The adulteration of food : conferences by the Institute of Chemistry on Monday and Tuesday, July 14th and 15th : food adulteration and analysis.

Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: The adulteration of food : conferences by the Institute of Chemistry on Monday and Tuesday, July 14th and 15th : food adulteration and analysis. Source: Wellcome Collection.

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    foil, through which cold water circulates, is then inserted in the vat, and allowed to remain for from 12 to 15 hours, the tempera- ture being carefully maintained at 47° C. This is an important point in the process, because, if the temperature falls below 40° C. the fermentation ceases, while if it rises to 52° the ferment is killed. At the temperature of 47° C. fermentation goes on rapidly, torrents of carbonic acid gas are evolved, and the whole mass seems to be in most active ebullition. This evolution of carbonic acid is most rapid from the sixth to the fifteenth hour; at this point the cooler is usually removed, as thereafter the chemical action becomes less violent and maintains the temperature at the right point. After about four days, as a rule, and without further treatment, the whole mass becomes solid owing to the formation of crystals of the neutral lactate of lime, but the action goes on slowly for a day or two longer. I will, not trouble you with details as to the purification of the crystals, as to the drying of the products, and as to other manufacturing details, which involve nothing which is essentially new in principle. By treating the neutral lactate of lime with just enough sulphuric add, the lime is converted into sulphate of lime and the lactic acid set free; the sulphate of lime is removed by filtration, and the lactic acid evaporated in the vacuum pan until it reaches the required degree of concentration. If only one half of the requisite quantity of sul- phuric acid is added, there is formed the bilactate or acid lactate of lime, which is, to be sure, not a perfectly definite compound; but this compound and the lactic acid of various grades are the principal commercial products. The next question is, to what uses are these products put ? The answer, in a general way is, that it is intended to offer them as substitutes for other more expensive substances already in use in the arts and in the household. The acid lactate of lime can replace the more expensive cream of tartar as a mordant in dyeing, and the acid itself is capable of useful application; but it is principally in connexion with articles of food that we have to consider these products. The most important use—at least in the United States—is in raising bread. In the States baking- powders are used to an enormous extent in making bread. In many parts of the country rolls—or biscuits^ as we call them— prepared in this way are eaten morning and evening hot and fresh from the oven. It was at first proposed to mix the acid lactate of lime and the bicarbonate of soda in proper proportions, and sell the mixture as a baking-powder; but this has proved imprac-