co-extruded product.

The present invention concerns a co-extruded product comprising a filling and an outside shell. More particularly, the present invention concerns a co- extruded product comprising a filling and an outside cereal and/or starch based shell.

This type of product is already known. In the text book ^Extrusion Cooking, Technologies and Applications', edited by Robin Guy, Woodhead Publishing, (2001), pages 178-179 co-extrusion of an expanded cereal biscuit in the form of a tube with a soft filling is described. It is also known to have a co-extruded product with liquid or pasty filling. However, to avoid the filling flowing out of the shell at the cutting stage or during subsequent processing, it is either necessary according to the art to cool the corresponding rope at the exit of the die or, for the incorporation of more liquid fillings, to crimp short lengths of filled extrudate to trap the filling such that it cannot leak out. In ^Extrusion Cooking, Technologies and Applications' it is explained that the filling fat must be chosen to have a melting point between 30-35 ⁰ C such that it sets between the die head (where it must be liquid to be pumped into the extrusion die) and the cutting station. Alternatively, for filling fats with lower melting points, it is explained that it is necessary to crimp the ends of the cereal shell to retain the filling.

It is desirable to be able to produce a co-extruded product comprising a filling and an outside open shell where the filling fat blend had a melting point below 30 °C. This avoids the greasy mouthfeel associated with higher melting

point filling fats and also avoid the need to use saturated and/or hydrogenated fats which are not always well accepted by consumers .

Furthermore, the products obtained with the processes known in the art are found in practice to have a rather high density. This is due to the limitation that when a highly expanded product exits from the extruder die it shoots forward at high speed. In order to set the filling in a sensible distance along the plant, cut the extrudate (for example with a guillotine) and prevent the cut lengths of co-extruded material exiting the cutter uncontrollably and becoming randomly dispersed, it is necessary to limit the speed of the extruded rope exiting the extruder. This in turn limits the degree of expansion at the exit of the die and so prevents the formation of highly expanded products.

It is desirable to produce lower density products comprising a filling and an outside cereal and/or starch based shell. Lower density products maximize the size impression for the consumer while at the same time delivering fewer calories and being able to be sold at a lower price by volume. The creation of low densities in combination with soft fillings provides new and desirable products.

It is an objective of the present invention to have a co- extruded product with a filling which does not flow out of the outside cereal and/or starch based shell at room temperature, at the cutting stage or during subsequent processing. It is another object of the present invention to provide an efficient process for preparing said product. The fact that the filling does not flow out means in the present specification that the possibility of flowing out

is so minimized that it does not spoil the product and does not block the process.

The present invention concerns a co-extruded product comprising a filling (second substance) and an outside open or closed cereal and/or starch based material ( first substance ) shell, wherein the amount of filling is comprised between 10 and 80 % in weight, the density of the product in the case of an open shell is comprised between 40 and 400 g/1 and the density of the product in the case of a closed shell is comprised between 40 and 190 g/1. The density (texture-range) described above allows a very mouth-melting texture, therefore a very indulgent product.

In the present specification, under open we understand that on the co-extruded product the filling is totally apparent as shown in the figures. Under closed shell, we understand in the present specification, that the co-extruded product has the pillow form, which means that the filling is totally embedded in the shell.

Under density of the product, we understand the density of the whole product, outside shell and filling. The density can be measured by determining the volume of a single product (for example by measuring the external dimensions) , weighing the product and then calculating the density as the ratio of the mass in grams to the volume in litres. An average of the density of 50 products should be taken. The density of the outside shell can be calculated in a similar way to the overall product density, except that the volume and weight of the filling are subtracted from those of the overall product. The density of the outside shell is between 30 and 200 g/1.

These densities allows to provide a very mouth-melting texture, giving a very indulgent characteristic to the finished product.

In a preferred embodiment of the invention, the filling is pasty or liquid at room temperature.

In a preferred embodiment of the invention, the product of the invention has a density comprised between 40 and 300 g/1 : this is already considered as an expanded outside shell product, giving a very mouth-melting texture.. In a more preferred embodiment the product of the invention has a density comprised between 40 and 260 g/1. In a most preferred embodiment of the invention, the density of the product is comprised between 40 and 190 g/1 : in this case, this product is considered as a super expanded outside shell, with maximum melting charactreristic and apparent volume .

It is also in the scope of the invention to have the co- extruded product comprising a coating. The coating can be any type of coating known in the art. More specifically, the coating is taken from the group consisting of peanut coating, chocolate coating, panned sugar coating and others known in the art.

With the coating, the product of the invention has a density, which is from 40 to 80 g/1 higher, in the most preferred embodiment. This increase depends on the type of coating and on the thickness thereof.

It is also envisaged to have a food product comprising one or more co-extruded products of the invention.

The composition of the outside cereal and/or starch based material shell is not critical and can be of any type. For example, the outside shell can be an expanded starch based material, for example using potato starch, or an expanded cereal material: Any type of cereal can be taken in consideration, for example corn, wheat, rice, barley and oat. It is also possible to have other types of outside cereal shell, like those used in confectionary, for example biscuit, no- or low-sugar wafer, or sugar wafer.

The product of the invention can be considered for human food, but also for petfood.

The filling of the product of the invention can be of any type. As said before, the filling is pasty or liquid and does not flow out of the outside cereal shell at room temperature, at the cutting stage nor during subsequent processing. It is possible to have a jam filling which is non-aerated or aerated. The jam can be any type of fruit jam known per se. In the case of a wafer as outside shell, a chocolate filling can be taken into consideration. Preferably the filling is a fat-cream filling, which is non-aerated or aerated. Under fat-cream filling, we understand in the present specification a filling comprising a continuous fat phase and a suspension of solid materials. The solid materials can be for example sugar, cocoa powder, milk powder, ground cereal shell material or fruit powder. In a more preferred embodiment, the filling fat blend used in the fat-cream filling has a melting point below 30 °C, most preferably the filling fat blend is completely liquid at 20 °C. The melting point of the filling fat blend can be determined by extracting the fat from the filling, for example by Soxhlet extraction, and then performing a slip melting point determination.

To characterise the rheological characteristics of suitable fillings extrusion measurements can be performed using a Texture Analyser HDplus from Stable Micro Systems (Godalming, Surrey, UK) , equipped with a 250 kg load cell and an extrusion assembly. The extrusion assembly consists of a cylindrical perspex barrel of internal diameter 48 mm and internal depth 103 mm, at the bottom of which is a countersunk circular aperture, i.e. a die, of internal diameter 14 mm and external diameter 10 mm. The depth of the aperture is 4 mm. The filling is transferred to this barrel and the filled barrel is placed in an air oven for 20 minutes at 80 degrees Celsius. At the end of this time, the barrel is quickly placed in the testing machine, and the filling forced through the die by the movement of a plunger downward into the barrel. At its point of contact with the filling the plunger has a horzontal disk of thickness 5 mm and diameter 40 mm. The applied rate of movement is 10 mm /s.

From a plot of the measured force as a function of the distance of travel of the plunger, it is possible to identify the point at which the force reaches a plateau. At this point, the flow rate of the filling through the die matches that imposed on the plunger by the machine. In the present specification, the yield point is considered to be the plateau force as measured in this manner.

In a preferred embodiment of the invention, the filling has a yield point at 80 °C of between 0.2N and 4ON, preferably between 0.5N and ION.

A temperature around 80 °C is used for the analysis because it is about the temperature at the cutting step.

The specified yield point values shows that the product is flowing but not as liquid as water.

In another preferred embodiment of the invention, the amount of filling is preferably comprised between 40 and 70 %. All percentages in the present specification are given in weight. The above-mentioned range allows a very high product-indulgence and processability .

The co-extruded product of the invention has a diameter around 8 to 30 mm and a length between 5 and 200 mm. In a preferred embodiment of the invention, the product has a diameter around 15 to 20 mm and a length between 10 and 50 mm. Normally, the product according to the invention has a circular cross section. But, it is also in the scope of the invention to have a product with a square, rectangular, triangular, or other cross section. Finally, the product of the invention, in its length, can be either linear or shaped (for example corrugated or dented) . The above- mentioned dimensions provide appropriate range for the product according to the invention, notably the snack- format sizes, from sticks or long snacks to nibbles.

It is possible according to the invention to have either an open-ended or a closed-ended product; the latter could be achieved for example with the help of a crimping knife.

The present invention concerns further a process for the preparation of a co-extruded product as described above, wherein

- a first substance is introduced in an extruder,

- a second substance , the filling is introduced in the same extruder,

- both substances are co-extruded to form a rope at the exit of said extruder, - the rope is travelling on a conveying device,

- the rope is introduced into the hole of a plate or a tube of which cross section can be of any shape,

- a moving knife cuts said rope at the exit of this hole into pieces, - said pieces are transported into means for preventing their random dispersion by the knife ,

- the obtained pieces at the exit of the means for preventing random dispersion are packaged.

Under substance, we understand herewith a powder or a powder with liquid or a paste. As already mentioned above, said powder can be from cereal origin. The liquid used is normally water with or without additives or oil. The conditions of the extrusion are well known from the man skilled in the art. It is in the scope of the invention to have either a cooking extrusion or a cold extrusion depending on the manufactured product.

Before the product is packaged, it is normally dried to reach a water content comprised between 1 and 8 %. However, processes without drying are also feasible.

As already mentioned above, a coating can be also applied on the product of the invention.

Before the cutting of the rope, it is necessary to stabilise during a certain period of time said rope : the rope is travelling on a conveying device, like a belt for example, at room temperature and at atmospheric pressure.

The distance of conveying is comprised between 0.5 and 20m, which gives a duration of around 1 to 20 seconds. It is also possible according to the invention to minimize the belt transportation : the less soft, chewy or sticky the rope at cutting process step, the shorter the conveying.

The important feature of the invention is to have after the conveying the cutting of the rope. This cutting is carried out after the passage of said rope in the hole of the plate or the tube. As mentioned above, a knife is disposed directly after said plate or tube to carry out said cutting. Means for preventing random dispersion of the pieces by the knife, placed downstream of the knife, can be for example a tube, a cone, a flat cone or another equivalent device, like a thick plate. The length of the tube, cone or thick plate is comprised between 2 and 30 cm. The diameter of the tube or of its entry if it is a cone is about 1.05 and 2 times the diameter of the rope. The type of movement of the knife is not critical : it can be for example either a rotating movement, or an oscillating movement or an alternating movement.

It is possible according to the invention to produce a co- extruded product with an opened shell, without any leaking out of the filling from the shell, because of the presence after the cutting of the rope of the means for preventing their random dispersion : this allows a transportation during a short length of the cut pieces into these means, providing a stabilisation of the filling.

In the process of the invention, the rope is travelling at a speed comprised between 10 and 100 m/minute. This speed is depending on the type of product which is prepared according to the invention. In the case of a super expanded

product, it is more a higher speed. In the case of a breakfast cereal, it is more a lower speed.

The drying is normally carried out at a temperature around 100 to 200 °C. Drying the cut pieces in bulk, which is the most efficient method, is possible because the moving knife, coupled with the means for preventing the random dispersion of the pieces by the knife, can cut the rope and deposit the pieces gently on the belt of the dryer such that the hot filling does not flow out.

The present invention concerns finally a device for carrying out the process of the invention. The device comprises - a extrusion apparatus for the formation of the rope,

- at the exit of the die of said apparatus a conveying device for said rope and

- a first plate or a tube with a hole for receiving said rope, means at the exit of said hole for preventing the cut pieces to be randomly dispersed by the knife, a second plate for supporting the said means and a knife fixed on the second plate to cut the rope at the exit of the hole of the first plate.

The distance between the first plate or tube and the second plate is not critical, but is normally or around the length of the tube or cone.

The means for preventing the random dispersion of the pieces have been already described above as well as the type of movement of the knife.

The invention is more precisely described hereunder in relation with the drawings, wherein

Figure 1 is a schematic view of the device according to the invention,

Figure 2 is a perspective view of the cutting part of the device,

Figure 3 is a perspective view of the product according to the invention and

Figure 4 is a perspective view of the product of figure 3 cut along the length.

Figure 5 is a plot of force against distance showing the yield point measurement of the filling of the example.

A cereal base is cooked in (2), a cream filling is added from (1) through a pipe (9) into the extruder (3), so that a co-extrusion is carried out through the die (10) . A rope (11) of co-extruded product is travelled on the conveyor (4) . Said rope is then fed into the cutting apparatus (5) and the small pieces (12) travelled in a dryer (6) . Finally, these small pieces are coated in the device (7) and packaged in (8) . The product is now ready to be stored or transported to the retailer. It is possible with the device of the invention to prepare open-ended product with a pasty or liquid filling at room temperature and at cutting process step without any dropping of the filling of the outside shell at said step in such a way that it would incapacitate the process.

Figure 2 shows more closely the cutting apparatus (5) of the invention. The direction of movement of the rope is given by arrow A. The first plate or entry tube of the

cutting apparatus is not shown on the figure, but is just before the knife (16) . The rope (11) enters in the hole of the first plate and then in the tube (18) . Just between the hole of the first plate and the entrance of the tube (18), the rotating knife (16) cuts the rope (11) to obtain small pieces of the product (12) according to the invention. These pieces are travelling in the tube and are exiting in (17) . The motor (13) and the knife hub (15) rotate the knife at the desired speed. As already mentioned above, the second plate (14) supports the tube (18) . The pieces (17) are then transported to the dryer (6) shown on figure 1.

Example 1

A corn based cereal is cooked at a temperature of 150 ⁰ C and a cream filling comprising vegetable oil (fully liquid at 20°C), cocoa powder, sugar, starch and vanilla flavour is fed into the cooking-extruder. A circular super expanded rope is co-extruded and travels on the conveyor belt at a speed of 80 m/min. The rope is cut and passed through a tube having a length of 10 cm.

The pieces obtained are shown on figures 3 and 4. In this specific example the piece (12) has a diameter of 18 mm and a length of 35 mm. The filling represents 60 % of the whole product and the filling diameter is 6.5 mm. The density of this product is of 75 g/1.

The product is then dried to a moisture of 2.5 % and coated. This product is stored and sent to the packaging process step.

Example 2

The yield point of a sample of the filling from example 1 was measured using a Texture Analyser HDplus from Stable Micro Systems (Godalming, Surrey, UK) , equipped with a 250 kg load cell and extrusion assembly. The extrusion assembly comprised a cylindrical perspex barrel of internal diameter 48 mm and internal depth 103 mm, at the bottom of which was a countersunk circular aperture, i.e. a die, of internal diameter 14 mm and external diameter 10 mm. The depth of the aperture was 4 mm. The filling was transferred to this barrel and the filled barrel was placed in an air oven for 20 minutes at 80 degrees Celsius. At the end of this time, the barrel was quickly emplaced in the testing machine, and the filling forced through the die by the movement of a plunger downward into the barrel. At its point of contact with the filling, the plunger featured a horzontal disk of thickness 5 mm and diameter 40 mm. The applied rate of movement was 10 mm /s.

From the force data as a function of the distance of travel of the plunger, it can be seen that a yield point is reached, whereby the force reaches a plateau. At this point, the flow rate of the filling through the die matches that imposed on the plunger by the machine.

The measured yield point for the filling of example 1 was 4 ± 1 N.