Milk is not truly a fluid food, for whenever milk enters the stomach the ferment rennin and the acid of the gastric juice change the milk into a solid curd. This is brought about under the influence of the salts of lime. The clotting of milk is well illustrated in the making of curds or junket. This coagulation or clotting of milk must be distinguished from the curdling of milk. Curdling is due to the casein separating out of the milk in the form of a fine precipitate of unaltered casein, this taking place under the influence of lactic acid fermentation, which removes the casein from its combination with lime salts. In the process of clotting, on the other hand, the casein is profoundly changed, and acquires new and distinctive characters. The clot consists of the solidified casein with fat entangled in its meshes. The clot gradually shrinks and becomes more tough and less easily digested. Under normal conditions this clot redissolves in the alimentary tract; but in pathological conditions, such as enfeebled states of the digestive ferments, a hard, firm, indigestible mass forms in the stomach, which proves an irritant to the whole intestinal tract, inducing pain, flatulence, diarrhcea, or constipation, and sometimes is recognisable unchanged in the faeces.

Various methods are adopted to control the density of the curd, and so improve the digestibility of milk.

(a) By reducing the proportion of casein; this is done by diluting the milk. The diluent may be simply plain water; a mixture of half and half will materially lessen the clotting. The addition of an aerated mineral water acts in two ways; firstly, by dilution, and, secondly, the aeration makes the clot more friable; potash, seltzer, soda, or Salutaris may be used. The admixture of barley-water, toast, rice, or oatmeal water is also useful; the thickened fluid hinders the formation of large curds and makes the clot more friable. Gelatine jelly, using it in the proportion of I teaspoonful to 2 ounces milk and 2 ounces of water, is also useful.

(b) By reducing the toughness of the clot, the addition of lime-water in the proportion of 1 in 3 acts in three ways on the milk. It dilutes it; the addition of lime renders some of the soluble lime salts insoluble, and so neutralises the acidity of the milk; this effects the desired result of lessening the toughness of the clot. Lime-water causes constipation, and if the patient is suffering from diarrhoea, this may be an advantage, but in other cases it is prejudicial. Sodium bicarbonate in solution (4 drams to 1 ounce) can be used in the same proportion as lime-water (1 in 3), and does not produce constipation.

The method of preparation of the diluents is as follows: -

1. Thick Barley-Water. (Barley Can Be Used Twice)

1 ounces pearl barley.

2 pints cold water.

Rind and juice of half lemon. Sugar to taste.

Method

Wash the barley well, put it into a saucepan with cold water to cover it. Bring the water to the boil, and then pour it away. Wash again with cold water, and rinse out the saucepan. (This is to blanch the barley, and if it were not done, the colour of the water would be dark.) Return the barley to the saucepan with 2 pints of cold writer and the thinly peeled rind of half a lemon. Simmer slowly for two hours, strain, sweeten, and strain in lemon juice. This is served hot or cold. Time, two hours.

Note

This is a refreshing drink, and a favourite with most invalids. The lemon juice must be omitted if it is to be used as a diluent for milk.

2. Clear Barley- Water

2 ounces pearl barley (Robinson's). 1 pint boiling water.

Rind of half a lemon. Sugar to taste.

Method

Wash barley well, and put into a jug with thinly peeled rind of a lemon and a little sugar. Pour freshly boiled boiling water on barley. Cover jug. and stand till cold. Strain, and it is ready for use.

3. Toast Water

I slice crust of bread.

1 pint cold water.

Method

The crust of bread is better than the crumb, as it does not sour so soon.

Toast well on both sides until dry and nicely browned - not burnt. Have the fresh cold water in a jug, and break the toast into pieces and put into it. (If the water is poured on to the toast it makes a thick muddy mixture.) Cover the jug, and let the toast remain soaking until the water is the colour of sherry wine.

4. Rice Water

1 tablespoonful rice.

1 quart water.

Wash the rice, then allow it to soak in a quart of water at the side of the fire for two hours, then boil for one hour, and strain.

5. Oatmeal Water

1 tablespoonful oatmeal.

1 pint water.

Mix the meal and boiling water, and then boil for one hour. Keep adding water to keep the quantity up to a pint. Strain.

6. Gelatine Jelly

Soak a teaspoonful of chopped leaf gelatine in half a pint of cold water for three hours, then stand it over boiling water until the gelatine is dissolved.

The boiling of milk does not apparently render it more easily digested. It has been found that a pint of buttermilk remains three hours, raw milk about three and a half hours, and boiled milk four hours in the stomach of a healthy man.