[Effect of treatment technologies on the nitrate and nitrite content of milk]

The nitrate contents of some evaporated milks or dry skim milks are sometimes abnormally high. Industrial thermal processings increase the amount of nitrates like. After flash pasteurization the level is two fold higher, after pasteurization and sterilization, the level is four hold higher. After heating during 120 minutes at 90 degrees C of an 2% casein solution the level of the nitrates like increases from 14,7 to 30,8 mg/kg E.S., while, the reactivity of milk proteins to the biuret reagent is enhanced. The dialysis of milk powder containing 106 mg NO3-/kg E.S. shows that more than 95% of the nitrate are in free state. The level of bound nitrates is nearly four times higher in soluble proteins than in casein.