Milk may be sterilized, pasteurized, or boiled.
Sterilization kills both germs and spores, but it is not nearly so necessary as it is to have the right proportion of sugar and fats. Place in an autoclave and keep at a temperature of 160° F. for an hour.
Pasteurization is desirable when a good, clean milk is not attainable. It kills the germs, but not the spores. The process must be carefully attended to, or the milk will sour more easily. Heat a quart of milk to 160° F. for twenty minutes. Cool rapidly to 40° F.
Boiling milk for two minutes kills all bacteria, and renders the casein more easy of digestion and prevents the formation of curds.
PUTTING FOODS TOGETHER
Whole milk contains 4 per cent fat, and must be thoroughly shaken before it is measured, for otherwise one child will get all the fat and another all the skimmed milk.
Fat-free, or skimmed milk, contains about 0.1 per cent fat. The cream has been removed by a siphon or centrifuge. If unable to get a fat-free milk from a dairy, the cream can be removed from a quart of whole milk quite easily with a siphon.
Sugars and flours should be weighed when used, for they vary greatly in volume.
In using flour ball or imperial granum, the flour must be mixed with water or cereal water, to make a smooth paste and brought to a boil. If the milk is to be boiled also, add the milk to the paste and boil all together. Cool and strain.
All baby feedings should be strained, as tiny lumps of food will clog the rubber nipple and the nurse may think the baby is not taking its feedings well. The following is a typical formula: