Process to sterilize food or pharmaceuticals by repeated exposure to vacuum cycles followed by steam treatment and scouring with inert gas

摘要

In a process to dry and sterilize granular food, the moist food is discharged into an air-tight chamber from which the air is repeatedly evacuated. The final pressure is progressively reduced in steps at the end of each cycle, following which the product is scoured with an inert gas and again evacuated. The product is then sterilized with hot steam for a given time, followed by evacuation and rapid chilling. Sterile air is then admitted to the sterilization chamber and the product discharged. An Independent claim is also included for a commensurate assembly in which in the first evacuation stage the pressure is reduced to 500 mbar, the second to 30-40 mbar. These evacuation cycles are repeated three times prior to product exposure to the sterilization temperature of 95-135 degrees C for 3-5 minutes. The product is subsequently vacuum-cooled to less than 25 degrees C before sterile aeration. The gas scouring process employs air, nitrogen or a light gas e.g. helium or hydrogen, with a dew point of less than 250 degrees K.