54 



FARMERS' REGISTER. 



[No. 1. 



Prom the Journal of the Franklin Institute. 

 DETECTION OP ADULTERATIONS IN FLOUR. 



M. Dubuc, senior, of Rouen, has applied him- 

 self with success to t ho. detection of farinaceous 

 mixtures in wheaten Hour. The principal sub- 

 stances with which (lour is adulterated are potato 

 starch, a fecula; beans, barley, chalk, plaster of 

 Paris, &c. An extract from his memoir is pub- 

 lished in the last Bulletin of the Society of En- 

 couragement, from which the following is taken. 



There are two methods of detecting adulterated 

 flour, mechanical and chemical. In Franco the 

 adulteration is principally with potato starch, as it 

 renders the bread whiter and heavier. If there be 

 more than ten per cent, of potato starch, it. may 

 be detected by the naked eye, or with the aid of a 

 magnifying "lass; the fecula is whiter, the par- 

 ticles are angular, and reflect the rays of lii^ht, 

 like minute crystals. To render the discovery 

 more easy, M. Dubuc dries the suspected flour in 

 a sand bath, at 100° to 110° of Fahrenheit; and 

 then, with a good magnifying glass, so small an 

 adulteration as five percent, may easily be de- 

 tected. 



But if the miller has boon cunning enough to 

 grind the potato starch with the wheat, other 

 moans of detection must be had recourse to. 



The first is, from the great difference between 

 the specific gravity of wheat flour and potato 

 starch. 



The second is, that Hour contains a certain per 

 centage of gluten, and the starch docs not contain 

 an atom of gluten. 



First method. — A vessel that will contain one 

 pound of flour, gently pressed down, will contain a 

 pound and a half of fecula, from these, data the 

 relative portions of Hour and fecula, in any par- 

 cel of Hour, may be easily ascertained very near 

 the truth. 



Second method. — The best flour contains about 

 twenty per cent, of gluten, and, as we have stated, 

 the starch not an atom. 



Experiment. — Take five ounces of pure wheat 

 flour, and two ounces and a half of warm water; 

 mix and work it well lor about ten minutes; the 

 paste will be firm and elastic. Lot a little warm 

 water fall continually upon it, while you continue 

 to knead it; by this moans, all the starch and sac- 

 charine mucilage will be extracted. The opera- 

 tion is finished when the water flowing from it 

 ceases to be white; what remains is gluten, the 

 weight of which will be about one ounce. If the 

 flour bo adulterated, the paste will be more liquid, 

 less cohesive, and loss elastic, and an intelligent 

 baker will soon be able to discover to what extent 

 the flour has been adulterated, from the appear- 

 ance of the paste, &c. 



Such are the mechanical means that may be 

 employed with success. 



Employment of chemical agents to discover frauds 

 in flour. — It will bo well to bear in mind, that 

 wheat flour is an annualized azotic matter, (ma- 

 ticrc animalise azot/'c,) and that, on the contrary, 

 fecula, or the starch extracted, pure from cereals, 

 is entirely of a vegetable nature: from this differ- 

 ence results the varied effects of the re-agents 

 employed. 



The three chemical tests which have boon found 

 best for general use, arc nitric and muriatic acid, 

 and the liquid nitrate of mercury, (deuto nitrate.) 



Their chemical effects on flour and fecula are as 

 follows: — 



1. Nitric acid has the property of coloringwheat 

 flour of a fine orange yellow, whereas it neither af- 

 fects the color of fecula nor starch. 



2. Pure muriatic acid colors good wheat flour of 

 a deep violet, but dissolves fecula and starch, and 

 lbrms with it a light, colorless, viscous fluid, de- 

 composable by alkalies. 



Experiments with nitric acid <f40°. — Take 100 

 grains of pure, wheat flour, pour on it 100 {trains 

 of nitric acid, (aqua fortis,) in a small earthen or 

 China cup, stirring it with a glass tube, it will 

 heat a little, and in a few hours it will change co- 

 lor from yellow to a fine orange color. 



Take 100 grains of fecula, and pour on it 100 

 grains of nitric acid; heat it in every respect the 

 same as above, but. no caloric will be evolved, and 

 the mixture will not change color. 



Take of flour 80 grains, and of fecula 20 grains, 

 and of acid 100 grains; mix well; the color will 

 now be much paler, and of a light citron color. 

 Take 50 grains of flour, and 50 grains of fecula, 

 and 100 grains of acid; mix well; the color is now 

 much paler than before, so that, with a little prac- 

 tice, the quantity of fecula may be detected by the 

 greater or less intensity of colors. 



Experiments with muriatic acid of 21° of 

 strength. — Take of wheat flour and acid, each 

 100 grains; mix well; the color will become at 

 first red, then violet, and finish by becoming of a 

 beautiful indigo color. This operation is accele- 

 rated if a gentle heat be applied. 



Take 100 grains of fecula, and 100 grains of 

 acid; the mixture, is at first of the consistency of 

 paste, and then becomes- liquid; the fecula is dis- 

 solved, and the solution colorless. 



On varying the proportions of flour and fecula, 

 wo shall soon bo able, to ascertain the. quantity of 

 fecula in a sample of suspected flour. 



Experiment in the liquid nitrate of mercury. — 

 Take of flour and nitrate each 100 grains; mix 

 well with a glass tube or rod. The paste will at 

 first be of a pale citron, then reddish, and in throe 

 hours will become a full red. The color is per- 

 manent. 



Take 100 grains each of fecula and nitrate; 

 they will not combine, nor will the color of the 

 fecula or starch be acted upon. 



By mixing flour and fecula in different propor- 

 tions, and observing the colors, we may soon be 

 able to detect the proportions in which flour is 

 adulterated by fecula or starch. 



It may also be observed, that fecula absorbs less 

 water than flour, which affords a ready means of 

 detection. 



The adulteration with bean or pea flour may be 

 detected by pouring boiling water upon it, which 

 developes the peculiar smell of these two sub- 

 stances. 



We may add, that the adulteration with chalk, 

 or gypsum, may be detected by pouring a diluted 

 acid on the suspected flour, as an effervescence 

 will take place, and carbonic acid gas be disen- 

 craeed.* 



* There will be no eirervescence from adding acid 

 to gypsum (if it is pure,) and therefore this as a test 

 for gypsum, is worthless.— Ed. Far. Reg. 



