Effect of ultrafiltration of acid whey at pH 4.6 or 6.5 on whey concentrate composition and resultant powder properties

This study investigated the effect of modifying the mineral composition through adjustment of pH prior to ultrafiltration on the functionality of acid whey protein concentrate (WPC; pH 4.6). Increasing pH to 6.5 prior to ultrafiltration produced a concentrate with a significantly higher calcium and phosphorous content, compared to ultrafiltration at pH 4.6. WPC produced at pH 6.5 also had significantly more calcium-phosphate precipitation following pasteurisation and evaporation and had a higher viscosity at 30% solids (300 s-1, 50 degrees C). In addition, both reconstituted powders (5%, w/w, protein) had strong gelation properties following heat treatment at 90 degrees C; however, the WPC produced at pH 6.5 had a significantly firmer gel strength, but such gels appeared to be more sensitive to breakage at increased frequency and oscillation strain. Overall, the pH prior to UF had a significant impact on the processing of acid whey and final product functionality. Adjusting the pH of acid whey to pH 6.8 prior to ultrafiltration, results in high levels of calcium phosphate retention, and high heat-induced gel strength in the subsequent whey protein concentrate. image