Yeasts and Oidia in High-grade Experimental Butter

Abstract

In studying butter, Redfield ~ has proposed a routine microscopic method of counting yeasts and oidia as correlated in some degree at least with the quality of the cream used in its manufacture. This method is based upon the examination of the curd-whey mixture separating out when the sample of butter is melted at 45°C. One-cubic centimeter samples of this mixture are removed to sterile containers and smears are made by transferring 0.01 co. samples of this mixture to slides with the Breed type of pipette, for microscopic study. The results shown in table 1 are selected from experiments made to test the accuracy of this method. These results based on the number of yeasts found in 10 microscopic fields, check as closely as those usually obtained by the official plate method, and therefore indicate that yeasts are fairly evenly distributed throughout the butter. Counts of this kind, check fairly closely when the totals are high as in these samples. 1V~uch greater differences occur in successive examinations of samples containing very low numbers of yeasts. These counts were based on numbers found in 100 microscopic fields. Each cell found was counted. The results indicate that yeasts are somewhat more evenly distributed than are the oidia. The mycelial character of Oidium lactis tends to result in more uneven distribution of the