CREAM-RIPENING 211 
so that when cream is ripened properly, it contains few other 
germs besides those which produce lactic acid. 
From the above it will be seen that there are practically two 
overlapping periods in the bacterial changes during the ripening 
of the cream, and especially is this so in the ripening of raw 
cream. The first includes the period when all the different 
varieties of germs grow, and the second includes the period 
when only the lactic-acid-producing germs grow. It is, there- 
fore, maintained that before the churning takes place the 
ripening of cream should be carried on to such an extent that 
the lactic-acid germs only predominate. Dr. Storch, who has 
made a detailed study of this, asserts that milk and cream 
both have a rather undesirable flavor at the beginning of its 
ripening period, while in the latter stage of the ripening period 
it takes on a pleasant, clean, acid taste. 
The number of germs, and the relative number of acid-pro- 
ducing germs in the cream when ripened, is as shown in the 
following table: * 
i mber Aci Per r Non- (er 
Date erty of Number per c.c. | ee Sed ¢ ent N Pelee plan Ne 
acl 
Feb. 11 | Fine 280,000,000 | 257,000,000 | 92 | 22,400,000 | 8 
Jul: 18° | Poor eases ssaeessuhsvosmes es ese | percefeawacs Bae ce 19 
‘© 30 | Excellent | 3,002,000,000 | 2,851,190,000 | 95 [150,810,000 | 5 
Aug. 11 | Good 1,107,000,000 | 1,012,072,200 | 91.5) 94,928,800 | 8.5 
Sep. 3] Fair 1,027,000,000 | 955,110,000 | 93 | 71.890.000 | 7 
os 5 | Good 2,007 958,000 | 1,827,370,000 | 91 {180,588,000 | 9 
Oct. 28 us 392,958,000 | 385,098,840 | 98 7,859,160 | 2 
«30 si 393,700,000 | 381,889,000 | 97 11,811,000 | 3 
Eckles found that when good-flavored cream is ready for 
churning the number of bacteria per cubic centimeter varies 
from 380,000,000 to 3,000,000,000. Of this number the acid- 
producing bacteria constitute from 91% to 98%. 
Chemical Changes.—The changes in cream during the process 
* Bul. 40, Iowa Experiment Station. 
