PASTEURISATION 533 



liquid food, and one grain per pound in solid food, its presence in 

 all cases to be declared. 



2. That the use of any preservative or colouring matter what- 

 ever in milk offered for sale in the United Kingdom, be constituted 

 an offence under the Sale of Food and Drugs Acts. 



3. That the only preservative which it shall be lawful to use in 

 cream be boric acid or mixtures of boric acid and borax, and in 

 amount not exceeding 0-25 per cent expressed as boric acid. 

 The amount of such preservative to be notified by a label upon 

 the vessel. 



4- That the only preservative permitted to be used in butter 

 and margarine be boric acid or mixtures of boric acid and borax, 

 to be used in proportions not exceeding 0-5 per cent expressed as 

 boric acid. 



5. That in the case of all dietetic preparations intended for the 

 use of invalids or infants, chemical preservatives of all kinds be 

 prohibited. 



6. That the use of copper salts in the so-called " greening " of 

 preserved foods be prohibited. 



7. That means be provided, either by the establishment of a 

 separate court of reference or by the imposition of more direct 

 obligation on the Local Government Board, to exercise supervision 

 over the use of preservatives and colouring matters in foods, and 

 to prepare schedules of such as may be considered inimical to the 

 public health. 



Pasteurisation and Sterilisation 



The chief facts respecting the effect of heat on milk have 

 already been stated, and reference has also been made to the 

 bactericidal properties of heat in relation to pathogenic organisms, 

 -uch as tubercle bacilli. Here it only remains to discuss briefly 

 :he application of heat to milk as a protective agency, in the 

 methods of pasteurisation and sterilisation. 



Pasteurisation was introduced, as the term denotes, by Pasteur, 

 who recommended heating to "jo^ C. for a short time, as sufficient 

 to destroy all the chief forms of adult bacilli. The thermal death- 

 point of almost all organisms, pathogenic or benign, is below 70" C. 

 The spores were left untouched by such a temperature, and on 

 cooling of the milk would naturally commence development 

 Consequently " intermittent " and " continuous " pasteurisation was 

 recommended, alternating heat at 70° C. with a cool period 

 jBhiring which the spores might develop and then be killed at the 



