DAIRY INDUSTRY.

New Zealand Herald, Volume LXV, Issue 20088, 27 October 1928, Page 22

DAIRY INDUSTRY.

PASTEURISING CREAM. THE KEEPING QUALITIES. ADVANTAGES CLAIMED. Tlio object of pasteurising crcim is fo - destroy tlie bacteria in it and thus proIons; tho keeping qualities, says a. writer in tho Farmer and Stockbreeder (London). 1 Tito souring of milk and cream is brought about by the action of bacteria, or germs, which convert a portion of the milk sugar into lactic acid. A considerable, number of germs ara present in milk produced under ordinary conditions, and the cream obtained from it. The production of milk under the best conditions of cleanliness is of great assistance in tho production of cream having a nice flavour and good keeping properties. Tho cleaner tho milk and the sooner it is separated the lower will be (lie bacterial content of the cream. Germs multiply at a rapid rate in warm milk and cream, henco tho reason for chemical preservatives until their uso was prohibited at the commencement of this year. A suitable method of pasteurising cream on the farm is as follows: — 1. Heat tho cream slowly (o MO degress F. in a water-jacketed vessel. 2., Maintain the cream at 145 degrees F. for half ari hour, then remove the vessel of cream from the hot water and leave tho cream to cool down to 120 degrees F. 3. .As soon as the cream has fallen to 120 degrees F., cool it quickly to as low a temperature as possible where water is the cooling medium. During tho heating process stir the cream occasionally so that tho temperature is uniform throughout. At creameries special appliances aro employed for pasteurising cream and keeping it at a very low temperature until despatched to the market. In cases where it is necessary to pasteurise cream occasionally, or a small quantity has to bo treated, special appliances are not needed. A small quantity of cream may bo heated in a double saucepan such as is used tor cooking porridge. A larger ! quantity could bo heated in an enamelled pail placed in a copper containing hot water at a suitablo temperature. Other methods of heating the cream without burning it may be devised. Heating cream to too high a temperature affects tho flavour, besides making tho cream thin. At creameries thin cream j may bo thickened to a certain extent by j reducing it to a very low temperature ! | by means of mechanical refrigeration. . ' The cooling of cream may be effected j bv placing a vessel of it in a larger |; one o) cold water—preferably running | J wafer. This, however, is a laborious i " method, as the cream needs to be kept j stirred and takes a long time to cool $ properly. A better method is to use a v small cream cooler through which cold J water is made to flow. ' ;

iSinall cold storago boxes made of 1111glazed clav may be procured from ironmongers; the, boxes are inexpensive and cost nothing for upkeep. A channel round the upper edge is filled with water, which is absorbed by the box. The evaporation of water from the clav box reduces the temperature of the interior. Die heating of cream should present no difficulty, but for the cooling a good supply of wafer is essential. Unless the cream is w'ell cooled its temperature during transit rises sufficiently for the acidifying organisms to become active