Refrigeration – Processes – Deodorizing – antisepticizing or providing special atmosphere
Patent
1992-06-09
1994-03-15
Capossela, Ronald C.
Refrigeration
Processes
Deodorizing, antisepticizing or providing special atmosphere
62440, 165 2, 165 58, F24F 316
Patent
active
052937534
DESCRIPTION:
BRIEF SUMMARY
This invention generally relates to a refrigerating or freezing plant for food, said plant comprising a substantially closed housing and, arranged therein, means for refrigerating food in said housing, and having an operating cycle which comprises a work period during which the refrigerating means are active, and a rest period during which the refrigerating means are inactive and the plant can be cleaned. More precisely, the invention concerns a method for preventing bacterial growth in such a plant, as well as a refrigerating or freezing plant for carrying out the inventive method.
At regular intervals, plants for refrigerating or freezing food on an industrial scale must be completely cleaned to remove any remaining food and prevent bacterial growth. In most cases, this is achieved by switching off the plant, which then is manually cleaned with suitable detergents and hot water. Alternatively, the plant can be cleaned by means of a fixedly mounted piping system having spray nozzles through which the detergents and the hot water are supplied.
The effect of such cleaning has, however, proved to be comparatively short-lived. When the plant is to be started up again, the temperature therein is, of course, reduced. This reduction in temperature is followed by a reduction in pressure, resulting in that air which may contain bacteria is drawn into the plant from the surrounding atmosphere. Also occasional pressure reductions during operation may entail the ingress of bacteria.
One object of the invention is, therefore, to provide a refrigerating or freezing plant preventing, or at least reducing the risk of, bacterial growth, especially upon the reductions in temperature and pressure taking place when the refrigerating means are reactivated. Another object of the invention is to provide a method for preventing bacterial growth in such a refrigerating or freezing plant for food.
According to the invention, the first-mentioned object is achieved by a refrigerating or freezing plant of the type mentioned in the introduction to this specification, which is characterised by means for raising the temperature in the plant, during a rest period, above a temperature requisite for killing bacteria, e.g. 72.degree. C., and means for supplying air free from bacteria to the interior of the plant in order to raise the air pressure therein above the ambient pressure, at least during the entire rest period, said air supply means comprising a fan which communicates with an opening in the housing of the plant and is adapted to supply air for as long as the temperature in the housing is above a given temperature, e.g. 0.degree. C.
Advantageously, the air supply means further comprises an air compressor which is connected in series to a compressed-air container having an air outlet disposed in the plant.
The second-mentioned object of the invention is achieved in that the cleaning includes raising the temperature in the plant above a temperature requisite for killing bacteria, preferably 72.degree. C., and that the air pressure in the plant is maintained higher than the ambient pressure, at least during the entire rest period, by supplying air free from bacteria by means of a fan for as long as the temperature in the housing is above a given temperature, e.g. 0.degree. C.
According to the invention, the air pressure in the plant is suitably maintained higher than the ambient pressure also during the work period by supplying air free from bacteria.
By air free from bacteria is meant both air which has been rid of bacteria, e.g. by filtering, and air in which the bacteria have been killed, e.g. by heating.
The invention will be described in more detail below, reference being had to the accompanying drawings, in which
FIG. 1 is a schematic view of a freezing plant according to the invention,
FIG. 2 is a cross-section of the inventive freezing plant,
FIG. 3 is a perspective view of part of the plant in FIG. 2,
FIG. 4 is a schematic view of a preferred embodiment of a subsystem of the inventive freezing plant, and
FIG. 5 schematically
REFERENCES:
patent: 3891779 (1975-06-01), Robinson
patent: 4845958 (1989-07-01), Senda et al.
patent: 5077009 (1991-12-01), Subotics et al.
Rothstein Sven-Olle
Solminger Jan
Capossela Ronald C.
Frigoscandia Food Process Systems AB
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