BREAD

(brĕd). Syn. Pa′nis , L.; Pain , Fr.; Brod , Ger.; Brood , Dut.; Bröd , Dan., Swed.; Breod , Sax. Loaves or cakes made from ground corn, and constituting the staple article of food of all civilised nations. This important article of food is made of the flour of different cereal grains, but only those that contain gluten admit of conversion into light or spongy bread. In this respect wheat-flour is superior to all others. When this flour is made into a paste or dough with water, and the dough, previous to baking, is left for some time in a moderately warm place, a state of fermentation comes on, owing to the sugar of the flour gradually undergoing the proce of conversion into alcohol, in every respect similar to that which takes place during the fermentation of wine and beer. In this proce a large quantity of carbonic acid gas is liberated, and the toughne of the dough preventing its escape, the whole ma becomes puffed up and spongy, and a light porous paste is formed, the porosity of which is still further increased by the heat of the oven. The natural proce of fermenting the dough just described is, however, tedious and uncertain, whilst the dough has a tendency to run into the acetous fermentation, and to acquire a sour and disagreeable taste, by which it is rendered le nutritious and le easy of digestion. This has led to the use of a ferment which produces a similar condition more speedily, and with greater certainty. Leaven or dough was originally employed for this purpose, and the bread so made was hence called LEAVENED BREAD . At the present time barm or yeast is almost universally used for this purpose. All that is e ential to make a loaf of bread is to add a proper quantity of yeast to the dough, and to allow it to remain for a short time in a warm place, and as soon as it rises or becomes spongy, to subject it to the proce of baking. In preparing his dough, the modern baker takes a part of the water needed for the batch, and having rendered it tepid or lukewarm (80° to 90° Fahr.) by the addition of boiling water, di olves his salt in it, and adds the yeast, together with a portion of the flour. With these he forms a thin dough, which he sets aside in a moderately warm place provided for the purpose, and technically called the ‘kneading trough,’ ‘prover,’ or ‘tryer,’ where it soon begins to ferment and swell up. This proce is called ‘setting the sponge,’ and according to the proportion the water in it bears to the whole quantity that is to be used, it receives the name of ‘whole,’ ‘half,’ or ‘quarter sponge.’ Here the sponge heaves and swells, and ultimately the surface bursts and subsides, and if not checked swells again and again in a similar manner and would continue to do so until the whole of the ‘saccharine matter’ was destroyed, and the dough had become sour. The baker is careful, however, to stop it before it has communicated a sourne to the ma . After the first, or, at the furthest, after the second or third ‘dropping of the sponge,’ he adds the remaining quantity of flour, water, and salt, nece ary to form the ‘batch,’ and then kneads the whole until it becomes sufficiently tough and elastic to bear the pre ure of the hand without adhering to it. The ‘dough’ is now left to itself for a few hours, during which the fermentation still goes on. The inflated ma is then again kneaded, cut into pieces, weighed, and shaped into loaves. In an hour or two these unbaked loaves swell up to nearly double their former size, and are then placed in the oven and baked. During this operation they continue for a time to increase in size, in consequence of the dilation of the pent-up gas by the heat. At length the fermentation is checked, and the dough becomes too solid to admit of further alteration. Such are the principles and practice of the art of baking. The operations are precisely the same on both the small and the large scale, and therefore need not be separately described. The kneading of the dough by hand is not only a very laborious proce , but it is unhealthy and additionally objectionable on account of its being uncleanly. Added to this, the uniform quality of the dough is not to be depended upon. Although it is impo ible to perform by machinery any labour which absolutely requires the touch of the human hand, bread-kneading machines have been introduced wherever the making of only one and the same kind of bread is required. Amongst the numerous kinds of machines devised for bread-making, is Clayton’s. ( See cut. ) The constituents of the dough are placed in the cylinder, A , mounted in the framework, b b , and provided with hollow axles, c and d , turning in their bearings at e . The interior of the cylinder is fitted with the framework, f , which may be made to revolve by the aid of the axles, g and h . The two halves of this framework are connected together by the diagonal knives i , i , which, when the machinery revolves, work up the dough; the trough or outer cylinder revolves in the opposite direction to the revolution of the framework. The crank, o , is connected with the axle of the trough or outer cylinder, the crank, p , with that of the inner framework; as the two cranks are turned in opposite directions, they impart opposite movements to trough and framework. The revolving of the machinery may be performed by one man by the aid of one crank, since the axle, h , of the crank, o , which is fitted to the inner frame by means of the hollow axle-tree, and revolves along with it, carries a conically shaped wheel, m , fitted to the wheel k , which, being connected with l , causes the trough also to revolve; when therefore the wheel m turns towards the right, the wheel t will revolve towards the left. Another kneading machine is that of Mr Stevens. It is employed at the Holborn Union, where more than 5000 lbs. of bread are made every week by one man and two boys. IMG:596405606043057898_i358.png: Adult. The adulteration of both flour and bread is carried to a fearful extent, more especially in London. The baker’s flour is very often made of the worst kinds of damaged foreign wheat; and other cereal grains, and particularly beans, are mixed with them in grinding them into flour. In this capital no fewer than six distinct kinds of wheaten flour are brought into the market—fine flour, seconds, middlings, fine middlings, coarse middlings, and twenty-penny flour. Among the principal substances which have been proved to have been used to adulterate wheat-flour and bread are the following:— | ** | Alum. | | * | Ammonia (Sesquicarbonate). | | ** | Beans. | | * | Bone dust. | | * | Chalk. | | Clay. | | Copper (Sulphate). | | Lime (Sulphate from the soda water makers). | | * | Magnesia (Carbonate). | | * | Plaster of Paris. | | * | Potash (Carbonate and bicarbonate). | | ** | Potatoes. | | ** | Rice. | | ** | Soda (Carbonate and sesquicarbonate). | | * | Starch (Potato). | | ** | Water (in exce ). | | Zinc (Sulphate). | Of these substances, those marked thus (*) are very frequently used; and those marked thus (**) almost universally so. In the absence of chemical analysis the unalumed loaf may be roughly distinguished from the alumed one by the following characteristics: it is neither so white, so bulky, nor so symmetrical; it bites shorter, and it is free from the sour taste which accompanies the presence of alum. Again, unalumed bread a day or two old will be found to crumble with great readine ; alumed bread, however old, crumbles, on the contrary, with difficulty. According to Mr Accum, the smallest quantity of alum that can be employed with effect to produce white, light, and porous bread, from the inferior kinds of flour commonly used by the bakers, is from 3 to 4 oz. to a sack of flour weighing 280 lbs. But Dr P. Markham states that the ordinary bread of the London baker is made of one sack or 5 bushels of flour; 8 oz. of alum; 4 lbs. of salt; 1 ⁄ 2 gall. of yeast; and about 3 galls. of water. Our own analyses, extending to many hundred samples of London bread, as well as those of other chemists, show that even this large quantity of alum is often very much exceeded by the bakers. Alkaline substances, as the carbonates of ammonia, soda, and potash, are often employed to realise the important consideration of producing light and porous bread from spoiled, or, as it is technically called, sour flour. The first salt becomes temporarily converted into a gaseous state during the operation of baking, causing the dough to swell up in minute bubbles, which thus render it light and porous; the salt itself being at the same time, for the most part, volatilised. Alum is added, not only with a like intention, but also to enable the dough to carry more water. There are several instances of convictions on record of millers and bakers having used gypsum, chalk, and pipeclay in the manufacture of their goods. A gentleman lately writing from the North of England says that he found in one sample of flour which he recently examined upwards of 16% of gypsum; and in another, 12% of the same earth. A few years since it was discovered that some of the bakers in France and Belgium added blue vitriol to their dough to make it take more water, in the same way as the English baker uses alum. 1 oz. of this sulphate was di olved in a quart of water, and a wine-gla ful of this solution added to the water nece ary to make about 50 4-lb. loaves. This enormous crime was soon detected, and deservedly caused the ruin of its heartle perpetrators. Exam. The following are the methods employed for the discovery of the principal sophistic ants of bread, and as the chief of these, and the one most difficult of identification is alum, we have given prominence to the proce es now generally adopted for the detection of this article:— 1. Alum :— a. (Robine and Parisot.) About 1 ⁄ 4 lb. of the suspected bread (somewhat stale or dry) is reduced to crumbs, macerated for 2 or 3 hours in cold water, and then squeezed through a clean piece of white linen. The liquid is next evaporated to dryne at a steam-heat, the residuum redi olved in a little hot water, and the solution filtered. Liquor of ammonia or a solution of sal-ammoniac, and a solution of chloride of barium added to the filtered liquid, give a white precipitate when ALUM is present. When nearly the whole of the alum has suffered decomposition in the loaf, as is frequently the case, the following proce is required:— b. (M. Kuhlman.) 4 or 5 oz. of bread are reduced to ash, which is powdered and treated with nitric acid, the mixture evaporated to dryne , and about 1 oz. of hot water added. A little caustic pota a is added to the last solution (unfiltered), the whole boiled a few minutes, and pa ed through a filter. The filtrate is next tested with a solution of sal-ammoniac, and the whole again boiled for 2 or 3 minutes. If a precipitate forms it is alumina; every 50 gr. of which are equivalent to 332 gr. of crystallised alum. c. The suspected sample is wetted with a weak solution of logwood, or, preferably, of cochineal. Pure bread is only slightly stained by this solution; bread containing alum strikes a lavender, lilac, or purple colour, according to the quantity of the adulterant present. If it acquires a pearl-grey or bluish tint, some alkali (potash, soda, or ammonia) is present. d. (J. A. Wanklyn.) 100 grams of bread are incinerated in a platinum dish, capable of holding the whole quantity at once. The incineration is managed at a comparatively low temperature, and takes some four or five hours; the platinum dish being heated by means of a large Bunsen burner, abundantly supplied with air. It is well to continue the ignition until the bread-ash is nearly completely burnt, and it is advisable to weigh the dish containing the ash. The weight of the ash should not sensibly exceed 2 grams. The ash having been obtained is then moistened with 3 c. c. of pure strong hydrochloric acid, and then some 20 to 30 c. c. of distilled water is added, and the whole is boiled, filtered, and the precipitate washed several times with boiling water. In this manner a precipitate consisting of a silica, together with some unburnt carbon, is left on the filter, whilst the filtrate contains the phosphates. The precipitate, which, after being burnt, consists of silica, is weighed. The filtrate is mixed with 5 c. c. of ammonia (sp. gr. 0·880), whereby it is rendered powerfully alkaline and opaque, owing to the precipitation of the phosphates. It is finally mixed gradually with some 20 c. c. of strong acetic acid, and as the acid is being poured in, it is to be observed that the liquid is alkaline and opaque, until some 5 c. c. of the acid have been added; that when about 10 c. c. have been added the liquid is acid and much clearer, and that at least 10 c. c. of strong acetic acid are added after the establishment of a distinctly acid reaction. The liquid is then boiled and filtered, and the precipitates, consisting of phosphates of alumina and iron, well-washed with boiling water, ignited and weighed. The last step is the determination of the iron in the weighed precipitate, and this is accomplished either by reduction and titration with standard solution of permanganate in the well known manner, or else by a colour proce , viz., by trituration with ferrocyanide of pota ium. Having ascertained the amount of iron in the precipitate of mixed phosphates, it is only nece ary to calculate it into phosphate of iron, and to subtract the weight of phosphate of iron from the total weight of the mixed phosphates, and the difference is the phosphate of alum yielded by 100 grams of the bread. The following results have been obtained by applying the above-described proce to samples of bread presumed to be free from alum:— From 100 grams of Bread. | Bread-ash. | Silica. | Precipitate insoluble in acetic acid. | | Grams. | Grams. | Grams. | | A | 1·408 |... | 0·010 | | B | 1·378 |... | 0·006 | | C | 1·730 | 0·018 | 0·010 | | D | 1·620 | 0·032 | 0·014 | | E |... |... | 0·012 | | (1)F | 1·383 | 0·030 | 0·012 | | (2)F | 1·324 | 0·025 | 0·014 | The precipitate insoluble in acetic acid contained in every instance a large proportion of iron, but in some cases at least did not wholly consist of phosphate of iron. On deducting the quantity of phosphate of iron from the total phosphates insoluble in acetic acid, there remains a residue of some five or six milligrams. It would therefore appear that unalumed bread is liable to contain a minute trace of alumina, which, expre ed as phosphate of alumina (Al 2 O 3 PO 5 ), equals five or six milligrams per 100 grains of bread, or 0·005 per cent. If the alum corresponding to this phosphate be calculated, it will be seen that 100 grams of unalumed bread may appear to contain 0·022 grams of alum; or expre ed on the 4-lb. loaf, there may appear to be 6 grams of alum in it. This agrees very fairly with Dr Dupré’s observation. e. (J. C. Thresh.) The author states that this proce requires only a few hours, and quotes experiments, showing the accuracy of the results:— Take 1250 gr. of bread (from middle of loaf) or flour, and char thoroughly in a platinum dish or on foil over a gas lamp. Powder the char and mix it with sufficient pure strong hydrochloric acid to make a thin cream. Boil gently for a few minutes, then add 100 c. c. of water, and continue the ebullition a few minutes longer. Dilute to 150 c. c., stir well, and filter off 120 c. c., which will contain the alumina from 1000 gr. of the bread or flour. To this filtrate add a slight exce of solution of ammonia, boil for a few seconds. Then let the precipitate subside, and decant the supernatant fluid. Add boiling water to the sediment, and again set aside to settle, and decant the clear fluid. Pa the fluids through a small filter to collect any particles of the precipitate which may have been suspended therein, and throw the filtrate away. Now add to the partially washed precipitate about a gram of pure caustic potash (or soda), warm, and pa the solution through the same filter employed for the previously decanted fluids. Wash the filter with hot water, to which a little KHO may be added, and proceed to precipitate the alumina in the filtrate by adding a few drops of dilute phosphoric acid and exce of pure acetic acid. Heat the solution and precipitate to the boiling point, and then wash the latter by decantation and filtration. Finally dry, ignite, and weigh. The weight of the resulting Al 2 PO 4 in grams, multiplied by 400, will give the amounts of ammonia alum in grains present in one pound of the bread or flour. f. (Mr Crookes.) The bread of which at least 500 grains should be taken is first to be incinerated on a platinum or porcelain dish, until all volatile organic matter has been expelled, and a black carbonaceous ash remains. The temperature must not be raised much beyond the point nece ary to effect this. Powder the coal thus obtained and add about thirty drops of oil of vitriol, and heat until vapours begin to rise; when sufficiently cool, add water, and boil for ten minutes. Filter and evaporate the filtrate until the fumes of sulphuric acid begin to be evolved, when 10 gr. of metallic tin and an exce of nitric acid must be added, together with water, drop by drop, until action between the acid and metal commences. When all the tin is oxidised, add water, and filter. Evaporate the filtrate until fumes of sulphuric acid are again visible, when more water must be added, and the liquid again filtered if nece ary. To the clear solution now add tartaric acid, then ammonia in exce , and sulphide of ammonium. Evaporate the liquid containing the precipitate suspended to it, in a dish, until all the smell of sulphide of ammonium has disappeared. Filter, evaporate to dryne , and ignite to get rid of the organic matter. Powder the black ash, boil it in moderately strong hydrochloric acid, filter, add a crystal of chlorate of potash, and boil for a minute. Now add chloride of ammonium and ammonia, and boil for five minutes. If at the end of that time any precipitate is observed, it will be alumina. From the filtered solution, if oxalate of ammonia be added, the lime will be precipitated; and if to the filtrate from this, ammonia and phosphate of soda be added, the magnesia will come down. Dr Dupré is of opinion that no baker should be fined in whose bread the amount of alumina found corresponds with le than 10 grains of potash alum in the 2-lb. loaf, unle there is direct evidence of adulteration by alum independent of the result of analysis. Mr Crookes says, “By treatment with a trace of alum, flour with a doubtful soundne is endowed with soundne . For this purpose a proportion of alum is required which does not exceed 20 grains to a 4-lb. loaf. 2. Copper :— a. Moisten the suspected bread with a few drops of a solution of ferrocyanide of pota ium. It will a ume a pinkish-brown colour if copper be present. b. A little of the bread may be steeped in hot water, or, better still, in water soured with a little nitric acid, and the clear liquor squeezed or poured off, and tested with ferrocyanide of pota ium, as before. 3. Magnesia :—Bread adulterated with magnesia, on digestion in hot water acidulated with sulphuric acid, furnishes a liquid which gives a white precipitate when tested with a solution of either carbonate of pota a or of carbonate of soda, especially on boiling. 4. Soda ; Pota a :—Hot water after digestion on the ashes or charcoal turns turmeric paper brown. The liquid may be evaporated to dryne , redi olved in distilled water, slightly acidulated with hydrochloric acid, and tested with bichloride of platinum. If a yellow crystalline precipitate forms, either at once or after some hours, it is potash; otherwise the alkali present is soda. 5. Chalk , WHITING , BURNT BONES , plaster of Paris , and similar substances are easily detected by calcining a little of the flour or bread in a clean open ve el, when the amount of ash left will indicate the quantity of adulteration. The quantity of the ash left by genuine bread or flour is very trifling indeed, about 2%.