Equation:
| Total amount of food × Percentage of fat desired | = Amount of this milk in the mixture. |
| Fat-strength of layer of milk used |
(1) Select from the “Layers of Milk” Table the milk which possesses the desired ratio of fat to protein.
(2) Substitute in the equation.
(3) As the sugar-percentage has been reduced equally with that of the protein, add sufficient sugar to raise to the desired percentage.
Example: 20–oz. mixture desired. Percentages desired = Fat 3, Sugar 6, Protein 1. Use upper 8 oz. (fat 12%, protein 4%, viz.: 3:1). Then 20 × 3
12 = 5 oz. of upper 8 oz., with 15 oz. of water in the 20–oz. mixture. The protein necessarily becomes 1%, and the sugar likewise. The mixture already containing 1% of sugar, add 5% of 20 oz., i. e., 1 oz. of sugar to increase this to the 6% desired.
To Determine the Percentages Present in Any Milk-Mixture Already in Use
| Quantity of substance used (milk,cream, or skimmed milk)× Its percentage-strength | = Percentage of element (F., S. or P. in the mixture.) |
| Total Quantity of Food |
Example: The mother has mixed: Upper 8 oz.; 6 oz.—Lower 8 oz.; 3 oz.—Milk-sugar 3 level tablespoonfuls.—Water 27 oz. Total quantity = 36 oz. The upper 8 oz. contains 12% fat (see Table). Both top and bottom milk contain 4% protein and sugar. Three tablespoonfuls sugar = approximately 1 oz. The fat of the lower 8 oz. may be ignored. Then 6 × 12
36 = 2 = Fat percentage from the top-milk. 3 × 0
36 = 0 = Fat-percentage from the bottom milk. 9 × 4
36 = 1 = Protein and sugar percentages from combined top and bottom milk. The 1 oz. additional sugar divided by 36 = approximately 3% sugar added. There being already 1% sugar derived from the milk, the total sugar = 4%.