H.—34.

REPORTS OF RESEARCH COMMITTEES OF THE COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH. DAIRY RESEARCH INSTITUTE. Dairy Research Management Committee : Mr. A. Morton (Chairman), Messrs. G. A. Marchant, W. E. Hale, A. Linton, T. C. Brash, Dr. C. J. Reakes, Messrs. W. Singleton, J. Murray, Quentin Donald, and Professor H. G. Denham. Director of Research : Professor Wm. Riddet. Secretary : Dr. E. Marsden. The Director, Professor W. Riddet, left for a visit to America and Europe early in the New Year in order to study modern developments in dairy science and related matters. At the request of the Government, Professor Riddet will also investigate methods of processing and marketing of dairyproduce in the chief dairy exporting countries. The Dairy Research Institute has made many advances during the year towards the solution of problems concerning the manufacture and transport of both butter and cheese. A clearer picture of the various reactions occurring during the manufacture and ripening of cheese has been formed, and this is gradually leading to the elimination of false ideas and to the substitution of fact for speculation in dealing with the various troubles which beset the manufacturer. Work on butter has been mainly in the direction of attempts to eliminate undesirable flavours (such as those originating from the cows' food) and to preserve the quality of the butter by packing and storing it under the best conditions. Cheese. —The important question of starters is gradually being clarified. Various strains of starter bacteria which will produce the best type of Cheddar cheese are now constantly available to factories. The trouble caused by bacteriophage is, however, still in evidence, and up to the present no sure method of overcoming it has been found. The role of lactobacilli in the ripening of cheese and in the production of faults such as openness and discoloration has been elucidated still further, thus bringing nearer the possibility of controlling the whole ripening process. The new method of paying for cheese milk on the basis of its cheese yielding capacity has been proved practicable in commercial factories. Butter. —Feed taints in cream used for the manufacture of butter have been traced to specific pasture-plants —the clovers. The co-operation in this work between the Institute, the Plant Research Station, and various commercial factories should prove very profitable in the future, and it is hoped that means will be found to minimize or to eliminate taints which in the past have been very prevalent in some districts. At the same time the facilities provided at the Institute for the investigation of the relation between feed, yield, and composition of milk from individual cows cannot fail to provide valuable information from many points of view. Many of the trials on methods of packing butter for export have been finalized during the year, and definite recommendations on the methods which should be standardized can now be made. The activities of the Institute and the results obtained in the various sections of the work are outlined in the following statements prepared by various members of the staff : — Cheese-making Investigations. (a) Starters. — Work in past years has shown that the old idea that flavour-producing organisms, necessary in butter cultures, play a part in the production of flavour in cheese is fallacious. It has been established now beyond all doubt that the starter required for the manufacture of Cheddar cheese is a culture of lactic streptococci which will produce acid at the required rate. It was found last year that strains of lactic streptococci which would continue to grow actively even at the comparatively high temperature of 100° P. produced the best results when used as starter in the cheese-vat. This observation has been amply confirmed both at the Institute and in commercial factories during the season. A selection of the most desirable strains has been made, and these are now in constant use in many cheese-factories throughout the country. The use of these pure-culture starters has incidentally proved to have a marked controlling effect on the incidence of slit openness. As will be noted in a later section of this report, the ultimate cause of slit openness has been established. At the present time, however, it is apparent that the use of active pure culture as starters is the most practical means of controlling openness, even when the germs which are the ultimate cause of the trouble are present in the cheese milk. The only factor which prevents the continual use of the pure-culture starters in all cheese-factories is the occurrence of bacteriophage, the virus which seems to attack all lactic streptococci under certain conditions. There is evidence which suggests that the phage is a product of the bacteria themselves ; thus it is not possible to avoid the trouble by taking care to avoid contamination of the starter culture. If appears that the only solution is to render conditions unsuitable for the development of the phage. These conditions seem to exist naturally in some factories, as is evidenced by the fact that in some instances the starters are used with success over long periods. In other places the trouble occurs to a greater or lesser extent, and up to the present it has not been possible to find out why this is so. An undefined difference between milk-supplies is indicated, and it is possible that in the future a correlation will be found between the suitability of milk for starter preparation and the feed and soil types of various farms. Thus the work which is proceeding in various directions may be linked up to provide explanations for many apparently unrelated troubles. In the meantime several possible ways for avoiding bacteriophage trouble have been tested with lit*" le success. Some factories find that cultures remain active for a reasonable period, and in these

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