Necessity of pasteurized milk freezing point revision in its Iranian standard (ISIRI 93) to improve dairy product safety

Pure water freezes at zero degrees of Celsius. By dissolving any material in the water its freezing point will be decreased، similar to water، some ingredients of milk such as lactose، ion Chlorides decreases the freezing point. The main factors affecting the freezing point of milk are: added water during milking and gathering، high microbial load، mastitis، adulteration including the addition of Ionizable materials for example salt and etc. To determine the average bovine milk freezing point، the percentage of none-fat-solid (SNF) and elemental mineral content (EMC) at the same time. This is a descriptive analytical study which was done in Kermanshah province by using 100 milk samples from complete milk of healthy cow in definite time point by simple random sampling. The samples transported to laboratory in less than 3 hours، freezing point of each sample has determinated by calibrated cryoscope، the percentage of SNF and EMC has determinate by calibrated Milk analyzer. beyond standard conditions of milking، collection and immediate testing، results showed that mean freezing point of milk was -0. 519، mean SNF was 8. 23 and mean mineral percentage was 0. 74.. Since the Institute of Standards and Industrial Research of Iran in the 4th revision of the pasteurized milk standard (Standard 93) has limited the percentage of SNF of milk to 8 and freezing point to -0/507 to -0/545، which are not at the same line. Moreover، other factors such as EMC have underestimated، we suggest that the freezing point of milk without measuring EMC