BACKGROUND TO THE INVENTION In many food industries off-cuts of food (which will hereinafter for the sake of convenience be referred to as"food pieces") are produced as a by-product of the main process. Examples are the fish and chicken processing industries where pieces of fish and chicken are produced. These are either sold at a lower price or, in some instances, used to create a reconstituted food product. The method involves mixing a hydrocolloid, such as alginate, with the food pieces.

In the known process the hydrocolloid is added to the food pieces which can, for example, be off-cuts of meat. The hydrocolloid can be in a powder form or can be pre-mixed with water to form a gel. The hydrocolloid is mixed thoroughly with the food pieces. The mixture is set by adding a setting substance in the form of a small quantity of a calcium compound or an acid such as lactic acid or a mixture thereof.

A problem which is encountered is that the setting action takes place so rapidly that the calcium or acid cannot be distributed evenly throughout the mass of food pieces sufficiently quickly. As a result, certain food pieces are overdosed and set too hard, while others are underdosed and do not set properly.

A secondary problem which occurs in that the setting action takes place so quickly that there is inadequate time to remove the mass of food pieces from the mixer and shape it into its desired form.

The overall process is extremely sensitive, and minor adjustments to the formulation or to the process, or inconsistences in the production environment, can result in any of the following : - the product sets unevenly - the product sets too hard - the product lacks cohesion - the product sets too rapidly Because the first step in the process is the mixing of the bulky food pieces with the hydrocolloid mixture, every subsequent step in the process requires the thorough mixing of a bulky mass. A production line for the conventional method thus requires a succession of conventional bulk mixers with a high power consumption.

Although there is a market for a variety of reconstituted products, it is because of these problems that some manufacturers choose not to make reconstituted products using hydrocolloids.

The present invention seeks to provide a new method of producing saleable reconstituted food products. using food pieces and hydrocolloids.

BRIEF DESCRIPTION OF THE INVENTION According to a first aspect of the present invention there is provided a method of manufacturing a reconstituted food product from food pieces, the method comprising adding a composition including a setting retardant and a hydrocolloid to a food product which naturally contains at least one substance which causes the hydrocolloid to set.

According to a second aspect of the present invention there is provided a method of manufacturing a reconstituted food product from food pieces, the method comprising mixing with the food pieces a substance which, on contact with a hydrocolloid, causes the hydrocolloid to set, and thereafter mixing a hydrocolloid and setting retardant composition into the mixed food pieces and setting substance.

According to a third aspect of the present invention there is provided a method of manufacturing a reconstituted food product from food pieces, the method comprising feeding the food pieces into the inlet end of a static mixer, feeding a hydrocolloid and setting retardant composition into the static mixer at the inlet end of the static mixer so that the food pieces and composition are mixed in the static mixer, and dividing the food product emerging from the static mixer into portions.

The method may include the further step of subjecting the food pieces to low pressure before the food pieces enter the static mixer.

Even further, the method may include the step of mixing the food pieces with a hydrocolloid setting substance before feeding the food pieces into the static mixer.

According to a third aspect of the present invention there is provided apparatus for manufacturing a reconstituted food product from food pieces, the apparatus comprising a static mixer having an inlet end and an outlet end, means for feeding food pieces into the inlet end of the static mixer, means at the inlet end of the static mixer for injecting a hydrocolloid and setting retardant mixture into the static mixer, and means at the outlet end of the static mixer for dividing the food product emerging from the static mixer into portions.

The apparatus may include a vacuum pump for creating a zone of low pressure through which zone the food pieces pass before they enter the static mixer.

The feeding means may be a lobe pump.

According to a fourth aspect of the present invention there is provided . a static mixer comprising walling defining a passageway through which the product to be mixed is forced so that it flows from an inlet end of the static mixer to an outlet end, and mixer blades protruding inwardly into the passageway from said walling, each blade having a first surface which faces the inlet end of the static mixer, a second surface which faces the outlet end of the static mixer, a root at which the blade is attached to said walling and a tip which is in said passageway, the tip of each mixer blade being downstream of its root.

The said walling may comprise a plurality of part cylindrical shells each having blades protruding therefrom, the shells being secured together along longitudinally extending edges thereof.

According to a fifth aspect of the present invention there is provided a food portioning device comprising a cylinder having a transverse bore, a shuttle in the bore which can move to and fro in the bore, means for forcing food product into said bore from one end thereby to displace the shuttle along the bore ahead of the food product entering the bore, and means for rotating the cylinder through a half turn upon the shuttle reaching said other end of the bore and having forced from the bore food product which was in the bore ahead of the shuttle.

DETAILED DESCRIPTION OF THE INVENTION The basic constituent of reconstituted food products are pieces of, for example, meat, cheese, vegetables, fruit or starch rich products such as cooked samp or cooked wheat. The pieces may be cooked or raw, and the basic constituent can be a mixture of different food pieces.

Some foods naturally contain substances which, upon contact with a hydrocolloid, result in the hydrocolloid setting. An example is cheese. Other foods, such as chicken and fish do not contain any setting substances. Calcium is a setting substance and hence food which is rich in available calcium results in rapid setting of the hydrocolloid. If there is a setting substance present, then the food pieces are chopped, diced, sliced or otherwise comminuted into a paste or into particles having dimensions of not more than, for example, twenty millimetres in any direction.

Smaller particles of two to three millimetres in all directions are preferred. If there is no naturally occurring setting substance, then one is added to the comminuted food pieces and the comminuted food pieces and substance are throughly mixed so that all the comminuted food pieces have their surfaces coated with said substance.

The comminuted food pieces coated with setting agent are then mixed with a pre-hydrated blend of a hydrocolloid and a setting retardant. The hydrocolloid mixture is allowed to stand for at least 30 minutes prior to use to ensure thorough hydration. The mixing of the comminuted food pieces plus setting substance with the hydrocolloid mixture will be described hereinafter.

The product which emerges from the mixer may then optionally be provided with a secondary, external coating of a setting substance by means of a spray or bath to coat the surfaces at a concentration suitable for rapid setting. This step prevents the product portions from sticking together or adhering to the equipment, and renders the product suitable for handling and packaging. The secondary setting substance can have the same formulation as the primary setting substance.

If certain setting substances are used, lactic acid being an example, a high dose may cause an undesirable side effect in some foods. For example, meat may suffer a loss of moisture. To counteract this effect the food pieces may be buffered so as to inhibit this reaction. The buffer may be added to the substrate and thoroughly mixed, then allowed to stand for a minimum of 30 minutes before the setting substance is added. Thereafter the hydrocolloid and retardant mixture is added. Suitable buffers are trisodium citrate and sodium citrate.

The invention will now be explained in more detail by way of the following examples.

Example 1-A cheese product suitable for grilling The cheese used already contains the substances necessary for setting a hydrocolloid (i. e. lactic acid and calcium salt) and therefore only the hydrocolloid mixture (hydrocolloid and setting retardant) is added. The hydrocolloid mixture also contains ingredients which, when used in combination, and subjected to a mixing action, have the effect of holding in oil (so that the emulsion will be maintained even when the cheese is grilled) and provide for an improved browning effect during grilling. The following formulation for a cheese product including a mixture of hydrocolloids has been found to give good results: % Ingredient Description 82.500 hard cheese such as cheddar 12. 200 water (4 degrees Celsius) 1.650 potato starch 0.700 sodium alginate 0.600 trisodium citrate 0.500 tetrasodium pyrophosphate 0.270 colflo 67 0.150 dextrose 0.150 polydextrose 0.140 carrageenan 1.100 lecithin 0.015 xanthan gum 0.024 dl-U-tocopherol Colflo 67 is a modified starch product made from waxy maize and is sold in South Africa by National Starch.

It will be understood that in this example the reconstituted food product does not use as its substrate by-products of any other process. A suitable cheese is cut into pieces of the requisite size specifically for the purposes of creating a product that can be grilled.

The hydrocolloid mixture is prepared and allowed to stand for at least thirty minutes. The hard cheese pieces are finely chopped to particle size of approximately two to three millimetres, then fed into a pipe in which a rotating spindle with blades provides a mixing and chopping action, and moves the cheese forward.

The hydrocolloid mixture is injected through another inlet into the same mixer pipe so that the cheese and hydrocolloid mixture are mixed together in the prescribed ratio. If necessary (depending on the type of cheese), air may be pumped into the pipe to prevent the compacting of the cheese mixture which might impede the flow.

The entire mixture passes into a vacuum-filler, and is extruded into its desired shape, cut, and then packed.

Example 2-A reconstituted chicken product The following formulation has been found to give good results.

No. Ingredient Group % Ingredient Description 1 83. 806 chicken 2 A 8.000 water 3 B 2.184 calcium sulphate 4 A 1.100 potato starch 5 A 0.350 sodium alginate 6 A 0.350 tetrasodium pyrophosphate 7 A 0.180 trisodium citrate 8 A 0.150 colflo 67 . 9 A 0.100 carrageenan 10 A 0.090 dextrose 11 A 0.090 polydextrose 12 B 0.090 calcium lactate 13 A 0.076 lecithin 14 B 0.050 sodium ascorbate 15 B 0.050 lactic acid 80% 16 A 0.020 xanthan gum 17 A 0.014 dl-a-tocopherol 18 B 3.300 water The chicken is preferably a mixture of breast meat and thigh meat in approximately equal proportions.

The chicken pieces are diced. The hydrocolloid mixture is prepared and allowed to stand for at least 30 minutes. A setting substance (consisting of the ingredients marked B) is thoroughly mixed with the chicken. The hydrocolloid mixture (consisting of the ingredients marked A) is thoroughly mixed into the previously mixed setting substance and chicken. The entire mixture is then extruded into a bath containing a secondary setting substance. The following formulation has been found to give good results for secondary surface setting.

% Ingredient description 94.00 water 4. 20 calcium lactate 1.80 lactic acid 80% liquid By nipping the product into portions in the bath, sinless sausage can be formed.

BRfEF DESCRIPTION OF THE DRAWINGS Apparatus for use in performing the method of the present invention will now be described with reference to the accompanying drawings in which :- Figure 1 is a schematic view of the equipment required for a first stage in the preparation of a food product of a first embodiment in accordance with the invention; Figure 2 is a schematic view of the equipment for a second stage in the preparation of a food product of the first embodiment; Figure 3 is a schematic view of the equipment required for the preparation of a food product of a second embodiment of the invention; Figure 4 is a schematic end view of a first static mixer; Figure 5 is an exploded perspective view of the parts of a first static mixer; Figure 6 is an inner perspective view of the inner face of one of the part- cylindrical shells which make up the first static mixer; Figure 7 is a developed view of three part-cylindrical shells ; and Figures 8a, 8b and 8c illustrate first, second and third versions of food portioning means.

DETAILED DESCRIPTION OF THE DRAWINGS A first embodiment of the invention is illustrated in Figures 1 and 2.

Referring firstly to Figure 1, reference numeral 10 designates a trolley which contains the food substrate such as pieces of chicken meat. A cutting apparatus is generally designated 12 and this incorporates a lifting mechanism 14 which enables the trolley to be lifted so that its contents fall into a chute 16 and thus enter the bowl of the cutting apparatus 12. The chute 16 forms part of the trolley 10. The cutting apparatus 12 can be of conventional form and include a bowl the centre portion of which rotates thus causing the substrate to move into the contra-rotating blades.

The apparatus is set to create a particle size of approximately three millimetres.

The cutting apparatus further includes a discharge disc 18 which is shown in its inoperative position. When the mass of chopped meat is to be removed from the bowl, the arm 20 on which the disc 18 is mounted is swung in an arc, as indicated by the arrow, so that it enters the mixing bowl. The effect of the rotating disc 18 is to lift the minced meat out of the mixing bowl and deposit it into a trolley designated 22.

The trolley 22 is also shown in Figure 2. It is illustrated as standing next to a hoist 24 which lifts the trolley to the position shown at 22.1 and simultaneously inverts it so that the chopped meat falls into a hopper 26 which forms the inlet to a mixing apparatus generally designated 28.

Within the hopper 26 there are rotating paddles which force the mass of minced meat through the bottom of the cone and into a mixing worm 30 so that the hydrocolloid is intimately mixed with the substrate and setting substance.

A vessel 32 supported on a stand 34 contains the hydrocolloid and setting retardant composition. A peristaltic pump 36 is mounted on the stand and is connected by way of a delivery pipe 38 to the inlet end of the mixing worm 30 so that the hydrocolloid is intimately mixed with the substrate and setting substance.

From the worm 30 the substrate and hydrocolloid/setting retardant mixture falls into a chamber 40 at the lower end of which there is a vane pump which forces the product through an extrusion nozzle.

The nature of the subsequent treatment depends on the desired final configuration of the product.

It will be understood from the preceding description that a setting substance is added in the chopping apparatus 12 if the substrate does not itself contain a suitable setting substance. Thus if pieces of meat are being chopped in the apparatus 12 then a suitable quantity of setting substance is added. If, on the other hand, the product being comminuted is cheese or fruit, then the step of adding a setting substance can be omitted as the cheese or fruit naturally has setting substances in it.

If the substrate being handled is cheese then it is desirable to activate the air pump which is provided in conjunction with the high speed mixing device. If this is not used then the cheese is compacted and does not form the light and fluffy homogeneous mass that is required.

Experimental work has shown that a mixture which comprises 90% of substrate and 10% of the hydrocolloid mixture gives acceptable results.

The second form of apparatus is illustrated in Figures 3 to 10.

Referring firstly to Figure 3, reference numeral 44 designates a feeder into which is fed the food substrate such as pieces of chicken meat. The feeder 44 contains cutting apparatus in the form of rotating blades 46. The blades 46 chop the substrate into smaller pieces. These substrate pieces are then fed via a chamber 48, from which air is evacuated, into a vacuum pump 50. The pump 50 creates a zone of low pressure through which the food substrate pieces pass and it then feeds the substrate pieces into the inlet end 52 of a static mixer 54. In the mixer 54 the pieces are mixed with a hydrocolloid and setting retardant composition which is fed in under pressure from a dosing means (not shown) into the inlet end 52 of the mixer 54. A setting agent is added to the substrate if required, as in the case of meat substrates, before the meat substrate is forced into the inlet end 52 of the static mixer 54.

The static mixer 54 is illustrated in more detail in Figures 4 to 7. The mixer 54 comprises an outer sleeve 65 and three part-cylindrical shells 61. Each shell 61 has, on the inner face thereof, a plurality of mixer blades 56. On assembly the shells 61 are welded together to form a cylinder having walling defining a passageway 67 through which the food substrate to be mixed is forced so that it flows from the inlet end 52 to the outlet end 68 of the static mixer 54. The cylinder is slid into the outer sleeve 65. The sleeve 65 is not shown in any of Figures 4 to 7.

Each blade 56 has a first surface which faces the inlet end 52 of the static mixer 54, a second surface which faces the outlet end 68 of the static mixer 54, a root 71 at which the blade 56 is attached to the walling on the inner face of each shell 61, and a tip 72 which is in the passageway 67. In Figure 7 the three shells 61 are shown in developed form, the weld lines between them being designated 63. The arrows indicate the path followed by the food substrate pieces as they are forced through the static mixer by the pump 50 in the direction indicated by the arrow A.

The mixer 54 is connected to a portioning means 66 which is located at the exit of the nozzle 64. The nozzle 64 is located at the outlet end 68 of the mixer 54 and the portioning means 66 has its entrance 70 connected to the nozzle 64.

One form of portioning means is shown in Figure 8a. A tube 74 conveys the food pieces from the nozzle 64 to a cylinder 78, there being drive means (not shown) for cyclically advancing the cylinder through 180°. A shuttle 80 is located in a transverse bore 82 of the cylinder 78, the shuttle 80 being able to move to and fro in the bore 82. The cylinder 78 and shuttle 80 are initially as shown at A1. The food product being pushed along the tube 74 from the nozzle 64 impinges on the shuttle 80 and moves the shuttle progressively through the positions shown at A2 and A3. The portion of food product designed P which is, in A, ahead of the shuttle 80 is progressively displaced out of the bore 82 as shown to the left of A4.

Upon the shuttle 80 reaching the position shown in A3, the cylinder 78 is rotated through 180°. In A4 the cylinder 78 is shown in its quarter turned position.

Once the cylinder has turned through a half turn, the shuttle has returned to the position shown in A1 and the portion designated P1 is now on the opposite side of the shuttle 80 to the tube 74. The cycle then repeats and the further portion of food product P1 is forced out of the transverse bore 82.

In Figure 8b, the transverse bore 82 is of greater dimensions than in Figure 8a with the result that the portions produced are of curved form rather than straight.

Figure 8c illustrates a construction in which there are two transverse bores 82 in the cylinder 78 and two shuttles 80. Thus two food portions are produced each cycle.

A spraying means 86 comprising a number of spray heads is located at the exit 76 so that the portions of food product P, P1 are covered by a secondary setting substance which forms a non-stick coating. This coating prevents the reconstituted and separated food portions from being sticky and thus prevents them from sticking to conveyer belt 84.