Page:Popular Science Monthly Volume 58.djvu/161

Rh salting, oiling and rubbing the surface. But bacteria appears to have, if not the chief share, certainly a large share in the production of the flavors. Experiment has shown that bacteria grow abundantly in the cheese during the ripening; that some species of bacteria can produce in milk flavors similar to those found in the ripened cheese; that treatment which prevents the growth of bacteria prevents also the development of the flavors in the cheese. Further, in the manufacture of the famous Holland cheese (Edam cheese), the cheese-makers have learned that by planting certain species of bacteria in the milk out of which the cheese is to be made, the ripening may be hastened and made more uniform. In Holland about one third of the cheese is made by thus inoculating the milk with 'slimy whey,' which is simply a mass of whey containing in great numbers certain species of bacteria. These facts indicate strongly that the bacteria are agents in this flavor production. But, at the same time, the subject has proved so difficult of investigation that our bacteriologists are as yet by no means satisfied with the results. Indeed, they differ very decidedly in their conclusions. Some believe that the ripening is chiefly due to the same class of bacteria which produce the souring of milk; others think it due to bacteria which produce an alkaline rather than acid reaction; some believe it to be a combination of the two, while others, again, decide that cheese ripening is a long process, involving the action of many species of bacteria and perhaps of molds as well. The difficulty lies in the fact that, since the ripening is a long process, many species of bacteria are found in the cheese at different times. This makes it almost impossible to determine what is the cause of the ripening and what is only incidental.

It will be readily understood that the problem of cheese ripening is one most eagerly studied by bacteriologists. The immense financial interests involved in the discovery of definite methods of handling the manufacture and the ripening of cheese would insure this, entirely independently of any scientific interest. A very large per cent, of cheeses are ruined by improper ripening, and the discovery of methods for preventing this loss would mean the saving of millions of dollars annually. Moreover, many favorite cheeses have hitherto been capable of manufacture only in certain localities, probably because these localities are filled with the peculiar species of micro-organisms needed for their ripening. If it were possible to cultivate the requisite organisms and use them for artificial inoculation, it might be possible to manufacture any type of cheese anywhere. Already it has been found that new cheese factories may sometimes be stocked with the proper microorganisms by rubbing the shelves and vessels with fresh cheeses imported from localities where the desired variety is nominally made. It is evident that immense financial interests may be involved in the proper