CHEESE PROBLEMS

Hokitika Guardian, 8 January 1931, Page 3

CHEESE PROBLEMS

INVESTIGATIONS AT READING

VITAMIN CONTENT

WHOLE MILK A PERFECT FOOD

LONDON, Nov. 24. Bread and milk, and nothing hut (bread and mik, from childhood to old age, is the fate of hundreds of rats at the National Institute for Research in Dairying near Reading, Berkshire, England, where with the aid of grants from the Empire Marketing (Board, the products of cow and dairy are the life study of about 30 specialised scientists.

Ratjs not only live on bread and milk alone— they thrive heartily and produee large families, even unto the fjourth generation. There are .rats whose fathers, grandfathers and greatgrandfathers knew no other food, and, far from being milksops, they are trim-whiskered, young rodents ready to match their wits against a cat any day. Tn the same shed are cages containing puny, emaciated rats half the size of ,their neighbours, and too weak to near families. They, too, have been brought up on bread and milk, but with ii s vital difference —the milk has been sterilised. An interesting fact which has incidentally come to light is that rath that have been starved for vitamin B and are then given unlimited supplies in the form of yeast, do not eat enough to make up the deficiency, and perish in the midst of plenty.

Captain Golding, the dairy chemist in charge of the- rat experiments, believes he has proved the far-reaching fact that whereas whole milk is a perfect food, storilsation destroys certain vitamins and other substances, and sterilised milk, therefore, loses much of its nutritional value. NEW ZEALANDER’S SUCCESS. This is, he thinks, of particular interest to New Zealand and Australia, where moist of the milk used tor cheesemaking is pasteurised. A special study of this and other problems has been made , at the Reading centre, by a New Zealander,. Dr George Moir, who won a two-years’ research scholarship in England and who has just returned to apply his knowledge m New Zetland.

While sterilising and paSteuCsing are, of course, quite separate processes, certain changes may occur in the chemical composition of the milk as a result of the ‘flash’ method of pasteurisation,and it possible that, tin* vitamins may he affected. Another study of the . vitamin content of milk and butter is being made in co-operation with Reading at the Lister Institute, as part of a general scheme of rtisearcli into the vitamin properties of Emigre produce under the Medical Research. Council.

The home of the rearch station, ol which I>r R,. Stenliouse Williams is director, is an old Maiior House about four miles outside Reading (famous for biscuits and beer). The house has been converted into up-to-date laboratories, and scientists now perform their titrations and analyses where the old Squire may once have polished ofi his second bottle of port every evening. Behind is the old farmstear, serving a fine 350 acre farm.

WHEN IS A CHEDDAR NOT A

CHEDDAR.

What is the difference between a Cheddar and a Stilton, or a Cheshire and a. Swiss cheese This is one of the problems that the Reading men are trying to solve. They cannot explain in scientific, terms why such small differences in manufacturing processes should result, in such very different, products. Still less can they explain why exactly similar treatment of th“ same raw material—milk —in different parts of the country, or in different countries, ebon Id produce cheeses with distinctly different flavours, textuios and keeping qualities. The real difficulty they are up against, as Mr A. T. Mattick, the bacteriologist, explained, is that milk is so tremendously variable. Its chemical composition, for instance, varies not only according to district, cow, feed, season, etc., but even in different quarters of '•the same cow’s udder. One of 3 the most remarkable pieces of work at Reading is a complete chemical analysis of “typical milk” over a period of several years. The milk is analysed every day and a chart made of the fluctuations of its chemical contents. The chart now stretches right across the laboratory and the rise and fall in the proportion of butter-fat minerals of various Isorts, casein, etc., can be seen at a glance. What are the real- causes of the*fluctuations and bow do they link up with feed, pasture, age and health o' the cow, season, etc.? These nr" tb" sort, of problems being tackled. They lead on to broad questions of the influence. of rations on the quality, e.g.. butter-fat content, .of milk, about which practically nothing is known.

SOCIOLOGY IN C-HEESES. Mr Mattick and bis team are making a close study of the relationship be tween the various groups of bacteria in milk and cheese. Bacteria, like men are not sufficient unto themselves Each race reacts on its fellows, and there h a constantly changing bn I mice between the groups. As in the world, the population rises and falls: wars and earthquakes for milk-quakes) reduce it again., revolutions destroy one group. and another takes its place. Bacteria’s life is not a fasinful one.

This sociology of bastcria is a lasinating study, over which the Reading men wax particularly enthusiastic, i They “inoculate” bacteria into “pure j cultures” of agar-agar (a Japanese seaweed) and grow them in glass dishes in incubators. By these means they can sort out the various kinds and observe the habits o. each. Some of 1 them are undesirable and do harm to cheese, and these, such as “red spot” ‘and “stinker’ ’organisms, must be discouraged. Others may speed up or retard ripening of cheeses. ELIMINATION OF RED SPOT. “Red Spot” causes very heavy losses to farmers in one of the biggest Cheddar cheese districts in England, and is also known in Canada and New Zealand. It is due to a bacterium which, under certain conditions, produces a blood-red pigment in the : cheese. This, naturally, ruins it for the market.

| The bacterium responsible was isolated by the Reading scientists, but would not produce red pigment when inoculated into the research station’s milk. Cheeses are made with milk containing the organism, but no red spots appeared. It was then found that it would only develop the pigment in milk which had been kept for a little time, or in dirty milk. This led to the discovery that the “red spot” bacterium lives upon the by-products of other bacteria. It is a sirt of hyaena in the bacterial world. When milk is several days old, bacteria have had timfe to grow and produce substanecs which stimulate the red spot organism’s growth. If cheese is made from very fresh milk, and if great care is taken in sterilising all utensils and allowing no traces of old milk to become mixed with the fresh, then “red spot” can Jbe entirely eliminated. • ~

Another fault which is being studied is “openness” in cheese, the most serious problem of the industry in New Zealand. (It has been estimated to cause New Zealand a loss of £I,(XX),(TOO a year.) The cause is still unknown, but. Reading is co-operating on an extended scheme of research with the Palmerston North dairy research station, to whom the Empire Marketing Board has just given a grant. A large batch of cheese made at the Massey College was recently sent over to Reading in refrigerated holds containing devices to keep a constant record of the temperatures throughout the voyage. An exactly similar batch was kept at the Massey College. Samples of all the cheeses were analysed at Nelson, and again at Reading in tincase of the exported batch. The object was- to study the effect of transport and refrigeration on ripening.