THE HARD CHEESES. 2OI 
and inoculated into the milk, and the use of commercial starters is 
also rapidly growing. It is interesting to find that the types of lactic 
bacteria that are useful in butter-making are not always satisfactory 
in cheese-making. Bacteria that give a fine flavor and aroma to 
butter may produce a bitter taste with ruinous results when used 
in cheese-making. The use of starters in the cheese industry seems 
to be firmly established at the present time and is practically sure 
to extend, for it is one of the methods of safe-guarding the cheese 
against undesirable fermentations. 
"Faults" in Hard Cheese. The value of a cheese is wholly 
dependent upon the success of the ripening. A great loss is entailed 
upon cheese-makers by an imperfect ripening, resulting from a 
variety of defects called faults. These are commonly due to the 
growth of certain kinds of microorganisms which do not grow in 
normal cheeses. The injury resulting to the cheese may be only 
sufficient to make the cheese a little "off" in flavor but still passable, 
or it may be so great as utterly to ruin the cheese and make it a total 
loss. Some of these faults have been traced to their sources and 
will be considered under the following heads : 
Swelled Cheese. This is, perhaps, the most common fault. 
It is due to the development of a considerable quantity of gas which 
fills the curd full of holes and causes it to swell and 
lose its shape. Sometimes the holes are extremely @ //O \ 
numerous and small, and sometimes they are fewer ^0 
but of larger size. In any case they are undesir- 
able. Even good cheeses are apt to show some gas 
holes, but so few as to do no special injury. Some- bacillus causing 
times the gas is so abundant as to cause the s ,% c l} c ^, heese 
(B. Shaffen). 
cheese to burst, in which case it is completely 
ruined. Between these extremes are all kinds of intermediate 
grades. The development of the gas is accompanied by an unusual 
fermentation and an unpleasant taste and smell. The cause 
of the trouble is the development of gas-producing bacteria. Several 
different species are known which have this power of developing 
gas in great quantities in the ripening cheese (Fig. 43). Most of 
them, perhaps all, belong to the type which has been referred to 
