Food or edible material: processes – compositions – and products – Surface coating of a solid food with a liquid
Reexamination Certificate
2000-11-09
2004-05-04
Becker, Drew (Department: 1761)
Food or edible material: processes, compositions, and products
Surface coating of a solid food with a liquid
C426S306000, C426S307000, C426S512000, C426S515000, C118SDIG004, C427S420000
Reexamination Certificate
active
06730344
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates, in a first of its aspects, to a method of and an apparatus for applying a coating to articles, eg an edible coating to food articles. The invention is particularly, but not exclusively, concerned with the application of edible coating materials which exhibit non-Newtonian behaviour, for example chocolate, to articles of confectionery and the like. The present invention also relates, in a second of its aspects, to an improved method of forming a curtain of material eg edible material which can be used to coat articles eg articles of food or which can be used in other ways in the formation of articles, eg articles of food.
2. Description of Related Art
It is well known to enrobe articles of food such as chocolate assortmnents, confectionery bars, biscuits, cookies and cakes with a layer of chocolate. This coating process is known as chocolate enrobing and is traditionally effected by moving the articles on a mesh-type conveyor belt through a curtain of liquid chocolate whose consistency is carefully controlled. However, it is difficult to achieve the desired coating because of the high viscosity. It is therefore common practice to subject the articles to a greater than needed coating, then controlling the amount of chocolate remaining on the articles by blowing by air from fans and using vibration to remove the excess.
Also, the temperature of chocolate cannot be increased so as to reduce its viscosity as it will lose its temper, causing problems of incorrect fat crystallisation which can deleteriously affect the appearance and/or eating quality of the chocolate. Thus, it is common for enrobing chocolate to have a higher fat content than standard chocolate used for making chocolate bars in order to reduce its viscosity. This has adverse cost implications.
In order to establish the curtain of chocolate, it is known to allow chocolate to pass under the action of gravity through an outlet slot in the bottom of a trough having inclined side walls leading to the slot. This type of apparatus has a relatively low throughput because of the high viscosity of the chocolate and the relatively low rate at which it can flow through the outlet slot. The common solution to this problem is to use a wider slot, which results in a thicker curtain which then requires removal of more excess from the articles. Because of the physical characteristics of the chocolate which passes through the slot, the curtain can “neck” to a substantial extent. In other words, the width of the chocolate curtain becomes substantially less than the length of the slot from which it issues. This means that the effective cover of the curtain over the width of the conveyor belt used to carry the articles through the curtain is reduced.
Another known form of apparatus for producing a chocolate curtain utilises a roller along which liquid chocolate is distributed and carried to a blade which causes the layer of chocolate on the roller to become detached and thereby establish the curtain. This can provide higher coating rates with a better control of curtain thickness, but difficulties still arise in coating.
With both of the above types of known apparatus, the amount of chocolate in the descending curtain is greatly in excess of that required to coat the articles. The excess drains through the mesh-type conveyor belt and needs to be recycled and its condition carefully controlled.
SUMMARY OF THE INVENTION
It is an object of a first aspect of the present invention to obviate or mitigate at least some of the above disadvantages.
In accordance with said first aspect of the present invention, there is provided a method of applying a coating to articles, comprising the steps of:
(i) providing a curtain of solidifiable liquid coating material;
(ii) effecting relevant movement between articles to be coated and the curtain so as to coat the articles with the solidifiable liquid coating material; and
(iii) subjecting the solidifiable liquid coating material to the action of at least one stream of gas under pressure whereby to modify the flow characteristics of the curtain.
Also in accordance with said first aspect of the present invention, there is provided apparatus for applying a coating to articles, comprising:
(i) supply means arranged to provide a curtain of solidifiable liquid coating material;
(ii) means for effecting relative movement between articles to be coated and the supply means whereby in use the articles are coated with the solidifiable liquid coating material in the curtain; and
(iii) means arranged to subject the solidifiable liquid coating material to the action of at least one stream of gas under pressure whereby to modify the flow characteristics of the curtain.
Preferably, the articles are articles of food and the coating material is an edible coating material.
In the case where the present invention is used in a coating apparatus of the type in which the coating material is caused to flow along a surface of the supply means (eg a trough) towards an outlet slot through which the coating material flows under the action of gravity to form the curtain, it is preferred for said at least one stream of gas to be introduced between the coating material and the surface of the supply means. In this way, a layer of gas can be introduced between the surface and the coating material as it flows towards the outlet slot. Preferably, in the case of a trough where the coating material flows over opposed surfaces towards the outlet slot, a layer of gas is introduced between the coating material and each of the opposed surfaces. This can not only substantially reduce the resistance to flow of the coating material over the surfaces, but can also reduce the viscosity of the coating material if it is of a type whose viscosity is reduced when subjected to shear.
It is particularly preferred to cause said at least one stream of gas under pressure to become attached to the surface of the supply means so as to assist in establishing the layer of the gas between the surface and the coating material. This may be achieved by positioning one or more gas-admission slots in such a way as to direct the gas against the surface of the supply means. The spacing between the outlet slot and the or each gas-admission slot depends upon the nature of the coating material and the geometry of the supply means, which may comprise a trough having V-shaped walls defining opposed surfaces which converge towards the outlet slot. If the or each gas-admission slot is disposed too close to the outlet slot, then the flow of gas through the outlet slot may actually restrict the flow of coating material therethrough. On the other hand, if the or each gas-admission slot is disposed too far away from the outlet slot, the coating material flowing over the surface may become re-attached to the surface of the supply means before it reaches the outlet slot.
In the case where the above-mentioned trough is employed, it is within the scope of the present invention to provide said at least one stream of gas under pressure at one or both convergent opposed surfaces of the trough leading to the outlet slot.
Said at least one stream of gas under pressure may be applied to the coating material after the curtain has been established in order to change the direction of the curtain and/or a physical property of the coating material forming the curtain. It is also within the scope of the present invention to subject the coating material to the action of at least one stream of gas both before and after the curtain has been established.
A curved surface may be provided adjacent to part of the curtain, and means may be provided for causing a stream of gas to flow over the curved surface by virtue of the Coanda effect and to use this to induce a change in the direction of travel of the curtain. In this way, it is possible to control the direction of flow of the curtain from any angle from vertical to substantially horizontal. This effect can be used whether or not the coating material is subjected to the act
Sanders Nigel Hugh
Smith Anthony Gregory
Thomas David Michael
Becker Drew
Cadbury Schweppes PLC
Ohlandt Greeley Ruggiero & Perle LLP
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