II.-THE COMPOSITION OF CIDER AS DETERMINED BY DOMI- 

 NANT FERMENTATION WITH PURE YEASTS. 



By WM. B. ALWOOD, R. J. DAVIDSON, and W. A. P. MONCURE. 



WORK OF 1901-2. 

 INTRODUCTION. 



In the autumn of 1901 a series of experiments upon the manufacture 

 of ciders with pure yeast cultures was begun at the Blacksburg station 

 in cooperation with the Bureau of Chemistry. 



The apple must or juice used for this experiment was made with the 

 power mill belonging to the station from ordinary mixed apples, 

 mostly of inferior varieties. Immediately after pressing, the juice 

 was placed in sound, clean, 50-gallon casks, and these were at once 

 bunged to prevent further access of organisms to the juice until it 

 could be sown with yeast. These casks, or 50-gallon barrels, were 

 placed on the second floor of the factory building and were sown with 

 yeast cultures about three hours after grinding the fruit. In these 

 experiments, which were made on a scale comparable with commercial 

 work, the juice or must was not sterilized or pasteurized before sow- 

 ing with the pure yeast cultures. While the destruction by use of 

 heat of the many microscopic organisms always present in fresh fruit 

 juice is practicable, even on a large scale in factory work, as yet it has 

 not been found to be desirable for commercial ciders. Heating the 

 must causes such changes in the flavor that the most careful cellar 

 work and use of pure ferments has failed to counteract this effect, and 

 thus the fine natural flavors are quite commonly injured by attempts 

 at sterilization. 



Control or dominant fermentation is easily secured if one sows a 

 sufficient amount of fresh culture of a strong yeast into the newly 

 made must. The question of the relative activities of the pure fer- 

 ments in comparison with mixed yeasts and " wild" ferments in steril- 

 ized and unsterilized must will be treated in a subsequent paper which 

 will deal more specifically with the ferment organisms. The station 

 is without suitable cellars or fermentation rooms, and therefore this 

 work was done under such varying conditions of temperature that the 

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