Drying and gas or vapor contact with solids – Material treated by electromagnetic energy – Microwave energy
Reexamination Certificate
2001-07-23
2002-09-03
Lazarus, Ira S. (Department: 3749)
Drying and gas or vapor contact with solids
Material treated by electromagnetic energy
Microwave energy
C034S259000, C034S264000, C034S266000, C219S388000, C219S686000, C219S701000, C432S152000, C426S242000, C099S472000
Reexamination Certificate
active
06442866
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for drying or heat-treating products or substances, namely food products. Further it relates to an apparatus for drying or heat-treating products, namely food products. Finally, the invention relates to a dried food product.
SUMMARY OF THE INVENTION
To accelerate drying and for a more gentle treatment, heat-treating substances, such as agricultural products for example, is often done at a reduced pressure in a pressure-tight treatment chamber in which a heating source is arranged. Liquid products are usually pumped into the treatment chamber for treatment where they are evenly distributed on an endless conveyor belt which guides them past a heating source. In this arrangement the conveyor belt serves two functions, namely transporting, on the one hand, and, on the other, receiving and guiding the product to be treated. For this purpose the conveyor belt is usually configured troughed, for example upswept or provided with side sealing means. On completion of drying the treated product is scraped from the rear end of the belt and discharged via a dual gating system, for example. If the product to be treated is available as a solid or lumpy product a dual gating system is usually also provided for charging.
One such system is disclosed for example from DE 295 17 499 U1. This system comprises a treatment chamber in which microwave treatment and vacuum drying take place, the product to be treated being conveyed by an endless conveyor belt into the treatment chamber. Charging and discharging the treatment chamber is done via a dual gating system in exploiting the force of gravity. On impacting the conveyor belt the infalling product may be deformed and remain adhering to the conveyor belt. The product to be treated comes into contact with various components, such as with the dual gating system and the conveyor belt, for example.
In systems for heat-treating products at a pressure other than atmospheric pressure it is usually so that a change from one product to another product can only be made with a lot of trouble since many of the components are accessible only with restrictions, and need to be cleaned or replaced. Furthermore, satisfying hygiene code requirements is only possible at great expense.
The object of the present invention is to improve a method and an apparatus for drying or heat-treating products in a treatment chamber operating at a pressure other than atmospheric pressure. More particularly, the intention is to provide a method or apparatus with which drying or heat-treating of products is possible by ways and means which are hygienic, preferably without detrimenting taste and quality of the product to be treated as well as being cost-effective and low-wearing. Where food processing is concerned, it is furthermore the intention to make an end product possible having improved properties. Preferably, the method and the apparatus are intended to be suitable for drying banana chunks into banana chips, as starting product for a banana powder to be produced. Further banana chips and the banana powder to be produced therefrom are to be produced with as instant-type banana chips and powder. Furthermore, it is the intention to provide a transport receptacle suitable for implementing the method.
In accordance with the present invention there is provided a method of drying or heat-treating products in a treatment chamber, in which a pressure other than atmospheric pressure prevails, in which the products to be treated are charged in a transport receptacle. The transport receptacle is transported into the treatment chamber via a charging lock chamber in which the pressure is made equal to that existing in the treatment chamber. In the treatment chamber the product to be treated is guided past a heating source, preferably a microwave and/or infrared source by means of a main conveyor means arranged in the treatment chamber. This is followed by the discharge via a discharging lock chamber in which the pressure is made equal to another pressure, preferably to ambient air pressure. Preferably, to each charging and discharging lock chamber conveyor means are associated, which are independent of the main conveyor means in the treatment chamber.
In accordance with the invention the product to be treated does not come into contact directly with any of the conveyor means or any other components, thus effectively preventing soilage or contamination of the components difficult to access, for example conveyor belts in the treatment chamber. One advantage is that a change from one kind of product to another may be simply done without any detriment to the other product in each case, especially as regards taste, in the case of food products. Another advantage is that in accordance with the invention alternating operation is possible in products differing in provenance and quality may be processed quasi-continuously and without the one detrimenting the other.
Yet a further advantage is that the product to be treated or remainders thereof need not be removed mechanically from a conveyor belt in a vacuum chamber. This adds to the life of a conveyor belt arranged in the treatment chamber due to its reduced wear. Furthermore, the conveyor means are hardly exposed to transverse forces, due to the gentle continual transport, thus reducing the maintenance expense of the apparatus to advantage.
Still another salient advantage is that due to the use of transport receptacles for receiving the products to be treated freedom of design of the conveyor means arranged in the treatment chamber is permitted. In particular it does not need to be configured troughed or expansive any longer.
Preferably the transport receptacles after having passed through the treatment chamber are cleaned before being returned to a repeated processing cycle, thus ensuring hygienic operating conditions by simple ways and means. It is furthermore of advantage that the hygienic condition of the transport receptacles may be simply inspected and that bacteria, germs or spores are unable to multiply unchecked in the treatment chamber, for example in liquid films or product spillage in the treatment chamber. This is especially of advantage when processing or producing medicinal drugs subject to stringent hygiene code requirements. More particularly, in the case of highly-sensitive food products, such as for example banana chunks, berries or mushrooms, using preservatives may now be substantially reduced or even avoided altogether by simple ways and means.
Where allowed by the nature of the product concerned, more particularly in the case of slightly sticky or non-flowable products or substances, the transport receptacle is configured as a plate which need not be rimmed. Should, however, the nature of the product require such a rim, especially where liquid or grainy substances are involved, the transport receptacle is to be configured as a dish having a rim so that the product to be treated is unable to fall or flow off on the side, for example into the treatment chamber, to thus save cleaning and operating costs. Preferably the rim is configured on all sides so that no side spillage whatsoever exists which would otherwise result in loss of the product. The rim may be configured upright, vertical to the bottom of the receptacle or in another suitable way to effectively prevent loss of the product during treatment.
Even better hygienic conditions are possible when the product is placed on a net or grid or on a replaceable net frame arranged in the transport receptacle. By configuring the portion coming into contact with the product as an airy, lightweight net, cleaning it may be affected even simpler and more effectively. Furthermore, moisture emitted by the product during drying is able to escape practically unrestricted on all sides, which accelerates drying and thus helps in saving costs. Preferably a gap is provided between the net or the receiving surface and the transport receptacle to enable the emitted moisture to be removed even more expediently.
It is particularly
Lazarus Ira S.
O'Malley Kathryn S.
St. Onge Steward Johnston & Reens LLC
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