PRESENT STATUS OF THE PASTEURIZATION OF MILK 21 
De Jong and De Graff (40) also describe seven strains of Escherichia 
coli which survived 149° to 152.6° F. for 30 minutes in milk. They 
concluded from then results that the presence of E. coli in pasteurized 
milk could not be taken as indicating improper pasteurization. Gage 
and Stoughton (26) showed that the majority of thermal death points 
of E. coli were from 132° to 140°. The temperature at absolute death 
point showed the presence of heat-resistant organisms in this group. 
Zelenski (66) also found a strain of E. coli which survived unusually 
high temperatures, while Tanner (56) states that in view of the 
results he obtained, it seems fan to assume that E. coli in concentra- 
tions in which it occurs in milk, would be destroyed by exposure to 
62.8° C. for 30 minutes, yet there is the possibility of encountering 
resistant strains or cultures containing some resistant cells. 
Beavens (11, p. 100) states: 
Reviewing the experimental evidence and the possible biological factors present 
in pasteurization, the statement can be made that organisms of the Escherichia- 
Aerobacter group may survive in milk that has been properly pasteurized. 
Therefore, the coli test can not be used as a true index of proper pasteurization. 
This statement opposes the findings of Swenarton (55) and Jenkins 
(39) but confirms those of De Jong and De Graff (40), Avers and 
Johnson (7), Shippen (53), and Hammer (31). 
The colon test as an index of the effectiveness of the process of pas- 
teurization is therefore complicated by the ability of certain strains 
to survive a temperature as high as 142° F. for 30 minutes and to 
develop rapidly when the pastuerized milk is held under certain tem- 
perature conditions met during storage and delivery. Consequently 
the presence of a few colon bacilli in pasteurized milk under ordinary 
market conditions does not necessarily indicate that the milk was not 
properly heated. The presence of a large number of colon bacilli 
immediately after the heating process indicates that the milk has not 
been heated to 142° for 30 minutes, and the colon test, properly ap- 
plied, should be valuable in control work. Fermentation tubes can 
be used for making the test, but when gas formation is noted the pres- 
ence of colon bacilli should be demonstrated by further tests. Often 
anaerobic spore formers that survive pasteurization and give the 
typical fermentation-tube test are encountered. 
PASTEURIZATION AND VITAMINS 
The discovery of vitamins within recent years has shown how im- 
possible it is to estimate nutritive requirements solely in terms of 
digestible protein, carbohydrates, fat, and inorganic salts. Little is 
known of the real chemical nature of vitamins, but they are necessary 
for normal growth and health. 
Six vitamins are now recognized (54). They are known as vitamin 
A (soluble in fat); vitamin B or Bi (soluble in water), often called the 
antineuritic ^tamin; vitamin G or B 2 (soluble in water), the antipel- 
lagric vitamin; vitamin C (soluble in water), the antiscorbutic; 
vitamin D (soluble in fat), the antirachitic; and vitamin E (soluble in 
fat), the antisterility vitamin. Vitamins A and G are abundant in 
milk, while vitamin B and vitamin C are present in small quantities 
only. Vitamins D and E do not occur in milk in sufficient quantities 
to make it an important source of these vitamins. 
