BACTERIOLOGY IN RELATION TO DAIRYING

New Zealand Mail, Issue 1675, 6 April 1904, Page 66

BACTERIOLOGY IN RELATION TO DAIRYING

Mr. Daniel Robb, F.H.A.S., N.D.D., West of' Scotland 1 Agricultural College, Glasgow, delivered a lecture on “Baceriollogy in Relation to Dairying,” at a meeting of the Closeburn Farmers’ Club. We give a few paragraphs. Mr. Robb, after dealing with the more scientific aspect of his subject, went on to refer to sources of contamination, and to indicate practical methods off combating the effects of bacteria. The cow was the most prolific source of contamination, the ducts of the udder being- full of bacteria,. The milk in the udder was itself .perfectly free from bacteria, and at this Time the milk drawn by a syphon direct from the udder would keep for a fortnight quite easily. To further extend the keeping quality of milk, therefore, it was advisable not to put the first washings of the ducts into the milk pail, but to collect these and give them to the pigs. Another source was the dust which gatlier-

eel unon tlio cow’s udder and around the teats', and it was this dust taking bacteria with it that caused trouble afterwards. Precaution siiould be taken to brush the udder and rub it with a piece of cloth to rid it of the dust. Oontani- • ination was often increased, too. by feed--1 ing tlie animals either before or during milking. It was a common practice to dip hands in the milk before milking. Let them imitate nature as much as possible in their methods, but they should not milk with hands dripping wet, because the stuff that dropped off the hands into the milk would toll a tale sooner or later. Recognising the undesirable condition of his milk at times, the dairyman learned to keep his milk vessels scrupulously clean. If he would keep hi.a cow as clean as his horse, use care in and around his byre, and keep the milk at a low tempera,tore, he meed not fear troubles. Bacteriology had taught them that, in order to obtain good sweet milk, it was only a question of sufficient care in avoiding' contamination with infectious germs and the too rapid growth of the common species. Bacteria, when properly controlled however, were a valuableAaid to the butter-maker and chee'se*maker; were direct allies rather than enemies. the ripening op cream. Coming to deal with tlio- question of ripening, the lecturer sam there wag far more butter spoiled by improper ripening than by actual manipulation. The great object of ripening was to develop the peculiar flavour and aroma which was characteristic of the finest product. One secret of successful bucter-making was the ripening of the or-earn—over-ripening and under-ripening were the two worst tilings in butter-making. The question was often asked, liow am: I to know when the proper ripeness is arrived ac-P He could only sa.y that that was only known through experience. Unfortunately the butter-maker was not always able to depend on the ripening. Instead of developing the pleasant flavour of properly ripened cream, unpleasant tastes were developed. These wore due to the different kinds of bacteria in the cream. If the blitter-maker obtained cream with a large number of bacteria capable of producing good flavours, the ripening would be satisfactory, and the butter of high quality. On tho other hand, should the cream contain only species' which produced unpleasant flavours, the character would be inferior and the butter of poor quality. These unpleasant flavours were not so very troublesome in well-kept dailies—lienee the common method of simply allowing the cream to ripen under the influence of any bacteria that happened to be in it usually produced good results. So long as butter was only made for private use, it way of comparatively little importance if there was a slight falling-off in quality; but to-day the but-ter-making industry was becoming more and more concentrated in the large cream- ! eries, and it was matter of great importance to discover some means by which a uniform .high quality could be ensured. FERMENTATION STARTER. had for some time been endeavouring to discover the proper species of bacteria to bring about the development of the proper acid for cheeseunak ing. It would seem that all that was necessary was to obtain species producing high results, and then supply these in large quantities to the butter-maker to inoculate his cream. This would be all very well provided tlio cream was entirely free from bacteria, but as it might contain many species, it Was plain that the addition of a starter or pure culture might not produce the desired result, because the cream would be ripened not by the pure culture alone, but by the pure culture plus all the bacteria originally present. It would be questionable whe- i ther, under these conditions, results | would be favourable, and this method | might not furnish any sure means of getting rid of bad tastes or flavour which had’ come from the presence of foreign j bacteria. It was important to get rid of. the bacteria in the cream before pure cult,uue was added. This could be done by heating it to a temperature of 156 deg. Fahr. for a short time. The subsequent addition of the starter or cream-ripening bacteria would cause the cream to ripen under the influence of the added culture alone. In some places this method nal not been very popular, because heating the cream took a good deal of trouble

and labour. There was still another method of adding bacteria to ensure more advantageous ripening. Ic was simpler and more commonly used. This was the addition of what wag commonly called natural ,starter, consisting simply of taking the milk from the best cow in the herd, allowing it to stand in a warm place until it became sour, and then putting it into the vessel of cream to be ripened. It was a good plan to keep a glassful of this to add to the following uay’a supply to hasten acidity. 'When thorough care was taken in the preparation of this starter, extremely good results could be obtained. It seemed probablo that the time would come when starters and pure cultures would be in general use among butter-makers and cheesemakers. THE RIPENING OF CHEESE. Bacteriology was offering in the near future a method of control ling the ripening process in a way to ensure uniform quality in butter, ,go far as. concerned flavour and aroma at least. If they nal good, pure, sour whey it would make a splendid starter but there was danger in it also. If the churning was baa, and if they added to it next day, they carried on evil from day to day, whereas with a separately prepared starter they had it fresh every day. The cheese merchant told them that the starter was the worst thing ever put into the hands of the cheese-maker. He (the lecturer) differed; he thought it the finest thing in the hands of the capable dairyman. In many places, if one vessel cOuld not hold all the cream, it was put into two cr three, and kept for a few days until churning day came round. They should try to keep the cream all in one body, and ripen ic fast by moans of a good starter, and they would find they had the finest butter. As to the ripening of cheese, the lecturer ' remarked that up to the present time no process had been discovered in the way of controlling it with any accuracy. As a matter of fact, no man could say at the present moment how cheese was ripened. Up to last year bacteriologists were inclined to think that ripening was due to a certain species of bacteria'. Many had tried to isolate it and supply it to the maker. but had found it impossible. Tn Canada they found they could make the best cheese in September or October, and they said to themselves if prices can be got for autumn cheese, the matter is worth investigation. They, therefore, built special ripening rooms', with a temperature from 56 to 53degs., at which they could procure at any time quite as good cheese as in September.