IT202100012719A1 - Plant and method for the production of sheet soap. - Google Patents

Description

DESCRIPTION

of the invention entitled:

"Plant and method for making sheet soap?

The present invention relates to a plant and method for the production of sheet soap for washing machines and for personal use as hand cleaners.

? sheet soap is known, which is used in washing machines instead of traditional liquid or powder detergents which, in addition to posing problems related to the frequent, occasional errors in dosing and loading into the machine, pose problems of space, since in general detergents liquids and powders are sold in rather bulky packages, which if on the one hand ensure a supply for a large number of washes on the other hand are cumbersome both for transport and storage before sale to the user, and for conservation near the user, especially if the washing machine ? placed inside furniture that does not offer adequate possibilities? containment, even more so if the? user requires more? types of detergents for different items of laundry.

Plants are known for producing sheet soap for washing machines. They use a particular liquid mixture of components, which is poured onto the heated surface of a slowly rotating cylinder and forms a layer which, in contact with the hot surface, is gradually deprived of the water content until it assumes a structural consistency suitable for allow it to be removed from the cylinder using a blade.

The continuous ribbon of soap so? The product is then cut with a cutter or with other known systems, so as to form sheets of dimensions corresponding to the dose of soap required for one wash.

A drawback of this known plant consists in the fact that it is considerably rigid and allows soap sheets to be produced having characteristics and performances suitable for their use in washing machines but not suitable for their use as hand cleaners. ? in fact known that while a sheet of soap for washing machines must have a certain thickness and present a solubility? slow, which ensures a duration of the sheet compatible with the washing cycle to which the laundry must be subjected, a sheet of hand washing soap must have a solubility? very rapid to ensure its total dissolution in the very short time corresponding to a few rubbings of the hands under a jet of water.

Purpose of the invention? to eliminate these drawbacks and to propose a plant for the production of sheet soap which, depending on the liquid mixture used for this production and the methods? preparation of the mixture itself, allows the production of both sheet soap for washing machines and sheet soap to be used as a hand cleaner.

Another purpose of the invention? to propose a plant which allows soap sheets to be produced for different uses and which, within each use, allows the characteristics of the soap sheet to be adapted to the different needs associated with that use.

Another purpose of the invention? to propose a method which, with a single plant, allows the production of sheet soap for different uses.

Another purpose of the invention? to create a plant that allows the production of small sheets of disposable hand soap to be used in all those situations (hotels, restaurants, etc.) in which bars of soap are used today which are intended for individual use but which very often remain partially unused and involve unnecessary waste.

All these objects and others which will appear from the following description are achieved according to the invention with a plant for the production of sheet soap as defined in claim 1 and with a method as defined in claim 10.

The present invention is hereinafter further clarified in some of its preferred examples of practical embodiment given for purely exemplifying and non-limiting purposes with reference to the attached tables of drawings, in which:

figure 1 shows a general schematic view of a plant for the production of sheet soap according to the invention,

figure 2 shows a schematic vertical section of the mixer of the plant,

figure 3 shows a side view of the unit? of loading of the solid products in the mixing cup of the unit? of kneading,

figure 4 shows a side view of the unit? of kneading with the bowl of dough raised in operating condition,

figure 5 shows a side view of the unit? of lifting the mixing bowl in the phase before lifting the mixing bowl, e

figure 6 shows it in the phase following the overturning of the cup of dough raised above the loading hopper of the casting box.

As can be seen from the figures, the plant according to the invention comprises: - a storage and mixing station 2, which in practice has the function of containing and keeping under continuous stirring a binding mixture advantageously based on polyvinyl alcohol in such a way to avoid the separation of its components before its use;

- one or more stations 4 for kneading the binding mixture with vaseline oil and with solid components which give the binding mixture, which in itself? has a gelatinous consistency and what? the creamy texture of a gel;

- a?unit? 6 for loading a casting box 8 (casting box);

- an oven 10 for drying a film of liquid soap, which is poured from the casting box 8 onto a conveyor belt 12;

- a station 14 for withdrawing a solidified ribbon of soap 16 from the conveyor belt 12, which leaves the drying oven 10.

The mixing station 2 comprises at least one mixing machine 18 (fig. 2), which in practice is consisting of a cylindrical container with a truncated conical bottom equipped with an axial stirrer 20, operated by an overlying electric motor 22 and provided with shaped blades 24 which are driven in slow rotation (preferably between 50 and 70 rpm). These blades 24, which preferably extend substantially on a diametral plane, have two inclined portions 26, which scrape on the conical bottom of the container 18, two vertical portions 28, which scrape on the cylindrical wall of the container 18 and horizontal portions 30, which extend radially from the vertical portions 28 towards the shaft 32 of the agitator 20.

At the bottom of the container 18 ? then foreseen an opening 34 for the unloading of the binder mixture and can? advantageously, at least one other opening 36 should be provided for the introduction of water to wash the container from below.

A duct 38 branches off from the binding mixture discharge opening 34, provided with traditional shut-off and measuring devices (flowmeter) and intended to connect the mixing station 2 with the kneading station 4.

The kneading station 4 comprises one or more? mixers 44 (fig.

4) fed through the duct 38 with the binding mixture coming from the mixing station 2. In the drawing of the plant two mixers 44 have been shown, since ? preferable that to ensure continuity? of production there is an alternation between a mixer that prepares the dough and another mixer that is transferred through the unit? of loading 6 (figs.

5,6) to the casting box 8 to feed it. If, however, continuity is not required? of production a single mixer 44 pu? be sufficient.

The mixer 44 ? preferably of the orbital type and comprises a structure with a base 46 for resting on the floor, a head 48 provided with a kneading tool 50 and a column 52, which in addition to supporting the head 48? provided with a lifting member 54 of a bowl of dough 56, so as to lift it towards the head 48 and to make the kneading tool 50 penetrate inside it for the entire time necessary to form the dough of the components introduced into the bowl 56. The glass of dough 56 ? advantageously provided with wheels 58 for its handling on the ground, as will be better seen? afterwards.

The lifting member 54 of the bowl of dough 56 comprises a pair of fork arms 60 which engage the bowl itself from the outside to lift it from the floor for the dual purpose of allowing the kneading tool 50 to remain inside it for the whole time of its activation and to stabilize its position with respect to the mixer 44 despite the fact that the bowl 56 is provided with wheels 58.

In the kneading station 4, in addition to the conduit 38 for the binding mixture which comes from the mixer 18, there is also one or more? other ducts 62 for other liquid components, in particular glycerine, to be introduced into the cup 56, and a discharge mouth 64 of a doser 66 (fig. 3) of solid products, which must be introduced into the mixing cup 56 to transform the mixture liquid into a mixture of gelatinous consistency, necessary for the production of sheet soap.

Pi? in particular, the dispenser 66 of these solid components, which generally essentially consist of corn starch, comprises a tubular structure 68 housing inside it a screw feeder mechanically coupled to an electric motor 70 for its rotation. The tubular structure 68 ? provided at the bottom with a hopper 72, into which the bags 67 of corn starch and any other solid products required by specific recipes can be poured, and ends at the top with the mouth 64, from which the measured solid products can be introduced by gravity within the glass of dough 56.

The plant according to the invention can advantageously also comprising equipment for pouring the dough formed in the mixer 44 into the casting box 8. This equipment, indicated globally by 74, comprises a support structure with a base 76 for resting on the floor and with a column 78 of guiding and moving a member 80 for gripping and lifting the kneading cup 56 through two articulated arms which, after lifting the cup itself, can overturn it (fig. 6) above a hopper 82, of which the casting box 8 ? provision, to pour the previously prepared gelatinous mixture into it.

At the top of column 78 ? a scraper member 84 is provided, which when the bowl of dough 56 is lifted and overturned, it adheres to its internal wall and with the rotation of this it strips on the wall itself to completely remove the mixture that is inside it.

The casting box 8 ? a container in itself? traditional, intended to contain the mixture prepared in the kneader 44 and to bring it down in quantity controlled on the underlying conveyor belt 12 for its transfer into the drying oven 10.

The casting box 8 ? provided at the bottom with a slit 86 for the escape of a continuous veil of gelatinous mixture.

? it is preferable that the casting box 8 is equipped with a level gauge 88, which has the function of keeping the mixing head constant within the casting box itself, to always ensure the same pressure of gelatinous mixture in correspondence with the slot 86 and therefore the uniformity? of which comes out of the casting box 8.

The conveyor belt 12, which transfers the veil of gelatinous mixture from the casting box 8 to the drying oven 10 and passes through the oven itself, is preferably made of steel and has a smooth and preferably mirror polished upper surface. It ? destined to longitudinally cross the oven 10, which ? advantageously constituted by a support structure of a plurality? of aligned tanks 90, having the longitudinal edges configured to guide the longitudinal edges of the conveyor belt 12, which runs along these and at the same time closes them at the top.

The tanks 90 are preferably supported by the support structure in a suspended condition so as to be able to perform small horizontal oscillations and in this way to be able to absorb any deformations and/or thermal expansions.

The tanks 90 and the conveyor belt 12 which closes them at the top are in turn covered by a tunnel cover 92, which closes the space above, within which a circulation of hot air is created, preferably having a temperature of about 110? 120?C, produced with steam or gas burners or electric or infrared heaters. Its function is to heat the upper surface of the soap ribbon 16 which is being formed. The lower surface of the conveyor belt 12 is instead heated with steam emitted by a plurality of of nozzles 94, which open inside the tanks 90, or with induction plates or with a catalytic gas burner or electrically with infrared heaters. Thanks to these heating systems, the temperature on the two upper and lower surfaces inside the oven is ? about 85? 95?C and there? allows you to remove at least 45% of its liquid content from the dough.

Conveyor 12 ? configured as a ring and runs inside the drying oven 10, from which it comes out at both ends. At the end? upstream ? placed the casting box 8 and ? preferable that this? extremity? of the conveyor belt is preheated, so that the veil of gelatinous dough that will form? the continuous ribbon of soap 16 falls on the conveyor belt 12 down? heat. ? preferable that the conveyor belt 12 is preheated to a temperature of 30? 40?C and this preheating pu? be advantageously obtained by heating the transmission roller 96, to which the conveyor belt 12 adheres, with steam or with induction plates or with another thermostatic system.

At the end downstream of the conveyor belt 12 ? the detachment of the continuous ribbon of soap 16, completely dried in the meantime, from the steel conveyor belt 12, before this returns to the oven 10 to complete the return section empty. This detachment? advantageously obtained for example with a scraper 98 and ? favored by the smooth nature of the conveyor belt 12.

All the components of the plant and in particular the mixer 44 are advantageously connected with a unit? controller (not shown) for their management on the basis of predefined programmes, linked to the different ?recipes? which allow you to prepare with the same system both soap sheets with characteristics suitable for use in washing machines and soap sheets with different characteristics, suitable for use as hand cleaners.

There? that differentiates the two types of products obtainable with the same plant are the basic recipes and the times with which the various components of the mixture and in particular the components of the gelatinous mixture to be poured into the casting box 8 are processed to form the ?dough itself.

Preparation of soap sheets for washing machine

The binder mixture based on polyvinyl alcohol is first poured into the mixer 18, which is kept under constant stirring until the soap in sheet is prepared.

At the time of preparation, the binding mixture is first poured into the kneader 44, where the bowl of dough 56 is? already been raised to the raised position so that the kneading tool 50 is introduced therein.

The quantity? percentage of binder mix compared to the weight of the final mix ? between 58 and 64% and ? preferably equal to about 60.9%.

After having poured the binding mixture into the bowl 56, powdered corn starch is poured into it, both manually and with suitable automated equipment. between 24.5% and 27.1%, preferably around 25.8% and the whole is subjected to the action of the kneading tool 50 for a time which generally is ? between 5 and 10 minutes, preferably about 7 minutes and ? advantageously determined on the basis of experimental tests in order to ensure in any case the complete mixing of the components of the dough. Furthermore, the speed drive of the kneading tool 50, which preferably ? orbital type, ? kept at rather low values, which can also be determined experimentally, in order to ensure the mixing effect of the powdered corn starch with the binding mixture, but at the same time to avoid, as far as possible, the formation of air bubbles inside the dough.

After this phase the mixer is stopped for a few minutes in order to let the dough rest and to allow the small quantity to come out of it. of air bubbles which, despite the precautions, had eventually formed.

After this first phase, Vaseline oil is poured into the bowl 56 of the kneader 44 in a quantity of between 0.38% and 0.42%, preferably around 0.4% and generally determined too, like all the components of the dough, with experimental tests, which allow to determine the optimal composition according to the quantity? and of the quality? of the components used.

After pouring the vaseline oil into the mixing bowl 56, the kneading tool will be reactivated and run for 25 ? 35 seconds, preferably for about 30 seconds in order to homogenize the dough that is being formed, and then it is stopped to once again allow the air bubbles inevitably generated during the formation and homogenization of the dough to be freed from this . The parking can last from 2.5 minutes to 3.5 minutes and preferably ? equal to about 3 minutes.

Then 99.8% pure glycerine is poured into the glass 56 of the mixer in the quantity? between 1.33% and 1.47%, preferably about 1.4%, which is then mixed with the dough already? formed for 25-35 seconds, preferably for about 30 seconds, in order to ensure the homogenization of the dough, which is then left to rest for about 3.5 ? 4.5 minutes, preferably for about 4 minutes, to ensure that any air bubbles are released.

Then a detergent mixture is poured into the mixing bowl 56 between 10.25% and 11.35%, preferably about 10.8%, keeping the kneading tool 50 still in this phase to avoid the formation of foam in the dough and then operating it for about 1.5-2.5 minutes, preferably for about 2.0 minutes to homogenize among them all the components of the dough; finally an OXI BLUE perfume is poured on the dough in quantity? between 0.66% and 0.73%, preferably about 0.7%, which performs the double perfuming and softening function.

The action of the kneading tool on the dough is so format lasts for 1.5-2.5 minutes, preferably for 2.0 minutes, depending on the type and quantity? of the components previously introduced, and in the end the dough? ready to form sheet soap.

The bowl of dough 56 is lowered, so as to cause the extraction of the kneading tool 50 from the dough that has just formed, and is subsequently transferred to the structure 76, where it is lifted and turned over so as to pour the dough with a gelatinous consistency , within casting box 8.

In this phase, the level of the gelatinous mixture inside the casting box 8 is accurately controlled by the measurer 88, which acts on the structure 76 so as to regulate the quantity? of dough which is poured into the casting box itself.

From the casting box 8, and precisely from its lower slot 86, is the a veil of gelatinous mixture which, thanks to the level control of the mixture itself within the casting box 8, has a substantially constant thickness over its entire width during dispensing.

Inside the oven 10 this layer of dough is progressively dried so that when it comes out of the oven it has a humidity content of equal to about 7-9% and its stability? dimensional and can be detached from the conveyor belt 12 by means of the scraper 98 to then be wound up in a reel or sent to the operations of cutting into sheets of the desired dimensions.

The contact time of the veil of dough with the conveyor belt inside the oven? significantly constant between 6 and 10 minutes and preferably equal to about 8 minutes for the various recipes; the productivity? of the oven can? be chosen in the design phase with an appropriate choice of speed? of transit of the product inside the oven and the cio? of the speed? movement of the conveyor belt 12.

Preparation of sheets of hand washing soap

How to ? said, the plant according to the invention ? able to produce a continuous ribbon of soap for washing machines or a continuous ribbon of soap for washing machines, which differs from soap for washing machines essentially for the presence of cosmetic products inside and for its degree of solubility? in the water, what? much greater as it must ensure its complete dissolution in a very short time, equal to a few rubbing of the hands under the tap of water, unlike soap for washing machines, which must ensure its dissolution much faster. slow, linked to the work cycle of the washing machine itself.

Even in the case of hand soap? it is provided that the various components are introduced into the mixer 44 in the same order as the previous ones and with pauses between successive activations of the mixer after the introduction in the predefined order of certain components of the gelatinous mixture to be formed.

There? which varies in the preparation of the soap sheet for the two different applications are the detergent mixture of the soap for washing machines, which ? replaced by a cosmetic blend of hand washing soap, which also has a degreasing function. In addition, the OXI BLU perfume also varies, which is? of different types, and finally varies the final activation time of the mixer after the introduction of the OXI BLU perfume, time that can? reach even 10-15 minutes, in order to generate a significant amount? of air bubbles, which makes the soap sheet more? soft and more rapidly soluble in water at the time of use.

After the continuous ribbon of hand washing soap ? been removed from the conveyor belt 12, it can? be cut, for example with a die-cutter into small disposable sheets, which can then be individually packaged in customizable sachets with instructions and/or with advertising messages of various kinds.

How to ? seen, the? mixer 44 ? managed by a? unit? command, in which the activation times of the mixer and the pause times between one activation and the next are memorized, so that based on the choice of the programme, a soap ribbon of the type can be produced with the same system corresponding to the desired use and the desired recipe. All the components can be introduced by hand into the mixer, but the invention provides that the dosing operations of these and/or their introduction into the mixer can also be automated and managed by the same unit. of command.

The present invention ? been illustrated and described in some of its preferred embodiments, but it is understood that executive variants can be applied to them in practice, without however departing from the scope of protection of the present patent for industrial invention.

Claims (17)

1. Plant for the production of sheet soap, in particular for producing sheets of soap for washing machines and sheets of hand washing soap, characterized in that it comprises: - at least one mixer (44), into which the components are introduced to prepare a mixture of gelatinous consistency, with which it will be? then formed a dimensionally stable continuous ribbon of soap (16), - means for introducing said mixture of gelatinous consistency into a casting box (8) for the formation of a continuous veil to be deposited on an underlying conveyor belt (12), - a drying oven (10), in which the film of substantially gelatinous dough, transported by said conveyor belt (12), is dried to form said dimensionally stable continuous ribbon of soap (16), - means (98) for separating said dimensionally stable continuous ribbon of soap (16) from said conveyor belt (12), - a?unit? control and management system to command both the activation times of the mixer (44), after the introduction of each of the components of the dough, and the pause times after predefined activation phases. 2. Plant according to claim 1 characterized in that it also comprises a unit? of mixing (2), in which the first component of the dough to be introduced into the mixer, consisting of a substantially liquid binder mixture based on polyvinyl alcohol, is kept under constant stirring until its introduction into said mixer (44). 3. Plant according to claim 2 characterized in that said unit? mixing device (2) comprises a container (18) provided inside with a rotating stirrer (20) provided with at least one shaped blade (24) configured to scrape on the inner wall of said container. 4. Plant according to one or more? of the preceding claims characterized in that said kneader (44) comprises a bowl of dough (56) provided with wheels (58) for its movement on the floor and an orbital kneading tool (50) inside it. 5. Plant according to claim 4 characterized in that the mixer (44) comprises a structure with a cantilevered head (48), which applied said orbital kneading tool (50) and the relative movement means, said head being supported by a column (52) provided with means (54) for gripping and lifting said bowl of dough (56) until causing the introduction in this of said orbital kneading tool (50). 6. Plant according to one or more? of the preceding claims characterized in that it comprises a unit? (74) for lifting said bowl of dough (56) and means (80) for its overturning in order to pour said dough of gelatinous consistency into said casting box (8). 7. Plant according to claim 6 characterized in that said casting box (8) is provided with a gauge (88) for the level of said gelatinous mixture, coordinated with said tilting means (80) to ensure a substantial constancy of the level of gelatinous mixture inside said casting box (8). 8. Plant according to one or more? of the preceding claims characterized in that the drying oven (10) comprises at least one tank (90) closed at the top by said conveyor belt (12), which has the longitudinal edges slidably engaged in the longitudinal edges of said tank and also comprises a tunnel (92) covering said tank (90), affected internally by a flow of hot air for heating the film of product to be dried placed on the upper section of said conveyor belt (12), the lower surface of which is? heated by steam introduced through at least one nozzle (94) placed inside said tank (90). 9. Plant according to one or more? of the preceding claims characterized by the fact that said drying oven (10) comprises a plurality of aligned tanks (90), covered by said conveyor belt (12) and mounted in said oven in a suspended condition so as to be able to perform limited longitudinal oscillations. 10. A method of making sheet soap characterized in that: - are they introduced into at least one mixer (44), with a pre-set sequence and according to the quantity? pre-set according to the particular type of soap sheet to be obtained, the components foreseen by a specific recipe to be followed, - said mixer is activated after the introduction of each of the components and certain activation phases are followed by a pause in order to cause any air bubbles that may have formed during the previous activation of the mixer to escape from the mixture, these phases of activation and said pauses being predefined on the basis of the particular recipe to be followed, - the gelatinous mixture is poured into a casting box (8), from which it is then released in the form of a continuous veil onto a conveyor belt (12) for its transfer into a drying oven (10), in which at least 45% of the liquid is removed, thus obtaining a dimensionally stable continuous ribbon of soap (16), - at the exit of the drying oven (10) the continuous ribbon of soap (16) is removed from the conveyor belt (12) and sent to the operations of winding into reels and/or cutting into sheets of predetermined dimensions. 11. Method according to claim 10 characterized by the fact that the continuous veil which comes out of said casting box (8) is dimensionally controlled by controlling the level of the gelatinous mixture inside it. 12. Method according to one or more? of the preceding claims characterized in that said conveyor belt (12) is preheated to a temperature of about 30-40°C before pouring onto it the continuous veil of gelatinous mixture to be transferred into said oven (10). 13. Method according to one or more? of the preceding claims characterized in that the following operating steps are carried out in order to produce sheet soap for washing machines: - introduction into the mixer (44) of a binder mixture based on polyvinyl alcohol in quantity? equal to 58-64% by weight with respect to the finished product, preferably about 60.9%, - introduction into the mixer of powdered corn starch in quantity? equal to 24.5-27.1%, preferably about 25.8%, and subsequent mixing for about 5-10 minutes, preferably for 7 minutes, and in any case for a sufficient time to ensure substantial homogeneity of the dough, - introduction into the mixer of vaseline oil in quantity? equal to 0.38-0.42%, preferably about 0.4%, mixing for about 25-35 seconds, preferably for about 30 seconds and subsequent pause of about 2.5-3.5 minutes, preferably about 3 minutes, and in any case for such a time as to cause the substantial elimination of air bubbles from the dough formed, - introduction into the mixer of substantially pure glycerin in quantity? equal to 1.33-1.47%, preferably about 1.4%, mixing for about 25-35 seconds, preferably for about 30 seconds and subsequent pause of 3.5-4.5 minutes, preferably about 4 minutes, and in any case for a sufficient time to cause the substantial elimination of air bubbles from the dough - introduction into the mixer of a detergent mixture with a degreasing function in quantity? equal to 10.25-11.34%, preferably about 10.8% and subsequent mixing for about 1.5-2.5 minutes, preferably for about 2 minutes, - introduction into the mixer of a perfume in quantity? equal to 0.66-0.73%, preferably about 0.7% and subsequent mixing for about 1.5-2.5 minutes, preferably for about 2 minutes. 14. Method according to one or more? of the preceding claims characterized in that to produce hand washing soap in sheet form the following operating steps are carried out in order: - introduction into the mixer (44) of a binder mixture based on polyvinyl alcohol in quantity? equal to 58-64% by weight with respect to the finished product, preferably about 60.9%, - introduction into the mixer of powdered corn starch in quantity? equal to 24.5-27.1%, preferably about 25.8%, and subsequent mixing for about 5-10 minutes, preferably 7 minutes, and in any case for a sufficient time to ensure substantial homogeneity of the dough, - introduction into the mixer of vaseline oil in quantity? equal to 0.38-0.42%, preferably about 0.4%, mixing for about 25-35 seconds, preferably for about 30 seconds and subsequent pause of about 2.5-3.5 minutes, preferably about 3 minutes, and in any case for such a time as to cause the substantial elimination of air bubbles from the dough formed, - introduction into the mixer of substantially pure glycerin in quantity? equal to 1.33-1.47%, preferably about 1.4%, mixing for about 25-35 seconds, preferably for about 30 seconds and subsequent pause of 3.5-4.5 minutes, preferably about 4 minutes, and in any case for a sufficient time to cause the substantial elimination of air bubbles from the mix, - introduction into the mixer of a cosmetic mixture with a degreasing function in quantity? equal to 10.25-11.34%, preferably about 10.8% and subsequent mixing for about 1.5-2.5 minutes, preferably for about 2 minutes, - introduction into the mixer of a perfume in quantity? equal to 0.66-0.73%, preferably about 0.7% and subsequent mixing for 12-14 minutes. 15. Method according to one or more? of the preceding claims characterized by the fact that said polyvinyl alcohol-based binder mixture is kept in a mixer (18) and is kept in a state of continuous stirring by means of a stirrer (20) at a speed? between 50 and 70 rpm, until said binding mixture has to be poured into said kneader (44) 16. Method according to one or more? of the preceding claims characterized in that the upper part of the conveyor belt (12) is heated inside the oven (10) with a flow of hot air at a temperature of about 110-120°C and the lower part of the same conveyor belt with a flow of steam at a temperature of about 100-110?C. 17. Method according to one or more? of the preceding claims characterized in that the layer of gelatinous dough is subjected to heating in the oven (10) for a time ranging from 7 to 10 minutes, preferably about 8 minutes.