Abstract
The method depends upon the fact that vitamin A can be easily destroyed by oxidation and that the higher the temperature the more rapid, apparently, is the destructive process. The apparatus illustrated in the accompanying diagram consists of an iron coil of about 7 mm. bore; two suction flasks interposed between the coil and the compressed air faucet; one improvised Marshall and Kolls'flowmeter; a shower expansion of about 28 cm. diameter, made of copper sheet; and a galvanized iron drum box enclosing the shower expansion. Through a large window in the drum the food is placed under the air shower. Exit of the air current is provided for by a tube inserted in an upper corner of the drum.
By using a four tube burner under the coil and setting the air stream running at the rate of about three thousand liters per hour, the temperature of the food is maintained at about 110° C. in the case of yeast and, in the case of casein and starch, about 120° C. Two hundred grams of the food are spread over a 26 cm. aluminium tray placed at a distance of 6 cm. under the shower plate. The food is stirred at half an hour intervals in order to secure a uniform surface of exposure.
Experimental tests have demonstrated that beyond the desired effect the basal foods thus treated for 6 hours are not injured or unfavorably affected. The basal ration was composed of casein 20, starch 65, yeast 10, and McCollum's 185 salt mixture 5. In a separate test it was found that 5 per cent of yeast whether oxidized, untreated, or extracted with .absolute alcohol was inadcquate as the source of vitamin B. Fresh butter-fat of proved potency after a six hour exposure loses practically all of its vitamin A content as shown by its complete failure to prevent or cure vitamin A deficiency disease in the rats.
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