_Arrowroot._
=Botanical Origin=—_Maranta arundinacea_[2330] L.—An herbaceous
branching plant, 4 to 6 feet high, with ovate-lanceolate, puberulous
or nearly glabrous leaves, and small white flowers, solitary or in lax
racemes. It is a native of the tropical parts of America from Mexico
to Brazil, and of the West Indian Islands; and under the slightly
different form known as _M. indica_ Tussac, it occurs in Bengal,
Java and the Philippines. This Asiatic variety is now found in the
West Indies and Tropical America, but apparently as an introduced
plant.[2331]
=History=—The history of arrowroot is comparatively recent. Passing
over some early references of French writers on the West Indies to an
_Herbe aux flèches_, which plant it is impossible to identify with
_Maranta_, we find in Sloane’s catalogue of Jamaica plants (1696),
_Canna Indica radice alba alexipharmaca_. This plant, discovered in
Dominica, was sent thence to Barbadoes and subsequently to Jamaica,
it being, says Sloane, “_very much esteemed for its alexipharmack
qualities_.” It was observed, he adds, that the native Indians used the
root of the plant with success against the poison of their arrows, “_by
only mashing and applying it to the poison’d wounds_”: and further,
that it cures the poison of the manchineel (_Hippomane Mancinella_ L.),
of the wasps of Guadaloupe, and even stops “_a begun gangreen_.”[2332]
[2330] Fig. in Bentley and Trimen’s _Med. Plants_, part 23 (1877).
[2331] We accept the opinion of Körnicke (_Monographiæ Marantaccarum
Prodromus, Bull. de la Soc. imp. des Naturalistes de Moscou_, xxxv.
1862, i.) that _Maranta arundinacea_ L. and _M. indica_ Tuss. are one
and the same species. Grisebach maintains them as distinct (_Flora
of the British West Indian Islands_, 1864, 605), allowing both to be
natives of Tropical America; but he fails to point out any important
character by which they may be distinguished from each other. According
to Miquel (_Linnæa_, xviii. 1844. 71) the plant in the herbarium of
Linnæus labelled _M. arundinacea_, is _M. indica_. We have ourselves
made arrowroot from the fresh rhizomes of _M. arundinacea_, in order
to compare it with an authentic specimen obtained in Java from _M.
indica_: no difference could be found between them.
[2332] Sloane, _Catal. plant. quæ in ins. Jamaica sponte proveniunt,
vel vulgò coluntur_, Lond. 1696. 122; also _Hist. of Jamaica_, i.
(1707) 253.
Patrick Browne (1756) notices the reputed alexipharmic virtues of
_Maranta_, which was then cultivated in many gardens in Jamaica,
and says that the root “_washed, pounded fine and bleached, makes a
fine flour and starch_”—sometimes used as food when provisions are
scarce.[2333]
Hughes, when writing of Barbadoes in 1750, describes arrowroot as a
very useful plant, the juice mixed with water and drunk being regarded
as “_a preservative against any poison of an hot nature_”; while from
the root the finest starch is made, far excelling that of wheat.[2334]
The properties of _Maranta arundinacea_ as a counter-poison are
insisted upon at some length by Lunan,[2335] who concludes his notice
of the plant by detailing the process for extracting starch from the
rhizome.
Arrowroot came into use in England about the commencement of the
present century, the supplies being obtained, as it would appear, from
Jamaica.[2336]
The statements of Sloane, which are confirmed by Browne and Lunan,
plainly indicate the origin and meaning of the word _arrowroot_, and
disprove the notion of the learned C. F. Ph. von Martius (1867) that
the name is derived from that of the Arnac or Aroaquis Indians of
South America, who call the finest sort of fecula they obtain from
the Mandioc _Aru-aru_. It is true that _Maranta arundinacea_ is known
at the present day in Brazil as _Araruta_, but the name is certainly
a corruption of the English word _arrowroot_, the plant according to
general report having been introduced.[2337]
=Manufacture=—For the production of arrowroot, the rhizomes are dug up
after the plant has attained its complete maturity, which in Georgia
is at the beginning of winter. The scales which cover them are removed
and the rhizomes washed; the latter are then ground in a mill, and
the pulp is washed on sieves, or in washing machines constructed for
the purpose, in order to remove from it the starch. This is allowed
to settle down in pure water, is then drained and finally dried with
a gentle heat. Instead of being crushed in a mill, the rhizomes are
sometimes grated to a pulp by a rasping machine.
In all stages of the process for making arrowroot, nice precautions
have to be taken to avoid contamination with dust, iron mould, insects,
or anything which can impart colour or taste to the product. The
rhizome contains about 68 per cent. of water, and yields about a fifth
of its weight of starch.[2338]
[2333] _Civil and Natural History of Jamaica_, 1756. 112. 113.
[2334] _Natural History of Barbados_, 1750. 221.
[2335] _Hortus Jamaicensis_, i. (1814) 30.
[2336] Thus in 1799 there were exported from Jamaica 24 casks and boxes
of “_Indian Arrowroot_.”—Renny, _Hist. of Jamaica_, 235.
[2337] Since the above was written, the following lines bearing on
this question have been received from Mr. Spruce:—“ ... I know not
Martius’ derivation of ‘_arrowroot_.’ On the Amazon it is called
‘_ararúta_’—plainly a corruption of the English name, and explained
by the fact that it was first cultivated, as I was told, from tubers
obtained in the East Indies.”
[2338] This was in the German colony of Blumenau in Southern
Brazil—Eberhard, _Arch. der Pharm._ 134 (1868) 257.
=Description=—Arrowroot is a brilliant white, insipid, inodorous,
powder, more or less aggregated into lumps which seldom exceed a pea in
size; when pressed it emits a slight crackling sound. It exhibits the
general properties of starch, consisting entirely of granules which are
subspherical, or broadly and irregularly egg-shaped; when seen in water
they show a distinct stratification in the form of fine concentric
rings around a small star-like hilum. They have a diameter of 5 to 7
mkm. when observed in the air or under benzol. If the water in which
they lie be cautiously heated on the object-stage of the microscope,
the tumefaction of the granules will be found to begin exactly at
70° C. Heated to 100° C. with 20 parts of distilled water, arrowroot
yields a semi-transparent jelly of somewhat earthy taste and smell.
By hydrochloric acid of sp. gr. 1·06, arrowroot is but imperfectly
dissolved at 40° C.
The specific gravity of all varieties of starch is affected by the
water which they retain at the ordinary temperature of the air.
Arrowroot after prolonged exposure to an atmosphere of average
moisture, and then kept at 100° C. till its weight was constant, was
found to have lost 13·3 per cent. of water. On subsequent exposure to
the air, it regained its former proportion of water.
Weighed in any liquid which is entirely devoid of action on starch, as
petroleum or benzol, the sp. gr. of arrowroot was found by one of us to
be 1·504; but 1·565 when the powder had been previously dried at 100° C.
=Microscopic Structure of Arrowroot and of Starch in general=—The
granules are built up of layers,—a structure which may be rendered
evident by the gradual action of chloride of calcium, chromic acid, or
an ammoniacal solution of cupric oxide. When one of these liquids in a
proper state of dilution is made to act upon starch, or when for that
purpose a liquid is chosen which does not act upon it energetically,
such as diastase, bile, pepsin, or saliva, it is easy to obtain a
residue, which according to Nägeli, is no longer capable of swelling up
in boiling water, nor is immediately turned blue by iodine, except on
the addition of sulphuric acid; but which is dissolved by ammoniacal
cupric oxide. These are the essential properties of cellulose; and
this residue has been regarded as such by Nägeli, while the dissolved
portion has been distinguished as _Granulose_ (Maschke, 1852).
C. Nägeli in his important monograph on starch[2339] has described the
action of saliva when digested with starch for a day, at a temperature
of 40° to 47° C.; he says that the residue is a skeleton, corresponding
in form to the original grain but somewhat smaller, light, and very
mobile in water. He concludes that its interstitial spaces must have
been previously filled with granulose.
This experiment, which has been repeated by one of us (F.), does not in
our opinion warrant all the inferences that Nägeli has drawn from it:
it is true that many separate parts of the grain are dissolved by the
saliva, while others have disappeared down to a mere film, and others
again have been attacked in a very irregular manner. But we cannot
agree with the statement that anything comparable to a skeleton of
the grain has been left. After longer action at a higher temperature,
which however must not exceed 65° C., a more copious dissolution of the
starch, either by saliva or by bile, takes place; but in no case is it
complete.[2340]
[2339] _Die Stärkekörner_, Zürich, 1858. 4°, also W. Nägeli,
_Stärkegruppe_, etc., Leipzig, 1874.
[2340] Further particulars on this question may be found in my paper
_Ueber Stärke und Cellulose—Archiv der Pharmacie_, 196 (1871) 7.—F. A.
F.
=Chemistry of Starch=—Its composition answers to the formula
(C₆H₁₀O₅)₂+3 OH₂, or when dried at 100° C., C₆H₁₀O₅. Musculus however
showed, in 1861, that by the action of dilute acids or of _Diastase_,
starch is resolved into _Dextrin_, C₁₂H₂₀O₁₀, and _Dextrose_, C₆H₁₂O₆,
with which decomposition, the formula, C₁₈H₃₀O₁₅, would be more
in accord. Sachsse (1877) on the other hand advocates the formula
C₃₀H₆₂O₃₁ + 12 OH₂.
Cold water is not without action on starch; if the latter be
continuously triturated with it, the filtrate, in which no particles
can be detected by the microscope, will assume a blue colour on
addition of iodine, without the formation of a precipitate. The
proportion of starch thus brought into solution is infinitely small,
and always at the expense of the integrity of the grains. It is even
probable that the solution in this case is due to the minute amount of
heat, which must of necessity be developed by the trituration.
Certain reagents capable of attacking starch act upon it in very
different ways. The action in the cold of concentrated aqueous
solutions of easily soluble neutral salts or of chloral hydrate is
remarkable. Potassium bromide or iodide, or calcium chloride for
instance, cause the grains to swell, and render them soluble in cold
water. At a certain degree of dilution a perfectly clear liquid is
formed, which at first contains neither dextrin nor sugar; it is
coloured blue, but is not precipitated by iodine water; and starch can
be thrown down from it by alcohol. This precipitate, though entirely
devoid of the structural peculiarity of starch, still exhibits some
of the leading properties of that substance; it is coloured in the
same manner by iodine, does not dissolve even when fresh in ammoniacal
cupric oxide, and after drying is insoluble in water, whether cold or
boiling. The progress of the solvent is most easily traced when calcium
chloride is used, as this salt acts more slowly than the others we have
mentioned. It leaves scarcely any perceptible residue. This fact in
our opinion militates against the notion that starch is composed of a
peculiar amylaceous substance, deposited within a skeleton of cellulose.
The remarkable action of iodine upon starch was discovered in 1814 by
Colin and Gaultier de Claubry. It is extremely different in degree,
according to the peculiar kind of starch, the proportion of iodine, and
the nature of the substance the grains are impregnated with, before or
after their treatment with iodine. The action is even entirely arrested
(no blue colour being produced) by the presence in certain proportion
of quinine, tannin, _Aqua Picis_, and of other bodies.
The combination of iodine with starch does not take place in equivalent
proportions, and is moreover easily overcome by heat. The iodine
combined with starch amounts at the utmost to 7·5 per cent. The
compound is most readily formed in the presence of water, and then
produces a deep indigo-blue. Almost all other substances capable of
penetrating starch grains, weaken the colour of the iodine compound
to violet, reddish yellow, yellow, or greenish blue. These different
shades, the production of which has been described by Nägeli with great
diffuseness, are merely the colours which belong to iodine itself in
the solid, liquid, or gaseous form. They must be referred to the fact
that the particles of iodine diffuse themselves in a peculiar but
hitherto unexplained manner within the grain or in the swollen and
dissolved starch.
=Commerce of Arrowroot=—The chief kinds of arrowroot found in commerce
are known as _Bermuda_, _St. Vincent_, and _Natal_; but that of
Jamaica and other West India Islands, of Brazil, Sierra Leone, and the
East Indies, are quoted in price-currents, at least occasionally. Of
these the Bermuda enjoys the highest reputation and commands by far
the highest price; but its good quality is shared by the arrowroot
of other localities, from which, when equally pure, it can in nowise
be distinguished. Greenish,[2341] however, points out that in Natal
arrowroot the layers (or laminæ) are more obvious than in other
varieties, although it appears that the former is also produced by
Maranta.
The importations of arrowroot into the United Kingdom during the year
1870 amounted to 21,770 cwt., value £33,063. Of this quantity the
island of St. Vincent in the West Indies furnished nearly 17,000 cwt.,
and the colony of Natal about 3000 cwt. The exports from St. Vincent
in 1874 were 2,608,100 lb, those of the Bermudas in 1876 only 45,520
lb.[2342] The shipments from the colony of Natal during the years 1866
to 1876 varied from 1,076 cwt. in 1873 to 4,305 cwt. in 1867.[2343]
[2341] _Yearbook of Pharm._ (1875) 529.
[2342] Papers relating to H.M. Colonial Possessions. Reports for
1875-76. Presented to both Houses of Parliament, July 1877. 54. 4.
[2343] Statist. Abstr. for the several Colonial and other Possessions
of the United Kingdom, 14th number, 1878. p. 60.
=Uses=—Arrowroot boiled with water or milk is a much-valued food in
the sick-room. It is also an agreeable article of diet in the form of
pudding or blancmange.
=Adulteration=—Other starches than that of _Maranta_ are occasionally
sold under the name of _Arrowroot_. Their recognition is only possible
by the aid of the microscope.
Substitutes for Arrowroot.
_Potato Starch_—This substance, known in trade as _Farina_ or _Potato
Flour_, is made from the tubers of the potato (_Solanum tuberosum_
L.) by a process analogous to that followed in the preparation of
arrowroot. It has the following characters:—examined under the
microscope, the granules are seen to be chiefly of two sorts, the first
small and spherical, the second of much larger size, often 100 mkm. in
length, having an irregularly circular, oval or egg-shaped outline,
finely marked with concentric rings round a minute inconspicuous
hilum. When heated in water, the grains swell considerably even at
60° C. Hydrochloric acid, sp. gr. 1·06, dissolves them at 40° quickly
and almost completely, the granules being no longer deposited, as in
the case of arrowroot similarly treated. The mixture of arrowroot
and hydrochloric acid is inodorous, but that of potato starch has a
peculiar though not powerful odour.
_Canna Starch, Tous-les-Mois_,[2344] _Toulema, Tolomane_—A species of
_Canna_ is cultivated in the West India Islands, especially St. Kitts,
for the sake of a peculiar starch which, since about the year 1836,
has been extracted from its rhizomes by a process similar to that
adopted in making arrowroot. The specific name of the plant is still
undetermined; it is said to agree with _Canna edulis_ Ker (_C. indica_
Ruiz et Pavon).[2345]
[2344] It is commonly stated that the name _Tous-les-mois_ was given
in consequence of the plant flowering _all the year round_. But this
explanation appears improbable: no such name is mentioned by Rochefort,
Aublet, or Descourtilz, who all describe the _Balisier_ or _Canna_. It
seems more likely that the term is the result of an attempt to confer
a meaning on an ancient name—perhaps _Touloula_, which is one of the
Carib designations for _Canna_ and _Calathea_.
[2345] Fig. in Bentley and Trimen’s _Medic. Plants_, part 8 (1876).
The starch, which bears the same name as the plant, is a dull white
powder, having a peculiar satiny or lustrous aspect, by reason of the
extraordinary magnitude of the starch granules of which it is composed.
These granules examined under the microscope are seen to be flattened
and of irregular form, as circular, oval, oblong, or oval-truncate.
The centre of the numerous concentric rings with which each granule is
marked, is usually at one end rather than in the centre of a granule.
The hilum is inconspicuous. The granules though far larger than those
of the potato, are of the same density as the smaller forms of that
starch, and, like them, float perfectly on chloroform. When heated,
they begin to burst at 72° C. Dilute hydrochloric acid acts upon them
as it does on arrowroot.
Canna starch boiled with 20 times its weight of water affords a jelly
less clear and more tenacious than that of arrowroot, yet applicable
to exactly the same purposes. The starch is but little known and not
much esteemed in Europe; it was exported in 1876 from St. Kitts to the
amount of 51,873 lb, besides 5,300 lb arrowroot starch.[2346]
_Curcuma Starch, Tikor_—The pendulous, colourless tubers of some
species of _Curcuma_, but especially of _C. angustifolia_ Roxb. and
_C. leucorrhiza_ Roxb., have long been utilized in Southern India
for the preparation of a sort of arrowroot, known by the Hindustani
name of _Tikor_, or _Tikhur_, and sometimes called by Europeans _East
Indian Arrowroot_.[2347] The granules of this substance much resemble
those of _Maranta_, but they are neither spherical nor egg-shaped.
On the contrary, they are rather to be described as flat discs, 5 to
7 mkm. thick, of elliptic or ovoid outline, sometimes truncate; many
attain a length of 60 to 70 mkm. They are always beautifully stratified
both on the face and on the edge. The hilum is generally situated at
the narrower end. We have observed that when heated in water, the
tumefaction of the grains commences at 72° C.
Curcuma starch, which in its general properties agrees with common
arrowroot, is rather extensively manufactured in Travancore, Cochin and
Canara on the south-western coast of India, but in a very rude manner.
Drury[2348] states that it is a favourite article of diet among the
natives, and that it is exported from Travancore and Madras; we can
add that it is not known as a special kind in the English market, and
that the article we have seen offered in the London drug sales as _East
Indian Arrowroot_ was the starch of _Maranta_.
[2346] Page 102 of the Reports quoted at p. 633, note 2.
[2347] Living roots of the plant used for making this arrowroot at
Cochin, have been kindly forwarded to us by A. F. Sealy, Esq. of that
place.
[2348] _Useful Plants of India_, ed. 2. 1873. 168.