655. The effect of pH on the extent of splitting or clumping of fat globules caused by agitation of hot cream

Extract

The effect of pH on the extent of splitting and clumping of globules in hot cream agitated by treatment in a Vacreator, by vigorous mechanical stirring or by simple aeration has been investigated. The size distribution of globules was determined in cream before and after treatment either by the microscopic method or by a rapid method involving separation of small and large globules by centrifuging and gravity creaming respectively.

It was found that at pH 8 splitting of globules was at a maximum and clumping at a minimum. As the pH of the cream to be treated was lowered towards pH 6, the amount of splitting decreased and clumping increased. The ‘clumping’ of globules in cream during single-stage homogenization was also increased as the pH was lowered.

Practical applications of the observations are suggested.

The thanks of the author are due to Mr J. A. Singleton, superintendent and Mr B. Le Heron, buttermaker of The Dairy Research Institute (N.Z.) experimental factory, for arranging and carrying out the Vacreator treatment of cream; to Dr F. H. McDowall for helpful advice and criticism, and to Miss R. P. Johnson for assistance with microscopic and analytical work.