Effect of processing operations on heat stability

Forewarming (preheating). Heating an unconcentrated milk, especially at 90°C X 10 min, before a heat stability assay, reduces its heat stability, 

Additives. Orthophosphates, and less frequently citrates, have long been used commercially to increase the stability of concentrated milk. The mechanism was believed to involve Ca-chelation but pH adjustments may be the principal mechanism. 

Numerous compounds increase heat stability (e.g. various carbonyls, including diacetyl, and ionic detergents) but few are permitted additives. Although added urea has a major effect on the stability of unconcentrated milk, it does not stabilize concentrated milks, although it does increase the effectiveness of carbonyls. 

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