DAIRY INDUSTRY

Manawatu Standard, Volume LV, Issue 194, 16 July 1935, Page 8

DAIRY INDUSTRY

APPLICATION OF SCIENCE. MANUFACTURE" PROCESSES. Under the heading of “Science in the Dairy Industry,” four members of the staff of the Dairy Research Institute at Massey College delivered a symposium of addresses to the meeting of the Manawatu branch of the Royal Society of New Zealand, last evening. Tlie speakers were Dr F. H. McDowall, Dr H. R. Whitehead, Mr C. R. Barnicoat, and Mr 1. R. Sherwood. Mr M. A. Eliott presided and had Professor W. Riddet, Dean of Dairying at Massey College, associated with him. Professor Riddet introduced the speakers stressing the value of milk and milk products. Dr McDowall, who dealt with tho nature of milk, said it was designed by nature as a food, but its production in the mammary gland was not well understood. It was a curious tiling that the animal world was quite dependent on the plant world in the final issue. Cow milk was designed as a satisfactory milk for the calf, the composition being carefully controlled by Nature, tho volume being naturally reduced, if necessary, to secure uniformity of quality. 'Tho speaker was not sure that the dairy farmer realised that during the off-season the cow was building up for the milk season. The constituents of milk were proteins (casein or albumen) to build up the body, fat and carbohydrates to produce fat, minerals for bone and blood, production, and accessory food factors in vitamins. Butterfat was very highly emulsified, 24,000 globules making only one linear inch. It had been interesting to discover that vitamin A was associated with the colouring of butter as well as plnnt life; when yellow butter was desired, concentrated feeding on carrots served the purpose. New Zealand had had the service of a great many scientists, who were breaking down the barriers confronting research workers. The evaporation and tinning of milk presented serious problems in the tendency to thicken, and hero a big problem had been presented. Casein found use in glues, a spreader for plant insecticides, a paint base, plaster materials, and fine paper. In lactose there was a valuable sugar secured as a byproduct of cheese and used for supplementing cow’s milk as humanised milk. BACTERIAL FACTORS.

Dr Whitehead spoke of the difficulties mot with by bacteriologists. Bacteria found an excellent food in milk and constituted an invisible population in the world. From the earliest time man had taken advantage of bacteria in the manufacture of butter and cheese, but he had not always known the reason for the result he obtained. Indeed, butter and cheese making had been an art instead of the science into which it was developing. It was hoped to reduce cheese failures to a minimum by the application of science, and, to secure this, undesirable bacteria must be excluded and useful bacteria controlled. Milk from the cow should be free of bacteria if the animal was healthy, and the fanner had to be taught aseptic procedure to keep the milk free from bacteria. There were insidious infections at times and these required attention, such as that attending sliminess in milk. A condition known as non-acid milk was due to the presence of a germ which prevented others from serving their purpose. Milk could be a harmful carrier of disease by being infected with disease germs, such requiring destruction by heat treatment or pasteurisation, tlie speaker added. The keeping quality was thus enhanced and made milk safe from a health point of view. In cheese manufacture it was used to prevent spoilage, and in all these applications it raised a host of problems in preserving tho product at a correct temperature. Pasteurisation, however did not cure the condition of non-ackl milk and in many cases did not remove an undesirable flavour. In the manufacture of cheese and butter certain bacteria were indispensable from a flavour point of view and other purposes. Tho germs necessary in the cheese vat were known as starter culture, which produced acid throughout the period of making. Until 1890 milk was allowed to sour naturally, or sour milk was added, hut by the development of bacteriology the method of making specific cultures was evolved, especially in Denmark. For tho last 20 years such cultures had been used as mixtures to control flavour. In 1919 it had been discovered that one type produced acid, and another acid plus a large amount of flavouring substance, and since then it had been recognised that cheese and butter were in different categories. This advance meant that chance was being replaced by a controlled method of manufacture. BUTTER AND FAT.

Mr Bamicoat dealt particularly with butter. P'at was an essential to life and most foods contained it, but in temperate countries the solid, spreadable emulsion known as butter was chiefly used, he said. Butter was so largely consumed because it was preferred, though seed fats were also valuable. The Eastern races, although fish oils and vegetable fats were obtainable, also preferred butterfat in the form of ghee. A pound of pure dry ghee (butterfat), if placed in a «Jark cool place for some months, would be well-preserved at the centre, but damaged at the surface, due to the action of the air. The churning of butter introduced moisture and air to the myriads of fine fat globules so that there was every chance of deterioration. From the scientific viewpoint, the harmful changes arose from three sources, bacteria (giving reason for salt being used as an antiseptic), metals (chiefly iron and copper), and the air. Highly flavoured butters were manufactured from high-acid constituents and presented a difficulty in successful exportation. People were becoming more critical in regard to butter, and a very superior article was demanded by a buyer. Mildness of flavour was sought. We in New Zealand were at a tremendous disadvantage in competition with Denmark, for stored butter, after many months, was expected to equal Danish only a few days old. Research entered .the field at this point, to remove storage flavours, and it was possible that the storage temperature might be altered, the present standard of 15 degrees being the one adopted from meat, when moulds were obviated. CHEESE MANUFACTURE. Dealing with cheese flavour, Mr Sherwood said that cheddar ami the ordinary processed variety were generally regarded as covering the field. The latter comprised cheddar blended to produce certain flavours. However, there were other different types, the main divisions being hard pressed (including cheddar), blue vein (Stilton), and soft cream (including Limburger and cottage cheese). The manufacture of each type was an art with the same underlying principle. Tn the manufacture of cheddar the milk was partially soured and rennet added, the subsequent process occupying about seven hours, a day being spent in the hoops. | The typical flavour was secured in the i curing period by bacterial action. Till the actual cheese process an immense I change was undergone in the imiltipli-

cation of bacteria. The cheese-maker in the past had relied on chance to produce germs of the right type, and the art had succeeded because of the kindness of Providence. Distinctiveness' of flavour was secured by having different bacteria in the ripening process, j but apart from this there was little difference in manufacture. I Professor Riddet said that it had! not been hoped to cover the entire; field, but it was hoped that some iiidi>; cation of the scientific difficulties had been given. , i On the motion of Mr Eliott the speakers were accorded a warm Vote of 1 thanks.