Abstract: The objective of this study was to identify raw milk, pasteurized milk and UHT milk using turbidity method. There is difference of turbidity after adding chelating salts in different heat treatment milk. So, according to this feature, screening out chelating salts that can be used to differentiate raw milk, pasteurized milk and UHT milk is essential. The results showed that citrates (trisodium citrate, ammonium citrate) and phosphates (sodium hexametaphosphate, sodium polyphosphate, sodium pyrophosphate) could disperse casein micelles and present quantitatively turbidity. However, trisodium citrate on raw milk, pasteurized milk and UHT milk turbidity distinguished most significantly, absorbance 600 value between 0 to 0.15 was raw milk, absorbance 600 value between 0.20 to 0.50 was pasteurized milk, absorbance 600 value between 0.60 to 1.00 was UHT milk. The main mechanism of this mehod included chelation of CN-bound Ca, dispersion of CN micelles, and formation of new types of calcium-chelating salts complexes. Turbidity method can identify raw milk, pasteurized milk and UHT milk fast, conveniently and more cheaply.

Key words: raw milk; pasteurized milk; UHT milk; turbidity; identification