CHAPTER XIX. BUTTER AND ITS ADULTERATIONS. DEFINITION OF ADULTERATION. Any foreign substance, as the fat of beef, mutton, or pork; flour, starch, or any mineral matter other than salt, which should not exceed 4 per cent. in fresh, and 8 per cent. in salt butter; curd, which should not exceed 4 per cent. ; and water, which should not be more than 12 per cent. As the method of making butter may not be known to many of the readers of this report, we will proceed, before entering upon the consideration of its adulterations, to give a very brief outline of the manner in which butter is usually prepared.. Butter is made for the most part from cream; the cream is collected from time to time, and placed in a covered jar, until sufficient has been obtained, when, having become sour by keeping, it is submitted to the process of churning. Butter is also prepared in small quantities from sweet cream, and this kind is esteemed a great delicacy. Very excellent butter is likewise sometimes made from full or entire milk; the disadvantages of this method are the large quantity of fluid to be acted on by the churn, which renders it necessary that steam or some other powerful mechanical means should be had recourse to, and the length of time which elapses before the butter forms. As soon as the butter has formed, it is removed from the churn, and well washed in water, it being kneaded at the same time until as much as possible of the adherent and incorporated whey is removed; this is known by the water ceasing to become turbid and milky. If intended for salt butter, the salt should be added as soon as possible after churning and washing, as, left for any length of time, the butter is apt to become rancid. Great attention should be paid to the quality of the salt used; the best descriptions are rock salt and that prepared from salt springs. Sea salt, generally, is not so good, on account of the presence of sulphate of magnesia, which renders it somewhat bitter, as well as of chloride of calcium, which has a strong affinity for water, even attracting it from the atmosphere. It would be out of place in this report to enter into the practical minutiæ of butter-making, such as the temperature at which the cream or milk should be churned, the best kinds of churn, the methods of churning, &c., all points of the greatest importance for the agriculturalist and the dairyman. COMPOSITION OF BUTTER. Butter consists of the glycerides of certain fatty acids, principally of stearic, palmitic, and oleic acids, with smaller quantities of butyric. capric, caproic, and caprylic acids; these latter are all distinguished from the former acids by their volatility. According to the analysis of Bromeis, they amount to only 2 per cent., they being embraced by that chemist in the term 'butyroleic acid.' But Messrs. Angell and Hehner have proved, as will be shown hereafter, that these volatile acids are present in much larger quantities, amounting on an average to 9-3 per cent. The true melting point of butter, taken in the manner described hereafter, we found to range from 32.8 to 34.9, the mean of all the observations made being 33.7° C. The oily or buttery part exists in milk in the form of innumerable very distinct globules, of various sizes. The effect produced by churning is to break down these globules, which then run together, and thus form butter. The operation of the churn is therefore chiefly, if not entirely, mechanical. THE ANALYSIS OF BUTTER. The analysis of butter is very nearly the same as that of milk, since it contains for the most part the like constituents, although in very different proportions. It is, therefore, not necessary to enter into any lengthy details on the subject. The water is to be estimated by the loss on evaporation, the fat by extraction with ether; the curd and salt are left on the removal of the fat; the quantity of the former may be estimated by incineration, and the mineral matter remaining may be calculated as salt, of which it usually almost entirely consists. Butter, when fresh, is of a yellowish colour, having a peculiar and characteristic sweet odour, but when exposed for a long time to the air it loses gradually its colour, becomes white, and acquires a tallowy odour, which was at one time considered to be characteristic of beef, mutton, and other analogous fats; and samples of perfectly genuine butter, when thus changed in colour and odour, have unquestionably in many cases been declared to be adulterated. In fact, by many a analysts the tallowy smell was considered to afford a conclusive proof of the adulteration of any butter with some foreign animal fat. THE OCCURRENCE OF CRYSTALS IN BUTTER. It is very generally believed that the occurrence of needle-like crystals, often arranged in the form of spherules or stellæ, is a cer tain proof of the adulteration of butter and of the presence of lard or some other foreign animal fat. This belief, however, is entirely erroneous; and although no crystals are found in freshly-made butter, yet they appear in it if kept for any length of time, and they are especially abundant in all butters which have been fused and allowed again to solidify. On the surface of all such butters a shiny scum or pellicle may be seen, composed in large part of such crystals, which are likewise to be found abundantly diffused throughout the whole mass of the butter. Again, they are frequently met with in great numbers in cream. They polarise light. Messrs. Angell and Hehner make the following remarks in reference to crystals in butter:-If a small quantity of a fat containing crystals be placed upon a slide, a drop of castor or olive oil be added, and the whole then pressed out by means of a thin glass cover, the depolarisation of light is much enhanced. A revolving black cross, not unlike that of starch grains, is seen in great perfection. These crosses are most clearly defined in the crystals obtained from butter. Dr. Campbell Brown, in his essay on the Adulteration of Butter,' remarks:-A microscopic examination with polarised light is the most reliable means of distinguishing pure butter from that which contains an admixture of less easily digestible and palatable fats.' But this statement, as we have seen, is erroneous. THE ADULTERATIONS OF BUTTER. Adulteration with water.-One of the most frequent practices had recourse to in the case of butter is to incorporate with it large quantities of water; the incorporation is effected in the following manner: the butter is brought to the melting point, water and salt are then stirred in until the mixture becomes cold. In reference to the adulteration of butter with water and salt, Professor Calvert, in his evidence before the Parliamentary Committee on Adulteration in 1855, made these remarks:- The quantity of water and salt that such an article as butter ought to contain is 24 per cent. of salt, and 10 per cent. of water. In the butter supplied to these Unions the quantity of salt varied from 2 up to 14 per cent., and the water from 10 to 15 per cent.' A butter factor wrote to us some time since, stating that 50 per cent. of water may be incorporated with butter in this way; but when you buy, say half a pound of butter, a considerable part of the water of adulteration escapes, and if you put it in paper more will be lost. Adulteration with starch.-Another adulteration to which butter is occasionally subject, especially the inferior kind known as Bosh, consists in the addition of starch, usually potato flour. This adulteration is practised only at particular times, and is dependent upon the wholesale price of butter. Adulteration with curd.-Again, butter has been known to be adul terated sometimes with curd. This adulteration is particularly mentioned by Sir John Gordon, mayor of Cork, in his evidence before the Parliamentary Committee above referred to. Adulteration with animal fat.--Lastly, animal fats are not unfrequently employed, as the fat of beef, mutton, veal, lard, &c. Beef fat is sometimes prepared on a large scale and made up in imitation of butter, being known and sold under the name of 'Butterine.' This article is mainly the olein of the fat, with only a small proportion of the stearin. When freshly prepared it is sweet and palatable, and being sold at a much lower price than butter itself, it is in some cases a useful substitute; but it is to be feared that such a preparation would be used in some cases for the adulteration of butter. Results of the Examination of Samples. The examination of forty-eight different butters, both salt and fresh, made some years since, and published in the Report of the Analytical Sanitary Commission of the Lancet' on the adulteration of butter, furnished the following results: All the salt butters examined contained variable and usually very large quantities of water, the amount ranging, with one exception, from 8:48 to 28.60 per cent. The fresh butters likewise contained variable and often considerable quantities of water, but in most cases very much less than the salt butters, the quantities ranging from 418 to 15:43 per cent. The quantity of salt contained in the salt butters varied from 1.53 to 8.24 per cent., showing that no fixed rule is acted upon in salting butter. In the fresh butters the salt varied from 0.30 to 2.91 per cent. The percentages of butter fat contained in the samples ranged from 67.72 to 96.93; that is, some of the samples contained 20, 30, and in one case even nearly 35 per cent. of water and salt. Now the presence of water in butter, in excess and when purposely introduced, assuredly constitutes an adulteration as much as does the addition of starch or animal fats. To many of the samples of salt butter examined, a quantity of salt over and above the amount necessary to ensure the preservation of the butter had no doubt been purposely added to increase the weight and bulk; in fact, for the sake of adulteration. It is equally certain that much of the water met with in many of the samples had been added for the same purpose. The quantity of water present in some inferior descriptions of butter, as especially Bosh and the worst kinds of Hollands,' is really surprising, amounting in some cases to more than a third of the article. The samples of which the analyses are given in the following table were recently analysed for the purpose of determining the percentage composition of butters as ordinarily met with, and very many of which it was known beforehand, from the sources from which they were obtained, were perfectly genuine. It must not, therefore, be concluded that these analyses represent the condition of the butters sold in London and other populous cities. With three exceptions they were all fresh butters, which are much less liable to adulteration than salt butters : Water Salt 9.193 7.683 8.580 6:370 8-615 23-981* 42-358* 7.834 2-689 *1 This butter had nearly the normal fusing point of genuine butter, but it furnished 92.87 per cent. of fatty acids, equivalent to 67 per cent. of foreign fat. |