No. 6. DEPARTMENT OF AGRICULTURE. 201 



and renovated butter. Of the foimer I will not speak since I under- 

 stand the consideration of this substitute has been more specifically 

 assigned to another. 



The term renovated butter is applied to butter which, after having 

 reached such an advaoced stage of decomposition as has led to its 

 rejection for human consumption, has been treated in such a manner 

 as to remove the decomposed materials most offensive to taste and 

 smell. In the days of our grandmothers, when butter was packed 

 in summer for use during the following winter, an occasional lot of 

 butter that had gotteo a little beyond the point of acceptability was 

 washed with a solution of baking soda, and thereby relieved some- 

 what of its disagreeable flavor and odor. The processes now in vogue 

 in establishments where renovation is carried out on a large scale, 

 are somewhat more complex. The butter, gathered without regard 

 10 its degree of decomposition or exjjosure to filth, is melted in a tank; 

 the decomposing curd the products of decomposition of the milk 

 sugar, the mineral salts and the water settle to the bottom, while 

 the fat is drawn oft' to an aeratiog tank. The process of aeration is 

 chiefly relied upon for removal of taint. The process is variously 

 conducted, blowing, pumping and spraying of the melted fats being 

 employed, one or all of them, to secure thorough contact of the fat 

 with the air. When the major part of the taint is removed, the par- 

 tially deodorized fat is conducted into ripened skim-milk, milk or 

 cream, usually the former, by which some positive, desirable flavors 

 are imported, for it is now- quite well established that instead of 

 butter flavors being wholly due to the fat. they are in very consider- 

 able degree due to the products made by the action of the ripening 

 bacteria upon the milk sugar and possibly upon its nitrogenous ma- 

 terials. Having been cooled in contact with the ripened milk, the 

 fat is gathered and then worked as fresh butter is. 



The manufacture of this renovated article has made very rapid ad- 

 vances in the imitation of fresh butter. Formerlv a verv waterv, 

 salvy article was made, whose water content decisively proclaimed 

 its nature. To-day, there is little difference in this respect between 

 the fresh and the renovated article. 



The detection of this substance has proven a difficult problem. It 

 is. in fact, excessively rancid butter from which the bad flavor and 

 odor have been largely removed. It is. furthermore, extremely sus- 

 ceptible to renewed decomposition whereby the bad flavor and odor 

 reappear. 



To secure a better understanding of the priaciples involved, a 

 consideration of the nature of rancidity is requisite. It is desirable 

 to distinguish between the rancidity that occurs in the pure fat, 

 separated from the curd and salt; and that which occurs in the but- 

 ter, containing the curd, salt and water. 



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