SOFT CHEESES. 203 
Rusty Spot. This is characterized by rusty, red spots on the 
outside and, indeed, not infrequently throughout the whole cheese. 
The cheese loses its value and may in the end become quite ruined 
if the trouble develops sufficiently. The cause is a bacterium, B. 
rudensis. 
Many other "faults" may be recognized as interfering with the 
normal ripening. Black spots and blue spots are sometimes noticed 
and a variety of "off" flavors that cannot be described. In regard 
to all of these troubles the cheese-maker has the serious disad- 
vantage that they cannot be discovered until the ripening has be- 
come partially completed, and then it is too late to apply any 
remedy. The method of meeting them must be by prevention 
rather than cure, and after an improper ripening has begun, practi- 
cally nothing can be done to stop it. By cleanliness, by frequent 
sterilization of vats, and by the use of vigorous lactic acid starters 
much can be done to prevent these troubles, but there seems to be 
no remedy after the improper ripening has begun. A vigorous 
lactic acid starter will go far toward preventing gassy cheese, and 
the slimy whey used in the Edam cheese prevents it in that particular 
brand. A regulation of temperature during ripening will also aid, 
since the gassy organisms grow best at higher temperatures, while at 
a lower, about 60, the common lactic acid bacteria are the more 
vigorous. When to these two suggestions of vigorous starters and 
cool temperatures we add great care in keeping all milk-vessels clean, 
and in sterilizing frequently by steam, we have included practically 
the only methods in use of much significance in guarding against 
the various cheese faults. 
SOFT CHEESES. 
The essential difference between a hard cheese and a soft cheese 
is that the latter has a very much higher percentage of moisture. 
To bring about this condition, the method of manufacture is de- 
signed to retain the whey in the curd. After the milk is curdled the 
^curd is sometimes dipped out directly into forms provided with 
holes in their sides, through which the whey drains naturally 
