DR VIETH ON CHEESE-MAKING.

Otago Witness, Issue 1893, 2 March 1888, Page 7

DR VIETH ON CHEESE-MAKING.

In his paper on "Micro-organisms, and' their Action on Milk and Milk-products,' quoted from last week, Dr Vieth points out that the main precaution to be observed in the keeping of milk and the making and preservation of butter must be the exclusion of objectionable microcosms as much as possible, in order to avoid the decompositions and deteriorations they involve. He proceeds to state: "With cheese the case is widely different. Cheese is a product of fermentation from beginning to end. Not only is it a fermentative process by which the caseine of milk is coagulated and thereby separated from the watery part, but those changes which are termed ripening, and which virtually consist in transforming curd into cheese, are decompositions brought about by micro-organisms — i.e., true fermentation." But a certain kind of micro-organism induces a particular fermentation with definite products, while other kinds give rise to other fermentations, as recognised by the production of totally different compounds. Curd, then, though, like milk, apparently a good soil for the majority of micro-organisms, is undoubtedly better suited to some than to others. The former will under favourable conditions develop and crowd out the latter. By changing the conditions they may become favourable to another kind again, and the operator has it — to some extent — in his power by his mode of operation to encourage the development of one or of another kind of micro-organism, and theieby produce cheeses of very different character.

Taking it for granted, as there is good reason to do, that the characteristic qualities, especially with regard to flavour of the many different kinds of cheese, are the consequences of the action of different kinds of micro - organisms, the practical question arises, Are all these micro-organisms present everywhere, so that the manufacture of a special kind of cheese with all its characteristic qualities is possible at any place, provided the conditions favourable to the development of the ferment peculiar to the cheese in question are well understood ? Dr Vieth says : " This question has been negatived, not only by abstract theory, but by practical experience. It has been contended that with due skill and knowledge cheeses similar in many respects to Stilton, Camembert, Neufchatel, and the like, can be made anywhere, but that they will be imitations only, distinguished from the genuine article in some particular point of flavour as long as they are made outside the district in which they have been made for generations. The explanation given is this : In a district in which a certain kind of cheese requiring fer its production the action of a special kind of micro-organism has been carried on for many years, it is to be expected that such micro-organisms will be present in abundance, while in other districts they may be very rare or even entirely absent. The success in making a foreign cheese would depend then not only on the introduction of the peculiar mode of operation, but also upon the importation oi a particular kind of ferment or ferments. While it may be an easy matter to make a particular kind of cheese at any place because it only requires ferments which are widely spread and met with anywhere, it may be a matter of impossibility in some i localities to produce the cheeses whose '

characteristic qualities are caused by rare organisms." It is necessary here to observe that this question — the making of cheese of special kinds— was the subject of a lengthened controversy in the Home agricultural journals some 12 months. On the one part it was contended that it was impossible to make Stilton cheese of the distinct and characteristic flavour for which it is prized outside of the district which has been famed for its production. Professor Long and other experts disputed this assertion, and maintained that provided the conditions were favourable, and the known details of the process of manufacture observed, Stilton cheese could be made by a skilled operator anywhere. It should however be further stated that some Camcrabert cheese prepared under Professor Long's supervision was exhibited at the British Dairy Farmers' Show, and failed to elicit the approval of the judges. Ur Vieth discusses at some length the question of moulds, with the appearance of which on cheese all makers are familiar, lie explains that moulds are larger organisms than other microcosms previously alluded to, and belong to the vegetable kingdom. At different stages of ripening these moulds assume different colours, and manufacturers are thus enabled to judge by " the successive appearance of the different moulds, the regular progress of the ripening process, and the stage the cheese is in." Some of these fungoid growths are desirable, while others are much dreaded and despised. " A micro-organism, for instance, resembling yeast in its shape and development, infesting certain kinds of cheese, and producing more and more spreading spots of a deep black colour, reduces the value of the cheese to a great extent, if it docs not make it altogether unsaleable on account of its affectiug the taste." On the ovher hand certain moulds in special varieties of cheese are considered indispensable. Roquefort is a cheese presumably made entirely from ewes' milk in a very limited district in France. This cheese contains veins of green mould, and so much is it thought necessary that the latter should be present that it is specially prepared. It is grown upon bread made of wheat or barley and incorporated inlo the curd of which the cheese is formed. The growth of the mould is further encouraged by piercing the cheeses at regular intervals while they_ are kept to ripen, and theieby admitting air to the interior. Roquefort'has a characteristic flavour, as have Stilton and Gorgon zola, also cheeses which contain the green mould. How far the fermentations going on in these cheeses are similar has not been ascertained.