DEFECTS IN BUTTER

Manawatu Times, Volume LIV, Issue 6844, 23 February 1929, Page 12

DEFECTS IN BUTTER

Contaminated Produce “FISHINESS” AND CAUSES RESEARCH IN ENGLAND. That New Zealand and Australian butter should travel half-way found the world and arrive in London in perfect condition is a remarkable achievement in the fields of dairy science. During this journey there must inevitably be a certain amount of waste through deterioration. Tho importance of even a small percentage of loss is obvious when it is realised that the lt'27 imports into England of New Zealand butter were 1,260,729 cwt., of a value of £10,387,206, while Australian butter had a volume of 488,721 cwt, the value of which was £3,836,345. One of tihe causes of waste is the arrival W butter in a "fishy’' condition and it was with tho object of eliminating loss from the importation of “fishy” butter the Empire Marketing Board granted a sum of money to the National Institute for Research in Dairying, to be devoted to research into the cause and cure of this defect. The cause of “fishiness” was explained to a recent investigator at a laboratory in an old manor house outside Reading (England), which was converted into research headquarters by the National Institute for Research in Dairying in 1923. Samples of butter were exhibited in various stages of deterioration, beginning with a slight tinge of “fishiness” and inding in a solid lump of what looked like candlegrease punctured with holes butter gone “tallowy”—the final state of the process of which “fishiness” is the first stage. Influence of Oxidation.

This kind of deterioration is liable to occur in all butter in process of time. But normally it will be consumed before this occurs . The cause is oxidation the process of adding atoms o± oxygen on to the molecule, which takes place when organic matter decays or when coal burrs. The difficulty arises when this happens too quickiy, and the butter goes “fishy” before it reaches its market in England, where it is sold for 8s or 10s a cwt. less than normal butter. The object of the research was to find out exactly why this deterioration occurs sooner in some samples than in others. It has been determined that the reason lies in the contamination of the milk or cream by minute traces of metal, chiefly iron ox copper. These metals act as cataylsts, to use the chemical term. Catalysts are chemical stimulants. Certain chemical substances which are sluggish in their reactions are goaded into action by catalysts so that the chemical change is effected more rapidly. These traces of metals found in “fishy” butter speed up oxidation, and cause tho “fishiness” to develop before an uncontaminated sample would begin to deteriorate. The result of the research has been a test by which the gauging of tho keeping qualities of butter when the sample is fresh from the creamery has been made possible. Over 700 samples have been tested, and now, given any sample, it can be seen if traces or metal are present, and so it can be prophesied whether the butter will become “fishy” quickly, or whether it will reach its market in a normal condition. The tost itself is simple. A small sample is mixed with diluted separated milk and a little methylene blue. When this mixture is heated, tho methylene blue is bleached and the colour disappears. Then comes the crucial part of the test. If the sample is badly contaminated, and so disposed toward “fishiness” the blue colour returns in full force. If it is healthy and so of good keeping quality hardly any of the colour reappears.

Minute Traces of Metal. A very minuto trace of metal, even 25 in one million, will cause “fishiness,” and there are many ways in which so small a quantity can be picked up by the milk or cream. Cream is often handled by means of utensils which are made of copper or iron covered with tin. If the tin wears off, then tho copper r iron may be removed in solution. Contamination may occur during the proceeding. For example, after pasteurising, the cream is left overnight in large vats, and stirred with iron rakes. These rakes may scrape the coating off the copper vats, and leave an exposed surface from which traces of copper are removed and go into solution in the fat globules. And there are other possibilities of infection whenever the milk or cream comes into contact with metal, as over the joint.- of tubing. Jt is intended to try out this test for commercial use by co-operation between Dominion and English scientists. Samples will be tested, and then sent from Australia and New Zealand, together with a report on their response to the test. Scientists at Reading will note the condition of the butter when it arrives, and they will then be able to see whether butter which gives a deep blue colour and therefore had bad keeping qualitde sascribed to it, does go “fishy.” and whether butter put down as “0.K.” always remains in good condition. If the test never misses contaminated samples nor condemns good ones, an enormous saving of money may bo effected; for butter which is likely to deteriorate would never leave the port of export. All wastage due to “fishiness” ou arrival would thus bo eliminated, and the reputation of New Zealand and Australian butter even further enhanced.