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Title:
METHOD FOR PREPARING FOOD COMPOSITIONS
Document Type and Number:
WIPO Patent Application WO/2018/109707
Kind Code:
A1
Abstract:
A method for preparing a food composition containing konjac flour comprises the following steps: dosing a predetermined amount of konjac flour; dosing a predetermined amount of a food ingredient that is different from the konjac flour; hydrating said predetermined amount of konjac flour and said predetermined amount of a food ingredient that is different from the konjac flour; mechanically processing said predetermined amount of konjac flour and said predetermined amount of a food ingredient that is different from the konjac flour, so as to produce a konjac-based food mixture. The method is characterised in that said hydrating and said mechanically processing are carried out contemporaneously and a predetermined viscosity is achieved and maintained in said mixture. Through the aforesaid method a food composition containing konjac glucomannan can be obtained, said food composition being characterized in that it is provided with a shear viscosity that is comprised between 5680 Pa x s and 21000 Pa x s and is measured at a shear rate of 1 sec-1.

Inventors:
MUSCI RICCARDO (IT)
COLOMBO PIERLUIGI (IT)
Application Number:
PCT/IB2017/057938
Publication Date:
June 21, 2018
Filing Date:
December 14, 2017
Export Citation:
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Assignee:
MUSCI RICCARDO (IT)
International Classes:
A21D2/36; A23L29/244; A23L33/10
Domestic Patent References:
WO1990015544A11990-12-27
WO2010140182A12010-12-09
Foreign References:
US20080292769A12008-11-27
CN103202438A2013-07-17
CN103766713A2014-05-07
Attorney, Agent or Firm:
COLOBERTI, Luigi et al. (IT)
Download PDF:
Claims:
CLAIMS

1. Method for preparing a food composition containing konjac glucomannan, said method comprising:

- Dosing a predetermined amount of konjac flour;

- Dosing a predetermined amount of a food ingredient that is different from the konjac flour;

- Hydrating said predetermined amount of konjac flour and said predetermined amount of a food ingredient that is different from the konjac flour;

- Mechanically processing said predetermined amount of konjac flour and said predetermined amount of a food ingredient that is different from konjac flour, so as to produce a mixture, said mixture corresponding to said food composition;

said method being characterised in that said hydrating and said mechanically processing are carried out contemporaneously and a predetermined viscosity is achieved and maintained in said mixture.

2. Method according to claim 1, wherein said predetermined viscosity is a shear viscosity comprised between 5680 Pa x s and 21000 Pa x s and measured at a shear rate of 1 sec"1.

3. Method according to claim 1, or 2, wherein said predetermined amount of konjac flour is comprised between 1% by weight and 99% by weight.

4. Method according to any one of claims 1 to 3, wherein said predetermined amount of a food ingredient that is different from the konjac flour is between 1% by weight and 99% by weight.

5. Method according to any one of claims 1 to 4, wherein said hydrating and said mechanically processing are carried out contemporaneously inside a same chamber of a mixing/kneading apparatus.

6. Method according to claim 5, wherein said mixing/kneading apparatus comprises a high-speed turbine continuous mixer, said high speed being comprised between 50 revolutions/minute and 2500 revolutions/minute.

7. Method according to any one of claims 1 to 6, wherein said mechanically processing is carried out for a time that is comprised between 1 minute and 30 minutes.

8. Method according to claim 9, wherein said mechanically processing is carried out for a time that is equal to 3 minutes.

9. Method according to any one of claims 1 to 8, comprising further processing said food composition containing konjac glucomannan, so as to obtain a food product containing konjac glucomannan.

10. Method according to claim 9, wherein said further processing includes extruding said food composition containing konjac glucomannan.

11. Method according to any one of claims 1 to 10, wherein said food ingredient that is different from the konjac flour is selected from a group consisting of: white rice flour, brown rice flour, broad bean flour, bean flour, amaranth (Amaranthus spp.) flour, potato flour, soybean flour, manioc or tapioca (Manihot esculenta) flour, maranta (Maranta arundinacea) flour, corn or maize flour, buckwheat (Fagopyrum esculentum) flour, millet flour, quinoa (Chenopodium quinoa) flour, sorghum flour, white teff or red teff (Eragrostis tef) flour, generally edible legumes (Leguminosae or Fabaceae) flour, chia (Salvia hispanica) flour, hemp flour, coffee flour, carob flour, coconut flour, chestnut flour, almond flour, banana flour, farro flour, kamut or Khorasan wheat (Triticum turgidum ssp. Turanicum cv. Khorasan) flour, barley flour, rye flour, spelt flour, triticale (hybrid x Triticosecale) flour, oat flour and mixtures thereof.

12. Food composition containing konjac glucomannan, said food composition being characterized in that it is provided with a shear viscosity that is comprised between 5680 Pa x s and 21000 Pa x s and is measured at a shear rate of 1 sec"1.

Description:
METHOD FOR PREPARING FOOD COMPOSITIONS

BACKGROUND OF THE INVENTION

The present invention relates to a method for preparing food compositions comprising glucomannan extracted from konjac, which are made from konjac flour, other flours that are different from the konjac flour and water. The invention further relates to a food product that can be prepared by the aforesaid method.

STATE OF THE ART

By the name "konjac" (Amorphophallus konjac K. Koch) a plant is indicated that belongs to the Araceae family, originating from tropical and subtropical jungles of south eastern Asia. The konjac is provided with a rhizome - i.e. a hypogean stem portion serving as storage organ - which is particularly rich in glucomannan. The latter is a water-soluble fibre, more exactly a high molecular weight water-soluble polysaccharide, consisting of D-mannose and D-glucose units. By drying and grinding the konjac rhizome a first product is obtained, which is called "konjac flour". By subjecting the latter to an aqueous phase extraction a second product is obtained, namely a hydrocolloid that is soluble in water, which is called "konjac gum".

The konjac, and more exactly its aforementioned by-products - flour and gum - are known both in therapeutic (Asian traditional herbal medicine) and dietary field

(Asian traditional cuisine; food industry of Western Countries). The Asian traditional herbal medicine considers konjac a useful therapeutic agent for treating cancer and diabetes, while the Asian cuisine and the western food industry take advantage of the dietary properties of the glucomannan contained in the aforesaid vegetable. The glucomannan is in fact a fibre that provides a poor caloric intake (9.6 kcal in lOOg of product) and, owing to a remarkable hygroscopicity (konjac glucomannan is able to absorb an amount of water 200 times its volume) causes a significant sense of satiety in the consumer. Since in fact glucomannan increases in volume when it is put into contact with the liquids (e.g. water), after being ingested this fibre tends to fill the stomach, causing satiety in the consumer, and thus contributing to a substantial weight loss of the latter. Furthermore, the hygroscopicity of this fibre enables the intestinal transit to be regulated, avoiding both constipation and diarrhoea and contributing to remove any toxins produced and/or present anyhow in the gastrointestinal tract.

In addition to the aforementioned dietetic effects, konjac glucomannan is able to play an efficient role as a regulator of the carbohydrate and lipid metabolism. In fact, the konjac glucomannan has a significantly reduced glycemic index, thus contrasting insulin and glycemic post-prandial peaks, and - as assessed by clinical studies - it contributes to reduce glycaemia in individuals suffering from diabetes and/or obesity. Other clinical studies have demonstrated that konjac glucomannan carries out a substantial cholesterol-lowering - in particular reducing the LDL cholesterol fraction - and triglyceride-lowering action. Finally, as verified in preliminary clinical studies, the konjac glucomannan would appear to be also able to reduce the ghrelin rate, a hormone that stimulates appetite and is produced by gastric (P/Dl cells) and pancreatic (epsilon cells) cells.

The konjac flour may be used as such (i.e., mixed with other food ingredients), may be administered in gelatine capsules (dietary supplement), may be further processed to produce a gelatinous paste which is shaped as a block (so called konnyaku) or as spaghetti (so called shirataki). While the konnyaku substantially represents a basic ingredient, from which to start preparing more elaborate foods, the shirataki - owing to an appearance that is substantially analogous to that of spaghetti - may be consumed as such and only need a suitable dressing.

However, although being a type of hypocaloric food that is substantially favourably received by consumers and consequently interesting for the food industry, in particular for the dietetic food industry, the known konjac spaghetti are affected by a not negligible drawback.

In fact, according to the known method for preparing shirataki, konjac flour is dissolved in hot water and the so obtained macromolecular structure (hydrogel or hydrocolloid) must be thermo-stabilized by addition of an additive, in particular a salt adapted to produce alkaline solutions, which can be potassium carbonate (K 2 CO 3 ) or calcium hydroxide (Ca(OH) 2 ). The calcium hydroxide is preferred as this additive is able to act contemporaneously as thermo- stabilizer and pH regulator. Consequently, the packages of shirataki currently commercially available contain the konjac spaghetti immersed in an aqueous solution (preserving liquid) including calcium hydroxide (Ca(OH) 2 ). The presence in the package of the calcium hydroxide solution forces the consumer to completely remove the liquid contained in the package and to rinse thoroughly spaghetti with water before use, in order to remove any additive residues.

It should be noted that the calcium hydroxide - although being used in form of additive for food use - represents a substantially undesired component and that it is able to affect the organoleptic properties of the product, in particular giving a substantially unpleasant lime taste to the latter. The consumer is thus forced to lose a certain amount of time, as well as waste a certain amount of drinking water, before being able to cook and consume shirataki.

It follows that a greater diffusion in the konjac spaghetti consumption - which is desirable in view of the beneficial effects obtainable through the regular taking of konjac glucomannan - is first of all hindered by the fact that the aforesaid food product is substantially scarcely easy to use.

Another drawback, which is particularly apparent to the regular consumers (e.g., in Italy) of dried and/or fresh traditional pasta, is the poor palatability (due to a low taste enjoyability) offered by the known konjac-based food products, such as for instance shirataki. For those who are used to consume a pleasantly firm food product - such as it is indeed traditional dried and/or fresh pasta after cooking - the shirataki appear substantially gummy and slimy. Therefore, the shirataki represent a food that is not particularly alluring and not comparable with the firmness (so called texture) of the pasta produced according to the Italian tradition.

A further drawback that can be found when it is desired using the konjac flour for producing food products, e.g. pasta, is the substantial difficulty to obtain a homogeneous mixture, in particular a lump-free mixture, mixing the aforesaid flour with water. This is due to the extreme hygroscopicity of the glucomannan and the consequent increase in viscosity, which cause a rapid and considerable increase in volume of the mass of the mixture making the latter hard to be processed in the industrial machines of the known type (kneader/extruders) used in pasta factories. In particular, the inhomogeneity of the mixture is such that it produces films and conglomerates of konjac flour in the various parts (shaft; extrusion screw; die plate) of the aforesaid machines, dirtying the internal parts of the latter and consequently subtracting raw material from the mixture being formed.

In order to overcome the above disclosed drawbacks, food products formulations have been proposed - e.g. pasta - in which the konjac flour is mixed with flour of other vegetable origin - for example a cereal flour as durum wheat flour - for the purpose of producing possibly more homogeneous mixtures and from which to obtain a pasta having a better palatability.

In fact, by using a cereal flour it is possible to make the mixture homogeneous and easily extrudable, owing to the formation of gluten and to phenomena of thermo- reversibility and thermo-stabilization. The gluten is a macromolecular complex, more exactly a viscoelastic three-dimensional lattice, basically composed of two classes of proteins, glutelins and prolamins (respectively called glutenins and gliadins in wheat). When water is added to a cereal flour, for instance durum wheat flour (semolina), the single protein chains of gliadin mutually associate forming fibrils, which make the gluten mass extendible, while the many protein subunits of the glutenins assemble, originating fibres of greater size and forming a stable structure, which makes the mixture firm and substantially resistant to the extension. When the mix of water and flour is treated mechanically (i.e. kneaded) the gliadin fibrils and the glutenin fibres begin to mutually interlace, forming a three-dimensional net (protein content 75-85%) that incorporates starch granules (10-15%), lipids (5- 10%), small amounts of mineral salts, water (which gluten can retain up to 70% of its weight) and small air bubbles.

Therefore, by exploiting the chemical-physical properties of the gluten it is possible to make "mixed" mixtures, including both konjac flour and cereal flour and provided with a substantially homogeneous structure. By extruding these "mixed" mixtures a food product can be produced, e.g. pasta, which is provided with firmness and palatability that are approximately comparable to those of the traditional pasta (obtained from mixtures made without the use of konjac flour).

In particular, the three-dimensional net formed by the gluten thermo-stabilizes the mixture, making the pasta (produced by extruding the mixture) resistant to cooking. The thermo-reversibility phenomena occur during the mechanical processing of the mixture, as no films and agglomerates of konjac flour are produced - which would dirty the inner parts of the machines (kneaders/extruders) - and the viscosity of the mixture can be adjusted according to the properties (in particular firmness) of the

(extruded) finished product.

However, the use of the gluten exposes the consumer to the risk of incurring in well- known nutritional and medical drawbacks (celiac disease; gluten intolerance) and appears substantially undesirable from a commercial point of view, given the current tendency of the consumers to prefer so called gluten- free food products.

Consequently, both the known food compositions based on konjac flour alone and the known "mixed" food compositions (based on konjac flour and flours of other vegetable origin) have various and not negligible drawbacks.

A strong need is therefore felt for food products based on konjac glucomannan and, consequently, for a corresponding production method which is free from the previously described drawbacks.

OBJECTS OF THE INVENTION

An object of the invention is to improve the known methods for preparing food compositions (food mixtures) comprising glucomannan extracted from konjac.

Another object is to make available a method allowing to avoid the use of food additives, such as calcium hydroxide, to stabilize the macromolecular structure of a konjac flour-based food composition.

A further object is to make available a method enabling a konjac flour-based food composition to be produced in a kneading machine in an easy manner, namely avoiding the formation of undesired films and agglomerates of konjac flour in the various parts of the kneading machine.

Another further object is to make available a method allowing to avoid the use of gluten to make a konjac flour-based food composition homogeneous.

Still another object is to make available a method allowing to produce a konjac flour- based food product which is substantially easy to use and, in particular, not requiring a waste of drinking water and time before being subjected to cooking and consumed. Still a further object is to make available a method allowing to produce a konjac flour-based food product that is provided with resistance, firmness and palatability after cooking which are suitable, i.e. comparable, to those of traditional food products, such as for instance the durum wheat flour (dried) pasta.

Still a further object is to make available a food product based on konjac flour and other gluten-free flours, which is gluten-free, has a high content of fibres and a low glycemic and caloric index.

BRIEF DESCRIPTION OP THE INVENTION

These and other objects and advantages of the invention can be achieved through the method as defined in claim 1 and the food composition as defined in claim 12. Hereinafter, both in the description and in the claims, the terms "konjac flour", "konjac glucomannan", "konjac glucomannans", "glucomannan extracted from konjac" and "glucomannans extracted from konjac" are to be intended as synonyms and are therefore used in a completely interchangeable way. Similarly, both in the description and in the claims, the terms "food compositions" and "food mixture" are to be intended as synonyms and are therefore used in a completely interchangeable way.

Thanks to the invention the drawbacks of the prior art (previously described) are overcome, as the method conceived by the Applicant allows to avoid the use of additives, such as calcium hydroxide, to thermostabilize the macromolecular structure of a food mixture based on konjac flour and water. Consequently, the consumer is no longer forced to waste time and drinking water - to remove additives - before cooking and consuming a food product obtained from the aforesaid mixture. Furthermore, the method according to the invention allows to produce a konjac flour- based food mixture - i.e. a food composition containing konjac glucomannan - in a kneading machine, avoiding the formation in the various parts thereof of films and agglomerates of konjac flour. Thereby, it is possible to avoid the use of gluten for making a konjac flour-based mixture homogeneous and resistant to cooking and the consequent risk, for the consumer, to incur in nutritional and medical drawbacks. Owing to the method according to the invention it is possible to produce a konjac flour-based food product provided with a suitable firmness and palatability after cooking, in particular a konjac flour-based food product having a firmness and a palatability after cooking that are comparable to those of traditional food products, such as for instance, dried pasta of durum wheat semolina.

The aforesaid food product can be obtained, for instance, by extruding the food composition (food mixture) according to the invention. The composition according to the invention is characterized in that it has a predetermined viscosity, in particular a shear viscosity that is comprised between 5680 Pa x s to 21000 Pa x s and is measured at a shear rate of 1 sec "1 . The aforesaid food product, being made from konjac flour and other gluten-free flours, is gluten-free, has a high fibres content and a low glycemic and caloric index.

It should be noted that the konjac flour can produce two different types of gel (or hydrocolloids), i.e. thermo-stable gels and thermo-reversible gels. The thermo-stable gels form when the konjac flour is heat-dissolved in slightly alkaline solutions. The thermo-reversible gels form in contrast when the konjac flour is associated to other substances - namely other hydrocolloids (such as carrageenans, starch, xanthan gum) or in general flours that can or cannot generate gluten - which are able to modulate, and particularly reduce, konjac viscosity, so as to make the mixture easily processable. More exactly, the other hydrocolloids and/or other flours (different from the konjac flour) reduce the hydration speed, thus preventing the formation of a strong hydrogel.

Therefore, when a gluten-free mixture is produced through the method according to the invention, for instance by mixing with water rice flour and konjac flour, the konjac flour provides the end product (e.g., an extruded product in form of dried pasta) with a suitable firmness and a suitable resistance to cooking. This is achieved owing to the (thermo- stable) konjac gel, which is adapted to form a three- dimensional net such as to thermo-stabilize the mixture.

The method according to the invention thus allows to obtain a gluten-free food mixture that is at the same time thermo-reversible, namely easily processable owing to the reduction in viscosity, and thermo-stabilized, namely able to give suitable firmness and resistance to cooking to a corresponding extrusion product (for instance, pasta). Thereby, the finished food product, e.g. a dried pasta, though gluten- free remains intact in boiling water (cooking step), without breaking and/or passing into solution.

More exactly, by extruding the food composition according to the invention a food product can be obtained, for instance in form of dried pasta, which maintains all the necessary organoleptic properties (shape, firmness and palatability) when subjected to the known and widely used methods of cooking pasta, namely: cooking in a pot, in water taken to the boiling point; cooking with a pressure pot; passive cooking; express cooking; double cooking; risotto-like cooking.

By "passive cooking" a cooking method it is meant that enables dispersion of starch and gluten to be prevented and includes the following steps: putting pasta in a pot containing boiling water; boiling for 2-4 minutes maximum; stopping heating; covering the pot with a lid and leaving pasta in the water for a time that is equal to the cooking time indicated on the pasta package. By "express cooking" a cooking method is meant that comprises the following steps: putting pasta in a pot containing boiling water; stirring periodically the pasta, following the cooking time indicated on the pasta package; taking pasta out one minute before the expiring of the maximum cooking time; straining and transferring the pasta in a frying-pan (in which cooking is completed) together with the seasoning. By "double cooking" a cooking method is meant that comprises the following steps: putting pasta in a pot containing boiling water and cooking for a time that is half the cooking time indicated on the pasta package; take the pasta out of the pot; straining and transferring pasta in a baking- pan adding a small amount of oil; cooling the pasta in a blast chiller; covering the baking-pan with a lid and storing the so cooled pasta in fridge at 0-3°C; putting the pasta in boiling water for 30-60 seconds before serving. By "risotto-type cooking" a cooking method is meant that comprises the following steps; putting the pasta in a saucepan; cooking the pasta in the saucepan by heating to a suitable temperature, adding progressively a liquid seasoning and contemporaneously stirring, until cooking is completed.

Among the various aforementioned known methods of cooking, it is in particular advisable to use the risotto-type cooking, or cooking in frying-pan, to cook the food product (for instance in the form of dried pasta) obtained by extruding the food composition according to the invention. In fact the aforesaid food product, during cooking, has a behaviour that is similar to the that of rice and is therefore particularly suitable for the above described cooking in frying-pan.

The method according to the invention further enables mixtures for food use to be prepared by mixing the konjac flour both with flours containing the protein precursors of the gluten (glutelins and prolamins) and with gluten-free flours.

Other characteristics and advantages will result from the dependent claims and the description.

DETAILED DESCRIPTION OF THE INVENTION

The method according to the invention is based on a new and surprisingly unexpected technical effect, namely the possibility to stabilize the macromolecular structure and the viscosity during the mechanical processing of a mixture containing a mix of konjac flour and other flours of different type (non-konjac). This allows to perform contemporaneously the hydration step, in which water is added to the mix of flours, and the step of mechanical processing of the mix, in which the mixture is produced. In fact, according to the known methods, the hydration step and the mechanical processing step must be performed in subsequent times, even by dividing the mechanical processing step into two sequential sub-steps (pre-mixing and mixing). However, if the raw material of the mixture is the konjac flour, the known methods do not guarantee optimal results, producing on the contrary the various above disclosed drawbacks (need to use calcium hydroxide to thermo- stabilize the mixture and/or viscosity regulators to stabilize the viscosity of the mixture; formation of film and agglomerates of konjac flour, which dirty the inner parts of the kneading machines).

However these drawbacks have been overcome, as experimentally verified by the Applicant, by contemporaneously hydrating and mechanically processing the various ingredients, as well as reaching and maintaining a predetermined viscosity in the so produced mixture, in particular a shear viscosity that is comprised between 5680 Pa x s and 21000 Pa x s and is measured at a shear rate of 1 sec "1 .

In order to contemporaneously hydrate and mechanically process the various ingredients, it is possible to use a suitable mixing / kneading apparatus - for instance a turbine continuous mixer - provided with a single chamber (or with more chambers, or portions of chamber, mutually communicating). The various ingredients of the mixture can be input in a dosed manner and contemporaneously mixed with water and mechanically processed (through one of more shafts that are motorized and provided with blades) inside the same chamber of the mixing/kneading apparatus. In one embodiment, the mixing / kneading apparatus comprises a high speed turbine continuous mixer, whereas by "high speed" a speed is meant that is variable between 50 rpm and 2500 rpm.

An example of turbine continuous mixer of the known type, usable to carry out the method according to the invention, is the Mini PTC 500 pre-kneader and turbine continuous mixer, provided with a batcher for flour products and pump for injecting liquids (Italiana Teknologie Sri; Senigallia, AN, Italy).

It is however clear that, depending on the desired type of mixture production - e.g. batch production or continuous production - a skilled in the art person is easily able to choose and use the most suitable type of mixer.

For exemplary but non limiting purposes, a procedure is hereinafter described, which is based on the method according to the invention and enables a food mixture to be produced starting from konjac flour, other flours of different type (non-konjac) and water. The obtained mixture can be subsequently extruded, so as to produce a food product that is completely analogous (for appearance, firmness and palatability) to a fresh food pasta of the known type, e.g. pasta made with eggs. The aforesaid extruded food product can further be dried, so as to result completely analogous (for appearance, firmness and palatability) to a dried food pasta of the known type, e.g. durum wheat pasta.

Example 1 - Production of an extrudable food mixture starting from konjac flour, white rice flour and water.

A mix of gluten-free flours is prepared, having the following composition: 0.01 Kg of konjac flour and 0.99 Kg of white rice flour.

In alternative to the aforesaid white rice flour it is possible to use a flour, or a mixture of flours, comprised in the following (exemplary but non limiting) list of gluten-free flours: brown rice flour, broad bean flour, bean flour, amaranth (Amaranthus spp.) flour, potato flour, soybean flour, manioc or tapioca (Manihot esculenta) flour, maranta (Maranta arundinacea) flour, corn or maize flour, buckwheat (Fagopyrum esculentum) flour, millet flour, quinoa (Chenopodium quinoa) flour, sorghum flour, white teff or red teff (Eragrostis tef) flour, edible legumes (Leguminosae or Fabaceae) flour, chia (Salvia hispanica) flour, hemp flour, coffee flour, carob flour, coconut flour, chestnut flour, almond flour, banana flour.

If desired, in alternative or in addition to the above listed gluten-free flours, it is possible to use a flour, or a mixture of flours, comprised in the following (exemplary but non limiting) list of gluten flours: farro flour, kamut or Khorasan wheat (Triticum turgidum ssp. Turanicum cv. Khorasan) flour, barley flour, rye flour, sorghum flour, spelt flour, triticale (hybrid x Triticosecale) flour, oat flour.

The aforementioned mixture of gluten-free flours is input in the internal chamber, or mixing chamber, of a turbine continuous mixer of the known type, e.g. the Mod. Mini PTC 500 (Italiana Teknologie Sri; Senigallia, AN, Italy) pre-kneader and turbine continuous mixer, and contemporaneously a volume of water of 1,5 L is added. Water is added, by actuating the continuous mixer, so as to hydrate and mechanically process the mixture of flours in a substantially contemporaneous way. The motorized shaft, rotating inside the mixing chamber at a rotational average speed of about 2000 rpm, is kept in operation for a substantially reduced time, e.g. equal to about 3 minutes. It is also possible to use a rotation speed that is comprised between 500 rpm 1500 rpm and/or mechanically process the mixture for a time that is comprised between 10 minutes and 15 minutes. A food mixture is thereby obtained containing konjac glucomannan, which can be later extruded by using an apparatus of the known type, for instance an extrusion unit including a cochlea, a compression cylinder and a die plate. The extruded product, whose final form depends on the type of die plate used, can be further processed, e.g. it can be laminated (reduced in thickness) by a refiner cylinder, and eventually dried, for example inside a static drying booth (about 50° for about 15 hours).

More generally, to produce an extrudable food mixture as disclosed in Example 1, the ranges of percentage concentrations by weight of the ingredients are those reported in Table 1 :

Table 1

In the mixture that is obtained by hydrating the ingredients of Table 1, the percentage concentration by weight of the water can be varied as a function of the percentage concentration by weight of the flours, in a way which can be easily understood and carried out by a skilled in the art person.

For the skilled in the art person it is further clear that, by varying properly the quantities of the various ingredients as well as the type of kneading machines and/or extruders to be used, the method according to the invention can be carried out both in an artisan laboratory and in an industrial productive line.

For the purpose of verifying the advantageous technical effect offered by the method according to the invention, the Applicant prepared some samples of food product, which were subsequently subjected to experimental tests at DeFENS laboratory (Department of Food, Environmental and Nutritional Sciences) of the University of

Milan. The results of the tests performed by DeFENS enable to state that, by applying the method according to the invention, it is possible to produce food mixtures based on mixes of konjac flours and other gluten-free vegetable flours having firmness and appearance that are significantly similar to the firmness and the appearance of the food mixtures containing gluten. The samples analysed at the DeFENS laboratory were prepared starting from durum wheat flour, as gluten was used as process indicator. The variables that affect the formation of gluten in a mixture are the energy supplied by the kneading machine used and the time during which the mixture is mechanically processed.

The tests carried out by the DeFENS laboratory aimed at comparing mixing technologies different from each other (traditional mechanical processing with fixed speed; batch mechanical processing with variable speed; continuous mechanical processing with variable speed) and at evaluating which technology is able to guarantee a better formation of the gluten and thus a greater firmness of the finished product.

More exactly, the formation of gluten was indirectly evaluated, in a mixture of durum wheat flour and konjac flour in which the latter was present in amount equal to 10 g for 1 kg of durum wheat flour (amount allowed by the Italian food legislation, according to the Ministerial Decree no. 183 of 10/03/2000).

To produce the samples analyzed by the study of DeFENS the following machines of the known type were used: "Parmigiana Mod. P45" (La Parmigiana; Fidenza, PR, Italy), "VIV Mod. 3 kg" (Italiana Teknologie Sri; Senigallia, AN, Italy) and "Mini PTC 500" (Italiana Teknologie Sri; Senigallia, AN, Italy). Technical details about these machines are illustrated below.

"Parmigiana Mod. P45" is a kneader/extruder, in which the extruder (or extrusion unit) is equipped with a die plate that is able to produce a rectangular sheet of pastry, having a minor side of 190 mm length. The extruder (or extrusion unit) is composed of a cochlea, a compression cylinder and a bronze die plate. The rotation speed is fixed both in the blade rotor of the kneader (37 revolutions/minute) and in the screw of the extruder (40 revolutions/minute on the extruder). The installed power is of 1,5 kW.

"VIV Mod. 3 kg" is a multi-function kneading tank for fresh pasta, having a variable rotation speed (minimum speed: 45 revolutions/minute; maximum speed; 425 revolutions/minute). The installed power is of 1,5 kW.

"Mini PTC 500" is a pre-kneader and continuous turbine mixer (also cited in the previous Example 1), provided with a batcher for flour products and pump for injecting liquids. The rotation speed is variable (minimum speed: 45 revolutions/minute; maximum speed: 2500 revolutions/minute). The samples and the analytical methods used in the laboratory tests, as well as the results of the aforesaid tests, are illustrated in detail in the following Examples 2 - 10. To prepare all the samples disclosed in Examples 2 - 10, the ingredients (konjac flour, durum wheat flour, water and/or egg) were placed in the machines at a starting time equal to zero and then hydrated, pre-kneaded and kneaded for a maximum time of 30 minutes. This standardized procedure was followed for all the prepared samples, regardless of the type of machine and the mechanical processing mode used.

Example 2 - Production of samples of dried food product based on durum wheat flour through first known method (PS-STL samples)

3 kg of durum wheat flour were input in the kneading tank of a "Parmigiana Mod.

P45" machine, then hydrated by adding 0,99 litres of water (equal to 33% of the amount of flour) and mechanically processed (pre-kneading and kneading steps).

After 30 minutes of mechanical processing, the bottom of the tank was opened to allow the mixture to flow into the extrusion unit (arranged under the kneading machine) and be extruded.

The extruded product (sheet of pastry) had a thickness of about 2 mm and was then refined (made thinner) by a refining cylinder, so as to obtain a final thickness of about 1 mm.

The refined extruded product was then cut into rectangular stripes (so called pappardelle) having about 35 mm width and about 210 mm length. The aforesaid rectangular stripes were dried in a static drying booth at about 50 degrees of temperature for about 15 hours. The dried rectangular stripes were subjected to the experimental tests described in the following Example 9.

In the present Example - as well as in the following Examples 3 and 4 - the mixture was prepared according to the known methods, namely by carrying out the hydration and mechanical processing steps (pre-mixing and mixing) in sequential manner. Example 3 - Production of samples of dried food product based on durum wheat flour and egg through first known method (PU-STL samples)

The PU-STD samples (rectangular stripes having about 35 mm width and about 210 mm length) were produced as disclosed in Example 2, by adding however an amount of eggs equal to 400 g for 1 kg of durum wheat flour, without adding water.

Example 4 - Production of samples of dried food product based on durum wheat flour and konjac flour through first known method (PK10-STD samples)

The PK10-STD samples (rectangular stripes having about 35 mm width and about 210 mm length) were produced as described in Example 2, by adding however an amount of konjac flour equal to 10 g for 1 kg of durum wheat flour (30g for 3 kg). The 3 kg of durum wheat flour and the 3 g of konjac flour were then hydrated by adding 0.33 litres of water (equal to 33% of the amount of flour).

Example 5- Production of samples of dried food product based on durum wheat flour through second known method (PS-ΓΤ samples)

3 kg of durum wheat flour were input in the "VIV Mod. 3 kg" multi-function kneading tank, subsequently hydrated by adding 0.99 litres of water (equal to 33% of the amount of flour) and mechanically processed (pre-kneading step) for 10 minutes. The mass of the mixture was then removed from the "VrV Mod. 3 kg" multifunction kneading tank, charged in the kneading tank of the "Parmigiana Mod. P45" machine and mechanically processed (kneading step) therein for 20 minutes. After 20 minutes of mechanical processing, the bottom of the tank was opened to allow the mixture to flow into the extrusion unit and be extruded.

The extruded product (sheet of pastry) had a thickness of about 2 mm and was then refined (made thinner) by a refining cylinder, so as to obtain a final thickness of about 1 mm. The refined extruded product was then treated according to the procedure disclosed in Example 2, so as to obtain the PS-IT samples.

Example 6 - Production of samples of dried food product based on durum wheat flour and egg through second known method (PU-IT samples)

The PU-IT samples (rectangular stripes having about 35 mm width and about 210 mm length) were produced as discloses in Example 5, by adding however an amount of eggs equal to 400 g for 1 kg of durum wheat flour, without adding water.

Example 7 - Production of samples of dried food product based on durum wheat flour and konjac flour through second known method (PK10-IT samples)

The PK10-IT samples (rectangular stripes having about 35 mm width and about 210 mm length) were produced as disclosed in Example 5, by adding however an amount of konjac flour equal to 10 g for 1 kg of durum wheat flour (30g for 3 kg). The 3 kg of durum wheat flour and the 3 g of konjac flour were subsequently hydrated by adding 0.33 litres of water (equal to 33% of the amount of flour).

Example 8 -Production of samples of dried food product based on durum wheat flour and konjac flour through the method according to the invention (PK10-NT samples) The PK10-NT samples (rectangular stripes having about 35 mm width and about 210 mm length) were produced in the following manner.

3 kg of durum wheat flour and 30 g of konjac flour (namely an amount of konjac flour equal to 10 g for 1 kg of durum wheat flour) were input in a "Mini PTC500" turbine continuous mixer and contemporaneously hydrated by adding 0.99 litres of water (equal to 33% of the amount of flour) and mechanically processed (pre-mixing step) for 3 minutes.

The mass of the mixture was then removed from the "Mini PTC 500" turbine continuous mixer, charged into the kneading tank of the "Parmigiana Mod. P45" machine and mechanically processed (kneading step) therein for 27 minutes. After 27 minutes of mechanical processing, the bottom of the tank was opened to allow the mixture to flow into the extrusion unit and be extruded.

The extruded product (sheet of pastry) had a thickness of about 2 mm and was then refined (made thinner) by a refining cylinder, so as to have a final thickness of about 1 mm. The refined extruded product was then treated according to the procedure disclosed in Example 2, so as to obtain the PK10-NT samples.

Example 9 -Production of a sample of dried food product based on durum wheat flour and konjac flour through an alternative version of the method according to the invention (PK10-MM samples)

The PK10-MM samples (rectangular stripes having about 35 mm width and about 210 mm length) were produced in the following manner.

3 kg of durum wheat flour were input in a "Mini PTC500" turbine continuous mixer and hydrated by adding 0.99 litres of water (equal to 33% of the amount of flour) and mechanically processed for 3 minutes.

After 3 minutes of mechanical processing, 30 g of konjac flour (i.e., an amount of konjac flour equal to 10 g for 1 kg of durum wheat flour) were subsequently input in the aforesaid turbine continuous mixer. The hydrated mixture of durum wheat flour and konjac flour was mechanically processed for another 3 minutes. The pre-mixing step totally lasted 6 minutes.

The mass of the mixture was then removed from the "Mini PTC 500" turbine continuous mixer, charged into the kneading tank of the "Parmigiana Mod. P45" machine and mechanically processed (kneading step) therein for 24 minutes. After 24 minutes of mechanical processing, the bottom of the tank was opened to allow the so produced mixture to flow into the extrusion unit and be extruded.

The extruded product (sheet of pastry) had a thickness of about 2 mm and was then refined (made thinner) by a refining cylinder, so as to obtain a final thickness of about 1 mm. The refined extruded product was then treated according to the procedure disclosed in Example 2, so as to obtain the PK10-NT samples.

Example 10 - Laboratory tests carried out on samples of dried food product

The following analyses and measurements were performed on all samples: humidity, water activity, visco-amylographic profile (to determine the properties of starch gelatinisation and retrogradation), thickness of the raw and cooked sample, behaviour during cooking, mechanical indexes of the raw and cooked sample.

The used methods and analytical instruments (of the known type) are synthetically disclosed below.

The humidity (%) was analysed with gravimetric method, subject to drying the milled sample in oven at 105°C.

The water activity was analysed on the milled sample, by using the ""Aqualab 3TE" instrument (Decagon Devices Inc., USA).

The visco-amylographic profile was analysed on the milled sample, by using a micro-visco-amylograph "MVA" (Brabender OHG, Duisburg, Germania).

The analysis was performed by preparing a suspension of milled sample in 12% w/v distilled water, with reference to a standard humidity of the sample of 14 g/lOOg (14%), and by applying the following thermal profile:

- heating from 30°C to 95°C with a gradient of 3°C/minute;

- keeping at 95°C for 30 minutes;

- cooling from 95°C to 50°C with a gradient of 3°C/minute;

- keeping at 50°C for 30 minutes;

- cooling from 50°C to 30°C with a gradient of 3°C/minute;

The thickness of the raw and cooked sample was measured by calibre.

The behaviour during cooking was assessed by analysing the increase in weight and in solid residue released during the cooking step.

The cooking tests were carried out under standard conditions, by keeping a fixed sample/water ratio equal to 100 g/3 litres, in absence of salt and using the optimal cooking times reported in the following Table 2: Table 2

The mechanical indexes of the raw and cooked sample were analysed by using a Instron 3365 dynamometer (lnstron Division of ITW Test and Measurement Italia S.r.L, Trezzano sul Naviglio, Italy) and a 100 N load cell. In particular, fracture tests were performed on raw samples by flexion (triple point bending test), by using a support (quadrilateral- shaped element so moved as to press the sample) 60 mm long and moving the movable crossbar (of the dynamometer) at a speed of 10 mm/s.

The cooked samples were analysed by tensile test, after being shaped in form of "dog-bone" through a suitable die (each shaped sample comprises an intermediate rectangular portion, extending longitudinally, and two square opposite ends having higher width than the intermediate portion) and by using a speed of the movable crossbar equal to 20 mm/minute.

To highlight any significant effects of the formulation of the sample and of the productive technology, the results relative to PS-STD, PS-ΓΓ, PU-STD, PK10-STD and PK10-IT samples were subjected to two-way variance analysis (MANOVA), followed by multiple comparison LSD (Least Significant Difference) test to assess the significance of the differences among mean values.

The results relative to PK10 samples obtained through the different technologies were elaborated by one way variance analysis (ANOVA) followed by multiple comparison LSD test to assess the significance of the differences caused by the different production technologies.

The statistical elaborations were performed by Statgraphics Plus 5.1 (Statistical Graphics Corp., Herndon, VA, USA) software and the (statistically elaborated) results of the performed various analyses are shown in the following Tables 3-16. In the Tables 3 -16 the various formulations are indicated with the PS (durum wheat flour), PU (durum wheat flour and egg) and PK10 (durum wheat flour and konjac flour) symbols and the methods used to produce the samples are indicated with the STD (first known method, as previously disclosed in Examples 2-4), IT (second known method, as previously disclosed in Examples 5-7), NT (method according to the invention, as previously disclosed in Example 8) and MM (alternative version of the method according to the invention, as previously disclosed in Example 9) symbols.

The data of the Tables 3 - 12 express the effects of the formulation and of the productive technology, wherein:

- The Tables 3, 5, 7, 9 report the mean values and the corresponding standard deviations (SD);

- The Tables 4, 6, 8, 10 report MANOVA results comprising the mean and standard error (SE) values.

The following Tables 3 and 4 illustrate the results relative to the humidity content and the level of water activity (aw).

The Table 3 reports the values (mean + SD) of humidity and water activity of the analysed samples:

Table 3

Sample Humidity (g/lOOg) a w

PS-STD 10.47 + 0.01 0.583 + 0.003

PS-IT 10.28 + 0.04 0.574 + 0.001

PU-STD 10.37 + 0.01 0.577 + 0.003

PU-IT 10.52 + 0.01 0.575 + 0.002

PK10-STD 9.95 + 0.02 0.552 + 0.001

PK10-IT 10.22 + 0.03 0.564 + 0.002

Table 4 reports the results of the MANOVA performed on the values (mean values + SE) of humidity and water activity :

Table 4

Factor Humidity (g/lOOg) a w

Formulation

PS 10.37 + 0.06 0.578 + 0.003

PU 10.45 + 0.06 0.576 + 0.003 PK10 10.09 + 0.06 a 0.558 + 0.003 a

Technology

STD 10.26 + 0.05 a 0.570 + 0.002 a

ΓΓ 10.34 + 0.05 a 0.571 + 0.002 a

From the statistical point of view, under the same considered factor and variable, the values followed by different letters ( a ' b ) are significantly different (p<0.05).

It results from the Tables 3 and 4 that only the formulation has a significant effect on the considered variables (humidity; water activity).

The samples produced with the mixture containing konjac glucomannan have a significantly lower value (p<0.05) of humidity and water activity than the other samples. The lower value of free water may be also justified by the presence of the hydrocolloid (glucomannan), which is able to bind significant amounts of water. The following Tables 5 and 6 illustrate the results relative to some indexes extracted from the visco-amylographic profiles, from which indications can be drawn on the state of the polysaccharide component of the samples, namely the starch.

In Tables 5 and 6 the abbreviation "U.B." means "Brabender Unit", while the "setback" is the difference between the viscosity at the end of the cooling at 30°C and the viscosity at the beginning of the cooling.

The Table 5 reports the values (mean +SD) of the visco-amylographic indexes of the analysed samples:

Table 5

The Table 6 reports the results of the MANOVA performed on the values (mean values + SE) of visco-amylographic:

Table 6 Factor Gelatinisation Viscosity at Final Setback temperature (°C) peak viscosity

(U.B.) (U.B.) (U.B.)

Formulation

PS 72.6 + 0.3 253 + 4 606 + 13 a 387 + 7

PU 77.6 + 0.3 c 242 + 4 a 607 + 13 a 363 + 7 a

PK10 69.6 + 0.3 a 256 + 4 585 +13 a 370 +7 a

Technology

STD 74.5 + 0.3 239 + 3 a 587 + 10 a 367 + 5 a

ΓΓ 72.0 + 0.3 a 262 + 3 611 + 10 a 379 + 5 a

From the statistical point of view, under the same considered factor anc variable, the values followed by different letters ( a ' b ) are significantly different (p<0.05).

It results from the Tables 5 and 6 that the behaviour of the PU sample distinguishes from the other formulations for the presence of egg proteins that coagulate during the analysis. IT technology appears to affect the starch to a lesser extent. In fact, during the analysis lower values of gelatinisation temperature, a greater viscosity at peak and a greater final viscosity (p<0,05) were recorded: these values indicate that, during the production of the sample, the starch was less gelatinised and retrograded. This is also in accordance with the highest setback values observed for PS-ΓΓ and PU-IT samples as compared to the corresponding STD samples. In the case of PK10 sample, in contrast, the technology effect is disguised by the presence of the hydrocolloid (konjac glucomannan).

The following Tables 7 and 8 illustrate the results relative to pre-cooking thickness, post-cooking thickness and behaviour during cooking. In the Tables 7 and 8 the "DS" abbreviation means "dry substance".

Table 7 reports the values (mean + SD) of thickness and behaviour during cooking of the analysed samples:

Table 7

Sample Pre-cooking Post-cooking Weight Solid residue thickness thickness increase released

(mm) (mm) during during

cooking cooking

(%) (g/lOOg DS) PS-STD 1.39 + 0.07 1.36 + 0.05 110.8 + 0.3 5.30 + 0.05

PS-IT 1.26 + 0.08 1.59 + 0.10 105.3 + 1.5 4.25 + 0.06

PU-STD 1.13 + 0.03 1.25 + 0.06 115.9 + 1.6 5.53 + 0.05

PU-IT 1.18 + 0.03 1.40 + 0.09 129.2 + 0.3 4.86 + 0.10

PK10-STD 1.15 + 0.06 1.19 + 0.05 119.5 + 0.6 4.52 + 0.08

PK10-STD 1.15 + 0.04 1.23 + 0.06 112.9 + 1.1 3.52 + 0.14

The Table 8 reports the results of the MANOVA performed on the values (mean values+ SE) of thickness and behaviour during cooking:

Table 8

From the statistical point of view, under the same considered factor and variable, the values followed by different letters ( a ' b,c ) are significantly different (p<0.05).

It results from the Tables 7 and 8 that the samples based on durum wheat flour (semolina) showed a slightly but significantly (p<0.05) higher thickness than the other formulations, both in the raw and cooked sample, while the konjac flour-based samples have a lower post-cooking thickness (p<0.05). This may be ascribed to the presence of the hydrocolloid (konjac glucomannan) that makes the structure of the mixture and the sample obtained therefrom firmer. The samples obtained with IT technology showed a significantly (p<0.05) higher thickness in the cooked samples, probably due to the greater swelling of the starch granules. The weight increase during cooking was significantly (p<0.05) affected only by the formulation. In particular, the samples based on durum wheat flour (semolina) showed the least increase, while the samples based on durum wheat flour and egg showed the highest increase.

This may be due to the presence of the egg yolk fat, which interrupts the meshes of the gluten and allows the starch granules to swell more and thus to release also a greater amount of solid substance in the cooking water. In fact, the samples based on durum wheat flour and egg produced the highest (p<0.05) solid residue released during cooking.

The konjac flour-based samples showed an intermediate weight increase during cooking if compared to the other two formulations. Further, the konjac flour-based samples showed the smallest (p<0.05) solid residue release during cooking, which indicates a good resistance of pasta.

The technology of production significantly (p<0.05) affects the solid residue released during cooking: the IT technology would appear to make the structure of pasta firmer, causing a smaller release of dry substance during the cooking.

The following Tables 9 and 10 illustrate the results relative to the mechanical indexes of the raw samples.

The indexes were normalised taking into account the actual thickness of the different samples.

Table 9 reports the values (mean + SD) of the mechanical indexes of the raw samples:

Table 9

values +SE) of the mechanical indexes of the raw sampli Table 10

From the statistical point of view, under the same considered factor and variable, the values followed by different letters ( a ' b,c ) are significantly different (p<0.05).

It results from the Tables 9 and 10 that both the formulation of the mixture and the technology used to produce the latter have a significant (p<0.05) effect on the aforementioned mechanical indexes.

PU resulted to be the most fragile sample, while PK10 and PS resulted to be the most rigid and the most elastic respectively. The IT technology appears to make pasta firmer and less elastic than the STD one.

The following Tables 11 and 12 illustrate the results relative to the mechanical indexes of the raw samples.

The indexes were normalised taking into account the actual thickness of the different samples. The Table 11 reports the values (mean + SD) of the mechanical indexes of the cooked samples:

Table 11

Sample Breaking load Strain Young modulus

(N) at break

(%) (MPa)

PS-STD 2.26 + 0.17 52.9 + 3.4 0.23 + 0.02

PS-IT 2.25 + 0.14 51.5 + 4.4 0.24 + 0.02

PU-STD 3.80 + 0.13 46.7 + 4.0 0.45 + 0.02

PU-IT 3.65 + 0.12 49.4 + 4.2 0.38 + 0.01

PK10-STD 2.11 + 0.12 51.9 + 4.1 0.27 + 0.02

PK10-IT 2.22 + 0.13 45.8 + 3.1 0.35 + 0.04 The Table 12 reports the results of the MANOVA performed on the mechanical indexes values of the cooked samples (mean values + SE):

Table 12

From the statistical point of view, under the same considered factor and variable, the values followed by different letters ( a ' b,c ) are significantly different (p<0.05).

It results from the Tables 11 and 12 that the formulation affects significantly (p<0.05) the mechanical parameters after the samples were cooked. The significantly stronger samples resulted those containing eggs, which showed the highest values of breaking load and Young modulus, together with a reduced strain at break. This result may be ascribed to the egg proteins which coagulate during the cooking step strengthening the protein lattice produced by the gluten. The konjac glucomannan hardens the structure of the corresponding sample (PK10) compared to that of the sample containing only durum wheat flour (PS) - which is attested by the higher values of the Young modulus - and thus makes the structure of the PK10 sample less elastic (lower values of strain at break), as already verified by the results obtained on the raw samples. The effect of the production technology resulted to be significant only on the strain at break, which slightly decreased (p<0.05) in the samples produced with IT technology.

The data from the Tables 13 - 16 express the effects of the production technology on the experimental samples containing konjac glucomannan (PK10-STD, PK10-IT, PK10-NT, PK10MM).

The Tables 13 - 16 relate to analytical results which were statistically elaborated by ANOVA. In these Tables the mean values and the corresponding standard errors (SE) are thus reported and any significant differences are highlighted.

In the following Table 13 the values (mean + SE) of humidity and water activity are reported for the various konjac flour-based samples.

Table 13

From the statistical point of view, on the same column, the values followed by different letters ( a ' b ' c ' d -) are significantly different (p<0.05). It results from the Table 13 that the different technologies used produce a slight though significant (p<0.05) influence.

In the following Table 14 the values (mean +SE) of pre-cooking thickness , post- cooking thickness and behaviour during cooking are reported:

Table 14

From the statistical point of view, on the same column, the values followed by different letters ( a ' b ' c ' d -) are significantly different (p<0.05).

It results from the Table 14 that the thickness was not affected by the technology of production.

With regard to the behaviour during cooking, the PK10-IT sample showed a better resistance during cooking, which is highlighted by the lower values of weight increase and solid residue released during cooking. The following Tables 15 and 16 respectively illustrate the results relative to the mechanical indexes of the raw and cooked samples.

The indexes were normalised taking into account the actual thickness of the different samples.

The Table 15 reports the values (mean + SD) of the mechanical indexes of the raw samples:

Table 15

From the statistical point of view, on the same column, the values followed by different letters ( a ' b ) are significantly different (p<0.05).

The Table 16 reports the values (mean + SD) of the mechanical indexes of the cooked samples:

Table 16

From the statistical point of view, on the same column, the values followed by different letters ( a ' b,c ) are significantly different (p<0.05).

It results from the Table 15 that the sample produced with ΓΓ technology is significantly (p<0.05) less elastic and harder compared to the other samples, except for the sample produced with MM technology, which showed a similar hardness. In the Table 16 the mechanical indexes of the samples of pasta after cooking are illustrated. The technology of production has significant (p<0,05) effects on all the measured parameters, although the detected differences are rather reduced. The toughest and more rigid sample is the one produced with IT technology.

In summary, the results of the above disclosed experimental tests confirm the possibility to use the method according to the invention for producing food mixtures which - despite being made with mixes of konjac flour and other gluten-free vegetable flours - have a firmness and an appearance that are significantly similar to the firmness and the appearance of the food mixtures containing gluten.

In addition to the tests carried out at the DeFENS laboratory, the Applicant carried out a further series of tests at an independent Company of research and development in material sciences (ABCS s.r.l. laboratory, Milan). In particular, rheological tests (determination of the viscosity curve) were performed on nine samples (mixtures) of food composition, made by using the method according to the invention.

The formulations of the nine samples and the percentage hydration of each sample are illustrated in the following Table 17:

Table 17

The samples 1-9 were made according to the procedure disclosed in Example 1 and thus using the Mini PTC 500 pre-kneader and turbine continuous mixer sample 1 (mixture of only durum wheat semolina) and sample 9 (mixture of only konjac flour) do not exemplify food compositions according to the invention, but were made and subjected to test for the purpose of obtaining the extreme values of a wide range of viscosity values. Once produced, the samples 1-9 were subjected to a measurement of viscosity, by using a known measurement method (rotational rheology) and a known apparatus ("Malvern Kinexus Pro+" rotational rheometer, with so called 20 mm "Parallel Plate" geometry). In particular, the shear viscosity at a shear rate of 1 sec "1 was measured. The features of the aforesaid measurement method and of the measured parameters are known to the skilled in the art persons and thus are not recalled in the following.

The results of the measurements are illustrated in the following Table 18:

Table 18

The experimental data of the Table 18 show that, by varying the formulation (percentage concentration of konjac flour; percentage concentration of non-konjac flour; percentage concentration of water) of a food composition according to the invention, it is possible to identify and quantify a corresponding variation of a measurable physical parameter, i.e. the shear viscosity.

Owing to the aforesaid parameter, it is possible to characterize correctly the food composition according to the invention, as well as the method through which the composition can be prepared. In fact, formulations of the food composition according to the invention that allow to produce a suitably homogeneous mixture correspond to shear viscosity values (determined at a shear rate of 1 sec "1 ) that are comprised in the range 5680 - 21000 Pa x s. By processing mechanically (e.g. extruding) this homogeneous mixture, a gluten-free food product (e.g. pasta) is obtained, but having a firmness and an appearance that are significantly similar to the firmness and the appearance of food products containing gluten.

From what hitherto disclosed, it is clear that, owing to the invention, the previously highlighted drawbacks of the prior art are efficiently overcome.

In fact, a method is made available that allows to make food mixtures based on konjac flour, through which it is possible to produce food products, which, after cooking, are provided with firmness and palatability acceptable to the consumer. Moreover, the method according to the invention allows to make konjac flour-based food mixtures that are suitably stable and homogeneous without need to use additives, such as calcium hydroxide, and/or gluten-originating flours, with a consequent clear advantage for the consumers of the food products obtained from the aforesaid mixtures.

What was disclosed was provided as an example of the innovative characteristics of the present invention. Variants and/or additions to what above disclosed are therefore possible.