The Chemistry of CookeryWilliams, W. Mattieu (William Mattieu)
Science
The Chemistry of Cookery
Williams, W. Mattieu (William Mattieu)
Cooking
Serious consequences have resulted from ignorance of this. The popular
notion that anything which thickens to a jelly when cooked must be
proportionally nutritious is very fallacious, and many a victim has
died of starvation by the reliance of nurses on this theory, and
consequently feeding an emaciated invalid on mere starch in the form of
arrowroot, &c. The selling of a fancy variety at ten times its proper
value has greatly aided this delusion, so many believing that whatever
is dear must be good. I remember when oysters were retailed in London
at fourpence per dozen. They were not then supposed to be exceptionally
nutritious, were not prescribed by fashionable physicians to invalids,
as they have been lately, since their price has risen to threepence
each.
More than half a century has elapsed since Dr. Beaumont published the
results of his experiments on Alexis St. Martin. These showed that
fresh raw oysters required 2 hours 55 minutes, and stewed fresh oysters
3½ hours for digestion, against 1 hour for boiled tripe and 3 hours for
roast or boiled beef or mutton. Oysters contain more than 80 per cent.
of water, and are, weight for weight, far less nutritious than beef or
mutton; less than the easily digestible tripe. But tripe is cheap and
vulgar, therefore kitchenmaids, footmen, and fashionable physicians
despise it.
The change which takes place in the cookery of starch may, I think, be
described as simple hydration, or union with water; not that definite
chemical combination which may be expressed in terms of chemical
equivalents, but a sort of hydration of which we have so many other
examples, where something unites with water in any quantity, the union
being accompanied with an evolution of some amount of heat. Striking
illustrations of this are presented on placing a piece of hydrated
soda or potash in water, or mixing sulphuric acid, already combined
chemically with an equivalent of water, with more water. Here we
have aqueous adhesion and considerable evolution of heat, without
the definitive quantitative chemical combination demanded by atomic
theories.
In the experiment above described for separating the starch from wheat
flour, the starch thus liberated sinks to the bottom of the water and
remains there undissolved. The same occurs if arrowroot be thrown into
water. This insolubility is not entirely due to the intervention of the
envelope of the granules, as may be shown by crushing the granules,
_while dry_, and then dropping them into water. Such a mixture of
starch and cold water remains unchanged for a long time—Miller says ‘an
indefinite time.’
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