THE COOKERY OF VEGETABLES.
MY readers will remember that I referred to Haller’s statement,
‘Dimidium corporis humani gluten est,’ which applies to animals
generally, viz. that half of their substance is gelatin, or that which
by cookery becomes gelatin. This abundance depends upon the fact that
the walls of the cells and the frame-work of the tissues are composed
of this material.
In the vegetable structure we encounter a close analogy to this.
Cellular structure is still more clearly defined than in the animal, as
may be easily seen with the help of a very moderate microscopic power.
Pluck one of the fibrils that you see shooting down into the water
of hyacinth glasses, or, failing one of these, any other succulent
rootlet. Crush it between two pieces of glass and examine. At the end
there is a loose spongy mass of rounded cells; these merge into oblong
rectangular cells surrounding a central axis of spiral tube or tubes
or greatly elongated cell structure. Take a thin slice of stem, or
leaf, or flower, or bark, or pith, examine in like manner, and cellular
structure of some kind will display itself, clearly demonstrating
that whatever may be the contents of these round, oval, hexagonal,
oblong, or otherwise regular or irregular cells, we cannot cook and
eat any whole vegetable, or slice of vegetable, without encountering
a large quantity of cell wall. It constitutes far more than half of
the substance of most vegetables, and therefore demands prominent
consideration.
It exists in many forms with widely differing physical properties, but
with very little variation in chemical composition, so little that
in many chemical treatises cellular tissue, cellulose, lignin, and
woody fibre are treated as chemically synonymous. Thus, Miller says:
‘Cellular tissue forms the groundwork of every plant, and when obtained
in a pure state, its composition is the same, whatever may have been
the nature of the plants which furnished it, though it may vary greatly
in appearance and physical characters; thus, it is loose and spongy in
the succulent shoots of germinating seeds, and in the roots of plants,
such as the turnip and the potato; it is porous and elastic in the pith
of the rush and the elder; it is flexible and tenacious in the fibres
of hemp and flax; it is compact in the branches and wood of growing
trees; and becomes very hard and dense in the shells of the filbert,
the peach, the cocoanut, and the _Phytelephas_ or vegetable ivory.’
Its composition in all these cases is that of a _carbo-hydrate_, _i.e._
carbon united with the elements of water, which, by the way, should
not be confounded with a _hydro-carbon_, or compound of carbon with
hydrogen simply, such as petroleum, fats, essential oils, and resins.
There is, however, some little chemical difference between wooden
tissue and the pure cellulose that we have in finely carded cotton, in
linen, and pure paper pulp, such as is used in making the filtering
paper for chemical laboratories, which burns without leaving a
weighable quantity of ash. The woody forms of cellular tissue owe
their characteristic properties to an incrustration of _lignin_, which
is often described as synonymous with cellulose, but is not so. It
is composed of carbon, oxygen, and hydrogen, like cellulose, but the
hydrogen is in excess of the proportion required to form water by
combination with the oxygen.
My own view of the composition of this incrustation (lignin properly
is called) is that it consists of a carbo-hydrate united with a
hydro-carbon, the latter having a resinous character; but whether the
hydro-carbon is chemically combined with the carbo-hydrate (the resin
with the cellulose), or whether the resin only mechanically envelopes
and indurates the cellulose I will not venture to decide, though I
incline to the latter theory.
As we shall presently see, this view of the constitution of the
indurated forms of cellular tissue has an important practical bearing
upon my present subject. To indicate this in advance, I will put it
grossly as opening the question of whether a very great refinement of
scientific cookery may or may not enable us to convert nutshells, wood
shavings, and sawdust into wholesome and digestible food. I have no
doubt whatever that it may.
It could be done at once if the incrusting resinous matter were
removed; for pure cellulose in the form of cotton and linen rags
has been converted into sugar artificially in the laboratory of the
chemist; and in the ripening of fruits such conversion is effected on
a large scale in the laboratory of nature. A Jersey pear, for example,
when full grown in autumn is little better than a lump of acidulated
wood. Left hanging on the leafless tree, or gathered and carefully
stored for two or three months, it becomes by nature’s own unaided
cookery the most delicious and delicate pulp that can be tasted or
imagined.
Certain animals have a remarkable power of digesting ligneous tissue.
The beaver is an example of this. The whole of its stomach, and more
especially that secondary stomach the _cæcum_, is often found crammed
or plugged with fragments of wood and bark. I have opened the crops of
several Norwegian ptarmigans, and found them filled with no other food
than the needles of pines, upon which they evidently feed during the
winter. The birds, when cooked, were scarcely eatable on account of the
strong resinous flavour of their flesh.
If my theory of the constitution of such woody tissues is correct,
these animals only require the power of secreting some solvent for
the resin, on the removal of which their food would consist of the
same material as the tissue of the succulent stems and leaves eaten by
ordinary herbivorous animals. The resinous flavour of the flesh of the
ptarmigan indicates such solution of resin.
I may here, by the way, correct the commonly accepted version of a
popular story. We are told that when Marie Antoinette was informed of a
famine in the neighbourhood of the Tyrol, and of the starving of some
of the peasants there, she replied, ‘I would rather eat pie-crust’
(some of the story-tellers say ‘pastry’) ‘than starve.’ Thereupon the
courtiers giggled at the ignorance of the pampered princess, who could
suppose that starving peasants had such an alternative food as pastry.
The ignorance, however, was all on the side of the courtiers and those
who repeat the story in its ordinary form. The princess was the only
person in the Court who really understood the habits of the peasants
of the particular district in question. They cook their meat, chiefly
young veal, by rolling it in a kind of dough made of sawdust mixed
with as little coarse flour as will hold it together; then place this
in an oven or in wood embers until the dough is hardened to a tough
crust, and the meat is raised throughout to the cooking point. Marie
Antoinette said that she would rather eat _croûtons_ than starve,
knowing that these _croûtons_, or meat pie-crusts, are given to the
pigs; that the pigs digest them, and are nourished by them in spite of
the wood sawdust.
When on the subject of cooking animal food, I had to define the cooking
temperature as determined by that at which albumen coagulates, and to
point out the mischief arising from exceeding that temperature and thus
rendering the albumen horny and indigestible.
No such precautions are demanded in the boiling of vegetables. The
work to be done in cooking a cabbage or a turnip, for example, is to
soften the cellular tissue by the action of hot water; there is nothing
to avoid in the direction of over-heating. Even if the water could be
raised above 212°, the vegetable would be rather improved than injured
thereby.
The question that now naturally arises is whether modern science can
show us that anything more can be done in the preparation of vegetable
tissue than the mere softening in boiling water. I have already said
that the practice of using the digestive apparatus of sheep, oxen, &c.,
for the preparation of our food is merely a transitory barbarism, to be
ultimately superseded by scientific cookery, by preparing vegetables
in such a manner that they shall be as easily digested as the prepared
grass we call beef and mutton. I do not mean by this that the vegetable
we should use shall be grass itself, or that grass should be one of
the vegetables. We must, for our requirement, select vegetables that
contain as much nutriment in a given bulk as our present mixed diet,
but in doing so we encounter the serious difficulty of finding that the
readily soluble cell wall or main bulk of animal food—the gelatin—is
replaced in the vegetable by the cellulose, or woody fibre, which is
not only more difficult of solution, but is not nitrogenous, is only a
compound of carbon, oxygen, and hydrogen.
Next to the enveloping tissue, the most abundant constituent of the
vegetables we use as food is starch. Laundry associations may render
the Latin name ‘_fecula_’, or ‘_farina_’, more agreeable when applied
to food. We feed very largely on starch, and take it in a multitude
of forms. Excluding water, it constitutes above three-fourths of our
‘staff of life,’ a still larger proportion of rice, which is the
staff of Oriental life, and nearly the whole of arrowroot, sago, and
tapioca, which may be described as composed of starch and water. Peas,
beans, and every kind of seed and grain contain it in preponderating
proportions; potatoes the same, and even those vegetables which we eat
raw, all contain within their cells considerable quantities of starch.
Take a small piece of dough, made in the usual manner by moistening
wheat flour, put it in a piece of muslin and work it with the fingers
under water. The water becomes milky, and the milkiness is seen to be
produced by minute granules that sink to the bottom when the agitation
of the water ceases. These are starch granules. They may be obtained by
similar treatment of other kinds of flour. Viewed under a microscope
they are seen to be ovoid particles with peculiar concentric markings
that I must not tarry to describe. The form and size of these granules
vary according to the plant from which they are derived, but the
chemical composition is in all cases the same, excepting, perhaps, that
the amount of water associated with the actual starch varies, producing
some small differences of density or other physical variations.
Arrowroot may be taken as an example. To the chemist arrowroot is
starch in as pure a form as can be found in nature, and he applies
this description to all kinds of arrowroot; but, looking at the ‘price
current’ in the ‘Grocer’ of the current week, November 22, 1884,
I find under the first item, which is ‘Arrowroot,’ the following:
‘Bermuda, per lb. 10_d._ to 1_s._ 5_d._;’ ‘St. Vincent and Natal,
1¼_d._ to 7¼_d._;’ and this is a fair example of the usual differences
of price of this commodity. Five farthings to 53 farthings is a wide
range, and should express a wide difference of quality. I have on
several occasions, at long intervals apart, obtained samples of the
highest-priced Bermuda, and even ‘Missionary’ arrowroot, supposed to
be perfect, brought home by immaculate missionaries themselves, and
therefore worth 3_s._ 6_d._ per lb., and have compared this with the
‘St. Vincent and Natal.’ I find that the only difference is that on
boiling in a given quantity of water the Bermuda produces a somewhat
stiffer jelly, the which additional tenacity is easily obtainable by
using a little more of the 1½_d._ (or say 3_d._ to allow a profit on
retailing) to the same quantity of water. Both are starch, and starch
is neither more nor less than starch, unless it be that the best
Bermuda, sold at 3_s._ per lb., is starch _plus_ humbug.[15]
The ultimate chemical composition of starch is the same as that
of cellulose—carbon and the elements of water, and in the same
proportions; but the difference of chemical and physical properties
indicates some difference in the arrangement of these elements. It
would be quite out of place here to discuss the theories of molecular
constitution which such differences have suggested, especially as they
are all rather cloudy. The percentage is—carbon 44·4, oxygen 49·4,
and hydrogen 6·2. The difference between starch and cellulose that
most closely affects my present subject, that of digestibility, is
considerable. The ordinary food-forms of starch, such as arrowroot,
tapioca, rice, &c., are among the most easily digestible kinds of food,
while cellulose is peculiarly difficult of digestion; in its crude and
compact forms it is quite indigestible by human digestive apparatus.
Neither of them are capable of sustaining life alone; they contain none
of the nitrogenous material required for building up muscle, nerve, and
other animal tissue. They may be converted into fat, and may supply
fuel for maintaining animal heat, and may possibly supply some of the
energies demanded for organic work.
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.’
When heated to a little above 140° Fahr., an absorption of water takes
place through the enveloping membrane of the granules, they swell
considerably, and the mixture becomes pasty or viscous. If this paste
be largely diluted with water, the swollen granules still remain as
separate bodies and slowly sink, though a considerable exosmosis of the
true starch has occurred, as shown by the thickening of the water. I
suppose that in their original state the enveloping membrane is much
folded, and that these folds form the curious marking of concentric
rings which constitutes the characteristic microscopic structure of
starch granules, and that when cooked, at the temperature named, the
very delicate membrane becomes fully distended by the increased bulk of
the hydrated and diluted starch, and thus the rings disappear.
A very little mechanical violence, mere stirring, now breaks up these
distended granules, and we obtain the starch paste so well known to the
laundress, and to all who have seen cooked arrowroot. If this paste be
dried by evaporation it does not regain its former insolubility, but
readily dissolves in hot or cold water. This is what I should describe
as cooked starch.
If the heat is now raised from 140° to the boiling point, and the
boiling continued, the gelatinous mass becomes thicker and thicker;
and if there are more than fifty parts of water to one of starch a
separation takes place, the starch settling down with its fifty parts
of water, the excess of water standing above it. Carefully dried starch
may be heated to above 300° without becoming soluble, but at 400° a
remarkable change commences. The same occurs to ordinary commercial
starch at 320°, the difference evidently depending on the water
retained by it. If the heat is continued a little beyond this it is
converted into _dextrin_, otherwise named ‘British gum,’ ‘gommeline,’
‘starch gum,’ and ‘Alsace gum,’ from its resemblance to gum-arabic,
for which it is now very extensively substituted. Solutions of this in
bottles are sold in the stationers’ shops under various names for desk
uses.
The remarkable feature of this conversion of starch into dextrin is,
that it is accompanied by no change of chemical composition. Starch
is composed of six equivalents of carbon, ten of hydrogen, and five
of oxygen—C_{6}H_{10}O_{5}, _i.e._ six of carbon and five of water or
its elements. Dextrin has exactly the same composition; so also has
gum-arabic when purified. But their properties differ considerably.
Starch, as everybody knows, when dried is white and opaque and
pulverent; dextrin, similarly dried, is transparent and brittle;
gum-arabic the same. If a piece of starch, or a solution of starch, is
touched by a solution of iodine, it becomes blue almost to blackness,
if the solution is strong; no such change occurs when the iodine
solution is added to dextrin or gum. A solution of dextrin when mixed
with potash changes to a rich blue colour when a little sulphate of
copper is added; no such effect is produced by gum-arabic, and thus
we have an easy test for distinguishing between true and fictitious
gum-arabic.
The technical name for describing this persistence of composition with
changes of properties is _isomerism_, and bodies thus related are said
to be _isomeric_ with each other. Another distinguishing characteristic
of dextrin is that it produces a right-handed rotation on a ray of
polarised light, hence its name, from _dexter_, the right.
The conversion of starch into dextrin is a very important element of
the subject of vegetable cooking, inasmuch as starch food cannot be
assimilated until this conversion has taken place, either before or
after we eat it. I will therefore describe other methods by which this
change may be effected.
If starch be boiled in a dilute solution of almost any acid, it is
converted into dextrin. A solution containing less than one per cent.
of sulphuric or nitric acid is sufficiently strong for this purpose.
One method of commercial manufacture (Payen’s) is to moisten 10 parts
of starch with 3 of water, containing 1/150th of its weight of nitric
acid, spreading the paste upon shelves, allowing it to dry in the air,
and then heating it for an hour-and-a-half at about 240° Fahr.
But the most remarkable and interesting agent in effecting this
conversion is _diastase_. It is one of those mysterious compounds which
have received the general name of ‘ferments.’ They are disturbers of
chemical peace, molecular agitators that initiate chemical revolutions,
which may be beneficent or very mischievous. The morbific matter of
contagious diseases, the venom of snake-bite, and a multitude of other
poisons, are ferments. Yeast is a familiar example of a ferment, and
one that is the best understood.
I must not be tempted into a dissertation on this subject, but may
merely remark that modern research indicates that many of these
ferments are microscopic creatures, linking the vegetable with the
animal world; they may be described as living things, seeing that they
grow from germs and generate other germs that produce their like. Where
this is proven, we can understand how a minute germ may, by falling
upon suitable nourishment, increase and multiply, and thus effect upon
large quantities of matter the chemical revolution above named.
I have already described the action of rennet upon milk, and the very
small quantity which produces coagulation. There appears to be no
intercession of living microbia in this case, nor have any been yet
demonstrated to constitute the ferment of diastase, though they may be
suspected. Be this as it may, diastase is a most beneficent ferment. It
communicates to the infant plant its first breath of active life, and
operates in the very first stage of animal digestion.
In a grain of wheat, for example, the embryo is surrounded with its
first food. While the seed remains dry above ground there is no
assimilation of the insoluble starch or gluten, no growth, nor other
sign of life. But when the seed is moistened and warmed, the starch
is changed to dextrin by the action of diastase, and the dextrin is
further converted into sugar. The food of the germ thus gradually
rendered soluble penetrates its tissues; it is thereby fed and grows,
unfolds its first leaf upwards, throws downward its first rootlet,
still feeding on the converted starch until it has developed the organs
by which it can feed on the carbonic acid of the air and the soluble
minerals of the soil. But for the original insolubility of the starch
it would be washed away into the soil, and wasted ere the germ could
absorb it.
The maltster, by artificial heat and moisture, hastens this formation
of dextrin and sugar; then by a roasting heat kills the baby plant just
as it is breaking through the seed-sheath. Blue Ribbon orators miss a
point in failing to notice this. It would be quite in their line to
denounce with scathing eloquence such heartless infanticide.
Diastase may be obtained by simply grinding freshly germinated barley
or malt, moistening it with half its weight of warm water, allowing it
to stand, and then pressing out the liquid. One part of diastase is
sufficient to convert 2,000 parts of starch into dextrin, and from
dextrin to sugar, if the action is continued. The most favourable
temperature for this is 140° Fahr. The action ceases if the temperature
be raised to the boiling point.
The starch which we take so abundantly as food appears to have no
more food-value to us than to the vegetable germ until the conversion
into dextrin or sugar is effected. From what I have already stated
concerning the action of heat upon starch, it is evident that this
conversion is more or less effected in some processes of cookery. In
the baking of bread an incipient conversion probably occurs throughout
the loaf, while in the crust it is carried so far as to completely
change most of the starch into dextrin, and some into sugar. Those
of us who can remember our bread-and-milk may not have forgotten the
gummy character of the crust when soaked. This may be felt by simply
moistening a piece of crust in hot water and rubbing it between the
fingers. A certain degree of sweetness may also be detected, though
disguised by the bitterness of the caramel, which is also there.
The final conversion of starch food into dextrin and sugar is effected
in the course of digestion, especially, as already stated, in the first
stage—that of insalivation. Saliva contains a kind of diastase, which
has received the name of _salivary diastase_ and _mucin_. It does not
appear to be exactly the same substance as vegetable diastase, though
its action is similar. It is most abundantly secreted by herbivorous
animals, especially by ruminating animals. Its comparative deficiency
in carnivorous animals is shown by the fact that if vegetable matter is
mixed with their food, starch passes through them unaltered.
Some time is required for the conversion of the starch by this animal
diastase, and in some animals there is a special laboratory or kitchen
for effecting this preliminary cookery of vegetable food. Ruminating
animals have a special stomach cavity for this purpose in which the
food, after mastication, is held for some time and kept warm before
passing into the cavity which secretes the gastric juice. The crop of
grain-eating birds appears to perform a similar function. It is there
mixed with a secretion corresponding to saliva, and is thus partially
malted—in this case _before_ mastication in the gizzard.
At a later stage of digestion, the starch that has escaped conversion
by the saliva is again subjected to the action of animal diastase
contained in the pancreatic juice, which is very similar to saliva.
It is a fair inference from these facts that creatures like ourselves,
who are not provided with a crop or compound stomach, and manifestly
secrete less saliva than horses or other grain-munching animals,
require some preliminary assistance when we adopt graminivorous habits;
and one part of the business of cookery is to supply such preliminary
treatment to the oats, barley, wheat, maize, peas, beans, &c., which we
cultivate and use for food.
I may add that the stomach itself appears to do very little, possibly
nothing, towards the digestion of starch. The primary conversion into
dextrin is effected by the saliva, and the subsequent digestion of this
takes place in the duodenum and following portions of the intestinal
canal. This applies equally to the less easily digested material of the
vegetable tissue described in the preceding chapter. Hence the greater
length of the intestinal canal in herbivorous animals as compared with
the carnivora.
Having described the changes effected by heat upon starch, and referred
to its further conversion into dextrin and sugar, I will now take some
practical examples of the cookery of starch foods, beginning with those
which are composed of pure, or nearly pure, starch.
When arrowroot is merely stirred in cold water, it sinks to the bottom
undissolved and unaltered. When cooked in the usual manner to form the
well-known mucilaginous or jelly-like food, the change is a simple case
of the swelling and breaking up of the granules already described as
occurring in water at the temperature of 140° Fahr. There appears to be
no reason for limiting the temperature, as the same action takes place
from 140° upwards to the boiling point of water.
I may here mention a peculiarity of another form of nearly pure starch
food, viz. tapioca, which is obtained by pulping and washing out
the starch granules of the root of the _Manihot_, then heating the
washed starch in pans, and stirring it while hot with iron or wooden
paddles. This cooks and breaks up the granules, and agglutinates the
starch into nodules which, as Mr. James Collins explains (‘Journal of
Society of Arts,’ March 14, 1884), are thereby coated with dextrin, to
which gummy coating some of the peculiarities of tapioca pudding are
attributable. It is a curious fact that this _Manihot_ root, from which
our harmless tapioca is obtained, is terribly poisonous. The plant is
one of the large family of nauseous spurgeworts (_Euphorbiaceæ_). The
poison resides in the milky juice surrounding the starch granules, but
being both soluble in water and volatile, most of it is washed away
in separating the starch granules, and any that remains after washing
is driven off by the heating and stirring, which has to reach 240° in
order to effect the changes above described.
I suspect that the difference between the forms of tapioca and
arrowroot has arisen from the necessity of thus driving off the last
traces of the poison, with which the aboriginal manufacturers are
so well acquainted as to combine the industry of poisoning their
arrows with that of extracting the starch-food from the same root.
No certificate from the public analyst is demanded to establish the
absence of the poison from any given sample of tapioca, as the juice of
the Manihot root, like that of other spurges, is unmistakably acrid and
nauseous.
Sago, which is a starch obtained from the pith of the stem of the
sago-palm and other plants, is prepared in grains like tapioca, with
similar results. Both sago and tapioca contain a little gluten, and
therefore have more food-value than arrowroot.
The most familiar of our starch foods is the potato. I place it
among the starch foods as next to water; starch is its prevailing
constituent, as the following statement of average compositions will
show: Water, 75 per cent.; starch, 18·8; nitrogenous materials, 2;
sugar, 3; fat, 0·2; salts, 1. The salts vary considerably with the kind
and age of the potato, from 0·8 to 1·3 in full-grown. Young potatoes
contain more. In boiling potatoes, the change effected appears to
be simply a breaking up or bursting of the starch granules, and a
conversion of the nitrogenous gluten into a more soluble form, probably
by a certain degree of hydration. As we all know, there are great
differences among potatoes; some are waxy, others floury; and these,
again, vary according to the manner and degree of cooking. I cannot
find any published account of the chemistry of these differences, and
must, therefore, endeavour to explain them in my own way.
As an experiment, take two potatoes of the floury kind; boil or steam
them together until they are just softened throughout, or, as we say,
‘well done.’ Now leave one of them in the saucepan or steamer, and
very much over-cook it. Its floury character will have disappeared,
it will have become soft and gummy. The reader can explain this by
simply remembering what has already been explained concerning the
formation of dextrin. It is due to the conversion of some of the
starch into dextrin. My explanation of the difference between the
waxy and floury potato is that the latter is so constituted that
all the starch granules may be disintegrated by heat in the manner
already described before any considerable proportion of the starch is
converted into dextrin, while the starch of the waxy potatoes for some
reason, probably a larger supply of diastase, is so much more readily
convertible into dextrin, that a considerable proportion becomes gummy
before the whole of the granules are broken up, _i.e._ before the
potato is cooked or softened throughout.
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 1½_d._ per lb., potatoes
should cost less than ½_d._ per lb. in order to be as cheap as bread
for the hard-working man who requires an abundance of nitrogenous food.
Potatoes contain 17 per cent. of carbon; oatmeal has 73 per cent.
Taking nitrogenous matter also into consideration, 1 lb. of oatmeal is
worth 6 lbs. of potatoes.
My own observations in Ireland have fully convinced me of the wisdom
of William Cobbett’s denunciation of the potato as a staple article of
food. The bulk that has to be eaten, and is eaten, in order to sustain
life, converts the potato feeder into a mere assimilating machine
during a largo part of the day, and renders him unfit for any kind of
vigorous mental or bodily exertion. If I were the autocratic Czar of
Ireland, my first step towards the regeneration of the Irish people
would be the introduction, acclimatising, and dissemination of the
Colorado beetle, in order to produce a complete and permanent potato
famine. The effect of potato feeding may be studied by watching the
work of a potato-fed Irish mower or reaper who comes across to work
upon an English farm where the harvestmen are fed in the farmhouse and
the supply of beer is not excessive. The improvement of his working
powers after two or three weeks of English feeding is comparable to
that of a horse when fed upon corn, beans, and hay, after feeding for a
year on grass only.
My strictures on the potato do not apply to them as used in England,
where the prevailing vice of our ordinary diet is that it is too
carnivorous. The potatoes we eat with our meat serve to dilute it, and
supply the farinaceous element in which flesh is deficient.
The reader may have observed that most of the starch foods are derived
from the roots or stems of plants. Many others are used in tropical
climates where little labour is demanded or done, and, therefore, but
little nitrogenous food required.
FOOTNOTE:
[15] In fairness to retailers I should state that the price of
arrowroot just now is unusually low; the ordinary range is from
twopence to two shillings. People who are afraid of having their
arrowroot adulterated should ask themselves what can be used to cheapen
the St. Vincent at the above-quoted prices, which are those of the
unquestionably genuine article.