Chemistry of butter and butter making III. The relationships between (1) the percentage fat and (2) the protein percentages of cream and the churning loss
1. The relationships among the cream test, the buttermilk test and the percentage of the total fat placed in the churn that is lost in the buttermilk were studied.
2. A similar study was made concerning the percentages of total protein, casein and albumin in the cream and the churning losses.
3. The variations of churning time with cream richness are presented.
4. The churning time variations that were obtained with change in richness of the cream were not such as to make it inadvisable to churn high-fat cream.
5. The results of the Mojonnier test of the buttermilk vary relatively little between lots of cream with 20 to 30 percent fat, while the variation with cream from 30 to 40 percent fat is comparatively great.
6. The reverse is true of the percentage of the total fat placed in the churn that is lost in the buttermilk. This value varies widely between 20 and 30 percent fat in the cream, considerably less between 30 and 35 percent cream and but slightly with cream having 35 to 40 percent fat.
7. The necessity of considering the fat test of the cream in calculating the churning loss was stressed.
8. The data presenting the relationship between the fat percentage of the cream and the churning loss are presented in a chart (fig. 7). This is so presented that the creamery operator can calculate his churning losses if the buttermilk and cream tests are available. The chart likewise enables him to determine whether or not his losses compare favorably with those he should obtain with the testing method he is employing.
9. The protein data indicate that casein may play an important part in the colloid-chemical relationships of the churning process.
10. The data indicate that the lowest churning loss that it is likely to attain (37.5 percent cream) is in the vicinity of 1.00 to 1.20 percent of the total fat churned. This represents approximately a 99 percent yield, which is exceptionally good. With 30 percent cream the lowest loss figure will fall between 1.40 and 1.60 percent of the total fat placed in the churn. These figures are based on the Mojonnier test of the buttermilk.