3 o 4 MILK AND ITS HYGIENIC RELATIONS 



The term sterilised is more frequently used to denote a milk 

 which has been subjected to a somewhat prolonged boiling either 

 at a temperature of 100 C. or as much below it as occurs when 

 the milk is merely surrounded by boiling water. Prolonged boiling 

 at this temperature does not, however, destroy spores nor certain 

 of the living organisms found in milk. Only a relative degree of 

 sterility is reached, although the term ' sterilised ' is very frequently 

 employed. It is often impossible to determine from the literature 

 when the term ' sterilised ' is used whether a prolonged heating has 

 occurred, or whether it is used loosely to denote a pasteurisation 

 in which the temperature has been allowed to approach that of 

 boiling-point. 



The French literature deals very frequently with milk to which 

 the term ' sterilise ' is applied. This usually, however, does not 

 imply that the milk is absolutely sterile, i.e. that it has been super- 

 heated, but that it has been kept at a high temperature, although 

 perhaps below boiling-point, for a considerable period. Used in 

 American literature, however, it appears usually to denote a super- 

 heated milk which will presumably keep for some days at least, if not 

 longer. 



In Germany the term is variously used, but appears more 

 usually to denote merely boiled milk. 



In this country it is difficult to suppose that there is any rule 

 at all as to terminology, and in determining the process which has 

 really been used it is necessary to ascertain the method employed 

 and the length of time of heating. 



DRIED MILK 



Of recent years a further method of heating milk has been used 

 as a result of which the solids in the milk are obtained in the form 

 of a powder. Several methods are used, two of which are described 

 in Appendix F. 



REFERENCES IN CHAPTER XIX 



AYERS AND JOHNSON, ' A Study of the Bacteria which Survive Pasteurisation/ 



U.S. Dept. of Agriculture, Bull. 161, 1913. 

 DELEPINE, ' Report to the L.B.G. upon the Effects of certain Drying and 



Condensing Processes used in the Preservation of Milk upon its Bacterial 



Contents,' L.G.B. Reports, New Series, No. 97, 1914. 

 FLUGGE, 'Die Aufgaben und Leistungen der Milchsterilisierung.' Zeit. f. 



Hyg. 1894, xvii. 272. 

 V. FREUDENREICH, ' Sur la pasteurisation du lait dans 1'alimentation de 



1'enfance,' Rev. gin du Lait, 1904-5, iv. 433. 

 JOHNSON. See Ayers and Johnson. 

 MCCLINTOCK AND PENNiNGTON. Quoted by Eastwood, Report to the L.G.B. 



New Series, No. i, 1909. 



MEDICAL OFFICER Article, 'Pasteurisation, So-called,' gth Oct. 1915. 

 ROSENAU, ' Pasteurisation/ Dept. of Hygiene, Washington, Bull. 56, 1912. 

 SAVAGE, Milk and the Public Health, 1912, p. 383. 



