466 



NA TURE 



[March i 5, 1906 



still in existence. An interesting introduction closes 

 with an account of the laws applying to local birds ; 

 and the volume is embellished with a map of the 

 district, four drawings by Mr. G. E. Lodge, and 

 reproductions of some most beautiful photographs of 

 birds by Mr. Smith Whiting, one of which we are 

 enabled to reproduce. O. V. Aplin. 



THE ADULTERATION OF BUTTER. 



DURING the last few years much unscrupulous 

 ingenuity has been applied to the sophistication 

 of butter. Both on the Continent and in this country 

 the adulteration of this, the best of edible fats, has 

 developed into quite an industry, having its own 

 factories and its own chemists, and conducting its 

 operations on a scale which, for a furtive, dishonest 

 business, is really of remarkable magnitude. Con- 

 siderable profits are alleged to be made, and it is there- 

 fore not surprising that the traffic has flourished in 

 spite of all attempts at suppression. Perhaps it may 

 be of interest to those readers of Nature who are 

 not chemists to have placed before them, with as little 

 technicality as maybe, a sketch of the modern methods 

 ot butter-adulteration, and of the means adopted or 

 suggested to checkmate this form of fraud. The 

 importance of the matter both to the consumer and 

 the agriculturist may be pleaded as a justification 

 for discussing the question at some little length. 



Butter, though consisting essentially of the fat of 

 milk, is always associated during manufacture with 

 more or less water, the quantity of which ranges 

 generally from 7 to 15 per cent. One of the simplest 

 forms of adulteration consists in working an excessive 

 proportion of water into the butter. To check this is 

 comparatively easy; a maximum limit of 16 per cent, 

 has been fixed by the Board of Agriculture, and per- 

 sons dealing in butter containing more water than 

 this are liable to prosecution. 



There exists, however, an insidious variant of this 

 water-logging in the production of what is called 

 " milk-blended " butter. In preparing this, skim 

 milk, costing about a penny per gallon, is largely 

 used. It may either furnish curd to be incorporated 

 with the butter, or, after a little " ripening " with 

 micro-organisms to improve the flavour, it may be 

 used for direct admixture. By working up butter 

 with such milk a product may be obtained containing 

 25 to 30 per cent, of water, as well as a substantial 

 quantity of curd. The proportion of butter-fat in such 

 a mixture will often be less than 65 per cent., whereas 

 ordinary butter contains from 80 to 90 per cent. Yet the 

 sale of the article is not, legally, a fraudulent transac- 

 tion, provided the substance is sold as " milk-blended " 

 butter, and not simply as "butter." At first sight 

 this may seem reasonable enough ; the purchaser is 

 told what he is buying, and for the rest — well, caveat 

 emptor. But, after all, some regard should be had 

 to attendant circumstances. It is the poor who chiefly 

 consume the manipulated butter, and neither they, 

 nor, indeed, any ordinary purchaser, would realise 

 that the fat-value of the blended article is only about 

 three-fourths of that of genuine butter. Of course, if 

 the price is correspondingly lower there is no fraud. 

 But the contention of those who oppose the sale is 

 that there is always a substantial margin of unfair 

 profit; " milk-blending," in fact, is held to be essen- 

 tially a device for supplying an excessive proportion 

 of water, relative to the amount of fat, without in- 

 curring the penalties provided for infringement of 

 the Sale of Butter Regulations. 



Be this as it may, a measure to prohibit the use of 

 the word " butter " for such mixtures, on the ground 

 that it is a misleading description, was brought for- 



NO. 1898, VOL. 73] 



ward two or three sessions ago, only to be sacrificed 

 to the exigencies of politics. It remains to be seen 

 whether a better fate is in store for it under the new 

 Administration. 



Perhaps, however, the most frequent, and certainly 

 the most troublesome, sophistication of butter consists 

 in the admixture with it of fat other than that of milk. 

 There are two chief adulterants of this class now in 

 use. One is a soft fat obtained from beef-suet by 

 removal of the harder "stearin" portions; this fat 

 may sometimes be mixed with or replaced by lard, 

 and is generally churned up with water (or with milk) 

 to facilitate the subsequent "blending." The other 

 adulterant is a refined cocoa-nut " oil " or fat, purified 

 so as to be practically tasteless. These substances, 

 supplied at about half the price of butter, are variously 

 known as " mixing article," " enricher cream," 

 "neutral fat," or "neutral blending," and are care- 

 fully prepared to simulate butter in consistency. A 

 still more subtle adulterant is formed bv a judicious 

 mixture of the two, which yields analytical figures 

 identical in some respects with those of genuine 

 butter. Let us examine this a little more closely. 



Chemically, butter-fat consists of a mixture of 

 glycerides — that is to say, compounds of fatty acids 

 with glycerin. For instance, one such glyceride may, 

 with sufficient accuracy for our present purpose, be 

 represented as the following combination : — 



/Oleic acid 1 

 Glycerin^Palmitic acid Yminm water. 

 \Butyric acid J 



When these acids are freed from their chemical 

 union with the glycerin, the butyric acid is found to 

 be sharply distinguished from the other two by the 

 fact that it is soluble in water and volatile on distil- 

 lation with steam. Now the chief difference between 

 butter-fat and other fats lies in the comparatively high 

 proportion of butyric acid (and similar volatile acids) 

 which the butter-fat contains. The following sum- 

 mary represents the composition of a specimen of the 

 prepared beef-fat and of two samples of butter-fat : — 



Volatile or soluble acids 



Insoluble acids 



Glycerin 



Prepared beef-fat 



Per cent. 

 Practically nil 



95'5 

 109 



Less combined water 



106 4 

 6-4 



5° 

 90 'O 



107-1 

 7-1 



No. 2 

 Per cent. 

 67 



. 88 a 

 12 7 



107-4 

 7'4 



Like other natural products, the fat of milk varies 

 in the proportions of its components, and the two 

 samples here quoted show the range of variation met 

 with in ordinary butter. Analytically, No. 1 is 

 butter of low quality; No. 2, on the other hand, is 

 above the average. The difference consists, as will 

 be seen, in No. 1 containing less volatile acids, 

 less glycerin, and more insoluble acids than No. 2. 

 These are precisely the directions in which beef-fat 

 differs from butter-fat. Broadly, one may say that, 

 analytically, the first specimen of butter has more of a 

 beef-fat character than the second. 



This is the point which the adulterator seizes upon. 

 " If," he argues, " I start with butter No. 2, I can 

 add to it quite a considerable quantity of my prepared 

 beef-fat before the mixture shows a smaller percentage 

 of volatile afcids than butter No. 1 contains ; and since 

 No. 1 is perfectly genuine butter, it is difficult to see 

 how any analyst will be able to swear that my 

 mixture is not also genuine butter." Indeed, the 

 analyst often finds it no easy matter to expose the 



