Sugar production process from beets

Abstract

Process for the production of sugar from beets. Process for the production of sugar from beets (B), the process comprising the steps in which at least one batch of beets is supplied; at least one pressing step of the beets is carried out to extract a sugar juice (Js1); the sugar juice is filtered using at least one filter membrane (18); the filtered sugar juice (Jsf) is concentrated by evaporation to obtain a concentrated filtered juice (Jsfc) having a dry matter concentration above a predetermined concentration threshold; a crystallization step is carried out in which the concentrated filtered juice is heated under vacuum to evaporate the residual liquid contained in the concentrated filtered juice, the heating being continued until a fully crystallized sugar (C) is obtained having a moisture content of between 0% and 10%. Figure for the abstract: Fig. 1.

Description

Title of the invention: Process for producing sugar from beets technical field

[0001] The present invention relates to the technical field of sugar production, and more specifically to the production of sugar from sugar beets. Sugar beets contain up to 20% sugar by mass. The sugar obtained from beets is sucrose. It is naturally white. Previous technique

[0002] Traditional sugar production processes from beets produce white sugar with a neutral taste.

[0003] According to these traditional processes, the beets are cut into cossettes before being subjected to a diffusion stage in which the cossettes circulate in a diffuser against the current of water heated to approximately 70°C, which then becomes charged with sugar by osmosis. A sweet juice is thus obtained.

[0004] One drawback of this known diffusion step is that it requires a significant contact time between the cossettes and the water in order to extract sufficient sugar from the cossettes. This also implies the use of large extractors and necessitates heating a large quantity of water for a considerable period. This diffusion step is therefore particularly expensive, both because of the specific equipment required and because of the energy consumption associated with heating this large quantity of water.

[0005] After the diffusion step, these known processes then involve a purification step of the sugar juice by treatment with lime, called liming, which precipitates the impurities. However, the use of chemicals such as lime is not satisfactory. This purification step also results in a significant generation of carbon dioxide and is therefore polluting.

[0006] According to these traditional processes, the purified juice is further concentrated before the concentrated juice is crystallized. Crystallization is carried out in successive phases, called "jets," during each of which the concentrated juice is heated and seeded by the introduction of fine sugar crystals to trigger crystallization. This produces a "massecue" consisting of a syrup, called molasses, in which the sugar crystals are suspended. This massecue is then centrifuged to separate the sugar crystals from the molasses, which is then removed.

[0007] One disadvantage of this method of crystallization by successive jets is that it is particularly complex and costly and generates significant consumption of energy. In addition, some of the minerals, nutrients, trace elements, and vitamins remain trapped in the molasses and are therefore lost. The sugar obtained by this traditional process thus loses nutritional quality. Description of the invention

[0008] One object of the present invention is to propose a sugar production process that remedies the aforementioned drawbacks.

[0009] To this end, the invention relates to a process for producing sugar from beets, the process comprising the steps according to which: - at least one batch of beets is supplied; - at least one pressing step is carried out on the beets in order to extract a sweet juice; - the sweetened juice is filtered using at least one filter membrane; - the filtered sugar juice is concentrated by evaporation to obtain a concentrated filtered juice with a dry matter concentration above a predetermined concentration threshold; and - a crystallization step is carried out in which the concentrated filtered juice is heated under vacuum in order to evaporate the residual liquid contained in the concentrated filtered juice, the heating being continued until a complete crystallized sugar is obtained with a moisture content between 0% and 10%.

[0010] The process according to the invention allows the production of sugar from sugar beets. Preferably, several batches of beets are supplied. Advantageously, only the white roots of the sugar beets are used in this sugar production process.

[0011] Preferably, but not exclusively, a preliminary step of crushing the beets is carried out before the pressing step. One advantage is to improve the extraction of sugar juice during the pressing step, or in other words, to improve the pressing yield. It is understood that the pressing step then consists of pressing the crushed beets.

[0012] The pressing step is preferably carried out using a press. The sugar juice obtained after the pressing step consists essentially of water and sucrose. Preferably, several batches of beets are pressed successively. Preferably, the process comprises several successive pressing steps of the same batch of beets, so that the same batch of beets is pressed at least twice. One advantage is to extract more sugar juice.

[0013] The beet pressing step of the process according to the invention eliminates the need for a diffusion step and consequently the use of a large extractor. The cost of the equipment for extracting the sugar juice is therefore less. Water consumption and energy consumption for heating the water are also particularly reduced since pressing requires only a small amount of water compared to a conventional diffusion stage.

[0014] The pressing step produces beet pulp containing a residual amount of sugar. This pulp can be recycled.

[0015] By way of non-limitation, the process may include several successive pressing steps.

[0016] Advantageously, the filtration step makes it possible to obtain a filtered sweet juice having a dry matter concentration greater than 50%, preferably greater than 60%.

[0017] The sugar juice filtration step separates filtered residues, also called retentates, from the filtered sugar juice, also called permeate. The filtered sugar juice is thus purified, and its purity, defined as the ratio of its sugar concentration to its dry matter concentration, is greater than 80%, preferably greater than 90%. This membrane filtration eliminates the need for a separate sugar juice purification step and therefore the use of lime or other chemicals. Furthermore, carbon dioxide generation is significantly reduced since the invention does not involve a liming step. The process according to the invention therefore has a reduced environmental impact.

[0018] The colour of the whole crystallized sugar that will finally be obtained depends in particular on the cut-off threshold of the filter membrane.

[0019] Preferably, the filtration is tangential filtration. The filtration may employ several successive filtration stages.

[0020] Preferably, the filter membrane is an ultrafiltration membrane. Without limitation, the filter membrane may be an organic or mineral filter membrane. The filter membrane has a cutoff threshold chosen to effectively filter retentates. Preferably, the sugary juice is heated before being filtered.

[0021] The use of mineral filter membranes makes it possible to filter juice at a higher temperature, in particular above 75°C, which helps to limit the proliferation of bacteria.

[0022] The concentration step advantageously implements a mechanical vapor compression technique.

[0023] During the concentration step, the filtered sugar juice is heated to evaporate some of the water it contains, thereby increasing its dry matter concentration, and thus its sucrose content. Dry matter refers to the matter remaining if the liquid, and in particular the water, contained in the filtered sugar juice were completely evaporated.

[0024] It is understood that evaporation is continued until the dry matter concentration reaches the predetermined concentration threshold.

[0025] The predetermined concentration threshold is chosen according to the input requirements of the crystallization unit. The higher this predetermined concentration threshold, the shorter the heating time during the crystallization step. The dry matter concentration can be measured by refractometry. It can be expressed in degrees Brix.

[0026] The concentrated filtered juice obtained by this concentration step forms a syrup. This concentrated filtered juice is preferably ready for crystallization. The sucrose concentration in the concentrated filtered juice is sufficient to allow substantially complete crystallization of the sugar by heating alone, and in particular without the need to seed the sugar to initiate crystallization.

[0027] By way of exception, the residual liquid evaporated during the concentration step may be essentially water or exclusively water. The vapors resulting from this concentration step may be used to heat the concentration unit, for heating during crystallization, or to heat the sugar juice before filtration.

[0028] During the crystallization stage, heating evaporates the residual liquid contained in the concentrated filtered juice, and also initiates and completes the crystallization of the sugar. According to the invention, the heating is carried out under vacuum, or in other words, by placing the concentrated filtered juice at a pressure lower than atmospheric pressure. One advantage is that this creates a pressure increase that lowers the boiling point of the liquid present in the concentrated filtered juice, particularly water, and therefore the temperature at which it evaporates. Consequently, the temperature required and the energy needed to evaporate the residual liquid are reduced. Energy consumption is thus further reduced thanks to the process according to the invention.

[0029] Furthermore, since the concentrated filtered juice is heated to a reduced temperature, the energy required to cool the whole crystallized sugar finally obtained is also reduced.

[0030] Whole grain granulated sugar is defined as granulated sugar obtained by continuing to heat the mixture until complete or nearly complete crystallization is achieved, or in other words, until complete or nearly complete evaporation of the residual liquid. Whole grain granulated sugar is sugar that retains its molasses. Whole grain granulated sugar is also called unrefined sugar.

[0031] According to the invention, the heating is therefore continued until the sugar crystallizes completely, or substantially completely. The liquid initially contained in the concentrated filtered juice is thus largely evaporated during the crystallization stage. The process according to the invention does not involve the separation of molasses by in relation to the sugar crystals. The resulting whole grain granulated sugar retains all of its molasses. During crystallization, the minerals, nutrients, trace elements, and vitamins initially contained in the concentrated filtered juice are fixed onto the sugar crystals by adsorption. Therefore, the whole grain granulated sugar obtained using the process according to the invention retains high nutritional qualities.

[0032] Preferably, heating is continued until a crystalline sugar is obtained with a moisture content sufficiently low to ensure fluidity and prevent the sugar crystals from clumping together. Heating, and therefore crystallization, is advantageously continued until the moisture content in the whole crystalline sugar is as low as possible.

[0033] The whole grain granulated sugar obtained can be consumed directly or packaged.

[0034] The process according to the invention is further devoid of a centrifugation step during or after crystallization, since, according to the invention, there is no separation of molasses that would need to be removed. The process is therefore simplified, allows for reduced energy consumption, and is consequently less expensive.

[0035] Preferably, the process according to the invention does not involve a refining step of the sugar obtained.

[0036] By way of exception, after the crystallization step, the process may include a further drying step in which dry air is blown onto the resulting whole crystallized sugar. One advantage is to further reduce the moisture content of the whole crystallized sugar.

[0037] Advantageously, said predetermined concentration threshold is between 65% and 85%, preferably approximately 80%. In other words, the sugar juice filtered by evaporation is concentrated to obtain a concentrated filtered juice with a dry matter concentration advantageously greater than 80%. One benefit is reducing the heating time required to initiate the formation of sugar crystals. Therefore, the overall heating time under vacuum required to achieve sugar crystallization is reduced. Energy consumption is thus further reduced.

[0038] Advantageously, the heating is continued until a whole crystallized sugar with a moisture content of less than 7%, preferably less than 5%, is obtained. One advantage is that more residual liquid is evaporated, thus obtaining a drier whole crystallized sugar.

[0039] Preferably, the resulting whole crystallized sugar has a sucrose concentration greater than 85%, preferably approximately 90%. Such a sugar is particularly pure. The resulting whole crystallized sugar is advantageously brown in color.

[0040] Advantageously, during the crystallization step, the concentrated filtered juice is preheated to a preliminary evaporation temperature, under a preliminary pressure between 250 millibars and 350 millibars, preferably about 300 millibars, said preliminary evaporation temperature being a function of said preliminary pressure.

[0041] This preliminary heating allows the liquid contained in the concentrated filtered juice to evaporate until the latter is supersaturated and thus until spontaneous crystallization is triggered. It is not necessary to inoculate the concentrated filtered juice to trigger crystallization.

[0042] This preliminary heating is advantageously carried out for 30 to 60 minutes. This preliminary heating step further concentrates the concentrated filtered juice. This preliminary heating step is optional.

[0043] At 300 millibars, the preliminary evaporation temperature is advantageously chosen to be approximately 75°C. This pressure and temperature combination helps to limit the coloring of the final whole crystallized sugar obtained.

[0044] Preferably, during the crystallization step, the concentrated filtered juice is heated to a main evaporation temperature under a main pressure of between 100 millibars and 200 millibars, preferably approximately 150 millibars, said main evaporation temperature being a function of said main pressure. This main heating step evaporates the residual bound water until substantially complete crystallization. The temperature and pressure parameters are chosen to achieve the fastest, most complete, and most cost-effective crystallization possible.

[0045] At 150 millibars, the main evaporation temperature is advantageously chosen to be approximately equal to 70°C.

[0046] According to the invention, it is understood that the main heating is continued until said whole crystallized sugar is obtained having a moisture content between 0% and 10%.

[0047] Preferably, before the beet pressing stage, the beets are ground. It is understood that the ground beets are then pressed. There is an advantage to facilitating the pressing of the beets by conveying them in ground form. This allows, in particular, for more efficient extraction of the sugary juice during pressing.

[0048] Advantageously, the concentrated filtered juice is agitated during the crystallization step. This prevents sugar caramelization and promotes the formation of sugar crystals. Crystallization is therefore faster. Agitation is preferably maintained continuously and at a constant speed.

[0049] Preferably, following the crystallization step, the whole crystallized sugar obtained is immediately placed at atmospheric pressure. The pressure reduction... The spherical shape is therefore not gradual but sudden. One advantage is to prevent the moisture content of the whole crystallized sugar obtained from increasing, for example, at the outlet of the crystallization unit.

[0050] Advantageously, the beet pressing step produces beet pulp, and a diffusion step is carried out in which this beet pulp is circulated through a diffusion liquid to obtain a sugary diffusion juice. This sugary juice can then be added to the sugary juice obtained by pressing the beets, and this mixture is then subjected to the filtration step. One advantage is to extract more sugar from the beets and thus reduce waste. The diffusion liquid is preferably heated to a temperature between 60°C and 100°C.

[0051] By way of non-limitation, the diffusion liquid may be the liquid evaporated following the step of concentration by evaporation of the filtered sugar juice.

[0052] The invention also relates to a sugar production installation using beets, comprising: - a press configured to press at least one batch of beets in order to extract a sweet juice; - at least one filter membrane configured to filter sugary juice; - an evaporation unit configured to concentrate the evaporated sugar-filtered juice, so as to obtain a concentrated filtered juice having a dry matter concentration above a predetermined concentration threshold; - a crystallization unit comprising an enclosure configured to receive the concentrated filtered juice, a vacuum pump configured to create a vacuum within the enclosure and a heating module configured to heat the concentrated filtered juice placed under vacuum in order to evaporate the residual liquid contained in the concentrated filtered juice, until a complete crystallized sugar is obtained having a moisture content between 0% and 10%.

[0053] Preferably, the press is a piston press, even more preferably a pneumatic press. It can be horizontal or vertical. The press advantageously includes an integrated filtration unit.

[0054] The evaporation unit is preferably a falling-flow evaporation unit. One advantage is that it allows for even faster evaporation. The evaporation unit is preferably configured to concentrate the vacuum-filtered sugar juice.

[0055] Preferably, the filter membrane is an ultrafiltration membrane with a cutoff threshold between 300 daltons and 15 kilodaltons. One advantage is that it filters very small molecules, and therefore retentates, more effectively. This results in a clearer, less cloudy filtered juice, leading to the production of sugar with a color closer to white. By adjusting the cutoff threshold, the color of the final whole crystallized sugar can be influenced.

[0056] Preferably, the cutoff threshold is between 0.1 pm and 0.01 pm.

[0057] Preferably, the evaporation unit comprises a falling-flow evaporator.

[0058] Preferably, the crystallization unit includes an agitator configured to agitate the concentrated filtered juice while the latter is heated. Brief description of the drawings

[0059] The invention will be better understood upon reading the following description of an embodiment of the invention given by way of non-limiting example, with reference to the accompanying drawings, in which:

[0060] [Fig. 1] [Fig. 1] illustrates one implementation of the sugar production process according to the invention; and

[0061] [Fig.2] [Fig.2] is a graph showing the evolution of the pressure and temperature of the concentrated filtered juice during the crystallization step. Description of the implementation methods

[0062] The invention relates to a process for producing sugar from sugar beets and to a sugar production installation for implementing this process.

[0063] Fig. 1 shows an implementation method, given by way of non-limiting example, of a sugar production process according to the invention, using a sugar production plant 10 also according to the invention.

[0064] As illustrated in [Fig. 1], the installation 10 includes a crusher 12 configured for crushing beets. The installation 10 also includes a press 14, which in this non-limiting example is a pneumatic piston press. The press 14 is configured for pressing beets to extract sugary juice.

[0065] The installation 10 comprises a filtration unit 16 including at least one filter membrane 18. The filter membrane 18 is a tangential flow membrane. It is an ultrafiltration membrane. It has a cut-off threshold between 300 daltons and 15 kilodaltons. The filter membrane 18 may be organic or mineral. Without limitation, the filtration unit 16 may comprise several successive filtration stages, each comprising a filter membrane.

[0066] The installation 10 further includes an evaporation unit 20 configured to concentrate a sugary juice by evaporation, by heating it. In this non-limiting example, the evaporation unit 20 is a falling-flow evaporation unit operating under vacuum and employing a vapor compression technique. Notwithstanding the limitation, the evaporation unit 20 may be multi-effect, such that it comprises a plurality of evaporators arranged in cascade. The vapor produced by one evaporator is then used to heat the next evaporator.

[0067] The installation further includes a crystallization unit 22 enabling the production The crystallization of sugar from concentrated sugar juice, so as to obtain whole crystallized sugar according to the invention. In this non-limiting example, the crystallization unit 22 is a vacuum dryer. It comprises a chamber 24 for receiving the concentrated sugar juice. The crystallization unit 22 further comprises a vacuum pump 26 configured to create a vacuum within the chamber 24. The crystallization unit 22 also comprises a heating module 28 configured to heat the interior of the chamber 24.

[0068] By way of non-limiting agreement, the crystallization unit 22 also includes an agitator 30.

[0069] In this non-limiting example, the installation also includes an extractor 32 enabling a diffusion step to be carried out, in particular of beet pulps p from pressing.

[0070] The installation is devoid of a centrifugation device.

[0071] With reference to [Fig.1], we will now describe the steps of the sugar production process according to the invention implemented using the installation 10.

[0072] According to a first step S1, a batch of sugar beets B is supplied, and more specifically sugar beet roots from which the leaves have been removed. These beets B have preferably been previously sorted, washed, and weighed. In a second, non-limiting step S2, these beets B are crushed using the crusher 12. This crushing step will then facilitate the extraction of the sugar juice during pressing.

[0073] According to a third step S3, the crushed beets B are pressed using the press 14 to extract a sugar juice Jsx. This sugar juice Jsise consists essentially of water and sucrose. A first pressing extracts approximately 70% of the sugar juice naturally present in the sugar beet B. Without limitation, the same batch of beets can be pressed several times to extract even more sugar juice.

[0074] This S3 pressing step eliminates the need for a diffusion step to extract most of the sugary juice, and therefore the use of a large and particularly expensive diffuser. Water and energy consumption for heating this water is significantly reduced. Carbon dioxide production is also reduced.

[0075] The pressing step produces beet pulp p containing a small amount of sugar. In this non-limiting example, a diffusion step is carried out using the beet pulp p obtained from pressing, in order to collect some of the residual sugar. This pulp is placed in the extractor 32 where a heated diffusion liquid L, here water, is circulated counter-currently. This diffusion liquid can be obtained from the evaporation of the liquid during the concentration step according to the This process, applied to a previous batch of beets, involves the diffusion liquid L becoming saturated with sugar through diffusion, resulting in a sweet diffusion juice Js2 at the outlet of extractor 32. This sweet diffusion juice Js2 can be added to the sweet juice Jsi obtained after pressing. One advantage is increasing the process yield by extracting more sugar from the beets.

[0076] The depleted pulps resulting from this diffusion step can be used in biscuit making, bread making or as a food supplement.

[0077] The sweet juice Jsx extracted by pressing, to which diffusion juice Js2 has been added here in a non-limiting manner, is conveyed to the filtration unit 16.

[0078] A filtration step S4 is then carried out using the filter membrane(s) 18 of the filtration unit 16, in order to obtain a filtered sugar juice Jsf. The sugar juice is heated to approximately 75°C before being filtered. The filtration performed is tangential ultrafiltration, which clarifies and purifies the sugar juice by retaining molecules whose size exceeds the cutoff threshold of said filter membrane 18. Without limitation, the filtration step S4 can be repeated several times to further purify the filtered sugar juice Jsf.

[0079] The filtered sugar juice Jsf obtained after filtration step S4 has a dry matter concentration advantageously greater than 60%, and its purity, considered to be the ratio of its sugar concentration to its dry matter concentration, is advantageously greater than 80%. Filtration step S4 constitutes a purification step for the sugar juice. Thanks to the invention, it is not necessary to purify the sugar juice with lime. The process according to the invention does not use any chemicals and also reduces carbon dioxide production. The purity of the filtered sugar juice is sufficient to allow its concentration by evaporation.

[0080] The filtered sugar juice Jsf is then conveyed to the evaporation unit 20, and a fifth step S5 is carried out, concentrating the filtered sugar juice Jsf by evaporation using said evaporation unit 20. Within the evaporation unit, the filtered sugar juice Jsf is heated, preferably under vacuum, so as to evaporate some of the liquid it contains. The filtered sugar juice Jsf is kept circulating within the evaporation unit throughout the concentration step. Some of the liquid, particularly water, initially contained in the filtered sugar juice evaporates until a concentrated filtered juice Jsfc is obtained, having a dry matter concentration above a predetermined concentration threshold. In this non-limiting example, the predetermined concentration threshold is approximately 80%, i.e., a dry matter concentration above 80%. The concentrated filtered juice Jsfc forms a syrup.

[0081] The concentrated filtered juice Jsfc is then brought into the chamber 24 of the crystallization unit. The chamber 24 is placed under vacuum using the vacuum pump 26, at a pressure lower than atmospheric pressure. A sixth crystallization step, S6, is then carried out in which the concentrated filtered juice, Jsfc, is heated under vacuum using the heating module 28 to evaporate the residual liquid and crystallize the sugar until complete crystallized sugar, C, is obtained. The evaporated liquid is essentially water. Alternatively, the heating may be carried out using a fluid heated to a set temperature, for example, water or steam.

[0082] Preferably, the concentrated filtered juice Jsfc is stirred using the stirrer 30 while it is heated, preferably continuously and throughout the crystallization.

[0083] An example of crystallization step S6 according to the invention will be described with reference to [Fig.2]. This [Fig.2] is a graph illustrating, in white dots, the evolution of the temperature T of the concentrated filtered juice Jsfc and, in black dots, the evolution of the pressure P within the enclosure 24 as a function of time t, during the crystallization step.

[0084] As shown in this graph, the concentrated filtered juice Jsfc is first preheated for a period tl of approximately 35 minutes. The concentrated filtered juice is heated by means of heated water maintained at a set temperature of approximately 100°C. During this preliminary heating, the chamber is placed under vacuum at a preliminary pressure P of approximately 300 millibars, so that the concentrated filtered juice Jsfc is brought to a preliminary evaporation temperature of approximately 76°C. By placing it under vacuum, the boiling point of the liquid, and in particular of the water contained in the concentrated filtered juice Jsfc, is lowered. The energy consumption required for the evaporation of the residual water is therefore reduced. This preliminary heating step further concentrates the concentrated filtered juice Jsfc until crystallization is initiated.The pressure P and temperature T combination applied during this preliminary heating step also helps to reduce the colouring of the final whole crystallized sugar C.

[0085] During a second period t2 illustrated in [Fig.2], from minutes 35 to 45, the concentrated filtered juice Jsfc is brought to supersaturation and crystallization begins spontaneously, without the need to seed it.

[0086] In a third period t3 of the crystallization, extending in this non-limiting example from minutes 45 to 55, the pressure P is lowered, so that the temperature T of the concentrated filtered juice Jsfc is also lowered. During this third step t3, the concentrated filtered juice is heated to a main pressure of approximately 150 millibars, with the concentrated filtered juice having a main evaporation temperature of approximately 70°C.

[0087] During this main heating stage, crystallization continues and is completed. According to the invention, the heating, and therefore here the main heating stage, is continued until a fully crystallized sugar C is obtained having a moisture content between 0% to 10%, preferably less than 7%, and even more preferably less than 5%. In other words, heating is continued until the sugar crystallizes completely, or almost completely. The liquid initially contained in the concentrated filtered juice Jsfc is therefore largely evaporated during the crystallization step. The process according to the invention, and in particular the crystallization step, leads directly to the formation of whole crystallized sugar C and does not involve the separation of molasses from the sugar crystals. Therefore, a final centrifugation step is unnecessary. The minerals, nutrients, trace elements, and vitamins initially contained in the concentrated filtered juice are bound to the sugar crystals by adsorption. Thus, the whole crystallized sugar obtained using the process according to the invention retains high nutritional qualities.

[0088] During the crystallization step, the formation of sugar crystals is substantially linear over time.

[0089] Following this third period t3, and therefore when crystallization is complete, the whole grain granulated sugar C obtained is immediately placed at atmospheric pressure to prevent its moisture content from increasing. Dry air may be blown over the whole grain granulated sugar. The whole grain granulated sugar C can then be packaged and consumed.

Claims

Demands

1. A process for producing sugar from beets (B), the process comprising the steps in which: - at least one batch of beets is supplied; - at least one step of pressing the beets is carried out in order to extract a sugar juice (Jsi); - the sugar juice is filtered using at least one filter membrane (18); - the filtered sugar juice (Jsf) is concentrated by evaporation in order to obtain a concentrated filtered juice (Jsfc) having a dry matter concentration greater than a predetermined concentration threshold; and - a crystallization step is carried out in which the concentrated filtered juice is heated under vacuum in order to evaporate the residual liquid contained in the concentrated filtered juice, the heating being continued until a whole crystallized sugar (C) is obtained having a moisture content of between 0% and 10%.

2. A method according to claim 1, wherein said predetermined concentration threshold is between 65% and 85%, preferably about 80%.

3. A process according to claim 1 or 2, wherein the heating is continued until an integral crystallized sugar (C) is obtained having a moisture content of less than 7%, preferably less than 5%.

4. A process according to any one of claims 1 to 3, wherein the whole crystallized sugar obtained has a sucrose concentration greater than 85%, preferably about 90%.

5. A method according to any one of claims 1 to 4, wherein during the crystallization step, the concentrated filtered juice (Jsfc) is preheated to a preliminary evaporation temperature, under a preliminary pressure of between 250 millibars and 350 millibars, preferably about 300 millibars, said preliminary evaporation temperature being a function of said preliminary pressure.

6. A process according to any one of claims 1 to 5, wherein, during the crystallization step, the concentrated filtered juice (Jsfc) is heated to a main evaporation temperature under a main pressure of between 100 millibars and 200 millibars, preferably about 150 millibars, said main evaporation temperature being a function of said main pressure.

7. A method according to any one of claims 1 to 6, wherein before the beet pressing stage (B) a beet crushing stage is carried out.

8. A method according to any one of claims 1 to 7, wherein the concentrated filtered juice (Jsfc) is agitated during the crystallization step.

9. A process according to any one of claims 1 to 8, wherein, following the crystallization step, said whole crystallized sugar obtained (C) is instantly placed at atmospheric pressure.

10. A method according to any one of claims 1 to 9, wherein the beet pressing step produces beet pulp (p), and wherein a diffusion step is carried out in which said beet pulp is circulated in a diffusion liquid (L) so as to obtain a sweet diffusion juice (Js2).

11. Installation (10) for the production of sugar from beets comprising: - a press (14) configured to press at least one batch of beets (B) so as to extract a sugar juice (Jsi); - at least one filter membrane (18) configured to filter the sugar juice; - an evaporation unit (20) configured to concentrate the filtered sugar juice (Jsf) by evaporation, so as to obtain a concentrated filtered juice (Jsfc) having a dry matter concentration above a predetermined concentration threshold; - a crystallization unit (22) comprising a chamber (24) configured to receive the concentrated filtered juice, a vacuum pump (26) configured to create a vacuum within the chamber and a heating module (28) configured to heat the concentrated filtered juice placed under vacuum in order to evaporate the residual liquid contained in the concentrated filtered juice, until a whole crystallized sugar (C) is obtained having a moisture content between 0% and 10%.

12. Sugar production plant according to claim 11, wherein the filter membrane (18) is an ultrafiltration membrane having a cut-off threshold between 300 daltons and 15 ki-daltons.

13. Sugar production plant according to claim 11 or 12, wherein the evaporation unit (20) comprises a falling-flow evaporator.

14. A sugar production plant according to any one of claims 11 to 13, wherein the crystallization unit (22) comprises an agitator (30) configured to agitate the concentrated filtered juice (Jsfc) while the latter is heated.

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