Food or edible material: processes – compositions – and products – Processes – Packaging or treatment of packaged product
Reexamination Certificate
2000-06-30
2001-12-11
Yeung, George C. (Department: 1761)
Food or edible material: processes, compositions, and products
Processes
Packaging or treatment of packaged product
C062S268000, C099S472000, C165S104270, C426S524000
Reexamination Certificate
active
06329005
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to rapid vacuum cooling generally and more particularly to rapid vacuum cooling of substances sealed in a package that have been hot-filled or heat processed.
BACKGROUND OF THE INVENTION
In food processing, particularly processing of proteinaceous food products, the speed of cooling is exceedingly critical. Failure to cool a food product sufficiently quickly may lead to undesirable effects on the flavor, aroma, texture or other important characteristics of the food product.
There are two general methods of cooling a hot product and filling a container with the product. In one method, the product is rapidly cooled and afterwards placed in a container. However, since the container is cold-filled, precautions must be taken to prevent post contamination of the product, making the procedure relatively expensive. In another method, the container is hot-filled with the product. Sealing the container while the product is still hot pasteurizes the package and prevents contamination of the product. However, the method does have a disadvantage of slow heat transfer. This is especially true of large drums or containers, wherein it can take hours for the product to cool.
U.S. Pat. No. 5,928,699 to Reznik, the disclosure of which is incorporated herein by reference, provides an improved rapid vacuum cooling system. The system comprises a housing, a hot fluid coil disposed in the housing through which flows a hot product, a cooling liquid disposed in the housing which fully covers the hot fluid coil, a vacuum pump operatively connected to an interior of the housing for reducing pressure in the housing until the cooling liquid boils and forms vapors, and a condensing coil disposed in the housing through which flows a cold fluid, the condensing coil condensing the vapors of the cooling liquid and thereby heating the cold fluid. The hot product transfers heat to the cooling liquid, causing it to boil.
The system of U.S. Pat. No. 5,928,699 solves the abovementioned problems of the art, because it rapidly cools any kind of flowable product in a closed, substantially germ-free system. However, a need still exists for rapid cooling of substances, such as certain vegetable products packaged in a sealed package. Of course, packages cannot flow in a hot fluid coil, and so the system of U.S. Pat. No. 5,928,699 cannot be used to cool them.
SUMMARY OF THE INVENTION
The present invention seeks to provide improved methods and apparatus for rapid vacuum cooling of substances in a sealed package.
There is thus provided in accordance with a preferred embodiment of the present invention rapid cooling apparatus including a vacuum chamber, a vacuum pump in fluid communication with the vacuum chamber for decreasing pressure in the vacuum chamber, a heat-transfer fluid disposed inside the vacuum chamber, and a substance generally sealed in a package in heat-transfer contact with the heat-transfer fluid inside the vacuum chamber. Preferably the package is constructed of an expandable material.
In accordance with a preferred embodiment of the present invention a condensing coil is disposed inside the vacuum chamber, the coil being adapted for flow therethrough of a coolant.
Further in accordance with a preferred embodiment of the present invention a spray device is inside the vacuum chamber which sprays the heat-transfer fluid onto the package.
Still further in accordance with a preferred embodiment of the present invention a CONVAC system is provided at an inlet to the vacuum chamber operative to generally continuously introduce the package and the substance into the vacuum chamber.
Additionally in accordance with a preferred embodiment of the present invention a CONVAC system is provided at an outlet of the vacuum chamber operative to generally continuously remove the package and the substance from the vacuum chamber. Preferably the CONVAC system at the outlet of the vacuum chamber includes a rotary feeder operative to receive therein the package, and a baffle mounted next to the rotary feeder, wherein as the rotary feeder turns, the package is pressed against the baffle, thereby contracting the package.
There is also provided in accordance with a preferred embodiment of the present invention a method for rapidly cooling a product, including providing rapid cooling apparatus including a vacuum chamber, a vacuum pump in fluid communication with the vacuum chamber for decreasing pressure in the vacuum chamber, a heat-transfer fluid disposed inside the vacuum chamber, and a substance generally sealed in a package in heat-transfer contact with the heat-transfer fluid inside the vacuum chamber, and reducing pressure in the vacuum chamber, thereby causing the heat-transfer fluid to boil, the package to expand in size, and a reduced pressure to be formed inside the package, until generally equilibrium is reached between the reduced pressure inside and outside the package, wherein any water present in the substance boils and condenses on inner walls of the package, and flows back to the substance, heat being transferred from the substance by convection to the inner walls of the package, by conduction through the walls of the package and convection from the package to the heat-transfer fluid.
In accordance with a preferred embodiment of the present invention the rapid cooling apparatus further includes a condensing coil disposed inside the vacuum chamber, and a coolant flowing through the coil, and wherein vapors of the heat-transfer fluid contact the condensing coil and condense thereon, heat being transferred to the coolant.
Further in accordance with a preferred embodiment of the present invention the method includes controlling a rate of condensation of the heat-transfer fluid by controlling a flow rate or a heat transfer characteristic of the coolant flowing through the condensing coil. Still further in accordance with a preferred embodiment of the present invention the method includes removing the package and substance from the vacuum chamber after cooling the package and substance, wherein the package and substance generally contract back to their original volume.
Additionally in accordance with a preferred embodiment of the present invention the pressure in the vacuum chamber is a vacuum of at least 27 inches Hg.
In accordance with a preferred embodiment of the present invention the package is hot-filled and sealed with the substance, such that a minimum quantity of non-condensable gas is present in the package.
Further in accordance with a preferred embodiment of the present invention the step of reducing pressure in the chamber is performed while the chamber is substantially closed.
Still further in accordance with a preferred embodiment of the present invention the package and substance are generally continuously introduced into and removed from the vacuum chamber.
REFERENCES:
patent: 2996898 (1961-08-01), Hosken et al.
patent: 4576014 (1986-03-01), Miller et al.
patent: 4826698 (1989-05-01), Reznik
patent: 5928699 (1999-07-01), Reznik
“Raztek Publications/News,” www.raztek.com
ews, pp. 1-5, 1998.
“Raztek Publications/Patents,” www.raztek.com/patents, pp. 1-3, 1998.
“Raztek Technologies,” www.raztek.com/technol.html, pp. 1-4, 1998.
“Raztek Technologies/Electroheating,” www.raztek.com/electroheating, pp. 1-3, 1998.
Pillsbury & Winthrop LLP
Yeung George C.
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