REVOLUTION IN THE DAIRY INDUSTRY.

Press, Volume LIV, Issue 9763, 26 June 1897, Page 9

REVOLUTION IN THE DAIRY INDUSTRY.

By H. P. Camkron-Homustrom. Writ-test for thk Webk_y Press. No more striking illustration of the importance of the linking of science with practice can be adduced, than is to be found in the discoveries made during the last few years in bacteriology of milk and in the practical application of the knowledge thus obtained to the improvement of dairy procedure. By the aid of the powerful lever thus afforded, the countries of Scandinavia have been enabled to obtain a position in the butter market of the world from which it will be extremely difficult to dislodge them, and an explanation of the way in which Sweden and/Denmark have thus captured the British butter market is not far to seek. For some years past great attention has been given in Scandinavia to theorganisatiouof thedairy industry, and to the developmentof its scientific relations generally ; and now three-fourths of the butter which is exoorted from these countries is made from milk and cream that has been pasteurised and then inoculated with a special germ, that has been found to give a product of high aud uniform quality. The movement in the improvement of butter making was commenced in Sweden in 1891 by Dr De Laval and I)r Engstrom, and at the Agricultural Show at Randers, in Danmavk, the first pflsteUvisstion plant was exhibited by th« D* Laval Company, and the process was immediately taken up in Denmark by Professor Storch, in Germany by Professor Wsigmann of Kiel, aad in the United States by Professor Conn, Messrs H. Russell and E. L. Farrington.

It is to these experimentalists that we chiefly owe the progress which ha 3 been lately made in the application of bacteriology

> to the practical work of butter-making, the 1 foundations of which had been previously ' laid by the celebrated pasteiu- Duclane and . Professor Nocarfc at the Kcole Vetinaire „" i Alport, France, and by Hueppe, Adametx, and a host of other workers in Germany. In Britain, with the exception of the , valuable work of Mr F. Y. Lloyd, very little has been done to advance the knowledge of the dairy aspect of bacteriology, but recently an important paper on bacteriology of mirk and the effects of ptwfeenrrsstron was read before the Royal Society at Edinburgh by Dr. Hunter-Stewart." Gknxrai, Rksfi.ts oy Invksttoatioxs. The result- 6f these Various investigations may be conveniently summarised ia the following propositions :— 1, That the chang-s which milk undargoe« from the moment that it leaves the udder of the cow are very complex in their ohatfaeter, and entirely dependent oft the influences to which the milk may Be sUbse- j qnently exposed. j 2. The deterioration of the milk commences at tne moment it leaves tke udder, partly by exposure «o filth parfc_ok» of all kind!, which are Hosting in the a!r, especially ia th- ease of cowe milked in the stall, ami partly -from tuberculosis in tbe udder, further J impurities b-ing derived from the teat aad I irom the bands of the milker.

3. That, broadly spe&ktng, the gems derived from these v_rraua su_4-o«4 nvty - be _lVt_etltnt_ twtJ C-tegoTieS—{&} those wliich tend to prod*** «onri6g<tt*l toefcuse eventually coagulation of .fie casein of the milk nto curd, anft [h) thoi« which We _nopposite eftect, HUlaly to felidw the i£ittk alkallOe, neTE to coagulate the casein, and theti to dissolve Up the ourd s# farmed, by a process which ts known as £i-pto_>B_tid_ from its analogy to similar ob«nge_ which are effected under tt* IbSuetice of t_te

intestine juice* in the alimentary canal ol the mammalia. Where the milk does not sour, but where curd is formed in it, the process of peptonisation thus initiated goes on with great rapidity, and soon passes into putrefaction.

•S. Like life of all otter kinds, micro-org-aisnis can only live within certain limits of temperature. That by exposing milk thus contaminated to an appropriate temperature the whole of these decomposing germs can be destroyed and the milk rendered as pure as, and in some cases even purer than, it came from the udder of the cow ; for not only are the ordinary acidifying and putrefactive germs thereby destroyed, but also those of specific infections, such as that of tubercle bacilli, and of infections allied to if not identical with those of scarlet fever and diphtheria, and possibly of other infectious diseases, which there is good reason to believe are derived from affection of the cow's ndder.

5. That milk thus artificially purified or pasteurised ia not merely deprived of ingredients which cause its rapid deterioration or render it more or less unfit for food, but that if placed when in this condition in vessels in which it can be preserved airtight it may be kept for a very considerable period without any serious change, and is thus " protected " against injurious influence until it is required for consumption.

6. That, apart from this advantage which pasteurised milk offers as an article of food the destruction of gorm life by the method indicated materially improves it for dairy purposes, by removing from it ingredients which are full of trouble to the makers of butter and . cheese, to say nothing of greatly facilitating the ordinary handling of ao perishable an article by those who supply it for human consumption. Milk thus freed from the mass of prejudicial germs with which it is ordinarily infected lends itself with ease to the reception of those special germs which are essential to the production of high-class butter and cheese, in regard to uniformity of quality, delicacy of flavour, and keeping properties. In the case of butter especially there is ample evidence that an article made on these lines is so unquestionably superior to one produced in the empirical and haphazard way hitherto alone available; that the maker who will manufacture his butter on these lines will be as sure of commanding the market for it as the man who in any other industry produces a firsfc-class and uniform article ia sure of driving out of it an inferior product.

7. Just as heat is effective in checking fermentative changes, so also is extreme cold. There is a difference, however, iv these two methods. Heat checks fermentative change by killing micro-organic life; cold checks it, as a rule, by merely suspending its activity. It has been found, for example, that spores of micro-organisms can stand a very low temperature. If milk, however, be kept at 70° Far hi no development of micro-organic Irfe will take place, moat of them, it may be said, hewever, do not develop at a temperature under 50° Farh.

8. In considering the action of heat on bacterial life, it should be noted that much depends on the length of time during which the heat is applied. Thus the application oj a certain temperature for a longer time, may have a fatal effect. Again, a very effective means of killing all germ life and avoiding the use of very high temperatures, ia the application of the method known aa" intermittent" sterilisation, which consists in heating the milk to a temperature judged to be fatal for adult germ life, then cooling the milk down to a temperature favourable for the development of any spores which may have escaped destruction, and after a considerable interval again heating the milk to the previous temperature, this-being repeated for a number of times, and precautions being taken to prevent any access of germ life during the process. By such a method milk may be ultimately sterilised. It need scarcely be pointed out, however, that such a process is very tedious and cumbersome. Putting it aside, then, as not suitable, we may say that the only way to make sure of j obtaining absolutely sterile milk—that is, milk absolutely free from germ life—is by heating it at boiling temperature for several hours. What is pAsrar/RrsATioN? Pasteurisation is not, as many people suppose, a method for preserving milk to prolong its keeping qualities. Pasteurised milk will ordinarily keep longer than unpasteurised, bnt the main object sought for is the destruction of germs already in the milk, so that if it is kept from the iair and no foreign substances allowed to* enter, it is practically pure. The important feature of the operation is to secure tbe exact temperature. A iew degrees too low will not do the work, and if heated too high the milk loses its original consistency, coagulates the albumen and has a cooked taste. In towns where the milk is often adulterated, pasteurised milk presents the double advantage of being better than unpasteurised and perfectly free from pathogenic semis. Experiments made on this subject demonstrated that the typhoid bacilln iss destroyed at 70° C., that of cholera at 62° to 68* C, and so on. In a word, none of the disease germs found in the milk resist the heating for twenty minutes at 70° C. There seems to be a general mi.-Hinderstanding as to what pasto_ri«vtion really is, pasteurisation and sterilisation being generally confounded. Pasteurisation of milk is first, the employment of heat, followed by effective cooling. The cooling is just as indispensable as heating. On the one hand, heating destroys microbes, bacteria, tubercular-bacilli, cocci, | &c, and even neutralises the first grade of spores for about three days; on tbe other f hand, cooling checks the lower grade of spores, and stop 3 the action caused by butyric acid, and also removes the heated flavour and restores the chetniea! composition of milk—deranged hy~ the .Seating—to its original consistency. Pasteurisation, as generally carried out, consists of submitting milk for longer or shorter period*, to heat ranging from 150 and 180° Faftr. I give 180* Fahr. as the limit because it has been proved that temperatures above this point impart to the milk a permanent boiled flavour. But this flavour is merely temporary, and disappears when the milk i_ oookd to 55" Fabr. Originally the Irani- of pasteurisation was given to a process introduced by Professor Pasteur at Lille, Normandy, for the prevention of Certain defects in wine and beet, which process consisted ol heating these liquids to about 17l3 a Fahr. . But the task of pasteurising wine and beer i# _*«fer than of pasteurising milk, as the former liquids by their alcoholic contents, &<*., do not form such a good feedaug gcouhct for -oi-robe* as

doe 3 milk. .Therefore special apparatus for pasteurising jrnilk has been invented, and it requires special knowledge not alone of dairying in general but of chemistry and bacteriology as well to manage the pasteurisation of milk and cream thoroughly. The researches undertaken on the continent make it certain that we are able to prevent the growth of the microbes in milk that leadsto its decomposition. T-UB RaVOIitTION IN THE USTJAX, WoaKIKO Plan*. Anyone who will reflect upon what changes these investigations indicated really mean will see that they practically amount to a complete revolution in the dairy industry, and at the same time it will be a very great encouragement for far off producers from the English market. This revolution is as great in its way as that which was introduced by the invention of the separator. It is not unlike in its character to that which, in the allied industry of brewing, has extinguished the practice of home-brewing, and even the numerous small breweries that in the past have catered for the somewhat rude laste of the public by the production of beers that were as variable in their character as the sources from which thej' were produced. It has thrown the trade into the hands of large concerns, carried on with all the advantages which the command of capital, good business management, and scientific precision can give them, and brewing an ale that is uniform in quality, digestible in character, and delicate in flavour, and m different in all these regpects from the muddy, intoxicating beverages that our fathers consumed, as the gilt-edged, choicest butter of to-day differs- from the salt, high-flavoured and badly-keeping article that is still turned out from many a farm dairy and factory. In view of the importance of the changes that are thus silently but inevitably revolutionising the dairy industry, it may be well to examine more fully the several stages of knowledge at which we have arrived, as numerically indicated above, since we will thus be able the better to appreciate the lines of practical work which will be needed. Pasteurisation in Bottes. Making. The practical importance of pasteurisation in butter-making obviously depends not only on its effect in ridding the milk and cream of objectionable micro-organisms, but upon the scope that it affords for planting the soil thus cleared of weeds with the most appropriate seed. In this direction the work has been done, and we find that the result of pasteurising milk and sweet cream and then churning was to produce an article of uniform quality and of good keeping properties, but defioient in the characteristic aroma which makes high-class butter so much appreciated. After further experiments in connection with the various bacteria fonnd in cream, it was ascertained that the desired aroma must be cultivated during the ripening process. This aroma was produced by the decomposition of the sugar of the milk by the bacteria in question, and lactic acid was at the same time produced by them. The Advantages of Pastjtomsa_ion. j The advantages claimed for pasteurisation are:—l. A more uniform produce both ia texture, flavour, and of a high aroma. 2. The butter has better keeping qualities, as it stops the germinating power of bacteria, and in most eases kills them and spores of the first grade. 3. It prevents rancidness in butter, and to a certain extent removes it from milk in which it has already appeared. 4. Thus whilst detaching the gases it acts as a purifier, and produces more uniformity in cream made from milk delivered in rariou* , conditions. 5. It wiH, during several months' storage, preserve perfectly the butter without preservatives and excessive salting, through the absence of bacteria in vital action. 6. That pasteurised butter stored for a length does not get stale, and consequently is more desirable for table use. Space will not allow of more than a genera, reference to the process. Practice with Skill in the employment of pasteurisation, and an effective cooling plant,, will soon convince the careful worker that the value of the method and treatment rests upon too sure a basis to be further questioned,