APPARATUS FOR MAKING PASTE FROM ALTERNATIVE ALIMENTARY FLOURS OR THE LIKE

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FIELD OF THE INVENTION

The present invention relates to an apparatus intended for food processing industry for making paste from flours alternative to hard wheat or soft wheat and the like. STATE OF THE ART

The use of alimentary flours alternative to hard and/or soft wheat for making paste products, such as pastas and the like, is widely known to date. For example, gluten-free flours are: rice and maize (the most well-known), pulses and cereals in general, such as chick peas, beans, lentils, millet, soy, etc. For the purpose, there is no single apparatus on the market which combines all the process steps capable of making paste from gluten-free flours without the addition of semolina binders, such as monoglyceride, egg white, rice starch, maize, etc.

Currently, there are alternative technologies which advantageously include the use of pre-cooked and pre-pregelatinized flours. This means an additional production cost resulting from the cooking process of the flour before it is processed, which implies the disadvantage of the final cost of the extruded product, which is higher than that obtained from simple flours.

Moreover, a further disadvantage is in that for such types of extruded products, the use of several apparatuses on a single production line is required to obtain the finished product, i.e. the use of a cooker and of a former, or alternatively of a double screw extruder assembly.

SUMMARY

It is the object of the present invention to solve the aforesaid drawbacks by providing a single extrusion apparatus for making paste from gluten-free flours, in which the use of pre-cooked flours or binders is not required. Therefore, the present

invention provides an apparatus essentially as described in the appended claims.

Furthermore, it is the object of the present invention the production method for making paste from gluten-free flours, wherein the use of neither pre-cooked flour nor binder is required, implemented by means of the above-described apparatus. DETAILED DESCRIPTION OF THE INVENTION

A detailed description of a preferred embodiment of the apparatus of the present invention will now be provided, by way of non-limitative example, with reference to the accompanying drawings, in which:

Figures 1a, 1b, 2a and 2b show perspective and side elevation views of the apparatus of the present invention, respectively;

Figures 3a, 3b and 3c are perspective, elevation and top plan views, respectively, of the liquid measuring device related to the measuring and pre-mixing assembly of the apparatus of the present invention;

Figures 4a, 4b and 4c are longitudinal-section, top plan and perspective views, respectively, of the pre-mixer assembly of the apparatus of the present invention;

Figures from 5a to 5d are perspective, elevation and top plan views, respectively, of the mixing and cooking tank of the apparatus of the present invention;

Figures from 6a to 6c are perspective, elevation and top plan views, respectively, of the vacuum rotary element of the apparatus of the present invention; Figures from 7a to 7d are perspective, elevation and top plan views, respectively, of the soaking assembly of the apparatus of the present invention;

Figures from 8a to 8c are perspective, section and elevation views, respectively, of the extrusion cylinder of the apparatus of the present invention; and

Figures 9a, 9b and 9c show generic extrusion screws for the apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to figures 1a, 1b, 2a and 2b, the apparatus of the present invention essentially appears as a paste press with the addition of steam in the first tank. More specifically, the apparatus consists of several parts and performs the

following production steps:

- mixing of water and semolina in a first part 1 ;

- steam cooking in a second part 2;

- passage to another space for cooling in a third part 3; - soaking of the product with vacuum ambient passage and corresponding loss of air in a fourth part 4;

- loading of the feeding screw in a fifth part 5; and

- compressing by bronze or Teflon drawing in a sixth part 6.

With reference to figures 3a, 3b and 3c, the first step is performed in the first part 1 which includes a measuring assembly 10 in which a meal measuring device 12, which is the starting part of the process, is included. The measuring device 12 comprises a volumetric system provided with a scroll 13 by means of which the amount of flour is measured. The assembly is entirely formed by stainless steel and is complete with an alarm rotary probe for product shortage. Furthermore, the measuring device 12 is complete with a bridge breaking stirrer 14 to prevent obstructions caused by the grain size and/or composition of the flour. The measuring scroll 13 may be formed either by plastic material or by metal (the choice depends of the type of row material) and the pitch and external sizes are dimensioned according to the capacity and the production. The capacity is controlled by an inverter and electronically adjusted by PLC.

The stirrer 14 is driven by means of a chain with reduction ratio directly by the motor shaft.

Obviously, a stainless steel supporting base with fastening holes is included. Next, with reference now to figures from 4a to 4c, a pre-mixing assembly or pre-mixer 15 is included for a first flour hydration.

The pre-mixer 15 is formed by stainless steel and consists of:

- a thrust bearing assembly 16 complete with motor, bearings and sealing rings,

- a mixing cylinder 17 provided with two liquid inlet nozzles, - an opening 170 for flour introduction and fastening of the possible

measuring device,

- an unloading hole 171 ,

- a front, hinged cleaning flap with corresponding safety micro switch and seals, - a mixer shaft 18, which is split into three parts: a) a first conveying area consisting of a two-lead scroll 180; b) a second area 181 formed by a series of constant pitch pins forming a scroll; and c) a third area with blades 182 which unloads and cleans the mixture by centrifugating it.

The liquids and the flour meet immediately after the end of the conveying scroll 180 (1 ^st area). A complete hydration of the wheat is obtained in this manner.

The unloading mouth 171 is positioned on the unloading tangent and in order to facilitate the introduction of the flour, the latter is unloaded at 45°, again towards the direction of rotation. Furthermore, the pre-mixer assembly 15 is supported only behind and secured with a through tie-rod to the motor shaft. In this manner, cleaning and disassembly may be performed faster.

A second step, which corresponds to part 2 of the apparatus, is required after the pre-mixer assembly 12 and 15. With reference to figures from 5a to 5d, the second part 2 of the apparatus comprises a series of mixing and cooking tanks 20, arranged in series and connected downstream of each other.

It is worth specifying here that according to the present invention, the number of tanks 20 is not limited to the above-described embodiment (e.g. two tanks 20 are shown in the figures), but on the contrary the number of tanks 20 depends on the type of product to be treated and on the production process.

The tanks 20 are entirely formed by stainless steel, each of which may have variable dimensions according to the capacity. The two very thick external walls are reinforced to alternatively offer the possibility of vacuum steaming. Furthermore, flanges for fixing the supports and containing the seals are welded onto the external

walls.

Each tank 20 has a first part closed by a plate 21 for connecting to the upstream device (e.g. the first tank 20 mounts the pre-mixer assembly 15, not shown in the figures) or possibly for mounting a measuring device. Each tank 20 is closed by a Plexiglas lid 22 of a predetermined thickness (e.g. a thickness of 40 mm), the lid being transparent facilitates the visual inspection of the process.

The lid 22 is hinged and secured by a micro magnetic device. Two series of selectable and adjustable steam nozzles 23 are arranged on the lower part of the tank 20. The choice of positioning the nozzles on the lower part of the tank 20 is determined by the fact of avoiding partial steaming of the paste.

A shaft 24 provided with blades 25 is rotationally mounted inside the tank 20. An extractable partition (not shown in the figures) is further included to contain and stop the paste. The unloading from the first tank 20 to a following tank 20 arranged downstream of the first one is performed by tipping the last blade 25. The shaft 24 of the kneader is formed by stainless steel and the blades 25 positioned at 120° may be adjusted by setting the inclination (this varies the angle and consequently the feed rate). The tank is intended for a paste supplement (liquid) and for possible vacuum extraction. The tank is obviously complete with a drive unit with inverter controlled motor reducer.

With reference to the figures from 6a to 6c, a vacuum rotary element 3, the capacity of which is controlled by PLC, is included after the last cooking tank 20. The vacuum rotary element 3 generates a vacuum in the upstream and downstream process. More precisely and with reference to the figures, the rotary element 3 is provided with a rotary star valve 30 made with a stainless steel rotor and a self- centering hood formed by Bral (self-lubricating material). The hood is adjusted by special springs pre-loaded by M8 tie-rods. The bearings and the sealing rings are mounted on aluminium flanges complete with a forced lubrication circuit. Motion is

transmitted by means of a chain joint. The capacity is adjusted by a PLC being this motor also inverter controlled.

A fourth processing assembly 4 related to the step of soaking of the product with corresponding cooling/heating is included downstream of the rotary element 3. More precisely and with reference to figures from 7a to 7d, the soaking assembly has a cylinder 40 provided with a conditioning liner 41 , an inlet port 410 and an outlet port 411 and a shaft 42 extractable for cleaning therein provided with adjustable blades 43. The treated product falls from the 2 ^nd tank to the soaking device and the soaking device may be similar to the first two upstream tanks. It is worth specifying here that after the rotary element the apparatus is under vacuum to the point of extraction.

Thus, a drawing assembly is typically included downstream of the soaking device 4.

The drawing assembly essentially consists of: - a cylinder and feeding screw from the soaking device 4, which is complete with thrust bearing and drive, the capacity being adjusted by an inverter;

- a cylinder and compression screw 5, constantly fed and independently conditioned in several areas, provided with outlet temperature control probes and product temperature control probes. The compression screw is of the multi-sector type with variable pitch and diameters according to the final product type; and

- a conditioned head 6, horizontal and/or at 90°, with pressure gauge, suitable for circular and/or rectangular drawing plates. The head 6 is complete with extraction system and adjustable product cutting assembly. A forced drawing plate ventilation and safety casing are also included. As shown in figures from 8a to 8c, the extrusion cylinder 5 is typically formed by Fe510 steel or iron, inside which a grooved liner 50 (preferably formed by 38Nicrmo4 steel) is included.

Advantageously, when the inside part of the cylinder 5 is worn, only the liner 50 which is split into several parts, is replaced. In order to generate a forced circulation channel 51 , a spiral is made on the thickness of the tube 5.

More precisely, the cylinder is conditioned in 3 stages. The first conditioning stage is at the attachment area of the feeding assembly by cooling only. The second stage is conditioned by diathermic oil to reach even temperatures of 120 - 130° C. The third stage is conditioned by water (hot or cold). All conditioning stages are managed by heat regulator and probes positioned on the system return lines. Two product contact probes interfacing with the system probe are further included (at the 2 ^nd and 3 ^rd stage).

A degassing hole for a possible relief after the first compression is included before the 3 ^rd stage. Furthermore, a thrust bearing-reduction assembly of the commercial type with square drive joint and flange for vacuum sealing ring seats, with forced lubrication, is typically included. Motion is transmitted by means of pulleys and V-be!ts and the rotation speed is adjusted by means of an inverter.

Figures from 9a to 9c describe an extrusion screw 52 according to three different embodiments thereof which are given by the type of product to be extruded.

More precisely and according to the invention, different embodiments of screws 52 may be provided. Each embodiment provides a polished, hardened stainless steel construction 420, tempered on the crests and ground. The external diameter and the length of the screw is predetermined by the process and the final product and, obviously, by the capacity.

The screws 52 consist of several parts according to the row material to be treated and the mechanical work to be applied to the paste. The main features of the screws are the number of sectors, the pitch, the width of the crest, the core diameter, the direction of the lead and the number of leads. These are the features which are adapted to modify the mechanical work of the screw. Indeed, figure 9a shows a screw 52 suitable for treating a moist product intended to be fried, figure 9b shows a screw 52 suitable for treating a cereal-based product, and figure 9c shows a screw 52 suitable for treating a pulse-based product.

As shown in the figures, the screws 52 may be split into 4 distinct areas: - Drive area with drive panel, bronze bearing with four-lead square threading,

1" pitch, direction agreeing with the feeding direction of the product The threading is used to keep the screw clean in the reducer-thrust bearing sealing ring area from product which could possibly slide in the opposite direction.

- Loading area of predetermined length and with constant one-lead pitch. The product enters this area pushed by the feeding screw. In this area, the pitch is wide to facilitate the loading of the screw and the core is slightly tapered (e.g. ratio 1.2 and 1.5 for the other two screws) to constantly load the cooking area of the 1 ^st stage. Furthermore, the end part of the crest is rounded again to facilitate the feeding of the product. - 1 ^st stage cooking area of predetermined length where the thermal and mechanical cooking of the product starts. According to the type of screw, the composition is different and the temperature of the product is displayed on the control panel, a probe controlling the temperature of the paste.

A thermal cooking may be added to the mechanical cooking by conditioning the cylinder. For example: o A light-cooking screw consists of a tapered sector (ratio 1.05) with constant pitch and of a sector with opposite lead (LH). The LH sector is used to slow down the feed rate of the product and heat it by friction. Furthermore, in this area the cylinder liner may reach temperatures of up to 120° C; or o A medium-cooking screw consists of a constant pitch cooking sector

(ratio 1.3) which loads a two-lead LH sector with compensation areas (the compensation areas are the interruptions of the spiral). The external temperature may reach 120° C as in the previous case; or o A hard-cooking screw which consists of 6 sectors for a hard cooking of the product. The first sector is LH with two leads, again with compensation areas, followed by a conveying sector (RH) with constant pitch and core. This sequence is repeated twice and ends in a so-called drawing sector and then in a so-called crushing sector. The pitch and the core are constant in the repetition of the first two sectors, while in the last part there is a strong compression of the product with consequent raising of the temperatures, a 1.3 ratio occurring in a very short time. The

crushing sector is used to break the paste which in this area is highly gelatinized.

- 2 ^nd stage cooking area of predetermined length in which temperatures of approximately 95° C can be reached in the external cylinder liner. This area is used to compact the paste and prepare it for the step of extruding. Also in this area, the composition of the screws varies according to the chosen type. More specifically: o A light-cooking screw in which a tapered sector with a 1.24 ratio and constant pitch followed by a two-lead sector complete with a compensation area is provided; or o A medium-cooking screw in which a tapered sector with a 1.27 ratio and constant pitch followed by a two-lead sector with constant core is provided; or o A hard-cooking screw in which 4 sectors for continuing with the mechanical cooking are provided. The first sector conveys and accumulates the product followed by a tapered sector with 1.27 ratio. The penultimate sector has two leads and constant core for loading the crushing sector with instantaneous reduction of the core, 1.14 ratio. it is worth noting here that some sectors may be moved to different positions on the same screw 52 for the purpose of finding and better optimizing the screw morphology. Furthermore, the figures and the foregoing description show that the compression ratios of the core of the three screws are similar. The main variation is the change of speed of the diameter which causes different temperature increases.

The choice of the type of screw to be used must be evaluated on a case-by- case basis and is in relation to: a) The temperature to be thermally reached; b) The mechanical work to be applied to the paste; c) The degree of gelatinization to be reached; and d) The type of row material.

The apparatus of the invention has many advantages. A first advantage is that it is very compact. Indeed, it can be advantageously positioned on a painted steel base, and has the normal control panels (not shown in the figures). For example, two

derived panels may be normally provided, a first panel for controlling the tanks and the second for controlling the extrusion. A general panel is complete with heat regulators for controlling the temperatures, the PLC which governs the capacity, adjusts the production and controls errors and/or alarms. Another considerable advantage is that in a single apparatus it is possible to make paste from most pulses and cereals without using pre-cooked flours and/or additives (monoglyceride, egg white, etc.).

A further advantage is obviously that the system and the management costs are considerably reduced due to the compactness of the apparatus.