GB1577733A - Salt bed cooking - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO SALT BED COOKING (71) We, UNITED BISCUITS (UK) LIM ITED, (formerly United Biscuits Limited), of 12 Hope Street, Edinburgh, Scotland, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an apparatus and a process for the treatment of food products and, more particularly to improvements in apparatus for carrying out salt bed cooking and other food treatment processes wherein food products are treated by contact with a granular material.

Although other granular materials can be used or envisaged, common salt is the heat transfer material usually employed and so reference is made at several places herein to salt and salt bed cooking, as convenient but non-limiting names for the granular material and the food treatment technique in question.

This invention provides an apparatus for subjecting food pieces to treatment by contact with a particulate medium, which comprises a first elongate chamber arranged for rotation about a substantially horizontal axis, a second elongate chamber mounted co-axially within the first chamber for corotation therewith, the chambers being arranged so that their co-rotation causes particulate medium to travel longitudinally in one direction within the first chamber and in the opposite direction within the second chamber, first transfer means provided at one end of the elongate chambers and arranged, in operation, to transfer particulate medium from the first chamber to the second and second transfer means provided at the other end of the elongate chambers and arranged, in operation, to transfer particulate medium from the second chamber to the first whereby food pieces introduced into the apparatus at the one end are treated in contact with the particulate medium as it travels longitudinally of the second chamber and the treated food pieces are discharged at the other end.

This invention also provides an apparatus for carrying out salt bed cooking, which comprises inner and outer co-axial chambers arranged for co-rotation about a substantially horizontal axis, first transfer means being provided at one end for transferring salt from the outer chamber to the inner and second transfer means at the other end for transferring salt from the inner chamber to the outer, whereby in use salt circulates from the outer chamber, where it is heated, to the inner chamber, where a food product to be heated can be introduced into the salt bed, and back to the outer chamber.

An apparatus according to this invention is extremely effective but also is simple to construct and use, as the two coaxial chambers and the transfer means effectively constitute a single rotatable part which rotates so as to cause controlled circulation of the salt or other particulate medium and its admixture with the food product, which is preferably passed axially into, through and out from the inner chamber in the same direction as the bed of salt, which is constantly replenished from the stream of salt passing in the opposite direction in the outer chamber.

Either or both of the chambers can be substantially cylindrical, helical guide members of appropriate hand being provided preferably on both of their respective inside surfaces, if desired, so as to assist in circulating the salt. The transfer means for feeding the salt from the outer chamber to the inner may suitably comprise one or more spiral guides disposed in an end cover attached to the outer chamber, whilst the means for transferring the salt from the inner chamber to the outer can merely comprise any arrangement which employs the natural tendency of the salt to fall under gravity as it reaches the end of the inner chamber. Preferably, however, each chamber is a conical frustum, tapered in the intended direction of movement of the salt bed therein, though a helical guide member is conveniently still provided to assist movement of the salt, at least in the outer chamber. Also, the means for transferring the salt from the inner chamber to the outer preferably comprise a size separator in the form of a series of apertures in the inner chamber wall, of such a size that the relatively fine granules of the salt pass through them into the upstream end of the outer chamber, whilst the food products do not pass through and thus move further axially of the apparatus and are discharged separately from the salt. The end cover desirably includes a central aperture, preferably leading to a tubular inlet, to serve as a feed duct for introducing portions of food product into the apparatus.

The invention provides an improved process for effecting salt bed cooking, which comprises forming a moving salt bed in a food treatment chamber located within a salt heating chamber, circulating salt from the food treatment chamber through the salt heating chamber and back to the food treatment chamber out of contact with the food product to be treated, heating the salt to a predetermined temperature as it traverses the salt heating chamber without directly heating the salt bed in the food treatment chamber and passing portions of the food product through the food treatment chamber within the moving salt bed.

The invention also provides a process of treatment of food pieces which comprises the use of the apparatus of the invention and, further a food product made by a process or in an apparatus of the invention.

In order that the invention may be readily understood a preferred embodiment of the apparatus is described below in conjunction with the accompanying drawing, in which: Fig. 1 shows the apparatus in diagrammatic side view; Fig. 2 shows the food treatment and salt heating chambers in diagrammatic perspective view, partly broken away.

A central substantially horizontal shaft 10 (Fig. 1) is provided at spaced locations with two spiders 11, 12, each consisting of, say, four arms. An inner drum 13 is mounted on the arms of the spiders 11, 12, the drum 13 tapering from right to left as shown in Fig. 1. Its wider end comprises a perforate section 14, whilst an inwardlydirected flange 15 is provided at its narrower end. An outer drum 16 is mounted on the arms of the spider 11 (which pass through the drum 13) and upon the wider end of the drum 13, the drum 16 tapering from left to right as shown in Fig. 1. The joined right-hand ends of the drums 13 and 16 can if desired be connected, as shown, by an annular plate 17. A helical baffle or guide plate 18 is disposed between the drums 13 and 16, by being mounted upon the inner surface of the outer drum 16 and extending at least partly across the gap to the outer surface of the inner drurn 13.

The outer drum 16 is a first elongate chamber which forms a heating chamber for taking a granular material, e.g. salt, up to a predetermined elevated temperature, whilst the inner drum 13 is a second elongate chamber within the first which forms a food treatment chamber in which, in use, a moving salt bed forms, as shown at 19, the drum 13 being located within the outer drum 16 in such a way that the inner drum 13 and therefore the moving salt bed 19 are kept out of direct contact with the means (indicated diagrammatically at 20) used to heat the outer drum 16 and the salt passing through it. The heating means 20 can be a series of gas burners or electrical elements, for instance.

At the wider end of the outer drum 16, which projects somewhat beyond the associated narrower end of the inner drum 13 carrying the flange 15, an end cover 21 is provided, which comprises an annular end plate 22 having a peripheral rim 23, by which the end cover 21 is fitted over the outside of the outer drum 16, and a central tube 24, which projects into the inner drum 13 through the hole formed in the centre of the flange 15. The shaft 10 passes out through the tube 24 at this end of the apparatus, as shown in Fig. 1. A pair of spiral plates 25 are located within the end cover 21, each plate 25 spiralling out from the tube 24 to the rim 23, the outer part of each plate 25 being associated with a blanking plate 26. The end cover 21 thus provides a means for transferring particulate medium from the outer chamber, i.e.

the drum 13. The hand of the plates 25 is related to that of the guide members 18 and the direction of rotation of the shaft 10, as shown by the arrows 27, so that in use the apparatus constituted by the drums 13 and 16 and the end cover 21 rotates as one piece and causes salt to pass from right to left through the drum 16, up the spiral plates 25 to the tube 24, from left to right through the drum 13 and down through the apertures 14 back to the outer drum 16, as indicated by the dotted arrows 28. The rate of movement of the salt bed 19 can be readily controlled by making the apparatus with suitable dimensions and rotating it at an appropriate speed, whilst the depth of the salt bed 19 depends upon these factors and also the total quantity of salt put into the apparatus. The rotatable unit formed by the shaft 10 and the parts mounted on it is mounted for rotation by means (not shown) within a heat chamber indicated by the chain-dotted enclosure 29. Portions of a food product to be subjected to salt bed cooking are fed from a supply, shown as a hopper 30, to the tube 24, where they fall into the upstream end of the moving salt bed 19, become cooked and expanded and rise to the surface of the bed 19 as it approaches the perforations in the section 14, which not only acts as a means to transfer the salt from the drum 13 to the drum 16 but also serves as a separator to cause the cooked food product portions to discharge from the apparatus, whilst the salt is retained. The food product passes into, through and out of the food treatment chamber formed by the drum 13 as shown by the full arrows 31, out of direct contact with the heating means 20, so that precise control of the cooking conditions can be readily provided. The cooked product is discharged from the apparatus, e.g. as shown by the conveyor 32. It will be appreciated that the apparatus described is simple to make and operate and yet it allows salt bed cooking to be carried out easily and with a high level of control, enabling accurately reproducible conditions to be employed and therefore a range of consistent products to be made.

WHAT WE CLAIM IS:- 1. An apparatus for subjecting food pieces to treatment by contact with a particulate medium, which comprises a first elongate chamber arranged for rotation therewith, the chambers being arranged so that their co-rotation causes particulate medium to travel longitudinally in one direction within the first chamber and in the opposite direction within the second chamber, first transfer means provided at one end of the elongate chambers and arranged, in operation, to transfer particulate medium from the first chamber to the second and second transfer means provided at the other end of the elongate chambers and arranged, in operation, to transfer particulate medium from the second chamber to the first whereby food pieces introduced into the apparatus at the one end are treated in contact with the particulate medium as it travels longitudinally of the second chamber and the treated food pieces are discharged at the other end.

2. An apparatus for subjecting food pieces to salt bed cooking, which comprises inner and outer co-axial chambers arranged for co-rotation about a substantially horizontal axis, first transfer means being provided at one end for transferring salt from the outer chamber to the inner and second transfer means at the other end for transferring salt from the inner chamber to the outer, whereby in use salt circulates from the outer chamber, where it is heated, to the inner chamber, where a food product to be heated can be introduced into the salt bed, and back to the outer chamber.

3. An apparatus according to Claim 1 or 2, wherein the first transfer means comprise at least one spiral plate disposed between annular plates attached respectively to adjacent ends of the chambers.

4. An apparatus according to Claim 1, 2 or 3, wherein the second transfer means comprise a size separator arranged to convey treated food pieces to be discharged from the chambers while allowing particulate medium to pass from one chamber to the other.

5. An apparatus according to any preceding claim, wherein at least one of the elongate chambers is a conical frustum diverging in the intended direction of travel of particulate medium.

6. An apparatus according to any preceding claim, wherein helical guide plates are mounted inside at least one of the chambers so as to cause or assist movement of the particulate medium longitudinally thereof.

7. An apparatus according to any preceding claim, wherein a tubular inlet for food pieces disposed co-axial with the chambers extends from the one end of the chambers to a region inside the second chamber.

8. An apparatus according to Claim 1, substantially as described with reference to the accompanying drawing.

9. A process of treatment of food pieces, which comprises maintaining a heated body of particulate medium in circulation in an apparatus as defined in any preceding claim and subjected to rotation about the substantially horizontal axis, introducing food pieces into the apparatus for treatment in contact with the particulate medium and discharging treated food pieces from the apparatus.

10. A food product when made by a process according to Claim 9.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. cooking are fed from a supply, shown as a hopper 30, to the tube 24, where they fall into the upstream end of the moving salt bed 19, become cooked and expanded and rise to the surface of the bed 19 as it approaches the perforations in the section 14, which not only acts as a means to transfer the salt from the drum 13 to the drum 16 but also serves as a separator to cause the cooked food product portions to discharge from the apparatus, whilst the salt is retained. The food product passes into, through and out of the food treatment chamber formed by the drum 13 as shown by the full arrows 31, out of direct contact with the heating means 20, so that precise control of the cooking conditions can be readily provided. The cooked product is discharged from the apparatus, e.g. as shown by the conveyor 32. It will be appreciated that the apparatus described is simple to make and operate and yet it allows salt bed cooking to be carried out easily and with a high level of control, enabling accurately reproducible conditions to be employed and therefore a range of consistent products to be made. WHAT WE CLAIM IS:-

1. An apparatus for subjecting food pieces to treatment by contact with a particulate medium, which comprises a first elongate chamber arranged for rotation therewith, the chambers being arranged so that their co-rotation causes particulate medium to travel longitudinally in one direction within the first chamber and in the opposite direction within the second chamber, first transfer means provided at one end of the elongate chambers and arranged, in operation, to transfer particulate medium from the first chamber to the second and second transfer means provided at the other end of the elongate chambers and arranged, in operation, to transfer particulate medium from the second chamber to the first whereby food pieces introduced into the apparatus at the one end are treated in contact with the particulate medium as it travels longitudinally of the second chamber and the treated food pieces are discharged at the other end.

2. An apparatus for subjecting food pieces to salt bed cooking, which comprises inner and outer co-axial chambers arranged for co-rotation about a substantially horizontal axis, first transfer means being provided at one end for transferring salt from the outer chamber to the inner and second transfer means at the other end for transferring salt from the inner chamber to the outer, whereby in use salt circulates from the outer chamber, where it is heated, to the inner chamber, where a food product to be heated can be introduced into the salt bed, and back to the outer chamber.

3. An apparatus according to Claim 1 or 2, wherein the first transfer means comprise at least one spiral plate disposed between annular plates attached respectively to adjacent ends of the chambers.

4. An apparatus according to Claim 1, 2 or 3, wherein the second transfer means comprise a size separator arranged to convey treated food pieces to be discharged from the chambers while allowing particulate medium to pass from one chamber to the other.

5. An apparatus according to any preceding claim, wherein at least one of the elongate chambers is a conical frustum diverging in the intended direction of travel of particulate medium.

6. An apparatus according to any preceding claim, wherein helical guide plates are mounted inside at least one of the chambers so as to cause or assist movement of the particulate medium longitudinally thereof.

7. An apparatus according to any preceding claim, wherein a tubular inlet for food pieces disposed co-axial with the chambers extends from the one end of the chambers to a region inside the second chamber.

8. An apparatus according to Claim 1, substantially as described with reference to the accompanying drawing.

9. A process of treatment of food pieces, which comprises maintaining a heated body of particulate medium in circulation in an apparatus as defined in any preceding claim and subjected to rotation about the substantially horizontal axis, introducing food pieces into the apparatus for treatment in contact with the particulate medium and discharging treated food pieces from the apparatus.

10. A food product when made by a process according to Claim 9.