97. Unorganized Ferments

There is another class of ferments which is termed unorganized, and to which the general name enzym is given. These are the ferments especially important in digestion. They are merely chemical compounds which produce a peculiar effect upon certain bodies with which they come in contact. If a thin piece of lean beef be suspended in an extract from the mucous lining of a pig's stomach, to which has been added a small proportion of hydrochloric acid, the liquid being kept at about 98° F., the beef will soon begin to soften, afterwards swell to a more or less jelly-like condition, and finally dissolve. The same general result would occur with fish, blood fibrin, or the coagulated white of an egg. When starch, which is not affected by pure, warm water, is placed in a warm water solution of crushed malt, it soon dissolves, leaving a comparatively clear liquid. A chemical examination of these preparations will reveal the fact that the compounds of the meat are present in solution in somewhat modified forms, and that the starch has been changed to a sugar or other soluble bodies. In both cases substances insoluble in water have become soluble and diffusible.

The cause of these changes is the presence of typical bodies, one in the pig's stomach and one in the malt, ferments of the enzym class, the former of which renders proteins soluble, the latter acting to produce a similar result with the insoluble carbohydrates. This action is different from that of the organized ferments, where oxidation occurs in many cases. The enzyms simply induce the proteins and starch to take up the elements of water, which apparently does not greatly diminish their energy value. How this is done cannot be explained in simple terms, if at all. Our knowledge of the manner of the change rests entirely upon theoretical grounds. The digestion of food is largely accomplished through the specific effect of enzym bodies, of which every digestive fluid contains one or more. Examples of these are the pepsin and pancreatin of the drug store that contain enzyms mixed with more or less of impurities. The various enzyms are often given names according to their function: invertase, which inverts or splits sucrose; glucose, that changes any carbohydrate into glucose; lactase, that splits lactose into simpler sugars. In general, the ferments acting on starch are called diastases. Those acting on proteins to produce hydrolysis and cleavage are designated as proteolytic.