Effect of calcium phosphate precipitation on ultrafiltration of acid whey

The high calcium content of acid whey can pose challenges to protein concentration using UF membranes due to calcium-induced fouling. This study examined the effect of pH and temperature on calcium precipitation, UF permeation efficiency and the removal of calcium through UF processing of acid whey across a pH range from 4.6 to 7.0 (15 & DEG;C) and a temperature range from 10 to 35 & DEG;C (pH 6.0). Calcium phosphate precipitation increased with increasing temperature and pH (from pH 5.6 onwards). This correlated with an increased retention of calcium in the UF retentate, indicating these parameters play a key role in determining the calcium content of the final product. While reducing pH can fully resolubilise calcium phosphate, reducing temperature only partially reverses calcium phosphate precipitation. From a manufacturing perspective, pH adjustment immediately prior to UF may be an effective tool for con-trolling calcium precipitation, process efficiency and product composition.& COPY; 2023 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the effect of pH and temperature on calcium precipitation, UF permeation efficiency, and the removal of calcium during UF processing of acid whey. The results showed that calcium phosphate precipitation increased with increasing temperature and pH. While reducing pH can fully resolubilize calcium phosphate, reducing temperature only partially reverses calcium phosphate precipitation. Therefore, adjusting pH prior to UF may be an effective method for controlling calcium precipitation and improving process efficiency and product composition.