The Chemistry of Cookery

by W. Mattieu Williams

I must here throw myself into the great controversy of jackets or no jackets. Should potatoes be peeled before cooking, or should they be boiled in their jackets? I say most decidedly in jackets, and will state my reasons. From 53 to 56 per cent. of the above-stated saline constituents of the potato is potash, and potash is an important constituent of blood—so important that in Norway, where scurvy once prevailed very seriously, it has been banished since the introduction of the potato, and, according to Lang and other good authorities, this is owing to the use of potatoes by a people who formerly were insufficiently supplied with saline vegetable food.

Potash salts are freely soluble in water, and I find that the water in which potatoes have been boiled contains potash, as may be proved by boiling it down to concentrate, then filtering and adding the usual potash test, platinum chloride.

It is evident that the skin of the potato must resist this passage of the potash into the water, though it may not fully prevent it. The bursting of the skin only occurs at quite the latter stage of the cookery. The greatest practical authorities on the potato, Irishmen, appear to be unanimous. I do not remember to have seen a pre-peeled potato in Ireland. I find that I can at once detect by the difference of flavour whether a potato has been boiled with or without its jacket, and that this difference is evidently saline.

These considerations lead to another conclusion, viz. that baked potatoes and fried potatoes, or potatoes cooked in such a manner as to be eaten with their own broth, as in Irish stew (in which cases the previous peeling does no mischief), are preferable to boiled potatoes. Steamed potatoes probably lose less of their potash juices than when boiled; but this is uncertain, as the modicum of distilled water condensed upon the potato and continually renewed may wash away as much as the larger quantity of hard water in which the boiled potato is immersed.

Those who eat an abundance of fruit, of raw salads, and other vegetables supplying a sufficiency of potash to the blood, may peel and boil their potatoes; but the poor Irish peasant, who depends upon the potato for all his sustenance, requires that they shall supply him with potash.

When travelling in Ireland (I explored every county of that country rather exhaustively during three successive summers when editing the 4th edition of Murray’s ‘Handbook’), I was surprised at the absence of fruit-trees in the small farms where one might expect them to abound. On speaking of this the reason given was that all trees are the landlord’s property; that if a tenant should plant them they would suggest luxury and prosperity, and therefore a rise of rent; or otherwise stated, the tenant would be fined for thus improving the value of his holding. This was before the passing of the Land Act, which we may hope will put an end to such legalised brigandage. With the abolition of rack-renting the Irish peasant may grow and eat fruit; may even taste jam without fear and trembling; may grow rhubarb and make pies and puddings in defiance of the agent. When this is the case, his craving for potato-potash will probably diminish, and his children may actually feed on bread.

I have been told by an American lady that in the fatherland of potatoes, as well as in their adopted country, they are always boiled or steamed in their jackets: that American cooks, like those of Ireland, would consider it an outrage to cut off the protecting skin of the potato before cooking it; that they are more commonly mashed there than here, and that the mashing is done by rapidly removing the skins and throwing the stripped potato into a supplementary saucepan or other vessel, in which they may be kept hot until the preparation is completed.

As regards the nutritive value of the potato, it is well to understand that the common notion concerning its cheapness as an article of food is a fallacy. Taking Dr. Edward Smith’s figures, 760 grains of carbon and 24 grains of nitrogen are contained in 1 lb. of potatoes; 2½ lbs. of potatoes are required to supply the amount of carbon contained in 1 lb. of bread; and 3½ lbs. of potatoes are necessary for supplying the nitrogen of 1 lb. of bread. With bread at 1½d. per lb., potatoes should cost less than ½d. per lb. in order to be as cheap as bread for the hard-working man who requires an abundance of nitrogenous food.