211. Relation of fat to casein in normal milk.—In order to understand the relation of the composition of the milk to yield of cheese, one must be familiar with the relation of the fat to the casein in normal milk. The following table[94] shows the relation of fat to casein in normal milk:
TABLE IX
| Summary Showing the Relation of Fat to Caseinin Normal Milk | |||||
| Group | Per Cent of Fat in Milk | Number of Samples | Average Per Cent of Fat in Each Group | Average Per Cent of Casein in Each Group | Average Pounds of Casein for Each Pound of Fat in Milk |
I | 3.0-3.5 | 22 | 3.35 | 2.20 | 0.66 |
| II | 3.5-4.0 | 112 | 3.72 | 2.46 | 0.66 |
| III | 4.0-4.5 | 78 | 4.15 | 2.70 | 0.65 |
| IV | 4.5-5.0 | 16 | 4.74 | 3.05 | 0.64 |
| V | 5.0-5.25 | 7 | 5.13 | 3.12 | 0.61 |
Table IX shows that the pounds of casein for each pound of fat are not constant but that the casein does not increase in proportion to the fat above 4.0 per cent of fat in the milk.
212. Influence of fat in milk on yield of cheese.—The following table shows the influence which fat in the milk has on the yield of cheese:[94]
TABLE X
| Summary Showing Relation of Fat in Milk to Yield of Cheese | |||
| Group | Sverage Per Cent of Fat in Milk | Pounds of Green Cheese Made from 100 Lb. of Milk | Pounds of Green Cheese Made for 1 Lb. of Fat in Milk |
I | 3.35 | 9.14 | 2.73 |
| II | 3.72 | 10.04 | 2.73 |
| III | 4.15 | 11.34 | 2.70 |
| IV | 4.74 | 12.85 | 2.71 |
| V | 5.13 | 13.62 | 2.66 |
Table X shows that as the fat in the milk increases, the pounds of cheese made from 100 pounds of that milk increases; but the amount of cheese made for each pound of fat in the milk does not increase. This is due to the fact pointed out in Table IX, namely, that as the fat increases in the milk the casein does not increase in the rich milk in proportion to the fat. From Tables IX and X this conclusion may be drawn: that as the percentage of fat increases in the milk the more cheese can be made from 100 pounds of that milk, but after the increase in fat gets above 4 per cent the amount of cheese that can be made for each pound of fat in the milk is decreased because the casein does not increase in proportion to the fat. No exact statement of yield can be made without first stating the moisture-content of the cheese. The losses also must be considered.
Van Slyke[95] in the following Table XI shows the effect of the fat-content of normal milk on the yield of cheese.