Effects of natural (or seasonal) variation in concentration of components of milk and addition of divalent cations on UHT processing characteristics

Interrelationships in composition of milk, ultra‐high temperature processing behaviour and weight and composition of deposits were investigated using bulked milks collected and processed at intervals over a one year period. The only statistically significant correlations of efficient run time with components of the milk were with concentrations of Mg and casein. In a separate experiment 0.62‐4.1 mM MgCl2 was added to milk before processing. This gave rise to a large reduction in the processing time as predicted by this correlation. The addition of 0.375‐2.5 mM CaCl2 gave comparable reductions in run time.