This standard applies to the control of any addition of water to raw or heated milk that has been completely, partially or not skimmed. The milk must not be soured or otherwis spoiled. If the milk is only slightly soured, an approximate value for the freezing point of the original, non-sourened milk can be calculated using the formula under 10.3. If the milk has been frozen, only an approximate value for the freezing point of the original (unfrozen) milk is obtained. If milk samples have been preserved, this may only have been done in one of the following three ways, namely by adding per liter of milk: a. 1.00 g potassium dichromate (K2Cr207) or b. 1.5 ml formaldehyde solution 34 to 37% (w/w) or c. 15 ml of a solution of 10 g mercury(II) chloride (HgCl2) and 8.5 g sodium chloride (NaCl) in 1 L of water. Note When preserved according to a. or b. a correction must be made to the freezing point (see 10.2). When preserved according to c. no correction is necessary, because adding the mercury-containing solution has virtually no influence on the freezing point of unadulterated milk.
NEN 3460-1982 history
1982NEN 3460-1982 Milk - Determination of the freezing point with a mercury thermometer (reference method)