Page:Popular Science Monthly Volume 29.djvu/77

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67
FOOD ACCESSORIES AND DIGESTION.

effect, and this superiority of champagne appears to be due to the "mechanical effects of its effervescent qualities."

The quantity of claret and hock often consumed by many persons at meals must exercise a considerable retarding effect on peptic digestion; but small quantities of these wines (and even of sherry) do not produce any appreciable retarding effect, but act as pure stimulants. These wines, then, may be taken with advantage, even by persons of feeble digestion, in small quantities, but not in large.

With regard to malt liquors, it was observed, as with wines, that they retarded peptic digestion in a degree altogether out of proportion to the amount of alcohol contained in them, and when taken in large quantities they must greatly retard the digestion, especially of farinaceous food; but a moderate quantity of light beer, when "well up," is favorable to stomach digestion.

It was proved by these experiments that the sparkling wines impede digestion less than the still ones, and when taken in moderate quantity "act not only as stimulants to the secretion of gastric juice and to the muscular activity of the viscus, but may, at the same time, slightly accelerate the speed of the chemical process in the stomach."

Next as to the influence of tea, coffee, and cocoa on the digestive processes:

Tea exerts a powerful retarding influence on salivary digestion, coffee and cocoa a comparatively feeble one.

Sir W. Roberts estimates the medium strength of the tea usually drunk at four to five per cent; strong tea may contain as much as seven per cent, weak tea as little as two per cent. Medium coffee has a strength of about seven per cent, and strong coffee twelve to fifteen per cent; cocoa, on the other hand, is generally weaker, not more than about two per cent, and this, he thinks, may be one reason why it is more suitable to persons with feeble digestions than tea or coffee.

Tea exercises a powerful inhibitory effect on salivary digestion, and this appears to be entirely due to the large quantity of tannin it contains.

It appears that tannin exists in two conditions in the tea-leaf. One, the larger portion, is in the free state, and is easily extracted by hot water; but about one fourth is fixed and remains undissolved in the fully exhausted tea-leaves. Some persons have supposed that by infusing tea for a very short time only two or three minutes—the passing of tannin into the infusion would be avoided. This is a delusion; you can no more have tea without tannin than you can have wine without alcohol. Tannin, in the free state, is one of the most soluble substances known. If you pour hot water on a little heap of tannin it dissolves like so much pounded sugar. Tea infused for two minutes was not found sensibly inferior in its retarding power on salivary digestion to tea infused for thirty minutes.

One gentleman of my acquaintance (says Sir W. Roberts) in his horror of tannin was in the habit of preparing his tea by placing the dry leaves on a paper