[ 756 ] 



ties with which the milk came subsequently in contact. 

 Redness of milk due to the mixture of blood from inflamed 

 udder is a different thing altogether, where the redness is 

 visible at the time of milking. 



1.306. There is not one bacillus only which curdles milk 

 and causes milk-sugar to split up into lactic acid and carbon- 

 dioxide gas. The curdling itself could be caused by any 

 acid, as in the preparation of chhdna out of boiled milk, and 

 also by certain enzymes, e. g. t rennet, and the milk of sheord. 

 The principal bacteria causing curdling are : (i) The bacillus 

 lactis of Hueppe which is a thick short rod growing best at 

 temperatures varying from 50 to ii3F, the optimum temper- 

 ature being 95F. This is the bacillus that produces the most 

 uniform dahi which does not liquify readily as some dahis do. 

 (2) The bacillus lactis of Grotenfelt produces alcohol as well 

 as lactic acid and carbondioxide gas. (3) Bacterium acidi 

 lactici, (4) Micrococcus lactis I and II of Heuppe, (5) 

 Micrococcus acidi lactici, (6) Sphserococcus acidi lactici, (7) 

 Bacterium limbatum acidi lactici, (8) Micrococcus acidi lactici 

 of Krueger, and (9) Streptococcus acidi lactici of Grotenfelt, 

 are other microbes also which produce lactic fermentation in 

 milk. As none of these are known to develop spores, they 

 do not require very much heat to kill them. A temperature of 

 I58F is sufficient to kill them and then a pure culture of bacillus 

 lactis of Hueppe may be used for obtaining first class dahi 

 and first class butter, such as are ordinarily obtained by some 

 gowdlds in some districts. 



1.307. When dahi is kept too long, a visible mould deve- 

 lops on the crust. This is the Oidium lactis, which is a higher 

 fungus consisting of hyphae and spores. 



1.308. Sliminess and stringiness of dahi are caused by 

 various fungi many of which have been studied. 



1.309. Cheese. Besides the lactic ferments there are the 

 cheese or casein ferments which break down the casein of 

 milk. These ferments being mostly spore forming ferments 



