ANNOT′TA. Syn. Anot′to, Annat′to, Annat′ta; Arnat′to, Arnot′to, &c.; Orlea′na, Ter′ra o.*, &c., L.; Roucol, Rocou, Roucou, Fr.; Orleans, Ger. A colouring matter forming the outer pellicle of the seeds of the bix′a orella′na (Linn.), an exogenous evergreen tree, common in Cayenne and some other parts of tropical America, and now extensively cultivated in both the E. and W. Indies. It is usually obtained by macerating the crushed seeds or seed-pods in water for several weeks, ultimately allowing the pulp to subside, which is then boiled in coppers to a stiff paste, and dried in the shade. Sometimes a little oil is added in making it up into cakes or lumps. A better method is that proposed by Leblond, in which the crushed seeds are simply exhausted by washing them in water (—? alkalised), from which the colouring matter is then precipitated by means of vinegar or lemon-juice; the precipitate being subsequently collected, and either boiled up in the ordinary manner, or drained in bags and dried, as is practised with indigo. Annotta so prepared is said to be four times as valuable as made by the old process.
Prop. Good annotta is of a brilliant red colour; brighter in the middle than on the outside; feels soft and smooth to the touch;
has a good consistence, and a strongly characteristic but not a putrid smell. It is scarcely soluble in water; freely soluble in alcohol, ether, oils, and fats, to each of which it imparts a beautiful orange colour, and in alkaline solutions which darken it; acids precipitate it of an orange red hue; strong sulphuric acid turns it blue. Its most important property is the affinity of its colouring matter for the fibres of silk, wool, and cotton.
Pur. Annotta is very frequently adulterated; indeed, nearly always so. To what extent the sophistication of annotta is carried may be judged from the statement of Mr Blyth, who says that on examination of thirty-four samples of various kinds, as imported and obtained from English makers and as purchased from dealers, he found only two that were genuine. As annotta is often used to give colour to different articles of diet, it is important that it should be as pure as possible; otherwise injurious effects detrimental to health may be caused by partaking of any food to which it is added. Now, amongst the list of adulterants given below are three, at least, unmistakeable poisons, viz. red lead, orange chrome, and sulphate of copper. It is but right to state of the first of these substances (red lead) that Mr Blyth says it is extremely doubtful whether it is now employed to the extent it formerly was. He also ascribes its presence in annotta to the impure Venetian red which is used, the employment of this colour being a necessity because of the large quantities of flour and lime which are mixed with the annotta, which thereby becomes so reduced in colour that it is essential to have recourse to salt, alkalies, and the red earths to restore it to its original standard. The adulterants are generally meal, flour, or farina, and often chalk or gypsum, with some pearlash and oil, or even soap, to give it an unctuous character; turmeric, Venetian red, red ochre, orange chrome, or even red lead, to give it ‘colour,’ and common salt, and sometimes even sulphate of copper, to prevent decomposition—the last two being poisonous. Sometimes a little carbonate of ammonia is also added to it to improve the colour. When quite pure it contains about 28% of resinous colouring matter, and 20% of colouring extractive matter (Dr John), and should leave only a small quantity of insoluble residuum after digestion in alcohol, whilst the ash resulting from its incineration should not exceed 11⁄2 to 2%. The quantity, colour, &c., of the ash will give an easy clue to the inorganic adulterants, if any are present, which may be then followed up by a chemical examination. The presence of red lead may be detected by heating it on a piece of charcoal in the reducing flame of the blowpipe, by which a small bead of metallic lead will be obtained. If it contains chalk, ochre, gypsum, &c., the undissolved residuum of the washed ash gives the amount of the adulteration (nearly).
Microscopical Examination of Annotta.—When annotta is subjected to a microscopical examination the outer red portion will be found to present an almost homogeneous appearance, whilst the surface of the seed proper will be seen to consist of narrow or elongated cells or fibres disposed in a vertical direction, while the inner white portion will be seen to be made up of cells filled with starch corpuscles, well defined, of medium size, and resembling in the elongated and stellate hilum the starch granules of the pea and bean.
When the annotta is manufactured, and an unadulterated sample is examined, but little structure is met with. Portions of the outer cells may be seen; and in those samples which in the course of their preparation have not been subjected to the action of boiling water, a few starch granules may be observed.
Since annotta, when manufactured, presents so few evidences of structure, we are easily able, with the microscope at our command, to detect the presence of most foreign vegetable substances. These consist of turmeric powder, wheat, rye and barley starch, and sago flours. The salt and alkali present in the fraudulent annotta generally greatly alter the appearance of the turmeric. Most of the colouring matter of the cells is discharged, so that the starch corpuscles contained within them become visible. Loose starch granules of turmeric may also be frequently seen, and in a much enlarged condition, owing to the action of the alkali upon them.
The following process for conducting the assay of annotta is given by Mr Blyth:—
“In order to estimate the commercial value and detect adulteration in a sample, the quickest and best way is the following: Weigh accurately a gramme in a small platinum dish; dry in the water-bath for a couple of hours, then weigh; the loss is the water. Finely powder, and digest it for some hours in alcohol; then boil, filter and treat with successive portions of alcohol until all the colouring-matter is dissolved; filter, evaporate the filtrate down and weigh; the result is the resin. The insoluble portion will in a good commercial specimen consist of woody matter, extractive, gluten, &c. For the ash weigh another gramme in a platinum dish; dry for a short time over the water-bath; then powder and burn until it ceases to lose weight. It is prudent to fuse a little on charcoal with carbonate of soda before the blow-pipe before burning it in a platinum vessel, as there may be lead in the annotta. The ash should then be submitted to the various reagents in order to detect lime, alumina, &c. A correct determination of ash and resin is all that is required to definitely pronounce upon the purity or impurity of the samples.”
The following is the analysis of a fair commercial sample:—