208 EXPERIMENT STATION EECORD. 



acid as compared with the old spontaneous fermentation method which is usu- 

 ally employed. The pure yeast and sulphurous acid process gave much more 

 alcohol than the natural fermentation. The natural fermentation showed the 

 presence of detrimental bacteria ; the other did not. 



Manufacture of unfermented grape juice in California, W. V. Cruess and 

 C. J. IIiNTZE {Jour. Indus, and Engin. Chnn., 6 (19U), No. 4. pp. S02-SOJt).— 

 The present output of unfermented grape juice in California is estimated at 

 from 80,000 to 100,000 gal. per year. The present methods for preparing and 

 bottling grape juice are considered, and various technical hints are included in 

 the text. In addition the results of experiments made during 1912 and 1913 

 are reported upon. 



" In view of these tests it is recommended that the process of grape juice 

 manufacture be modified to conform to the following outline : Use a mixture of 

 ripe grapes to give flavor with grapes of high acid to remedy the lack of acid 

 in the ripe grapes. Add 8 to 12 oz. of potassium metabisulphite per ton of 

 grapes at the crusher, to prevent fermentation during defecation. Allow the 

 juice to defecate 24 to 48 hours and rack from the sediment. 



"Add to each 100 gal. of juice 4 to 6 oz. of casein dissolved in sodium car- 

 bonate or ammonium hydroxid. Add a small amount of tartaric acid to increase 

 the rate of separation of the cream of tartar. Heat the juice to 165° F. and 

 store in 50 gal. barrels until most of the excess cream of tartar has separated. 

 Rack from the sediment and filter, if necessary. Add a small amount of citric 

 acid to prevent fux'ther separation of cream of tartar, and bottle. Pasteurize in 

 bottle at 160°. 



" Note that a temperature of 165° is recommended for the first cooking and 

 160° for the final heating. These are high enough temperatures to keep well- 

 handled juice and will give a great deal less of the objectionable cooked flavor 

 so evident in all grape juice now on the market." 



See also a previous note (E. S. R., 30, p. 316). 



Clarification of grape juice, F. T. Bioletti (California Sta. Rpt. 1914. PP- 

 190, 191). — These data are noted above. 



Amounts of wine and of by-products yielded by grapes in a California 

 winery, F. T. Bioletti (California Sta. Rpt. 1914. pp. 192. 193). — '"In order 

 to determine the degree of efficiency of our methods of wine making in utilizing 

 the raw material as accurate an account as practicable was kept of the intake 

 and output of a winery of moderate size." The results are given in tabular 

 form. 



"Use of sulphurous acid and pure yeast in wine making, F. T. Bioletti 

 (California Sta. Rpt. 1914, pp. 191, 192). — Modern methods of using pure yeast 

 and sulphurous acid in the fermentation of wine were introduced into many 

 wineries during the last vintage with excellent results. The wines produced 

 were analyzed and compared with those made by the old methods in the same 

 districts from the same varieties of grapes. 



A very marked superiority as to the lowness of the volatile acid of the wines 

 fermented with sulphurous acid was noted. The presence of a large number of 

 injurious bacteria in most of the wines fermented without sulphurous acid was 

 shown, not only by the high volatile acidity, but also by direct microscopic ex- 

 amination. The presence of a few bacteria in one-third of the wines fermented 

 with both sulphurous acid and pure yeast probably indicate that owing to the 

 greater clearness of these wines small numbers of bacteria were more easily 

 observed. 



