DEODORISATION OF CREAM

Shannon News, 4 March 1927, Page 4

DEODORISATION OF CREAM

A New Era in Butter Making APPLYING THE VACUUM PROCESS The introduction of the deodorisation of cream by vacuum process has marked a new era to butter-making, and its use as a factory unit ensures uniformity of quality and simplifies the work of the factory manager. Mr. A. F. Neilson (general manager of the Pihama Dairy Company) delivered the following addres 3 to a meeting of factory managers at NewPlymouth last week. The handling of liquids with applied heat under vacuum is a process not widely known to those engaged in the manufacture of butter and cheese and perhaps less understood as a means of variation in the temperatures at which boiling-point can be reached. The boiling-point of any liquid is jurely that at which rapid evaporation takes place due to violent ebullition, whether the temperature be 60deg. Fahrenheit or 212 Fahrenheit, and since such evaporation is governed by the essentials of heat and air pressure, both of which active principals are subject to control, mechanical or otherwise, the application of a steam-jacketed vacuum pan for the manufacture of condensed milk was found to be the only means of successfully overcoming the attendant difficulties of concentrating milk by boiling at atmospheric pressure. It has generally been accepted in the manufacture of condensed milk that ordinary feed flavours give the makers no concern owing to their volatility, the chief deterrent being ] the bacteria life due to careless handling of the raw material. Two of the chief difficulties with which we have to contend in the manufacture of butter are: (a) the bacteria life with which the cream is so often conI. terminated before it reache a the factory, and (b) the feed flavours which appear to be more or less prevalent in all pastures. In so far as (a) is concerned a great deal has been done by ou r farm dairy instruction system, a s well as the farmers themselves in an honest endeavour to improve their methods 0/ working. It has been generally accepted that in the treatment of cream for buttermaking, the adoption of temperatures has given the best results. The obvious conclusion is that such, temperatures are conducive to killing: the life which may prove a deterrent: to the keeping quality of the butter, and as the process does not necessitate maintaining such high temperatures for any appreciable time the flavour is in no way impaired, provided the fat content of the cream is not unduly high. There is a limit, however, to the temperature at which cream can be heated, and any attempt to reach boiling point at atmospheric pressure for the purpose of throwing off volatile impurities which affect the flavour would be impracticable, if for no other reason than that the liquid 1 would be uncontrollable in the abi sence of proper means of handling the ! vapour.

The exposure to the atmosphere of cream at a high temperature during the process of pasteurisation has been sought a s a means of eliminating undesirable flavours, and while this practice has been known to effect quite an improvement, there is the inherent danger of oxidation of the fat as well as the destruction of the fat soluble vitamines. The result of such is rancidity, which will develop in storage. It can be assumed that working under the flash system of pasteurisation, temperatures ranging from 190 to 240 deg. Fahrenheit according to the quality of the cream are essential under existing conditions of milk production, and while the deodorisation of cream by continuous process under vacuum ensures a greater margin of safety owing to a ; > more prolonged period of treatment which will be explained later, the use; of the pasteuriser in conjunction with the deodoriser is firstly, an economically necessity as a preheater, and secondly an insurance against life producing gorms which may not be destroyed at the lower temperature employed in the deodorisation. In the deodorisation of cream, care needs to be exercised in the intensity of the treatment which should be varied according to the quality of the cream. Treatment is varied by:— «.l) The quality of the cream fed to the machinery; (2) the amount of \ steam applied. ! The finest quality of cream can be I fed to the. deodoriser at the rate of | 1000 gallons per hour, first grade at I 700 gallons per hour, the second !' grade at 300 to 4uo gallons per hour. with careful handling there should be very little difference in the three classes of cream after treatment. The capacity can be reduced to 100 gal- , lons per hour if desired and the steam so regulated as to give pre-, tisely the same treatment as the. higher rate of feed.

At 1000 gallons per hour the cream would get six minutes treatment, at 700 gallons per hour 8J minutes, and tt 400 gallons per hour 14 minutes. Prom the time it enters the machine intil it is discharged, the cream is ibjected to vigorous boiling (from

six to 15 minutes), travels, from li to 11 miles, ana is distributed over un area of 200 square feet an average depth of one inch. When the machine is working at a low capacity of say, 300 or 400 gallons per hour, the result is a high" degree of concentration, up to 25 or '6Z per cent.' so that a corresponding dilution of the cream before treatment i 3 necessary, otherwise it will be inconveniently thick for churning, and the resultant butter may have an undesirable condensed.milk flavour. It is found that rather less neutralking .agent, is required than that prescribed in the table issued by the Dairy Division, which is no doubt due to the cream being subjected to violent ebullition during treatment.

Whey cream is handled similarly to second grade ci earn, i.e., it is diluted with water (or buttermilk) and given an intensive treatment. The water after passing through the condenser has a pronounced whey flavour, indicating that' this undesirable flj-vour in whey butter has, to a great extent been eliminated after the cream has been deodorised)

One special feature in the deodoriser is the absolute consistently even temperature at which the cream Is discharged from the machine, no matter how irregular the temperatures may be at the inlet pipe. The best results are obtained at a' vacuum of just under 15 inches -with a corresponding boiling point of 180 deg. Fahrenheit.

Cream gaining admission at 13Odeg B'ahrenheit comes in .contact with the steam jacket of the deodoriser and da the distance of travel is so greac and the time tt Is retained at its greatest capacity six minutes, it is brought up to the common temperature of the mass and begins to boil long before it reaches the outlet pipe. That entering at 206 deg. Fahrenheit being 26deg. higher than the boilingpoint of the cheam in the machine, immediately gives off its latent heat and automatically follows its course to the outlet, boiling the while at 180 deg. Fahrenheit.

The efficiency of the machine Is reduced as a deodoriser when the cream is fed to it at a, temperature below that of the boiling-point at which it is regulated, as it is functioning partly a s a pasteuriser in raising the temperature of such cream hence a shorter deodorising treatment follows.