Sterilisation of liquids in hermetically closed vessels

Abstract

The process for sterilizing or pasteurizing a liquid (3) contained in a hermetically closed container, comprises transporting the container to a treatment zone in which the container is submerged in an external fluid flow, simultaneously heating the liquid by electromagnetic waves at a rate of greater than 30[deg] C per second up to a treatment temperature (T) of 20-66[deg] C and agitating the container, and applying a pulsed alternating electric field (5) and a pause to the liquid up to 10-100 microseconds for electroporation treatment depending on the value of the treatment temperature. The process for sterilizing or pasteurizing a liquid (3) contained in a hermetically closed container, comprises transporting the container to a treatment zone in which the container is submerged in an external fluid flow, simultaneously heating the liquid by electromagnetic waves at a rate of greater than 30[deg] C per second up to a treatment temperature (T) of 20-66[deg] C and agitating the container, and applying a pulsed alternating electric field (5) and a pause to the liquid up to 10-100 microseconds for electroporation treatment depending on the value of the treatment temperature. Total heat energy provided to the liquid by electric field pulse is less than 0.05 J / cm 3>. The electric field has an oscillation frequency of 100-1000 KHz and a pulse repetition frequency of 10-100 Hz. Amplitude (E) of the alternating electric field in V / cm is given from the equation, C(T)= log (E +1)= B(T), where B(T)=-2.340x 10 -> 5>T 3>+1.290x 10 -> 3>T 2>-3.110x 10 -> 2>T+5 and C(T)=-4.503x 10 -> 5>T 3>+2.888x 10 -> 3>T 2>-5.900x 10 -> 2>T+4. The transport liquid is turbulized in rotation around the container. Static pressure developed in the treatment zone is created by pumping and locking system and by a liquid column constituting an external fluid overhanging in the treatment zone of the container. The transport fluid is water or water-based liquid. An independent claim is included for a device for sterilizing or pasteurizing a liquid to be treated.

Description

technical field [0001] The invention relates to a method of sterilizing a liquid contained in a closed container, and a device for carrying out the method. Background technique [0002] The current method of sterilization in the industry is with steam sterilizers, in which containers are processed in batches for several minutes at a rate of thousands of containers per hour, usually at a temperature of 90°C to 130°C. However, sterilization at these temperatures may significantly alter the properties (colour, taste, odor, biophysical and biochemical quality, etc.) of the item being treated. In traditional heat sterilization methods, the temperature rise is slow to allow the microorganisms to adapt and better tolerate the temperature rise. [0003] In patents US 4,695,472 and EP 1,328,167 are described methods aimed at lowering the temperature threshold necessary to sterilize aqueous liquids by applying an electric field. However the method described in US 4,695,472 only conc...

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