H.—34.

On the other hand, pastures not top-dressed at all often develop (on relatively poor land) a sole in which trefoils predominate, and these cause flavours, even more intense than white clover, when active growth commences in late October. Progress results indicate that modification of methods of grassland management and the grazing of cows on " grassy " paddocks may overcome the difficulty, but these are deductions which yet need to be proven by practical trial. It is believed that, in addition to management of the pasture and of the herd, stage and rate of growth of the plants are important. It is also possible that special treatment of the cream may be a means of overcoming the defect without otherwise injuring the quality of the butter. These are matters which await clarification in experiments planned for the next dairying season. (i) Deodorization of Cream. —Many butter-factories, in efforts to control feed taints, have installed plants to pasteurize cream in partial vacuum. These aim at volatilizing the odoriferous compounds and carrying them off in the steam. The Institute has been supplied, by the generosity of the makers, with two types of such plants, and trials are in progress to determine the influence of the treatment of the cream by these on the quality of the resultant butter. Results are not yet sufficiently advanced for report. (j) Butter-boxes and Mould-growth. —Trials were carried out with the assistance of Mr. J. C. Neil, Field Mycologist, Plant Research Station, to determine the protection which different types of butter-boxes offer to the growth of mould on the surface of the butter packed therein. It was shown that the type of box and extent of infection are both important. With ordinary precautions to protect the timber from infection mould did not readily grow on the surface of butter packed in standard and sub-standard boxes, even when exposed to conditions specially conducive to mouldgrowth. Saranac boxes made from sawn timber were somewhat less resistant to mould-growth ; it spread readily across the surface of the butter when the ends of the box sprung after handling. Boxes of this type made from rotary-peeled timber developed profuse growth of mould, both externally and internally, especially when the timber was of open texture and, as in the other case, when the ends sprung. Infection of the timber with mould-spores accentuated the growth of mould, thereby emphasizing the need for hygienic milling and handling of butter-box timber. Treatments of susceptible timbers with fungicides brought about some improvement, but at the strengths used were not quite effective in avoiding trouble. This aspect needs further investigation. The wrapping of butter in parchment, sandwiching a layer of aluminium foil, proved an effective protection of the surface of the butter from mould-contamination ; in contradistinction to this wrapping-material, ordinary parchment paper was readily pierced by mould mycelia originating on the surface of the timber. The investigations pointed plainly to the need for using butter-boxes which are well secured, especially at the ends, and do not readily admit air to the surface of the butter, and on which moisture would not readily condense during defrosting. Ghee. Over 1,000 lb. of tinned ghee of various types has been sent to various parts of the East from this Institute. New Zealand cow butterfat melts at a lower temperature, and has a much deeper yellow colour than Indian buffalo milk-fat, commonly used in the preparation of Eastern ghee. Both these differences cause difficulties in adapting New Zealand cow butterfat to this trade. Reports received from the East on our products almost invariably condemned all samples which were not bleached, and the problem is further complicated by the fact that different regions appear to demand different types of products. The bleaching process has required a considerable amount of experimental work, and while it is now possible to avoid off-flavours in the process the bleached fat is still rendered more or less flavourless by the action of the bleaching-agent. The production of bleached butterfat of the correct flavour is still under investigation. It was originally assumed that ghee could be made from surplus butter, but the materials so produced were far too mild in flavour to be of interest to Eastern buyers. It has now been found necessary to make ghee from specially ripened cream in order to obtain the characteristic flavour in the finished product. The small commercial scale methods of manufacture that have been tried include —(1) direct evaporation of butter by closed steam and decantation ; (2) centrifugal separation of melted butter ; (3) bleaching of fat prepared by methods (1) or (2), and subsequent clarification in order to remove the bleaching-agents. A shipment of 800 lb. was prepared by the Institute on behalf of a firm which made arrangements for its sale with an Eastern trading company. Prices quoted by firms operating in various Eastern countries indicate that there is at present little hope of developing a more profitable trade in ghee than in butter. Pure ghee has to compete with products made from vegetable oils, which can be sold cheaply. Prices quoted by Eastern countries for pure ghee have mostly varied from about lOd. to fully Is. (N.Z. currency) per pound, c.i.f. and e. Since 100 lb. of butter are required to make approximately 80 lb. ghee it is apparent that the manufacture of ghee, except of special quality for a limited trade, has to be viewed more as a means of disposing of surplus butter than as a highly remunerative venture. Routine Work. (a) Analyses of Salt. —For control purposes several samples of standard brands of salt have been analysed during the year. The results show that the brands in common use are of a high quality. One sample of a new brand has not given such satisfactory results, and managers would be well advised to submit samples of new brands of salt to qualified analysts before departing from brands which have been tested and found to give satisfaction, or, alternatively, to purchase salt according to a satisfactory formula guaranteed by the seller.

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