THE EFFECT OF RENOVATION OF BUTTER UPON THE REICHERT MEISSL NUMBER AND SAPONIFICATION VALUE

Abstract

In connection with the examination of a series of samples of ice cream by the Health Department Laboratory of Chicago, in the course of which the presence of foreign fats was demonstrated in a few instances, the contention was raised by scientific counsel representing one of the ice cream manufacturers that reprocessed butter often yields a low Reichert Meissl number and saponification value; that, judging from the data furnished by these tests, it is often impossible to distinguish renovated butter from mixtures of butter and foreign fat. As a basis for this contention it was stated that the alleged lowering of the findings of these two tests was due to a loss of volatile acids occurring during the process of renovation, as a result of the heating and washing. The assertion was confidently made that the aforementioned loss of volatile fatty acids may represent as much as one third of the volatile fatty acid content, as determined by the Reichert Meissl method. It was the opinion of the city's experts that the loss of volatile acids occasioned by the process of renovation would be slight, and would not in any case be sufficient to invalidate the test as a means of distinguishing genuine butter from other fats. The firm in question admitted that renovated butter had been purchased for the preparation of homogenized cream, used in the manufacture of ice cream, but disclaimed any knowledge of the use of oleomargarin or other foreign fats for this purpose. The purchase of supplies, however, had not been controlled by laboratory tests. As very little definite data could be found upon the point in question, however, it was decided to undertake the series of tests here reported. The procedure adopted was as follows: Samples of butter purchased in the open market were subjected to tests for the determination of the Reichert Meissl number and saponification value. They were then placed in an incubator, at 37°C., for from three to five weeks, until an extreme degree of rancidity developed. The samples were then reprocessed by blowing steam through them for two