Hawera Experience Proves the Value of Vacreator in Cheese Quality

Taranaki Daily News, 30 September 1940, Page 19 (Supplement)

Hawera Experience Proves the Value of Vacreator in Cheese Quality

Definite improvement in grading has been achieved by the Hawera Co-opera-tive Dairy Co. Ltd. since it installed a Vacreator at ,its Glover Road factory last October. Vacreation, which replaces other forms of pasteurisation, pasteurises perfectly, removes fecd flavours and most other impurities, and cools the raw material rapidly under exact control in vacuum. As a result of the successful experience with Vacreation at this and other butter factories throughout New Zealand, the manufacturers are confident that with the general adoption of this appliance a great and important improvement would be brought about in the. quality of the Dominion's butter. This opinion is born out by the higher grading results obtained in the Auckland province where most leading factories have already installed Vacreation units. The initial three months of the season had elapsed before the Vacreator was put into operation at the Glover Road factory, but in spite of this and the fact that it took the best part of a month before the operators became accustomed to it the grade for the season showed an improvement from 93.371 to 93.9X2, an increase in grade of .541. After allowing for seasonal conditions and other factors that might tend to improve grade it was estimated that the Vacreator was responsible for an improvement of half a point. The effect of the Vacreator is reflected in the premiums earned since its iristallation. During the season before the introduction of the new machine the factory had 19 per cent. of its output graded at 94 or over, but last season the amount was 58 per cent. Whereas in the previous season the amount graded 93

to 931 was 67 per cent. last season it was only 33 per cent. Similarly a reduction was effected in the 92 to 921 grading, there being only 9 per cent. compared with 12 per cent. the previous season. There was only 2 per cent. of butter graded below 92, but after the installation of the Vacreator this was reduced to nil. The need for the elimination of feed flavours Tn Taranaki has been disputed in some quarters but it is held by men responsible for the operation of the machine at Hawera that since the installation of the -Vacreator it has been possible to eliminate undesirable flavours and retain desirable ones, anj thereby improve the quality of the product. The improvement effected in the Hawera product was said to be sufficient evidence that there was room for improvement of butter manufactured in Taranaki by the removal of undesirable feed flavours. It was pointed out that under the Vacreation system it was possible to vai'y the treatment and its intensity acCording to the nature- of the cveam receivcd. This was a decided advantage not possessed by other forms- of pasteurisation, • :f ' The major source of foreign flavour in cream is the fodder eaten by the cow. Certain fodder, plants and weeds contain odourous oils. During fermentation of the mass in the pauch of the cow the oils are converted into vapours which .when the cud is chewed and when the cow belches become drawn into the lungs and are then conveyed by the blood-stream to the mammary gland. There the oils become fused to the fat globules. It would appear also that other vegetable flavouring prodUcts pass through the system of the cow into the rnilk stream. ' A cream processor's job is to treat -the cream so that its contaminations will be lemoved as completely as possible without harm to its physical balance or to its natural "bloom." The pure food laws permit the use of chemical agents only for dealing with excess acidity: Such aids, however, are not permitted for dealing with the contaminations in cream and therefore the processor has

to rely solely- on- physical' means to achieve his purpose. and he is limlted to the use of'heat and evaporation. Organisms are living bodies c'onstituted to thrive under normal conditions of temperature and pressure. Nevertheless they have the ability to adapt themselves to cohsiderable changes if such occur slowly. The preferable system of pasteurisation therefore -is' bne which effects an instan't heat rise coupled with instant reduction in pressure. It is also essential that each particle of cream is evenly affected.' Such a system is employed in the pasteurising phase of a Vacreator, where ' maximum temperatures can be applied with impunity under super-flash conditions. Removal of Impurities. The removal of volatile impurities freed fatty' acids, certain bacterial products, and vegetable oils; is best achieved.- by a process of steam distillation in vacuum. The molecules -of a liquid are nover at rest. They are continually jumping clear of- the liquid's surface and if entrained by a sweeping agent such as a current of air or steam are carried off. thus effecting evaporation of the liquid, The more volatile- the liquid the more intense the activity of the molecules. Application of heat, reduction in pressure and increase of the sweeping agent accelerates the evaporation of volatile substances. These principles are utilised in Vacreation to remove volatile contaminations. On reaching peak pasteurising temperature the cream starts to boil. Blended with free uncondensed steam Ihe mixture becomes increasingly rarefied and vapourous as it becomes subject to the progressively increasing vacuum en route.. The heat stored in the fat globules plus .the lowered pressure stiniulates the evaporation of the volatiles and as thcir molecules escape they are entrained by the steam. conveyed to the condenser and off to the water jet. The condensation of the free steam raises the temperature of the water and the "rise" is a direct indication of the- intensity of tfie distillation process.