UTILISATION OF SKIMMED AND SEPARATED MILK.

Otago Witness, Issue 1897, 12 June 1890, Page 6

UTILISATION OF SKIMMED AND SEPARATED MILK.

The profitable utilisation of the large quantities of separated milk daily on hand at butter factories has been a crucial question with the proprietors of these establishments since their institution, and the subject much concerns as well the owners of extensive private dairies. Prominence has been attracted recently to the question in New South Wales by a report from Mr Angus Maokay, F.C.S., the instructor in the Agricultural Teohnical College, Sydney, and which the Minister for Agriculture ordered to be published, The circumstances, Mr Maokay explains, under which the subject was brought to his notice were somewhat novel, Mr Jeanneret, a student of the Technical College of Agriculture, while visiting the extensive dairy factories in New South Wales during last summer, "saw the difficulties in the way of using up the large mass of material discharged from the centrifugal machines each morning, and having a fair general knowledge of the chemistry of milk and its various properties, it ocourred to him that if the separated milk could be got into a portable form bo that it could be carried cheaply, and without risk from souring or other form of decay, it would relieve the factories of what is really a trouble to many of them. Mr Mackay was consulted in the matter, "and with the aid of Mr Jeanneret a series of operations were set on foot which, as the case appears to me now," he Bays " overcomes the difficulties in the way of using this machine milk for various purposes of human and animal food." And he adds: "As Mr Jeanneret has voluntarily withdrawn all right he may have had for what ia likely to prove a valuable process, I am now in a position to make the same public as requested by you " (the Minister of Agriculture). It is explained in the report that a difference is found between the " machine milk " and the skimmed milk got in the old way from the milk pans ; and this arises because of them uch more effective way iv whioh the centrifugal machine extracts the cream than ia possible by the ordinary process of Bkimming. But this defect as a porfeot food material can be made good by using other fat-forming materials with it. "It was therefore towards converting the milk into a solid form in conjunction with flour, maize meal, pollard, bran, &0., that our efforts were direoted This milk, the material to be oonverted, we find is composed of about 92 parts of water and eight parts of solid matter. That is to Bay, in 10 gallons of the machine milk there are 81b, as an average, of solid food material of the very riohest kind. It is bone, muscle, and flesh forming to a greater extent than fat-forming, and for that reason it iB not so rich for feeding, or rather fattening, pigs as those who use it for feeding pigs might expect." The object to be attained was necessarily to devise means which must be distinctly and readily practicable for getting rid of the superabundant constituent water of the milk in order to secure a residue in portable form ; and Mr Mackay thus descibes the process recommended : "As the milk in the state it is expelled from the machines is a chemical compound that cannot be separated by any process of filtering, we brought to bear on it a prooess of evaporation similar to that used in sugar making, while tho open air process -of the sugar manufactory was followed. This answered admirably, and some 70 ,per cent, of the water was expelled in such a way as can be done in connection with the ordinary buttar factory appliances, by using the waste steam with a little extra from their boilers, for evaporating purposes. There are various forms of evaporating pans that could be used, such as the bow, Wetzell, steam coils, and other forms. . . . There iB no npeoial skill required to operate any of these pans— no more than is employed in butter-making— and the factories have the steam and such motive power aB ia neoesßary for their use, When 70

per cent, of the water had been evaporated wa then had the solid matter of the milk at about the consistency of treacle, and in that state it is quite portable and could be sent to a central factory or other place for further treatment. It can be made alkaline by the addition of a very little lime watei when that is considered desirable to prevent fermentation, but the thickened milk has much less tendenoy towards fermentation, The addition of lime water would be benefioial for food or other purposes, and as much cannot be said for all the substances recommended for preserving milk. The thickened milk-essence was then mixed with maiz9 meal, with bran and pollard. I have since mixed it with flour. There is no limit to the food Bubstances with which it can be mixed ; and as in the operation first carried out, the romaininp 'moisture can be easily disposed of by kiln or other available process of drying. Then we have the flour, maize meal, bran, pollard, or other amalgamating Bubstances in much its original form, but there is in it the strength of the milk in addition. By test we found that the solids of 101b of milk could be put up in l£lb of maize meal, and m a smaller quantity of bran, 21b of fine roller-made Sydney flour from a well-known mill absorbed the solids from 101b of milk, and the weight of the flour was then a trifle under 31b, It has been made into cakes and fine bread of various kinds. The maizo meal compound made very excellent puddings. When the milk iB put up in bran, pollard, maize meal, &c, we have feed for horses, cows, poultry, pigs, &c, the valuable nature of which need not be enumerated. The process ia adapted to the appliances of factories, as they are up to the stage of concentrated or condensed milk. Drying appliances are necessary to complete the process, When dried the flour, feed, &c, could be put up in bags, and would be portable in the usual way." Commenting on Mr Mackay's report and recommendations, it is remarked in a leading article in the Sydney Mail of the 17th ult. :— " It appears to us that the treatment suggested ia to produoe condensed milk— an article of food which has been before the public for many years. . . . Nor do we perceive how it ia that Mr Maokay seems unawaro of what has been done in the way of treating skimmed milk in other countrioß where operations havo long passed tho experimental stage." In Buppott of the statement the Mail reproducOß a report which appeared in that journal of the 19th April. That report waß as follows :—

A Swedish dairy instructor, Mr Ehenstrom, has successfully dealt with the question of profitably disposing of all refuse material. Whey to be run into the gutter, or ekim milk to be fed at little profit to calves or pigs, are, in Sweden, things of the past. In the most modern method of Swedish dairying, skim milk, sweet and sour, and whey become valuable raw material, which, properly handled adds much to the income of the dairyman. Skim milk is handled as in the manufacture of "skim cheese." except more rennet is used and the precipitation is made at a higher temperature in order to be more complete. This product is pressed, dried, and .'ground, and in this form, containing as it does a very large percentage of protein, is used with milk stuff in making compound feeding cakes for horses, cattle, dogs, &c The whey remaining after the curds have been removed, as above dnscribecl , or in ÜBualoheese-making, is mixed with an equal quantity of skim milk and evaporated. When the evaporation is complete the produot is dried in cakes, cut iv small cubes, ronstedand ground, retidy for use. The product of skim milk finds a more legitimate aud profitable use than if the milk was fed to swine or calves or turned into " skim cheese" and offered on a market where there is not or never will be a demand for it. The process of evaporation make useful absolutely all the solids of the skim milk and whey. The skim milk produot may be stored up on the farm in the form of feeding cakes for future use or shipped at slight expenae to any available market. The product of the evapoiation process has a dozen profitable uses. Mixed with coffee or cocoa, it is used with satisfaction by the best Swedish families. It is also used as a body for soups and sauces. The manufacturers of these goods in Sweden pay for the dry pressed curds and the evaporated product a price equivalent to about 2jd per gallon for skim milk. When it is understood that aB a food for calves and pigs it can hardly be worth more than id per gallon, and that the cost of producing the pressed curds or evaporated cakes is at most but trifling, the importance of this innovation will readily be understood.