Food or edible material: processes – compositions – and products – Surface coated – fluid encapsulated – laminated solid...
Reexamination Certificate
1999-11-23
2001-11-06
Bhat, Nina (Department: 1761)
Food or edible material: processes, compositions, and products
Surface coated, fluid encapsulated, laminated solid...
C426S289000, C427S460000, C118S626000, C118S629000, C099S451000
Reexamination Certificate
active
06312740
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to apparatus and methods for electrostatically coating surfaces, and more particularly to coating surfaces of food products with an edible coating material.
BACKGROUND OF THE INVENTION
The use of electrostatic techniques for coating surfaces is well known in the art. Typically, electrostatic techniques are used for paint coating wherein the powdered “paint” material is pneumatically forced through an electric field to cause the particles of the material to become charged. These particles are then directed to a target having an opposite charge. The electrostatic attraction between the target and the respective particles causes the powder to change its direction and flow around the target to contact exposed surfaces. In this manner, it is possible to obtain complete coverage of an exposed target surface and create a bond between the powder and the target. If the target is completely covered by previously applied or attracted particles, then the excess powder particles are allowed to simply fall to a conveyor or floor of the processing area to later be collected and reused.
In prior art painting operations, such over-spraying does not represent a problem since the systems are designed to incorporate an overspray to insure complete coverage of the target area and the excess powder is simply recycled and reused. Since the materials used in such operations are reusable, and since there is no consideration given concerning the possibility of bacterial growth, these prior art techniques are completely satisfactory. Typically, this prior art painting operation results in a forty percent to fifty percent excess paint powder that is injected into the operative coating area. Using normal exhaust systems and excess spray collection systems, the excess powder dissipates its charge and falls into a collection container at the base of the system, such as a hopper or a bin, and is carried back to the feed hopper and reintroduced for coating.
The application of such prior art systems to the coating of edible products with an edible coating results in the exposure of the excess spray to the possible growth of bacteria. Typical regulations governed by federal agencies require food handling facilities to be kept clean including machinery that is thoroughly cleaned (sometimes several times a day) to prevent the possibility that substances could accumulate and become bacterial breeding grounds. Further, typical food processing plants are labor intensive that would militate against permitting over-spray or excess powder to be released into the workplace. Therefore, prior art electrostatic coating technology fails to provide the necessary assurance against bacterial infestations and environmental cleanliness.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for applying electrostatically charged particles of an edible coating material to a food surface to be coated. The coating material is placed in a fluidizing hopper on a fluidizing plate having pressurized air passing through the plate to partially fluidize the material. The material is also fluidized through the use of an agitator system incorporating an agitator blade and lifting blades which lift and stir the fluidized coating material. A venturi tube is positioned at a predetermined precise distance above the fluidizing plate within the hopper to withdraw the fluidized coating material at a predetermined density. The fluidized material is withdrawn through the venturi tube, is then finely adjusted to a precise density and supplied to an application gun. The particles of the fluidized material pass through a corona discharge provided at the exit of the application gun and are directed toward the target. The individual particles thus become electrostatically charged and are attracted to the oppositely charged target. A controller provides the necessary filtered and pressurized air to the system and also provides electrical power to the gun for creating the electrostatic field or corona. The amount of coating material required for the individual targets is predetermined (and may be determined empirically) and the controller is set to precisely shut off the flow of fluidized material from the hopper to the gun at a value equal to the predetermined amount. The present invention also provides for the prefluidization of the material through use of plural hoppers that are operated in an area remote from the food processing area to permit the fluidization of the coating material to be stabilized at a desired density distribution in the hopper prior to the connection of the individual hopper to the coating system. The prefluidizing step is facilitated through the utilization of quick disconnect couplers to enable the hopper to be rapidly changed to thereby avoid significant delays in the coating process.
REFERENCES:
patent: 3828729 (1974-08-01), Goodridge
patent: 4169903 (1979-10-01), Scholes
patent: 4296142 (1981-10-01), Vasudevan et al.
patent: 4702932 (1987-10-01), Cosentino et al.
patent: 5356577 (1994-10-01), Boldis et al.
patent: 5846587 (1998-12-01), Kelly et al.
patent: 6054154 (2000-04-01), Wang
Bhat Nina
Cahill Sutton & Thomas P.L.C.
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