BACTERIA IN FOODS 22/ 



43 per cent. ; the other point is that the whey left in the 

 curd shall contain, developed in it before the curd is put in 

 the press, at least I per cent, of lactic acid if the cheese is 

 required for sale within four months, and not less than 8 

 per cent, of lactic acid if the cheese is to be kept ripening for 

 a longer period. 



3. The quality of the cheeses will vary with the quality 

 of the milk from which they have been made, and propor- 

 tionately to the amount of fat present in that milk. 



4. " Spongy curd " is produced by at least five organisms, 

 and one of these is responsible for a disagreeable taint found 

 in curd. They occur in water. Hence the desirability of 

 securing clean water for all manipulative purposes, and also 

 for the drinking purposes of the milch cow. 



5. The fact that certain bacteria are found in certain 

 localities and dairies is due more to local conditions than to 

 climatic causes. 



It is needless to remark that these conclusions once more 

 emphasise the fact that strict and continual cleanliness is the 

 one desideratum for bacteriologically good dairying. That 

 being secured in the cow at the milking, in the transit, and 

 at the dairy, it is a comparatively simple step, by means of 

 pasteurisation and the use of good pure cultures of flavour- 

 ing bacteria, to the successful application of bacteriology to 

 dairy produce. 



Methods of Examination of Milk : 



i . Preparation of Microscopic Slides. This course might 

 at once occur to the mind as the first to adopt in searching 

 for bacteria in milk. Devices have accordingly been pro- 

 posed for saponification previous to staining. Some recom- 

 mend the addition of a few drops of a solution of sodium 

 carbonate; others use methylene blue and chloroform. 

 But, whatever plan of staining is adopted, this method of 

 examination in its simplest form is in no degree a criterion 

 of the bacterial content of a large quantity of milk. 



