rich solution. The first was the precipitation of impurities during the desalting stage at optimized pH values. The second was ultrafiltration under selected pH value conditions. A low nitrogen/phosphorous (N/P) atomic ratio is considered a quality parameter, with 3.6 ± 0.2 being the value of the phosvitin-rich supernatant. The two purification processes provided highly purified phosvitin with a similar N/P value of 2.5 ± 0.1. The high level of purification of the phosvitin was confirmed using electrophoresis and ion-exchange chromatography. In particular, the purified phosvitin obtained via ultrafiltration is already desalted and membrane technology is more easily scalable than that based on chromatography, thus facilitating the industrial separation and commercialization of the phosvitin.