Method and membrane system for sterilizing and preserving liquids using carbon dioxide
First Claim
1. A method for preserving a liquid by exposure of the liquid to pressurized dense carbon dioxide comprising the steps of:
- directing the flow of said liquid along a liquid flow path which extends along a first surface of a porous membrane and directing a flow of said pressurized dense carbon dioxide along a separate carbon dioxide flow path which extends along an opposite surface of said porous membrane including contacting said liquid and pressurized dense carbon dioxide at pores in said membrane, and recirculating said flow of pressurized dense carbon dioxide through said carbon dioxide flow path including maintaining the pressurized dense carbon dioxide in the pressurized dense condition throughout the recirculation thereof.
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Accused Products
Abstract
Microorganisms are destroyed and enzymes can be inactivated in liquids, such as juices for example, by continuously flowing the liquid and continuously flowing pressurized dense CO2 along flow paths which are separated by membrane having minute pores at which the flows contact each other in a nondispersive manner. Pressures in the two flow paths are equalized and the dense CO2 flow is continuously recirculated without depressurization. Contact between the flows can be maximized by using a plurality of parallel hollow fiber porous membranes with one of the flows being directed into the hollow fibers and the other of the flows being directed along exterior surfaces of the fibers. The process does not adversely affect properties of the liquid, such as taste, aroma and nutritional content, as heating of the liquid to a high temperature is unnecessary.
25 Citations
18 Claims
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1. A method for preserving a liquid by exposure of the liquid to pressurized dense carbon dioxide comprising the steps of:
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directing the flow of said liquid along a liquid flow path which extends along a first surface of a porous membrane and directing a flow of said pressurized dense carbon dioxide along a separate carbon dioxide flow path which extends along an opposite surface of said porous membrane including contacting said liquid and pressurized dense carbon dioxide at pores in said membrane, and recirculating said flow of pressurized dense carbon dioxide through said carbon dioxide flow path including maintaining the pressurized dense carbon dioxide in the pressurized dense condition throughout the recirculation thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Apparatus for preserving liquids by exposure of the liquids to pressurized dense carbon dioxide comprising:
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a membrane contractor having a liquid flow path and a pressurized dense carbon dioxide flow path therein, said flow paths being separated from each other by porous membrane having pores which enable contact of a liquid flowing in said liquid flow path with pressurized dense carbon dioxide flowing in the carbon dioxide flow path, a liquid pressurizing pump having an outlet communicated with said membrane contactor to direct liquid into said liquid flow path, and a pressurized dense carbon dioxide recirculation pump having an inlet communicated with said membrane contactor to receive pressurized dense carbon dioxide which flows out of said carbon dioxide flow path and having an outlet communicated with said membrane contactor to return the pressurized dense carbon dioxide to said pressurized dense carbon dioxide flow path. - View Dependent Claims (11, 12, 13, 14, 15)
a first receiver tank having an inlet communicated with said membrane contactor to receive liquid from said liquid flow path, a pressure equalizing flow conduit communicating said dense carbon dioxide flow path with said first receiver tank, and a second receiver tank having an inlet communicated with said first receiver tank to receive treated liquid therefrom through a pressure reducer.
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16. A method for sterilizing a liquid by exposure of the liquid to pressurized dense carbon dioxide comprising the steps of:
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directing a flow of said liquid along a liquid flow path which extends along a first surface of a porous membrane and directing a flow of said pressurized dense carbon dioxide along a separate carbon dioxide flow path which extends along an opposite surface of said porous membrane including contacting said liquid and pressurized dense carbon dioxide at pores in said membrane, and recirculating said flow of pressurized dense carbon dioxide through said carbon dioxide flow path including maintaining the pressurized dense carbon dioxide flow in the pressurized dense condition throughout the recirculating thereof.
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17. Apparatus for sterilizing liquids by exposure of the liquids to pressurized dense carbon dioxide comprising:
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a membrane contactor having a liquid flow path and a pressurized dense carbon dioxide flow path therein, said flow paths being separated from each other by porous membrane having pores which enable contact of a liquid flowing in said liquid flow path with pressurized dense carbon dioxide flowing in the carbon dioxide flow path, a liquid pressurizing pump having an outlet communicated with said membrane contactor to direct liquid into said liquid flow path, and a pressurize dense carbon dioxide recirculating pump having an inlet communicated with said membrane contactor to receive pressurized dense carbon dioxide which flows out of said carbon dioxide flow path and having an outlet communicated with said membrane contactor to return the pressurized dense carbon dioxide to said pressurized dense carbon dioxide flow path.
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18. A method for sterilizing a liquid by exposure of the liquid to pressurized dense carbon dioxide, which liquid contains at least one constituent which is soluble in said pressurized dense carbon dioxide, comprising the steps of:
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directing a flow of said liquid along a liquid flow path which extends along a first surface of a porous membrane and directing said pressurized dense carbon dioxide to an opposite surface of said porous membrane including contacting said liquid and pressurized dense carbon dioxide at pores in said membrane to sterilize said liquid and to saturate said pressurized dense carbon dioxide with said soluble constituent of said liquid, and maintaining the pressurized dense carbon dioxide at said opposite side of said porous membrane in the saturated condition during continued sterilization of said flow of liquid.
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Specification