Natural variation in heat stability of concentrated milk before and after homogenization

An examination has been made of the seasonal variations in the heat stability of skimmed milk, concentrated (22.5 per cent total solids) skimmed milk, and concentrated (31 per cent total solids) whole milk. Marked seasonal differences were found to exist in the effects of homogenization on the heat stability of subsequently concentrated milk. ‘Summer’ milks were found to be much more stable than ‘winter’ milks after homogenization and to be more readily stabilized by added sodium phosphates and citrate. Milk serum rather than milk fat was shown to be the major determinant in the heat stability of concentrated homogenized milk, and all such milks were found to be very sensitive to small changes in their level of soluble calcium.