Evaluating volume reduction of clarified acid bovine milk whey via falling film vacuum evaporation

Abstract

This research evaluates the effect of falling film vacuum evaporation on the characteristics of clarified acid bovine milk whey. The clarified acid whey was obtained by microfiltration (ceramic membranes, 0.2 µm cut-off, ∆TMP: 2 bar) and concentrated by a falling film evaporator. The clarified whey composition was mainly protein (0.32 ± 0.06 % w/w), ashes (0.56 ± 0.08 % w/w), soluble solids (5 ± 1 % w/w), and turbidity (16 ± 5 NTU). During the concentration step, the number of cycles changed notoriously for each volume reduction factor (VRF), being four the highest value achieved, with an average number of cycles of 18. The characteristics of concentrates were not affected by differences in the number of cycles, increasing proportionally with the VRF; it could be noticed in the final content that protein, ashes, and °Bx increased linearly around 3.5 times the initial composition. However, turbidity was different for each VRF because of heat treatment during the concentration stage (above 60 °C). A thermal treatment step after ricotta preparation would be advisable to remove the remaining protein. Tukey’s test was carried out at a 95 % CI, revealing statistical differences among means; therefore, there was a change in the characteristics of the final concentrated whey. Regarding color (absorbance), there were no considerable changes during the concentration process.