This invention relates to an apparatus and a method for coating food items with a powdered substance, and particularly, but not exclusively, to coating hard confectionery products with a finely powdered edible substance.

It is known to provide a confectionery product, such as a lozenge or boiled sweet, with a finely powdered coating such as starch or icing sugar. The most common method used in the art to achieve this is to dust the finished sweets with the powdered coating. This has the disadvantage that the sweets can only be dusted on one side at a time, and so provision must be made for turning them over. It can also be difficult to ensure that the sweets are evenly coated.

According to one aspect of the invention we provide food item coating apparatus comprising a support surface, fluidisation means arranged in use to create a fluidised cloud of edible powdered coating material, and vibration means which in use causes the support surface to vibrate, the apparatus being so arranged that, in use, the vibration means causes food items to move along the support surface by way of a jumping motion through the fluidised cloud of powdered coating material. The food items are thus provided with a coating of the powdered coating material on their outer surfaces.

According to a second aspect of the invention we provide a method of coating food items comprising vibrating a support surface in such a way that food items thereon are caused to move along the support surface by way of a jumping motion through a fluidised cloud of edible powdered coating material.

A preferred embodiment of the invention will now be further described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a longitudinal cross section through confectionery item coating apparatus, and,

Figure 2 shows a perspective view of the confectionery coating apparatus of figure 1 with the hood removed.

Referring to the figures, a confectionery coating apparatus 1 comprises a trough 3 and an air manifold 5, the base of the trough being defined by inclined rigid porous membrane 7 made, for example, of microporous plastic material. A porous sintered material could be used however. The membrane 7 could be semi-rigid. In the embodiment shown the membrane 7 is fixedly held in position by supports 9. The rigid porous membrane 7 supports a layer of powdered starch 13. Air from the manifold 5 fluidises this starch towards a perforated deck 19. The trough and the membrane are vibrated by two out of balance motors 35.

In use, the air manifold 5 receives pressurised air via a conduit 11 from a fan (not shown) . It is to be understood that 'air' in this context includes any inert gas, such as nitrogen, which may be used to create a fluidised bed suitable for use with edible products.

The trough 3 comprises an end wall 28 and two side walls (not shown) . The membrane 7 is permeable to air, or other inert fluidising gas, but is not permeable to the edible coating material, in this case starch. The trough communicates at the opposite end thereof with a starch feed region 47. The region 47 comprises a base 16 of non-porous construction which is impermeable to air or starch. The base 16 is

formed integrally with an end wall 23, and said base is inclined downwards slightly from the wall 23 towards the porous membrane 7 to assist with starch feed or supply.

Starch is introduced into the starch feed region 47 by starch feed tube 15 comprising an elongate aperture provided on the underside thereof. The starch feed tube 15 houses a cross screw feed (not illustrated), or other suitable means, to ensure that starch is deposited evenly along the length of the feed, from one side of the trough to the other. The starch feed region 47 has minimal fluidisation of the starch around the starch feed 15 so as not to hinder the introduction of the starch. The provision of an area that is substantially free from the fluidised starch cloud is further desirable for reasons explained below.

A starch level control gate 17 is provided substantially on the boundary between the trough 3 and the starch feed region 47. This allows the level of the layer of starch on the porous membrane 7 to be controlled or modified, allowing the properties of the fluidised cloud to be adjusted as desired by moving the gate up of down. The gate 17 also assists in ensuring that the starch within the section of the starch feed region 47 is substantially unfluidised, thus improving control of the starch introduction and confining the fluidised starch cloud to the part of the trough above the porous membrane 7.

The perforated deck 19 is fixed to supports 21 at the top of the walls 23 and 28. The perforated deck 19 may be substantially horizontal or may be inclined slightly in the direction of the product flow, indicated by arrow 25. The perforated deck 19 extends beyond the longitudinal ends of the trough 3 to facilitate the delivery of products from a feed conveyor 41 onto the perforated deck and to a take away conveyor 43 from the perforated deck. Perforations 27 in the deck 19 are sufficiently

large so as to allow the flow of the fluidised starch therefore resulting in the function of a starch cloud 29 around the confectionery items 31, but not so large as to hinder the flow of the items 31 by, for example, allowing an item to fall through or get stuck in the perforations. The perforated deck comprises retaining side walls 45 (as shown in figure 2) which ensure that the items cannot fall over either side of the deck 19.

A hood 32 is disposed above the perforated deck 19 and clear of the items being conveyed thereon. Together, the hood 32 and the trough 3 form a coating chamber 33 though which the products to be coated 31 pass.

The two out of balance motors 35 attached to the trough so that, in use, the trough and the fixedly attached perforated deck 19 are caused to vibrate. The apparatus is isolated from its supporting frame 37 by rubber mounts 39 so that the vibrations are confined to the coating apparatus only.

In use the coating apparatus operates as follows. Pressurised air from the fan (not shown) is blown though the rigid porous membrane 7, having been distributed by the manifold 5. The air blows up though the starch layer 13 creating a fluidised cloud of starch 29 above it, which envelops the perforated deck 19. The perforations 27 ensure that the fluidisation of the cloud is not inhibited by the deck, and helps to ensure that the undersides of the items 31 can be coated.

The confectionery items to be coated 31, are delivered by feed conveyor 1 onto the perforated deck 19. In use, the motors 35 cause the manifold 5, the porous membrane 7 and the deck 19 to vibrate. This vibration serves a number of purposes. Primarily, it causes the products to move along the deck in the direction of arrow 25. This motion may be

assisted by a slight downwards incline in the deck from the feed conveyor towards the exit 49 of the apparatus. The vibration assists to some extent with the fluidisation of the starch by stirring up the starch layer 13. The vibration also has the added benefit of causing the products to 'jump' as they are conveyed along the deck, allowing the undersides of the products to be evenly coated by the fluidised starch cloud 29 without the need for additional apparatus, such as a stepped conveyor, to turn the products over, as in conventional dusting techniques.

The products 31 move slowly through the fluidised cloud 29, becoming evenly coated with starch as they progress. The speed of the products across the membrane, and hence the time spent in the fluidised cloud, can be varied by adjusting the motor frequency of the balance motors and/or the incline of the perforated deck. As the products approach the exit 49 of the apparatus they pass out of the fluidised starch cloud approximately at the point when they move onto the portion of the perforated deck 19 which lies over the non-porous part of the base 16 of the trough. In this part of the apparatus, the products are no longer being coated, and now the vibration serves the additional purpose of dislodging any loose starch from the products. This excess starch is not wasted, and falls through the perforated deck onto the inclined non-porous base 16 where it rejoins the starch layer 13 for recirculation. The products then pass out of the exit 49 of the apparatus and are delivered to the take away conveyor 43, which removes them for further processing or packaging.

It will be appreciated that the apparatus 1 could be used to coat other edible items such as medicinal tablets or dried fruit. It will be appreciated that instead of starch powdered sugar or powdered colourings/flavourings could be used for the fluidised bed.