| Popis: |
Summary A study of the physical and chemical properties of milk remade from three types of whole milk powder and reconstructed skim milk powder and butter led to the following results: Remade milk shows the freezing point of fresh milk when made with the proper proportions of powder and water. For the drum process powder this was found to be 10.6 per cent powder, for the centrifugal spray 12.8 per cent powder, for the pressure spray 12.5 per cent powder, and for the reconstructed milk, 9.16 per cent powder and 4.16 per cent butter. The specific gravity of the remade milks was found to lie within the limits of variation of fresh milk when made up in the proportions which give a normal freezing point. The viscosity of the remade milks was higher than normal. This was especially true of milk remade from the drum process powder. The specific electrical conductivity of each type of milk except the drum process was normal when the milks were made up in the proportions which gave a normal freezing point. The drum process milk exhibited a high conductivity which may have been due to the fact that this powder is made from partially skimmed milk. The milk made from the centrifugal spray powder was the only one which gave a normal cream layer on standing. The milk made from the centrifugal spray powder showed no deficiency of soluble proteins, but the soluble protein content of the other milks was less than normal. This was especially true of the milk made by the drum method. The drum process milk and the reconstructed milk failed to coagulate with rennet. The spray process milks showed a rennet coagulability and character of curd somewhat like that of pasteurized milk, the centrifugal spray milk being the nearest to the pasteurized milk in this regard. At a low concentration of added acid and alkali all the remade milks showed less buffer than normal milk in terms of pH. Peroxidase was absent from the drum process milk, but was strongly active for the other remade milks examined. |
