2IO BACTERIOLOGICAL METHODS 



Grape juice is apt to become moldy. The nature of the con- 

 tamination will depend upon the relative amounts of sugar and 

 acids present. 



21. The Microscopical and Bacteriological Examination of Fer- 

 mented Foods and Drinks 



The examination of alcoholic drinks and other fermented 

 hquids and fermented food substances including certain fermented 

 products used in the preparation of foods, on the part of the 

 bacteriologist, is of minor importance and is largely supplementary 

 to the analyses of the chemist and the organoleptic testings of 

 the expert taster. The methods of procedure will be largely 

 limited to the microscopical examination of concentrates, of natural 

 and centrifugalized sediments, of sedimentary suspensions and 

 of surface formations or deposits, with a view to the detection of 

 added or other impurities and the recognition of abnormal fer- 

 mentative changes, and invasions by objectionable bacteria, yeasts 

 and molds. "Diseased" or "sick" wines, beers, porters, ales, 

 vinegars, pickles, sauerkraut, etc., should be carefully examined 

 as to the quantity and identity of the objectionable organisms 

 present. In order that the report of the bacteriologist may 

 supplement the report of the expert taster, it is absolutely essential 

 that the bacteriologist have a thorough knowledge of the micro- 

 scopical appearance of normally fermented products. This 

 knowledge may be gained only through experience. The yeasts 

 and other organisms concerned in normal wine fermentation are 

 well known to the specialists who have made a long study of wine 

 ferments. 



There appears to be no recognized standard as to the number 

 or kind of organisms which may be permissible in properly fer- 

 mented and properly clarified wines and in other fermented 

 drinks, nor does the present status of the subject warrant the 

 adoption of numerical limits as to the organisms present. There 



