EFFECT OF MECHANICAL TREATMENT ON THE HARDNESS OF MARGARINE AND BUTTER

The work-softening of margarine and butter resulting from passage through perforated plates was determined. Various plates were used differing in size and number of perforations, but identical in the total area of perforations. Greater work-softening was obtained with plates having many small perforations, but the back-pressure in the equipment was higher. Passing the product through two or three plates slightly increased work softening. Additional mechanical action was provided by a propeller rotating immediately behind the perforated plates. Only small additional work-softening was obtained by this action and little remained after 8 days storage. Increasing the speed of the propeller up to 100 r.p.m. increased work softening. Increasing it to 300 r.p.m. did not further increase work softening. It appears that excessive mechanical action has little permanent softening effect on plastic fats.