Whey protein in samples of raw milk (C), in boiling milk (B), and in milk treated in a microwave oven (M750 and M900, indicating
that raw milk was subjected to microwave treatment at 750 and 900 W, respectively, for 75 s immediately after its delivery to the laboratory).
Different letters (a–c) indicate significant differences (P < 0.05). The error bars represent the SD calculated on 30 samples collected from 3 different
vending machines at different sampling times.