1 May, 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 345 
The action of this chemical ferment can best be understood if we compare it 
with that of other well-known ferments, like pepsin and trypsin of the stomach 
and pancreas, that are concerned in the digestion of food. This milk ferment is 
more closely related to trypsin, the digestive ferment of the pancreas, inasmuch 
as it acts more rapidly in neutral solutions, and is quickly affected by the 
presence of free acids. These ferments that dissulve proteid substances, 
such as white of an egg, lean part of meats, casein of milk, are intimately 
concerned in preparing the food so that it can be absorbed and assimilated by 
the tissues of the body. While these chemical ferments ate not alive, and 
therefore incapable of reproduction, still they possess many characteristics that 
ally them to living substances. Their action is retarded by cold, and if the 
temperature exceeds a certain point their activity ceases entirely. 
This explains why a’variation in temperature exerts such a marked effect 
on the rate of ripening of the cheese, If cheese is cured at relatively low 
temperatures, the digestive change, due to the ferment, is very much retarded, 
whereas an increase in temperature, that would occur under ordinary conditions, 
hastens very much the course of these changes. If cheese could be kept at a 
temperature of 160 degrees to 170 degrees Fahr. without injuring its- texture, 
we would find that the ripening or “breaking down” would be inhibited, 
because the milk ferment would be destroyed under these conditions. ; 
The production of the peculiar flavours that characterise the different 
kinds of cheese is undoubtedly due to the action of bacterial causes, at least, in 
part. But our knowledge concerning the details of this action is yet so vague 
that it would be presumption to forecast what future investigation will disclose. 
In a number of cases, however, the production of the peculiar flavours is so 
directly associated with the development of living organisms that the relation 
may already be said to be securely established. 
This is seen particularly in the case of the mouldy cheese, such as the 
Roquefort of France, the Stilton of England, and Gorgonzola of Italy. These 
cheeses obtain, in large part, their characteristic flavours on account of the 
presence of various moulds that develop in their interior. Thus the ordinary 
green mould that is so common on bread and other substances that are kept in 
a moist atmosphere, gives to some of these cheeses the delicate and peculiar 
flavour for which they are so highly prized. These moulds do not belong to 
the bacteria, but are fungi. ‘They are, nevertheless, living ferments, and 
therefore we may say that the production of these flavours is due to biological 
causes. ; 
The manufacture of these different varieties of cheese has grown up entirely 
as the result of empirical knowledge, but it is curious to see how cheesemakers 
unwittingly employ means that are precursors of modern bacteriological | 
methods in their work. For instance, in the Roquefort cheese, in order to 
thoroughly incorporate the desired mould into the substance of the cheese 
itself, the maker takes a lot of bread that has been most carefully allowed to 
mould, and mixes this with his curd, so that the mould germs are introduced 
throughout the whole mass of the cheese. ‘This is a rough species of inocu- 
lation. By experience he has also found that the mould sometimes does not 
develop luxuriantly, and, in order to induce copious growth of the fungus, 
some of these mouldy cheeses are pricked with needles that penetrate the 
cheeses to a considerable distance. his allows the air to enter, and in these 
minute orifices the threads of the mould fungus can spread more thoroughly. 
MILK-THSTING. | 
Te old system of buying milk by the gallon, regardless of its richness in butter 
fat, has of late years been almost entirely superseded in butter factories and 
creameries by paying each supplier a price which is regulated by the percentage of 
butter fat contained in the milk delivered by him. This method at once does away 
with any temptation to dishonest dairy-farmers to water their milk, and at the 
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