The invention relates to an apparatus and method for the manufacture of popcorn.

There are presently two known types of popcorn, namely toffee popcorn and oiled popcorn.

Although toffee popcorn can be made by a substantially continuous process, using rotary kilns to pop the maize kernels, oiled popcorn is made in a batch process, which is relatively cumbersome and old fashioned, leading to low production rates.

It would be desirable to manufacture oiled popcorn using a substantially continuous process, but attempts to adapt the rotary kilns used for toffee popcorn have been unsuccessful. We have discovered that a coating of oil tends to build up on the surface of the kilns, which eventually catches fire.

By abandoning the teachings of the old production processes and starting again from first principles, we have developed an apparatus and method by which oiled popcorn can be produced in a substantially continuous manner.

The invention provides an apparatus for the manufacture of popcorn, the apparatus comprising a conveyor and a popcorn popping station, the conveyor being drivable to convey maize kernels continuously through the popping station.

The apparatus may include means to precoat the maize kernels with oil.

The popping station may comprise a tunnel oven.

Preferably the tunnel oven is inclined to the horizontal, the conveyor being drivable to convey the maize kernels along a downward slope through the oven.

We have discovered that with this downward slope the kernels tend to eject themselves from the oven using the energy released by popping, thus avoiding overheating of the kernels.

The angle of the slope may be in the range 30° to 70° The preferred angle is substantially 48°.

The conveyor may comprise a continuous conveyor travelling from a maize kernel input station to the popping station.

The conveyor may be heated.

A conveyor cleaning station may be provided between the popping station and the kernel input station.

The cleaning station may comprise washing and drying means.

The washing means may comprise one or more wash tanks.

The drying means may comprise a drying tunnel.

The drying tunnel may extend in the upward direction and may, for example, be arranged vertically.

The conveyor may comprise a continuous belt conveyor. The belt conveyor may comprise flexible steel.

Preferably the apparatus has means to cause the maize kernels to roll on the belt conveyor to promote even distribution of an oil coating over the kernels and to reduce any tendency for the kernels to stick to the conveyor.

The means to cause the kernels to roll may comprise a plurality of ribs which move with respect to the belt conveyor along the length of the belt conveyor.

There may, for example, be a ladder conveyor superimposed on the belt conveyor but moving at a slightly different speed.

The invention includes a method of manufacturing popcorn comprising popping maize kernels utilising the apparatus defined above.

The invention includes popcorn when manufactured using the apparatus defined above or the method defined above.

While the apparatus and method have been specifically developed for the continuous production of oiled popcorn, the apparatus and method may be capable of manufacturing other forms of popcorn or other food products.

By way of example, specific embodiments of the invention will now be described, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic side view of one embodiment of continuous oil popped popcorn popping apparatus according to the invention;

Figure 2 is a more detailed side view of part of the conveyor of the apparatus shown in Figure 1;

Figure 3 is a side view, to a larger scale, of some ancillary equipment; and

Figure 4 is a diagrammatic side view of an alternative embodiment of apparatus according to the invention.

When manufacturing popcorn according to this embodiment, maize kernels are mixed with oil (and possibly salt or sugar) in a conventional pre-mix system not shown in the drawings. The prepared kernels are then fed into the apparatus shown in Figure 1 through a hopper and mixer unit 10 and distribution unit 11, which include a rotary feed valve, not visible in Figure 1.

The apparatus shown in Figure 1 comprises supporting frames 12, on which are mounted the various other components of the apparatus. The two primary components are a tunnel oven 13, inclined at an angle of 48° to the horizontal, and a continuous belt conveyor 14, which travels through the apparatus around supporting rollers. The upper part of the oven 26 extends horizontally.

Other components comprise an outlet flue 15, outer and inner conveyor belt wash tanks 16 and 17, a vertical drying tunnel 18, an electric control unit 19 and a gas and temperature control unit 20.

The whole apparatus is supported on adjustable length legs 21 and 22.

A section of the conveyor 14 is shown in greater detail in Figure 2.

There is a flexible steel base conveyor 23 and superimposed on this there is a flexible ladder conveyor having spaced apart rungs 24 extending between side members 25. The ladder conveyor is driven at a slightly different speed to the base conveyor, so that there is slight relative movement between the rungs 24 and the base conveyor.

In use, the oiled maize kernels are deposited onto the conveyor in the upper part of the oven 26 and they are then conveyed along a downward slope through the oven 13, which is heated through direct gas heating. Because of the relative movement between the rungs 24 and the base conveyor 23, the maize kernels tend to roll on the base conveyor 23, which promotes even heat transfer to the kernels and also reduces any tendency for the kernels to stick to the base conveyor.

The heating in the oven causes the kernels to expand rapidly in the conventional manner. The increase in size, the release of energy, and the downward angle of the oven and conveyor combine to promote ejection of the popped maize out of the lower end 27 without overheating or burning.

The supply of gas to the oven, and the temperature of the oven, are controlled by the unit 20. The driving of the conveyors and operation of other electrical components

of the apparatus are controlled by the electrical control unit 19.

After the conveyor emerges from the oven it is directed by rollers through the outer wash tank 16 and the inner wash tank 17 to clean the belt. The belt then rises vertically through the drying tunnel 18 to return to the kernel receiving point 26.

The apparatus may be operated in conjunction with ancillary equipment, for example the unit 28 shown fully in Figure 3 and partially in Figure 1.

The popped kernels enter this unit via a ramp 29. By using a unit separate from the oven, the popcorn can be given other treatment without heat damage. For example, the unit may be used to carry out a controlled method of applying flavouring and colouring ingredients. Flavouring and colouring ingredients may be carried on an alcohol base, which can be evaporated in a fluidised chamber of the unit 28 to remove the alcohol and dry the corn. Thus the final quality of the product can be controlled in a unit which is not subjected to the potentially damaging heat from the oven.

Modifications are possible. For example, microwave heating may be possible instead of gas heating.

Figure 4 illustrates diagrammatically an alternative embodiment in which a horizontal conveyor belt 30 is used.

The horizontal conveyor belt 30 is a flexible steel and passes around drive rollers 31 at one end of the apparatus and idler rollers 32 at the other end of the apparatus.

Maize kernels are individually precoated in oil in a premix apparatus 33. The precoated kernels are then transferred from the apparatus 33 into a loading hopper 34, which feeds the kernels on at one end of the belt 30. A spreading roller 35 evenly distributes the kernels over the belt and they then pass to the popping station 36. In the region of the popping station 36, the steel belt is heated with gas burners 37 and this part of the belt is covered by an insulated cover 38.

In an alternative arrangement, the steel belt may be heated in the region of the popping station 36 using electrical induction heating.

The drive rollers 31 may be mechanically or electronically controlled to set the desired speed of the machine for effective popping of the corn. The insulated cover 38 may be ventilated as necessary to control the temperature above the metal belt.

Although heating by gas and electrical induction have been specifically mentioned, other forms of heating may be used, including microwave or infrared heating. The heat source may be thermostatically controlled to achieve the desired quality of popped corn.

To reduce the risk of burning of the corn and provide effective heat distribution, there may be agitation in the form of linear, circular, reciprocating, secondary ladder conveyor or other form of motion. The agitation may be mechanical, electrical, or may use air or other forms of propulsion.

Although precoating of the corn with oil has been specifically mentioned, other precoating ingredients may

include sugar and salt. In some embodiments it may be possible to deliver the coating ingredients and the maize kernels simultaneously into the machine, without the need for premixing.

Side guides may be provided in contact with the steel belt, which may be spring loaded to form an enclosed cavity to reduce leakage of ingredients from the side of the belt.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) , may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s) . The invention extends to any novel one, or any novel combination, of the features

disclosed in this specif ication ( including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.