Method for processing sugar BEET to obtain a solid extrudate and a liquid extrudate and plant configured to implement said method

Abstract

The present invention relates to a method (1) for processing sugar beet to obtain a solid extrudate (30) and a liquid extrudate (40). This method (1) comprises the following steps in sequence: a) performing a cleaning step of a plurality of sugar beets (10); b) performing a dry griding step of the beets (10) in such a way as to obtain a ground mass (20) of these beets (10); C) performing a pressing step of the ground mass (20) directly obtained from the dry griding step b) in such a way as to obtain the aforesaid solid extrudate (30) and the aforesaid liquid extrudate (40), wherein said pressing step c) comprises at least double-screw pressing of the ground mass (20); d) performing a filtration step of the liquid extrudate (40) in such a way as to obtain a filtered liquid extrudate (50) substantially free of suspended solids; e) performing a thickening step of the filtered liquid extrudate (50) in such a way as to increase its sugar content titre.

Description

[0001] METHOD FOR PROCESSING SUGAR BEET TO OBTAIN A SOLID EXTRUDATE AND A LIQUID EXTRUDATE AND PLANT CONFIGURED TO IMPLEMENT SAID METHOD.

[0002] DESCRIPTION

[0003] The invention relates to a method for processing sugar beet to obtain a solid extrudate and a liquid extrudate.

[0004] The present invention also relates to a plant configured to implement such a method.

[0005] Methods for processing sugar beet to obtain a solid extrudate and a liquid extrudate are known today.

[0006] Such a known method comprises a step of cleaning a plurality of sugar beets, slicing them and subsequently immersing them into a tank containing water at a high temperature in such a way as to obtain a liquid extrudate with a high sugar content.

[0007] Once the liquid part has been removed from the aforesaid tank, the residual solid extrudate is then subjected to a pressing step in order to obtain further liquid extrudate.

[0008] Finally, the liquid extrudate obtained from the previous steps is subjected to a filtration step and a subsequent thickening step.

[0009] Such a method, although known and appreciated, however, has some important limitations.

[0010] In particular, a first limitation is linked to the fact that the solid extrudate obtained by means of the aforesaid method is degraded by the high temperature of the water into which the beets are immersed for the extraction of the liquid extrudate. A second limitation is linked to the fact that the solid extrudate, although it is subjected to a pressing step, is wet at the end of the pressing step and therefore requires a drying step to prevent its rapid deterioration.

[0011] A third limitation concerns the liquid extrudate which, also because of the immersion of the beets into water, has a sub-optimal sugar content titre and requires a water evaporation step to reach a sugar content titre higher than 20%. Finally, a fourth limitation is linked to the fermentability of the liquid extrudate due to the residual presence of water also following the aforesaid evaporation step.

[0012] The task of the present invention is to develop a method capable of obviating the mentioned drawbacks and limitations of the prior art. In particular, it is an object of the present invention to provide a method in which the solid extrudate obtained is less degraded than similar methods of known type.

[0013] Still, an object of the invention is to develop a method where the solid extrudate obtained does not require a drying step to prevent its rapid deterioration.

[0014] A further object of the invention is to develop a method in which the liquid extrudate obtained has a sugar content titre higher than that obtainable through a similar method of known type and without implementing an evaporation step of the water contained in said liquid extrudate.

[0015] Furthermore, it is an object of the present invention to develop a method in which the liquid extrudate is less fermentable than that obtainable with a similar method of known type.

[0016] The above task and purposes are achieved by a method according to claim 1 . Further characteristics of the method according to claim 1 are described in the dependent claims.

[0017] The aforesaid task and objects, together with the advantages that will be mentioned hereinafter, are highlighted by the description of an embodiment of the invention, which is given by way of non-limiting example with reference to the attached drawing, where:

[0018] - figure 1 represents a flowchart of the method according to the invention.

[0019] With reference to the cited figure, a method according to the invention is indicated as a whole with number 1.

[0020] The method 1 for processing sugar beet is adapted to obtain a solid extrudate 30 and a liquid extrudate 40.

[0021] In particular, this method 1 comprises the following steps in sequence: a) performing a cleaning step of a plurality of sugar beets 10; b) performing a dry griding step of these beets 10 in such a way as to obtain a ground mass 20 of these beets 10; c) performing a pressing step of the ground mass 20 directly obtained from said dry griding step b) in such a way as to obtain the aforesaid solid extrudate 30 and the aforesaid liquid extrudate 40; d) performing a filtration step of the liquid extrudate 40 in such a way as to obtain a filtered liquid extrudate 50 substantially free of suspended solids; e) performing a thickening step of the filtered liquid extrudate 50 in such a way as to increase its sugar content titre. It is emphasized that the solid extrudate 30 as well as the liquid extrudate 40 are obtained without immersing the beets 10 into water, but exclusively through the griding step b) and the subsequent pressing step c).

[0022] Therefore, it is clear that the solid extrudate 30 thus obtained is less degraded compared to similar methods of known type that employ high temperature water. Furthermore, considering that the solid extrudate 30 thus obtained is not wet, it does not require a drying step to prevent its rapid deterioration.

[0023] The liquid extrudate 40 obtained by the method 1 has a sugar content titre higher than 20% without implementing an evaporation step of the water contained in said liquid extrudate 40.

[0024] It should also be noted that the filtered liquid extrudate 50 following the thickening step e) reaches a sugar content titre of more than 60%.

[0025] Equally advantageously, always considering that the beets 10 are not immersed into water in order to extract the sugar content titre thereof, the liquid extrudate 40 thus obtained turns out to be less fermentable than that obtainable with a similar method of known type.

[0026] In the present embodiment of the invention, the cleaning step a) consists in using a shaker for detaching soil and stones from the beets 10, in using a weeding brush for the removal of grasses and leaves from the beets 10 and again in using an iron separator for the removal of metal bodies from the beets 10.

[0027] It is not excluded, however, that the cleaning step a) is implemented in a different way from what has just been presented, for example using a different combination of the cleaning techniques of the beets 10 just presented.

[0028] In the present embodiment of the invention, the cleaning step a) comprises at least sanitizing the beets 10 by exposing such beets 10 to an ultraviolet light.

[0029] It is not excluded, however, that this sanitization is implemented by using hypochlorous acid or through sanitization means different from what has just been presented.

[0030] In the present embodiment of the invention, the griding step b) is performed until obtaining the ground mass 20 with a diameter of less than or equal to 4 mm, preferably between 1 and 2 mm, wherein said grinding is implemented by means of a grinding mill.

[0031] In addition, again with reference to the present embodiment, the griding step b) provides for a further griding step implemented by means of a crusher with milling cutter adapted to obtain the ground mass 20 with a diameter of less than or equal to 1 .5 mm, preferably less than 0.5 mm.

[0032] It is not excluded, however, that grinding takes place in a different way from what has just been presented.

[0033] In the present embodiment, the pressing step c) comprises at least doublescrew pressing of the ground mass 20.

[0034] In particular, this pressing step c) is implemented by two frustoconical counterrotating propellers with length between 5 and 10 m configured to rotate with a number of revolutions between 2 and 8 revolutions per minute.

[0035] It is not excluded, however, that this pressing step c) is implemented differently from what has just been presented.

[0036] In the preferred embodiment of the invention, the filtration step d) is preceded by a chemical purification step for the precipitation of impurities.

[0037] This purification step involves heating the liquid extrudate 40, having about 15 °Bx, to a temperature of about 72°C to inhibit the start of any fermentations. Subsequently, in a pre-liming step, lime milk CaO is gradually added until the pH of the liquid reaches a value of about 11 .2.

[0038] A liming step follows in which an additional quantity of lime milk is added and the liquid is brought to a temperature of about 85°C.

[0039] At this temperature, a first carbonation is performed by blowing carbon dioxide Co2 through porous candles until a pH of 11 .2 is reached again, thus obtaining the precipitation of non-sugars.

[0040] At this point, a coarse filtration is performed, preferably hot at a temperature of 80-85°C, using a rotary drum filter or a filter press to remove the precipitates.

[0041] Subsequently, a second addition of Co2 is implemented until a pH of 9.2 is reached, followed by a brightening filtration, for example with candle filters, to obtain the filtered liquid extrudate 50 with a very low content of suspended solids.

[0042] In the present embodiment of the invention, the filtration step d) comprises at least tangential filtration of the liquid extrudate 40.

[0043] As regards the thickening step e), in the preferred embodiment, the filtered liquid extrudate 50 is processed in a multiple-effect concentrator, operating continuously, to increase the sugar content titre thereof from about 15 °Bx to about 70 °Bx.

[0044] Furthermore, the thickening step e) comprises at least cold evaporation of the filtered liquid extrudate 50. In particular, a vacuum-operating pump with cold evaporation with descending flow performs the continuous thickening cycle of the filtered liquid extrudate 50. Even more precisely, the filtered liquid extrudate 50 is brought to a sugar content titre of more than 65% by activating its cold evaporation and thus concentrating the presence of the sugars dissolved in the liquid.

[0045] It should also be pointed out that the evaporated liquid thus obtained is free of mineral salts, but advantageously has volatile solids and can therefore be used in the agri-food sector.

[0046] As mentioned earlier, a sugar beet processing plant is also an object of the present invention, configured to implement a method 1 for processing sugar beet as described above.

[0047] It should also be noted that this processing plant can be connected in output to means for the production of sugar or inverted sugar syrup.

[0048] Practically, it has been established that the invention achieves the intended task and objects.

[0049] In particular, with the invention, a method has been developed in which the solid extrudate obtained is less degraded than similar methods of known type.

[0050] A method has also been developed where the solid extrudate obtained does not need a drying step to prevent its rapid deterioration.

[0051] A method has also been developed in which the liquid extrudate obtained has a sugar content titre higher than that obtainable through a similar method of known type and without implementing a step of evaporation of the water contained in said liquid extrudate.

[0052] Furthermore, a method has been developed in which the liquid extrudate is less fermentable than that obtainable with a similar method of known type.

Claims

CLAIMS1 ) Method (1 ) for processing sugar beet to obtain a solid extrudate (30) and a liquid extrudate (40), characterized by comprising the following steps in sequence: a) performing a cleaning step of a plurality of sugar beets (10); b) performing a dry griding step of said beets (10) in such a way as to obtain a ground mass (20) of said beets (10); c) performing a pressing step of said ground mass (20) directly obtained from said dry griding step b) in such a way as to obtain said solid extrudate (30) and said liquid extrudate (40), said pressing step c) comprising at least double-screw pressing of said ground mass (20); d) performing a filtration step of said liquid extrudate (40) in such a way as to obtain a filtered liquid extrudate (50) substantially free of suspended solids; e) performing a thickening step of said filtered liquid extrudate (50) in such a way as to increase its sugar content titre.2) Method (1 ) according to claim 1 , characterized in that said cleaning step a) comprises at least sanitizing said beets (10) by exposing said beets (10) to ultraviolet light.3) Method (1 ) according to claim 1 or 2, characterized in that said griding step b) is performed until obtaining said ground mass (20) with a diameter less than or equal to 4 mm.4) Method (1 ) according to any one of the preceding claims, characterized in that said filtration step d) comprises at least tangential filtration of said liquid extrudate (40).5) Method (1 ) according to any one of the preceding claims, characterized in that said thickening step e) comprises at least cold evaporation of said filtered liquid extrudate (50).6) Sugar beet processing plant, characterized in that it is configured to implement a method (1 ) for processing sugar beet according to any one of the preceding claims.

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