The BDI method - Part I: Determination of free fatty acids in cream and whole milk powder

Using the Bureau of Dairy Industries (BDI) method, the effects of whole mil k powder (WMP) reconstitution temperature and the dilution of cream on free fatty acid (FFA) levels were determined. WMP reconstitution temperatures ( 20, 40, 60 degrees C) did not affect the FFA results and the ease of fat se paration of the sample/BDI reagent mixture after treatment in a 100 degrees C water bath did not depend on the degree of reconstitution. Diluting samp les of cream with skim milk or high purity water resulted in under-estimati ons of the cream FFA level by up to 15% and 55% for skim milk and water as diluent respectively. The percentage FFA recovery was constant at any given fat level of the diluted cream, and was independent of the FFA level and f at content of the original cream. A program to predict the FFA level of the original cream from the FFA level and fat content of the diluted cream was written.