We can easily supply our natural deficiencies in the matter of grinding, and do so by means of our flour mills, but at first thought the idea of finding an artificial representative of the saliva of oxen does not recommend itself. When, however, it is understood that the chief active principle of the saliva so closely resembles the diastase of malt that it has received the name of ‘animal diastase,’ and is probably the same compound, the aspect of the problem changes.
Not only is this the case with the secretion from the glands surrounding the mouth, but the pancreas which is concerned in a later stage of digestion is a gland so similar to the salivary glands that in ordinary cookery both are dressed and served as ‘sweetbreads;’ the ‘pancreatic juice’ is a liquid closely resembling saliva, and contains a similar diastase, or substance that converts starch into dextrin, and from dextrin to sugar. Lehmann says, ‘It is now indubitably established that the pancreatic juice possesses this sugar-forming power in a far higher degree than the saliva.’
Besides this, there is another sugar-forming secretion, the ‘intestinal juice,’ which operates on the starch of the food as it passes along the intestinal canal.
This being the case, we should, in exercising our privilege as cooking animals, be able to assist the digestive functions of the saliva, the pancreatic and intestinal secretions, just as we help our teeth by the flour mill, and the means of doing this is offered by the diastase of malt.
In accordance with this reasoning I have made some experiments on a variety of our common vegetable foods, by simply raising them—in contact with water—to the temperature most favourable to the converting action of diastase (140° to 150° Fahrenheit), and then adding a little malt extract or malt flour.
This extract may be purchased ready made, or prepared by soaking crushed or ground malt in warm water, leaving it for an hour or two or longer, and then pressing out the liquid.
I find that oatmeal-porridge when thus treated is thinned by the conversion of the bulk of its insoluble starch into soluble dextrin; that boiled rice is similarly thinned; that a stiff jelly of arrowroot is at once rendered watery, and its conversion into dextrin is demonstrated by its altered action when a solution of iodine is added to it. It no longer becomes suddenly of a deep blue colour as when it was starch.
Sago and tapioca are similarly changed, but not so completely as arrowroot. This is evidently because they contain a little nitrogenous matter and cellulose, which, when stirred, give a milkiness to the otherwise clear and limpid solution of dextrin.
Pease-pudding when thus treated behaves very instructively. Instead of remaining as a fairly uniform paste, it partially separates into paste and clear liquid, the paste being the cellulose and vegetable casein, the liquid a solution of the dextrin or converted starch.
Mashed turnips, carrots, potatoes, &c., behave similarly, the general results showing that so far as starch is concerned there is no practical difficulty in obtaining a conversion of the starch into dextrin by means of a very small quantity of maltose.