CLEAN FACTORIES

Evening Post, Issue 98, 27 April 1936, Page 10

CLEAN FACTORIES

STERILISATION PROBLEMS

KILLING HARMFUL BACTERIA

The need for cleanliness in all food industries and especially in' those plants handling perishable goods was emphasised by Mr. H. H. Edwards, A.N.Z.I.C, Auckland, in a paper on "Sterilisation in Industry," read at a meeting of the New Zealand Association of Refrigeration, Wellington, last week. Modern practice in overseas factories, he said, demanded that close attention be paid to the control of ventilation and to the conditioning of the air to provide the best working conditions and to reduce air-borne contamination to a minimum. "In New Zealand our factories are, in this respect, very primitive," the lecturer added. "No factory, as far as I am aware, can boast of air-conditioning apparatus and the air supply is therefore a sort of 'Hobson's Choice'—the wind blows from any. direction it pleases and it may arrive via manure heaps, stock yards, or dusty roads, and it may be hot or cold or dry. So that until such times as we have air conditioning we must do our best to keep bacteria and moulds in check by the best means at our disposal." Sterilisation by heat, Mr. Edwards said, was the simplest method of killing bacteria and moulds, but there were obviously cases where it was not applicable. Furthermore, it gave the surface no protection against recontamination. Live steam had the advantage, however, that it cleansed the surface of debris and grease upon which the bacteria lived. It was an utter waste of labour and money to attempt to sterilise a dirty surface. For the initial cleansing operation steamnot water vapour—was the ideal method. In cases where . steam was not available recourse might be had to hot water and a good potash-oil soap, which was more effective for removing grease than caustic soda soaps. For cleansing metal surface, the ideal chemical was sodium, metasilicate, owing to its non-corrosive properties and its powerful grease-removing qualities. Preservative substances such as salt, saltpetre, sodium sulphite added to food were more in the nature of inhibitions of bacterial growth. Chemical sterilisers of the phenol types of disinfectants varied enormously in their Rideal-Walker co-efficient and were often erroneously judged by their smell, which, however, had nothing to do with disinfecting properties. Formalin was useful more for disinfecting the atmosphere than the surface of large areas such as freezing chambers and cooling rooms. Of the gaseous disinfectants, ozone was very important in that is was also a powerful deodorant.

Sterilisers of the chloride type were the cheapest sterilisers available and lent themselves admirably to use in meat works and packing plants.

"lk need hardly be said," the lecturer concluded, "that sterilisation is. not a substitute for cleanliness. Cleansing does not sterilise; sterilisation does not clean and will not take the place of cleanliness. Therefore, clean first, sterilise afterwards."