Heat-induced changes in flavour of milk

Flavour is a very important attribute of all foods heating/cooking makes a major contribution to flavour, both positively and negatively. Good-quality fresh liquid milk products are expected to have a clean, sweetish taste and essentially no aroma any departure therefrom can be considered as an 

On the positive side, thermization and minimum pasteurization should not cause the formation of undesirable flavours and aromas and should, in fact, result in improved flavour by reducing bacterial growth and enzymatic activity, e.g. lipolysis. If accompanied by vacuum treatment (vacreation), pasteurization removes indigenous off-flavours, i.e. those arising from the cow s metabolism or from feed, thereby improving the organoleptic qualities of milk. 

Also on the positive side, severe heat treatment of cream improves the oxidative stability of butter produced therefrom due to the exposure of antioxidant sulphydryl groups. As discussed in section 9.2.2, lactones formed from hydroxyacids are major contributors to the desirable cooking quality of milk fats but contribute to off-flavours in other heated products, e.g. milk powders. 

Since sulphur compounds are important in the off-flavour of UHT milk, attempts to improve its flavour have focused on reducing the concentration of these, e.g. by adding thiosulphonates, thiosulphates or cystine (which react with mercaptans) or sulphydryl oxidase, an indigenous milk enzyme (which oxidizes sulphydryls to disulphides Chapter 8). 

Driessen, F.M. (1989) Inactivation of lipases and proteinases (indigenous and bacterial), in Heat-induced Changes in Milk (ed. P.F. Fox), Bulletin 238, International Dairy Federation, Brussels, pp. 71-93. 

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