OA20731A - Preparation and use of a tiger nut hydrolyzate for a drink. - Google Patents

Abstract

The subject matter of the present invention relates generally to a tiger nut-based beverage which involves the manufacture of various tiger nut-related constituents, including a tiger nut hydrolysate, and a whole tiger nut flour.

Description

PREPARATION AND USE OF A HYDROLYZATE OF TITANIUM FOR A DRINK

The object of the present invention relates generally to a drink based on tiger nut which involves the manufacture of various constituents related to tiger nut, including a hydrolyzate of tiger nut, and a complete flour of tiger nut.

INTRODUCTION

Tiger nuts (Cyperus esculentus) is an edible perennial rhizomatous herbaceous plant of the Cyperaceae family. This plant is known by various names, such as tiger nut, ground acorn, sweet pea, ground almond, sultan tiger nut, etc. It is found in the Mediterranean basin (North, West and Central Africa, Southern Europe, Near East). Nutsedge tubers have a slightly sweet, nutty taste, which explains its use in food. In particular, Tigernut is used to prepare a sweet refreshing drink known as “horchata de chufa” in Spain (Tigernut milk), but also found in other regions under other names.

However, tiger nut tubers are quite hard and have different layers that are difficult to separate from each other: epidermis, cuticle, sclerenchyma, collenchyma, seated parenchyma generating rootlets and rootlets that extend from the center of the tuber outwards (G. Lorougnon "Morphological and Biological Study of Two Varieties of Cyperus Esculentus Linn. (Sedges)"; Cah. Orstom, Ser. BioL, No. 10 - December 1969). The outer layers (epidermis, cuticle, sclerenchyma and at least part of the collenchyma) form a tissue rich in lignified fibers (thickened and brown - brown in color). Thus, the tuber is rich in vegetable fibers which are not desired for food use, and which are extremely hard. Traditionally, tigernuts are usually soaked in water before they can be eaten, making them much more flexible and of better texture.

For an industrial application, ES 1156258 discloses a device for the mechanical peeling of tigernut tubers.

ES 2364740 also discloses a process for peeling nutsedge using concentrated sulfuric acid and water under pressure.

On the other hand, it should be noted that these processes are difficult to implement, and the final yield is limited (partial use of tigernut tubers: heart vs. outer woody layers).

It is therefore clear that this peeling/husking step is a limiting step in the process for manufacturing products derived from tiger nuts.

For horchata, the stripped nuts are then soaked, drained and ground with water. The juice is extracted. In this way a thick and milky liquid mainly rich in fats and starch is obtained. This juice is then sweetened, mixed. In order to increase the shelf life of the product and to improve its transportability, the juice can be concentrated. The drink is then reconstituted by the user who dilutes it in water (typically one part concentrate and 3 parts cold water). On the other hand, it is obvious that the bacteriological control of this juice is difficult under these conditions. Thus, the diluted juice must be refrigerated while the concentrate can be stored at room temperature like a syrup, then diluted at the time of consumption. The addition of preservatives is not desirable (in order to limit production costs and/or taste alterations, etc.). In addition, it would be desirable to increase the nutritional value of the drink (which is relatively low at present) without altering its taste values in order to be able to offer a range of products allowing a diet adapted to the different scenarios ( especially in food aid). There is no mention in the art a priori of such an object.

The present invention makes it possible to overcome the problems mentioned above. Indeed, the applicant has developed a process allowing the outer layer of tigernut tubers to be used by producing a wholemeal flour, which is therefore enriched with fibre. On the other hand, the applicant has developed a process for the hydrolysis of the starch contained in the extracts of tiger nut. This hydrolysis was made possible thanks to a preliminary gelatinization of the starch which was then hydrolyzed. This process thus allows an improvement in nutritional values, production yield, bacteriological control while facilitating the use and implementation of tiger nut products.

SUMMARY OF THE INVENTION

The present invention relates to a process for the preparation of a tiger nut hydrolyzate comprising the following steps:

(a) step of dissolving or suspending a tiger nut extract at a temperature between 5 and 55°C, preferably between 10 and 25°C, in a solvent comprising water, (b) step of gelatinization by temperature increase, preferably greater than SO°C, (c) hydrolysis of the product obtained in step (b) by the action of at least one amylase, (d) recovery of the tiger nut hydrolyzate thus obtained .

The present invention thus relates to a tiger nut hydrolyzate characterized in that said hydrolyzate comprises less than 25% by mass of starch dry matter relative to the total dry matter of the hydrolyzate.

In addition, the present invention relates to a method for manufacturing a wholemeal tigernut tuber flour, characterized in that said method comprises the following steps:

(w) a step of bringing the tigernut tubers into contact with a solvent comprising water at a pH of less than 7, preferably less than 6;

(x) an optional step of removing all or part of the solvent from step (w), (y) a step of grinding the tubers obtained following step (x) or (z) characterized in that the product ground has an average particle size of less than 500 μm in diameter, preferably less than 100 μm in diameter, and (z) a stage for recovering the complete flour, optionally in suspension.

Thus, an object of the present invention relates to a complete flour of tiger nut tuber characterized by an average size of flour particles of less than 500 μm in diameter, preferably less than 100 μm in diameter.

In addition, the present invention relates to a tiger nut drink with a starch dry matter content of less than 10% relative to the total dry matter of the drink, preferably less than 5%.

The present invention therefore also relates to a method for manufacturing a drink comprising a tiger nut hydrolyzate, characterized in that it comprises the following steps:

(m) a step for increasing the sweetness of a tiger nut hydrolyzate by adding at least one sweetener, (n) an optional step for refining the mixture obtained in step (m) comprising homogenization involving if necessary, grinding, high pressure homogenization and/or degassing of the product obtained after step (m), and (o) a beverage recovery step.

More generally, the object of the present invention relates to the use of the tiger nut hydrolyzate as described herein for the manufacture of a tiger nut drink.

DEFINITIONS "Nutsedge hydrolyzate"

A hydrolyzate is a product resulting from a hydrolysis reaction of a substrate, here tiger nut. A hydrolysis is typically a decomposition of a body by fixation of H ⁺ and OH ions coming from the dissociation of water. Thus, the presence of water is necessary for the hydrolysis to take place. The substrate can react in the presence of pure water or in a mixture of water and one or more other solvents.

“Tigernut sedge/extract of tiger nut”

In the context of the present invention, the term “sedge” is equivalent to a “sedge extract”, that is to say the isolation of part of the tiger nut plant from the rest of the plant. Of course, in the context of this, it is an edible extract of the tiger nut. Typically it is the tubers that are isolated from the nutsedge, and possibly the peeled tubers.

“Wholemeal flour / fine flour”

A wholemeal flour is conventionally a flour containing a large part of the elements of the grain. In the context of the present invention, a wholemeal flour therefore relates to a flour derived from most of the elements of the tigernut tubers, in particular the fibrous parts of these tubers. By contrast, fine flour relates to flour sifted by the dry process, that is to say by exclusion of the external fibrous part, which is equivalent to peeling the tubers before grinding them.

“Solvent comprising water”

In the context of the present invention, any type of organic or inorganic solvent can be used, more precisely food “solvents”. The term “solvent” is used by abuse of language to designate a liquid (most of the mixtures obtained at the start of the processes according to the present invention are rather suspensions). Water is the preferred solvent according to the present invention. Oleaginous solvents could also be used in the context of the present invention.

"Gelatinization"

Gelatinization is the process which, by heating (from about 70-80°C) in an aqueous medium, allows the starch to hydrate and swell. Part of the amylose then the amylopectin contained in the starch then passes into a colloidal solution (starching). This dissolving facilitates the hydrolysis of the starch. In addition, the gelatinization temperature can be increased to sterilize the assembly. To guarantee complete and rapid gelatinization (less than 15 minutes), the gelatinization temperature is greater than 90° C., 100° C., or 110° C., or even greater than 120° C., possibly under pressure.

“Amylase”

Amylase is an enzyme that catalyzes the hydrolysis of starch into its sugars. In the context of the present invention, a UHT, that is to say very heat-resistant, amylase can be used.

" Recovery "

The term "recovery" in the context of processes according to the present invention relates to all the usual techniques for collecting, extracting and purifying the products resulting from the process.

"Sweetness"

"Sweetness" is the perception of the sweet taste using ordinary sugar as a benchmark (ie sucrose, caster sugar, also called sucrose), having as an index one (1.0). In the context of the present invention, the compounds carrying this sweetening activity are sweeteners, which may be natural or synthetic. The following table gives examples of the sweetness of some of these sweeteners that can be used in the context of the present invention (more particularly the drink):

Sweetener Sweetness Sweetener Sweetness Regular sugar 1 Inverted sugar 14-1.2 Saccharin 400-500 Cyclamate 30-40 Aspartame 100-200 Palantinosis 0.4-0.5 Xylitol 1.0 Sorbitol 0.4-0.5 moneline 2500 Mannitol 0.4-0.6 Maltitol 0.7-0.9 Isomalt 0.4-0.5 Neohesperidin 1000 Acesulfame 200

"Homogenization"

A homogenization step according to the present invention can be carried out by the usual methods of the art, making it possible to mix, more particularly on an industrial scale, foodstuffs which can be liquid, pasty, or even in the form of a suspension. However, in the context of the present invention, the Applicant has used in the beverage preparation process, a high pressure homogenizer (300 bars, plus or minus 10%), which is not commonly used in the context of suspensions, but rather for liquids. Thus the optional step (n) of refining can be carried out by using a high pressure homogenizer, characterized in that the pressure applied is between 50 and 1000 bars, preferentially between 100 and 500 bars, more preferentially between 150 and 450 bars, even more preferably between 200 and 400 bars, or even between 250 and 450 bars. Most preferably, in the process for preparing the drink, the optional step (n) of refining can be carried out by using a high-pressure homogenizer, characterized in that the pressure applied is 300 bars, plus or minus 10%. The high-pressure homogenizer makes it possible to reduce the size of the particles and to reduce the size of the fat globules. This stage of homogenization of the different phases (solid, fatty, aqueous) allows an excellent final organoleptic rendering.

“Refining”

The purpose of the refining step according to the present invention is to make the product resulting from the hydrolysis of tiger nuts more acceptable in organoleptic terms. Typically, this refining step includes grinding the hydrolyzate, possibly with filtration or a settling step. The refining step may further comprise homogenization under pressure as defined above. Advantageously, the refining stage is reinforced (one or more grindings, one or more filtrations and/or one or more decantations) when wholemeal tigernut tuber flour is used in the hydrolysis process.

Nevertheless, in a preferred embodiment of the present invention, the refining step essentially consists in reducing the size of the particles in suspension in order to reduce, on the one hand, the grainy/fibrous perception in the mouth and, on the other hand, the speed settling after dilution and/or phase separation.

DETAILED DESCRIPTION

The object of the present invention relates more particularly to the process for preparing a tiger nut hydrolyzate as described above, characterized in that the tiger nut extract according to step (a) is a tiger nut flour, more particularly tigernut tuber flour.

Advantageously, the process for preparing a tiger nut hydrolyzate as described above can be characterized in that the tiger nut tuber flour is a fine flour or a wholemeal flour whose average size of flour particles is less to 500 μm in diameter, preferably less than 100 μm in diameter.

The process according to the present invention can therefore be applied to tiger nut flour, whether wholemeal or fine, or a mixture of the two. Advantageously, the flour used, or the product resulting from their mixtures, has a particle size of less than 500pm, preferably less than 450pm, more preferably less than 400pm, even more preferably less than 350μιη or even less than 300pm.

Thus, the flour (or mixtures thereof) used has a particle size of less than 250 μm, preferably less than 200 μm, more preferably less than 150, even more preferably less than 100 μm.

Preferably, the flour (or mixtures thereof) used has a particle size of between 0.1pm and 600pm, preferably between 0.2pm and 500pm, more preferably between 0.3 and 450μιη, more preferably between 0 ,4 and 400pm.

The particle size is measured by the usual techniques in the art, preferably in the liquid phase, preferably in the aqueous phase by laser diffraction.

In addition, the flour (or their mixtures with fine and/or wholemeal flours) used has a Dv(50) of less than 200 μm, preferably less than 150 μm, more preferably less than 100 μm, even more preferably less than 90 μm, or even less than 80 μm.

The Dv 50 is a common measure in the art and represents the median size of all the particles of a measured sample. For example, a Dv50 of 90pm means that 50% of the particles in the sample analyzed are larger than 90pm and 50% smaller than 90pm.

In addition, the process for preparing a tiger nut hydrolyzate as described above can be characterized in that step (b) of gelatinization is carried out at a temperature greater than or equal to 70° C., or even 80° C. optionally under pressure, preferably greater than or equal to 90° C. optionally under pressure, more preferably greater than or equal to 100° C. optionally under pressure, even more preferably greater than or equal to 110° C. under pressure.

Preferably, the method for preparing a tiger nut hydrolyzate as described above can be characterized in that said method comprises a step (bl) of checking or correcting the pH of the solution or suspension obtained after step ( b) at a pH of between 4 and 8, preferably between 5 and 7, before the hydrolysis of step (c).

Advantageously, the method for preparing a tiger nut hydrolyzate as described above can be characterized in that said method comprises a step (bl) of checking or correcting the pH of the solution or suspension obtained after the step (b) at a pH of between 4.5 and 8, preferably between 5 and 7.5, more preferably between 5.5 and 6.5, even more preferably at around 6, before the hydrolysis of step ( vs). The means for measuring the pH are those usually used in the art. The correction of the pH, if necessary, can be made by the controlled addition of any mineral or organic acid, or mineral or organic base, preferably food. For example, the acids that can be used are lactic acid, malic acid, citric acid, tartaric acid, sulfuric acid, hydrochloric acid, phosphoric acid, fumaric acid, l adipic acid and/or mixtures thereof. For example, the bases which can be used are soda, potassium hydroxide, ammonia, sodium or potassium bicarbonate, an ammonium salt, or the alkaline salts of the acids mentioned above, or their mixtures.

At the same time, the process for preparing a tiger nut hydrolyzate as described above can be characterized in that said process comprises a step (cl) after step (c) of concentration of the hydrolyzate, preferably by evaporation. All concentration techniques are applicable: for example the use of permeable exchange membranes, lyophilization, or evaporation. Preferably, the concentration technique is evaporation, possibly with lowering of the pressure, or even under vacuum, the objective possibly being to lower the temperature in order to preserve the taste properties of the product.

Another object of the present invention therefore relates to a tiger nut hydrolyzate as described above, characterized in that the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 15% relative to the dry matter. total hydrolyzate, preferably less than 14%, more preferably less than 13%, even more preferably less than 12%, more preferably less than 11%, or even less than 10.5%. Advantageously, the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 10% relative to the total dry matter of the hydrolyzate, preferably less than 9%, more preferably less than 8%, even more preferably less than 7%, more preferably less than 6%, or even less than 5%. More advantageously, the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 4% relative to the total dry matter of the hydrolyzate, preferably less than 3%, more preferably less than 2% , even more preferably less than 1.5%, more preferably less than 1%, or even less than 0.5%. Most preferably, the hydrolyzate is free of natural starch.

The tiger nut hydrolyzate as described above can be characterized in that the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 15% relative to the total dry matter of the flour. tiger nuts used in the process, preferably less than 14%, more preferably less than 13%, even more preferably less than 12%, more preferably less than 11%, or even less than 11.5%. Advantageously, the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 10% relative to the total dry matter of the hydrolyzate, preferably less than 9%, more preferably less than 8%, even more preferably less than 7%, more preferably less than 6%, or even less than 5%. More advantageously, the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 4% relative to the dry matter of the tiger nut flour used in the process, preferably less than 3%, more preferably less than 2%, even more preferably less than 1.5%, more preferably less than 1%, or even less than 0.5%.

By “natural starch”, it is understood in the context of the present invention, tiger nut starch. The usual analysis techniques for determining the starch content are applicable in species (chromatographic techniques, mass spectrometry, possibly coupled, NMR, etc.). Preferably, a simple iodine test makes it possible to verify the absence or reduction (by assay) of starch.

Preferably, the hydrolyzate according to the present invention can be characterized in that it comprises less than 5% by mass of dry matter of amylase relative to the total dry matter, preferably less than 4%, preferably less than 3 %, more preferably less than 2%, even more preferably less than 1%, more preferably less than 0.5%, even less than 0.1% by mass of dry matter of amylase relative to the total dry matter .

Another object according to the present invention therefore relates to a process for the manufacture of a drink comprising a tiger nut hydrolyzate as described above, characterized in that step (w) is carried out in water with an acid or a base. organic or mineral as a pH corrector. The same techniques, acids and/or bases (organic or mineral) as mentioned above for adjusting the pH in step (bl) can be used here, namely: lactic acid, malic acid , citric acid, tartaric acid, sulfuric acid, hydrochloric acid, phosphoric acid, fumaric acid, adipic acid or mixtures thereof. Advantageously, the method for preparing a tiger nut hydrolyzate as described above can be characterized in that said method comprises a step (bl) of checking or correcting the pH of the solution or suspension obtained after the step (b) at a pH of between 4.5 and 9, preferably between 5 and 8, more preferably between 5.5 and 7.5, even more preferably between 6 and 7, before the hydrolysis of step (c ).

Thus the beverage according to the present invention may comprise a tiger nut hydrolyzate as described herein.

In addition, the drink according to the present invention can be characterized in that said drink has been enriched with at least one sweetener, such as aspartame, stevioside, glucose, sucrose, fructose, ammonium glycyrrhizinate, invert sugar, saccharin, cyclamate, palatinose, xylitol, acesulfame, sorbitol, monellin, mannitol, neohesperidin, maltitol, isomalt as well as their mixtures. In a particular embodiment, the beverage according to the invention has been enriched with at least one sweetener, as defined above, on a dilution support such as maltodextrin. In a particular embodiment, the drink according to the invention has been enriched with a single sweetener, preferably chosen from the list consisting of aspartame, stevioside, glucose, sucrose, fructose, ammonium glycyrrhizinate, invert sugar, saccharin, cyclamate, palatinose, xylitol, acesulfame, sorbitol, monellin, mannitol, neohesperidin, maltitol and isomalt. This implies that the process for the manufacture of a drink comprising a tiger nut hydrolyzate according to the present invention can be characterized in that at least one sweetener of step (m) is chosen from the list consisting of aspartame, stevioside, glucose, sucrose, fructose, ammonium glycyrrhizinate, invert sugar, saccharin, cyclamate, palantinose, xylitol, acesulfame, sorbitol, monellin, mannitol, neohesperidin, maltitol, isomalt and mixtures thereof.

The amounts of sweetener(s), possibly in the presence of their dilution carrier such as maltodextrin, may vary in the final drink depending on the taste and desired sweetness. The amounts may be between 0 and 90% by mass of dry matter of sweetener relative to the total dry matter of the drink, advantageously between 10 and 80%, more advantageously between 20 and 75%, even more advantageously between 30 and 70%, or between 50 and 65%. Advantageously, its quantities of sugars relate to a 1:1 mixture by mass (more or less 10% by mass relative to each other) of caster sugar and invert sugar syrup at 75% dry extract.

The drink according to the present invention can further be characterized in that it is a concentrated drink.

By "concentrated drink" according to the present invention, it is understood that it can be diluted before consumption. Preferably, the dilution is greater than 1 dose volume of concentrated tiger nut drink for 0.5 dose volume of water: i.e. “greater than 1: 0.5 V/V”. More preferably the dilution is greater than 1:1 V/V, even more preferably the dilution is greater than 1:1.5 V/V, more preferably the dilution is greater than 1:2 V/V, or even greater than 1: 2.5V/V.

Advantageously, the dilution is less than 1:20 V/V, more preferably the dilution is less than 1:15 V/V, even more preferably the dilution is less than 1:10 V/V, more preferably the dilution is less than 1: 8 V/V, or even less than 1: 5 V/V or 1: 4 V/V. Preferably, the dilution is 1:3 V/V (plus or minus 10%).

Thus, advantageously, the dilution is between 1: 0.5 V/V and 1: 20 V/V, more preferably the dilution is between 1: 1 V/V and 1: 15 V/V, even more preferably the dilution is between 1:10 V/V, more preferably the dilution is between 1:1.5 V/V and 1:8 V/V, or even between 1:2 V/V and 1: 5V/V. Preferably, the dilution is between 1:3 V/V and 1:4 V/V.

Of course, the drink according to the invention needs to be packaged. For this, step (o) of recovery of the process for manufacturing a drink comprising a tiger nut hydrolyzate according to the present invention may comprise or consist of packaging. This packaging can be done at a temperature above 56°C in order to be at a pasteurization temperature. Preferably, the conditioning temperature is greater than 60°C, more preferably greater than 70°C, even more preferably greater than 80°C, or even greater than 90°C. In a particular embodiment, the packaging is done at the sterilization temperature, i.e. close to 100°C.

Alternatively, the packaging can be done in ultra-clean conditions after a sterilization schedule of the high temperature - short time (UHT) type and cooling of the product, as usually carried out in the art.

FIGURES

Figure 1: This is a representation of the different stages of the hydrolysis process, on the one hand, and beverage manufacturing on the other. A process for making invert sugar from caster sugar is also illustrated.

Figure 2A /2B: these are graphical representations of the soaking water comparison results from Table 5.

Figure 3: This is a representation of the particle size distribution (i.e. distribution of particle sizes) of the wholemeal flour according to the invention obtained by wet laser granulometry (see Table 6).

EXAMPLES

Conventional materials were used in these examples. In particular, the sterilizations were carried out with a Stephan-Proxes® brand UMSK E24 sterilizer (useful capacity 18 kg). Sterilizations for higher loads were carried out in “batches”.

A mixing tank (400L useful) of the Fryma-Proxes® brand was used.

The transfer was carried out on a progressive cavity pump.

A BOSS® type MG2 100L/h homogenizer, Nova brand dosing machine and a Schwarze® brand vertical bagging machine.

The grinding of the refining stage was carried out with a 1700-30CV Comitrol, Urschel® grinder (190 blades cutting head inclined at 2°).

Example L illustration of the state of the art: illustration of the artisanal production process of horchata de chuffa.

Ingredients :

• Dehydrated dried sweet tigernut tubers (called CHORON) • water

Step 1: cleaning the peas

Soak the peas for 12 hours (helps wash them / remove residual soil from the peas)

Remove from water

Rub the peas with each other, with the flat of the hand to wash them

Rinse the peas again

Spread the peas to sort them, and remove the seeds that are not good. The good seed turns yellow, the bad one turns partially black, or the inside is not white but a little yellow.

The bad ones are physically damaged (much like the degradation of corn) Rinse after sorting. The water should be clear after rinsing, it is a sign of cleanliness.

Step 2: transformation of the peas into pea paste

Bring the seeds to the mill (put ice on them to crush them because the seeds must not heat up otherwise they will become sticky and can no longer be used)

After passing through the mill, a paste is obtained [i.e. not a flour]

In the bucket that collects the dough, put ice

This paste is heavy, non-elastic, white/yellow in color, non-homogeneous, it is more of an agglomerate.

Step 3: transformation of the paste into a “drink”

Add water to the batter (in addition to the ice from the bucket), and stir.

Place in a cloth and squeeze to remove the juice.

Add salt to the juice obtained, sugar for those who wish, and possibly vanilla or vanilla sugar. (For 4.5 liters = 1.5 kilos of sugar)

Maintain an ice cold temperature throughout the process.

Can be kept for a maximum of one week in the refrigerator, can also be stored longer in the freezer.

Yield :

About 3 kilos of peas for 4.5 L of drink (It depends on the desired viscosity).

When it degrades, the product becomes sticky, viscous and the foam disappears when shaken.

Example 2: soaking tests

Comparative tests were carried out between tigernut tubers soaked in an acid medium and soaked in a neutral medium.

Table 1: Qualitative interest of acid soaking compared to alkaline soaking (addition of potash)

Samples (numbers) Witness (basic) 1 2 3 4 Seeds (kg) 1 1 1 1 1 Water (L) 3 3 3 3 3 Acid H3PO4 75% (g) Φ 5 7 9 12 initial pH 7.6 2.6 2.5 2.3 2.2 Final pH (6011, 35°C) water 5.4 4.4 3.7 3.3 2.9 suspension (1kg seed+300ml crushed water) 6.3 6.2 6 5.8 5.8 end of soaking smell unacceptable beer beer beer beer

These results show the interest of soaking in an acid medium. Soaking in an alkaline medium does not seem to make it possible to obtain tiger nut tubers that can be used later. The basic pH causes a saponification of the fats present then a degradation of the product with favorable conditions for the undesirable development of the microbial flora. In contrast, the acidic conditions make it possible to regulate the flora present and to obtain a controlled fermentation with a typical aroma of fermentation by yeasts.

Table 2: effect on seed hydration and Brix

Sample Measures T°C ES seed ¹ pH Brix Mass of 50 seeds Cgr) Witness to TO soaking water El 17°C(water) 18°C (hanging) 98% (powder) 8(water) 6.5 (hanging) 0 Grinding supernatant ² 12.1 Acidified grinding E4 31.8 4 Neutral soak T 5h soaking water El 30 75 7.3 0 21 T l Oh soaking water E2 31.8 67.9 7 0 24 T24h soaking water E3 31 64.6 5.4 0,! 30 Neutral soak 34h soaking water El 32.4 68.1 4.9 0.3 29 Grinding supernatant ² 8.5 Acidified grinding E4 22.3 Av 6.5 apr4 Neutral soaking 48h soaking water El 33.3 50 4.9 0.5 32 Grinding supernatant ² 7.6 Acidified grinding E4 27.26 4 Acid soak T5h soaking water El 30 75.9 Av 5.5 apr4 21 T l Oh soaking water E2 34.6 63 Av 4.7 after 4 24 T24h soaking water E3 34.4 59.2 Av 4.5 after 4 30 Neutral soak 34h soaking water El 31.1 55.6 4 0.6 29

Grinding supernatant ² 8.2 Acidified grinding E4 25.2 Av 6.4 apr4 Neutral soaking 48h soaking water El 31.6 42.5 4.1 1.5 34 Grinding supernatant ² 7.2 Acidified grinding E4 25.9 Av 6.2 aft 4

¹ Seed dry extract measured at thermo-balanced Îa ² Filtered grinding supernatant / 0.2 μηι

In view of the results, and in particular the measurements of dry extracts, it would seem that acid soaking accelerates seed hydration compared to neutral soaking and tends to reduce the Brix degree of the supernatant.

Table 3: Content of free sugars

Sample Measure Sugars (g/lOOg) glucose fructose sucrose lactose maltose Total sugars Witness to TO Precipitation supernatant 1/1 (m/m) EtOH 95% E3 <0.2 <0.2 3.7 <0.2 <0.2 3.7 Neutral soak Neutral soak 34h Precipitation supernatant 1/1 (m/m) EtOH 95% E2 <0.2 <0.2 2.2 <0.2 <0.2 2.2 Neutral soaking 48 h Precipitation supernatant 1/1 (m/m) EtOH 95% E2 <0.2 <0.2 2.5 <0.2 <0.2 2.5 Acid soak Soaking neutral 34h Precipitation supernatant i/1 (m/m) EtOH 95% E2 <0.2 <0.2 2.4 <0.2 <0.2 2.4 Neutral soaking 48 h Precipitation supernatant 1/1 (m/m) EtOH 95% E2 <0.2 <0.2 2.1 <0.2 <0.2 2.1

it would seem that soaking tends to reduce the content of crushed seeds in soluble sugars; there is probably a diffusion of sugars from the seeds to the soaking water.

Table 4: microbiological comparison

Sample Measure Total flora (CTL/g gross) Yeasts (CFU/g gross) Molds (CFU/graw) Enterobacteriaceae (CFU/graw)

Witness to TO Acidified grinding E4 1E+05 8E+01 <10 <10 Neutral soak Neutral soak 34h Acidified grinding E4 4E+05 3E+02 2E+03 >1.5E+04 Neutral dip 48b Acidified grinding E4 >3E+O6 IE+03 1E+03 >1.5E+04 Acid soak Neutral soak 34h Acidified grinding E4 9E+04 <10 5E+02 >1.5E+04 Neutral soaking 48h Acidified grinding E4 IE+06 >1.5E+04 < 10 IE+03

The acid soaking of the seeds for 4 hours at 30-35°C makes it possible to direct the flora towards the production of yeasts, which makes it possible to control the microbial flora and avoid the development of pathogenic flora.

Table 5: Detailed comparison of soaking waters

Time (hours) Temperature (°C) ES seed (%) pH Brix Neutral soak (unbuffered water) 0 18.2 98 8 0 5 30 75 7.3 0 10 31.8 67.9 7, 0 24 31 64.6 5.4 0.1 34 32.4 68.1 4.9 0.3 48 33.3 50 4.9 0.5 Acid soak (water) 0 18.2 98 8 0 0.1 18.2 98 4 0 5 30 75.9 5.5 0 5.1 30 75.9 4 0 10 34.6 63 4.7 0 10.1 34.6 63 4 0 24 34.4 59.2 4.54 0 24.1 34.4 59.2 4 0 34 31.1 55.6 4.04 0.65 48 31.6 42.5 4.07 1.5

All of these soaking water comparison results are reported on the graphs of Figures 2A and 2B.

This detailed comparative study seems to confirm that acid soaking accelerates seed hydration compared to neutral soaking and that acid soaking favors (with perhaps a delayed effect) the diffusion of sugar from seeds to the soaking water.

Example 3: Example of obtaining wholemeal tigernut tuber flour

Several wet grinding tests were carried out on crown mills of the MICRONUT MC 15 type (STEPHAN-PROXES). The raw material is a suspension of tigernut tubers in water, having been soaked for 24 hours (in an acid solution as mentioned above). The results have been obtained on these shredders when the tigernut tubers are subjected to at least two successive shreddings, the first shredding is carried out with a 0.35 crown closed with a 12-tooth cutting head, then the second shredding with a crown 0.35 open, with a 19 tooth cutting head. A possible recycling of the seed mixture with water from the passerby can be carried out on a grinder with a 0.35 closed crown, with a cutting head with 19 teeth.

Of course, other grinding techniques are entirely applicable in this case, the key stage of the process being the acid treatment of the tigernut tubers before grinding.

Example 4: Particle size study of a wholemeal flour according to the invention

Operating conditions:

Device used:

Mastersizer 3000, Malvem

HydroMV Module Accessory

Operational Parameters:

Dispersant: Water

Stirring speed; 2800

Measurement time: 6 sec.

Table 6: results of particle size measurements of a flour according to the invention:

Size (μm) % Passing Volume Size (μΜ) % Passing Volume 0.460 0.00 40.1 41.01 1.13 4.53 51.8 53.03 5.21 13.67 111 87.92

11.2 17.31 211 97.51 21.2 23.58 400 100

Dv (50): 48.7μιη

Figure 3 is a graphical representation of the grain size obtained in Table 6.

Table 7: results of particle size measurements of a second flour according to the invention:

Size (μηι) % Passing Volume Size (gm) % Passing Volume 0.460 0.00 40.1 30.09 1.13 3.03 51.8 38.00 5.21 10.81 111 75.15 11.2 14.23 211 97.77 21.2 19.35 400 100

Dv (50): 68.7 pm

Example 5: hydrolysis test dependent on particle size

The hydrolysis (of the flour) of the tiger nut tuber is first carried out by suspending the flour in water (e.g. 80 kg of dry extract for a suspension of 234 kg), then subjected to a gelatinization at a temperature above 100°C for 5 min. A correction of the pH to 6 is carried out if necessary. Then amylase (e.g. UHT) is added and the hydrolysis is done at 80°C for 90min. If necessary, this hydrolyzate is concentrated and the amylase inhibited. The hydrolyzate can be used to manufacture the drink according to the invention.

The impact of the quality of the grinding on the efficiency of the enzymatic hydrolysis was confirmed: after soaking the seeds for 14 hours at acid pH (2.2) a single grinding was carried out on MICRONUT MC 15 with a single head cutting edge with 12 teeth and a grinding crown with 0.35 mm opening (closed type). After 1h30 of hydrolysis, the positive iodine test indicates that there is still some starch in the suspension, whereas double grinding (as mentioned in Example 3) with this pennet grinder obtain complete hydrolysis of the starch after 30 minutes.

Example 6: Impact of the refining of the finished product (Urschel grinder) on formulas prepared from sifted flours at different cut-off thresholds

Refining consists of grinding the formulas (prepared sweetened hydrolyzate).

Table 8: particle size results following refining

Sample 1 2 3 4

Refining No Yes No Yes No Yes No Yes raw material physical sieving threshold (microns) 400 400 500 500 1000 1000 1000 1000 Dv (95) by laser granulometry on the finished product (microns) 400 144 428 161 748 266 738 410

Refining makes it possible to reduce the size of the fibers in the final preparation, which allows a better organoleptic rendering of the product. In fact, the fibers do not settle as quickly and the final product has a more homogeneous and pleasant texture in the mouth.

An evaluation of the yield stress of the finished product (threshold stress of the order of 0.01 Pa) > fluid product showed that the viscosity properties of the product are quite acceptable.

Example 7: preparation of a packaged tiger nut juice:

A tiger nut juice is prepared according to the method of the invention as illustrated in Figure 1.

The hydrolysis (of the flour) of the tiger nut tuber is first carried out by suspending the flour in water (e.g. 80 kg of dry extract for a suspension of 234 kg), then subjected to a gelatinization at a temperature above 100°C for 5 min. A correction of the pH to 6 is carried out if necessary. Then 447 g of UHT amylase and 447 g of A30 amylase are added and the hydrolysis is carried out at 80°C for 90 min. The hydrolyzate obtained is concentrated to 62% dry extract. 129.8 g of concentrated juice are obtained. Add 167.5 kg of sugar (caster sugar/invert sugar 50/50) while mixing at 30°C.

The sugar juice is heated to 60°C and ground. After degassing and homogenization, it is packaged in batches of 50g.

Claims (19)

1. Process for the preparation of a tiger nut hydrolyzate comprising the following steps: (a) step of dissolving or suspending a tiger nut extract at a temperature between 5 and 55°C, preferably between 10 and 25°C, in a solvent comprising water, (b) step of gelatinization by temperature increase, preferably greater than 70°C, (c) hydrolysis of the product obtained in step (b) by the action of at least one amylase, (d) recovery of the tiger nut hydrolyzate thus obtained . 2. Method according to claim 1 characterized in that the tigernut extract according to step (a) is a tigernut flour, more particularly a tigernut tuber flour. 3. Process according to claim 2, characterized in that the tigernut tuber flour is a fine flour or a wholemeal flour, the average flour particle size of which is less than 500 μm in diameter, preferably less than 1 00 μm in diameter. 4. Method according to any one of the preceding claims, characterized in that step (b) of gelatinization is carried out at a temperature greater than or equal to 100°C under pressure, preferably greater than or equal to 110°C under pressure. 5. Method according to any one of the preceding claims, characterized in that said method comprises a step (bl) of checking or correcting the pH of the solution or suspension obtained after step (b) to a pH of between 4 and 8, preferably between 5 and 7, before the hydrolysis of step (c). 6. Method according to any one of the preceding claims, characterized in that said method comprises a step (cl) after step (c) of concentrating the hydrolyzate, preferably by evaporation. 7. Tiger nut hydrolyzate characterized in that the said hydrolyzate comprises less than 25% by mass of starch dry matter relative to the total dry matter of the hydrolyzate. 8. Hydrolyzate according to claim 7, characterized in that the percentage by mass of dry matter of the starch included in the hydrolyzate is less than 15% relative to the total dry matter of the hydrolyzate, preferably less than 10%. 9. Hydrolyzate according to claim 7 or 8 characterized in that it comprises less than 5% preferably less than 2% by mass of dry matter of amylase relative to the total dry matter. 10. A process for manufacturing a complete tigernut tuber flour, characterized in that said process comprises the following steps: (w) a step of bringing the tigernut tubers into contact with a solvent comprising water at a pH of less than 7, preferably less than 6; (x) an optional step of removing all or part of the solvent from step (w), (y) a step of grinding the tubers obtained following step (x) or (z) characterized in that the product ground has an average particle size of less than 500 μm in diameter, preferably less than 100 μm in diameter, and (z) a step for recovering the complete flour, optionally in suspension. 11. Method according to claim 10, characterized in that step (w) is carried out in water with at least one organic acid and/or dietary mineral such as citric acid, lactic acid, or alternatively phosphoric acid as pH corrector. 12. Whole nutsedge tuber flour characterized by an average flour particle size of less than 500 μm in diameter, preferably less than 100 μm in diameter. 13. Nutgrass drink with a mass content of starch solids less than 10% relative to the total dry matter of the beverage, preferably less than 5%. 14. Drink comprising a tiger nut hydrolyzate according to any one of claims 7 to 9. 15. Drink according to claim 13 or 14 characterized in that said drink has been enriched with at least one sweetener, such as aspartame, stevioside, glucose, sucrose, fructose, ammonium glycyrrhizinate, sugar invert, saccharin, cyclamate, palatinose, xylitol, acesulfame, sorbitol, monellin, mannitol, neohesperidin, maltitol, isomalt and mixtures thereof. 16. Drink according to any one of claims 13 to 15 characterized in that it is a concentrated drink. 17. Process for manufacturing a drink comprising a tiger nut hydrolyzate, characterized in that it comprises the following steps: (m) a step for increasing the sweetness of a tiger nut hydrolyzate by adding at least one sweetener, (n) an optional step for refining the mixture obtained in step (m) comprising homogenization involving if necessary, grinding, high pressure homogenization and/or degassing of the product obtained after step (m), and (o) a beverage recovery step. 18. Process according to claim 17, characterized in that at least one sweetener of step (m) is chosen from the list consisting of aspartame, stevioside, glucose, sucrose, fructose, glycyrrhizinate of ammonium, invert sugar, saccharin, cyclamate, palatinose, xylitol, acesulfame, sorbitol, monellin, mannitol, neohesperidin, maltitol, isomalt and mixtures thereof. 19. Process according to claim 17 or 18, characterized in that step (o) consists of conditioning, preferably at a temperature above 56°C.