BULLETIN 493, U. S. DEPARTMENT OF AGRICULTURE. 

 METHOD OF UNDERTAKING THE INVESTIGATION. 



It was felt that it would be wholly unsatisfactory to make this in 

 vestigation by means of laboratory brewings on a small scale, as the 

 results thus obtained would not show the true conditions, because it 

 is not possible in the laboratory to duplicate exactly the mashing or 

 fermenting processes actually used in a commercial way. It was 

 decided, therefore, to attempt, with the cooperation of several brew- 

 eries, to make this study under the exact conditions prevailing in 

 commercial plants. Access was secured to several breweries making 

 different types of products from various kinds of raw materials, under 

 such conditions that it was possible to obtain a complete history of 

 the beer through its various stages to the finished product. One of 

 the writers (Kiley) watched the method of manufacture during its 

 whole process and obtained samples of the product at the various 

 stages of manufacture. Thus, it was possible to procure finished sam- 

 ples with practically the same degree of certainty, as regards knowl- 

 edge of composition and history, as would have been the case had they 

 been prepared in the laboratory. 



In three different breweries manufacturing a wide range of products 

 samples of the wort and beer were obtained in this manner, the entire 

 process of manufacture being studied in detail. A record showing 

 the kind and amount of raw materials placed in the mash and in the 

 cooker was made of the samples collected from these three breweries. 

 A record also was kept of the time and temperature of each operation 

 until the mash was ready to run into the kettle. The filtering and 

 sparging 1 of the mash, the time of boding in the kettle, the amount 

 of hops added and the point at which they were added, and the break 2 

 of the wort were all noted. After the wort had been pumped from 

 the kettle its course was followed through the hop jack 3 over the 

 coolers to the settling tank. The specific gravity or Balling 4 of the 

 original wort, the temperature at which the product was pitched, 5 

 the aeration of the wort, the kind and amount of yeast added, as 

 well as the time and maximum temperature of the primary fermen- 

 tation, also were noted. The course of the beer through the storage 

 vats, chip casks, and filters to the racks was watched, and samples 

 of the wort and of the beer in its various stages of production were 

 collected and examined. 



i Washing the grains with hot water to remove the extract or valuable constituents as completely as 

 possible. 

 ' Precipitation and uniting, in the form of flakes, of the coagulable albuminoids, leaving the liquid clear. 

 3 A filtering tank. 



• Percentage of solids in the liquor according to the Balling hydrometer. 

 6 Pitching is the operation of adding the yeast to the wort. 



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