Covers dried whole milk, dried partly skimmed milk and dried skimmed milk manufactured by the spray process. The method is also applicable to all types of instant dried milk. The heat class of the dried milk is derived from the heat number according to a proposed heat-classification scheme consisting of four classes, i.e. low heat; medium heat; medium-high heat; high heat. The Kjeldahl method is described in Annex A and Annex B includes the proposed heat-classification scheme for spray-dried milk.