Method of Disintegrating and Fluid Drying of Sugar Beet Material Preventing the Degradation Reaction of the Material

Abstract

A method for the disintegration and fluid drying of sugar beet material which prevents the material's degradation reaction from taking place and which includes the steps of disintegrating the sugar beet material to particles with a particle surface area of at least 2.0 cm.sup.2, and subsequent immediate exposure of the disintegrated material to a drying gas(es) at a temperature of 25° C. to 160° C. and a flow rate of 5 m.s.sup.31 1 to 40 m.s.sup.−1, where the relative humidity of the drying gas(es) at the inlet to the drying space is at most 85%; and subsequent mixing of the disintegrated material with a flow of drying gas(es) until attaining a value of dry matter of at least 70% by weight.

Claims

1. A method of disintegration and fluid drying of the sugar beet material preventing the degradation reaction from taking place, comprising: disintegration of the sugar beet material into particles where the surface area of the particle is at least 2.0 cm2, immediate exposure of the disintegrated material to a flow of drying gas(es) at a temperature of 25° C. to 160° C. and at a flow rate of 5 m.s−1 to 40 m.s−1, where the relative humidity of the drying gas(es) at the inlet to the drying space in the fluid dryer is at most 85% and were the drying takes place until a dry matter value of at least 70% by weight has been attained.

2. The method according to claim 1, wherein the material is disintegrated into particles, where the smallest dimension of particle is at minimum 0.5 mm.

3. The method according to claim 1, wherein the temperature of the drying gas flow is 45° C. to 119° C.

4. The method according to claim 1, wherein the flow rate of the drying gas is 5.5 m.s−1 to 25 m.s−1.

5. The method according to claim 1, wherein the relative humidity of the drying gas is 0% to 80%.

6. The method according to claim 1, wherein the mixing of the material with the drying gas flow takes place until attaining a value of dry matter of at least 85% by weight.

7. The method according to claim 1, wherein the drying gas is selected from a group consisting of: air, air with reduced oxygen content to at most 12% by volume, nitrogen, a mixture of nitrogen and carbon dioxide, carbon dioxide, preferably the drying gas is carbon dioxide.

8. The method according to claim 7, wherein the drying gas is a mixture of nitrogen and carbon dioxide in a ratio of 10:1 to 1:10.

9. The method according to claim 1, wherein the drying gas is air at a temperature of 25° C. to 140° C.

10. The method according to claim 1, wherein the flow rate of the drying gas in the drying space is inversely proportional to its temperature at inlet, and where the drying gas at a temperature of 25° C. flows at a minimum speed of 12.0 m.s−1, and where the relative humidity of the drying gas at the beginning of the drying is at most 75% by weight.

11. The method according to claim 1, wherein it takes place in an environment in which the radiation intensity with a wavelength of 200 nm to 420 nm is at most 0.010 mW cm−2 and/or the amount of energy emitted in the listed spectrum is at most below 300 mJ cm−2.

12. The method according to claim 1, wherein it takes place in an environment in which the radiation intensity with a wavelength of 200 nm to 1100 nm is at maximum 0.040 mW cm−2, and the amount of energy emitted in the state spectrum is at most below 600 mJ cm−2.

13. The method according to claim 1, wherein the drying takes place in a controlled gas atmosphere, where the oxygen content is at maximum 12% by volume.

14. The method according to claim 1, wherein the disintegrated material is first dried with a drying gas at a temperature above 100° C. for a period of 10 to 30 minutes, with the drying gas temperature being subsequently decreased proportionally with the decrease of the water content in the material down to 90° C. when a moisture content below 30% by weight in dried material is achieved.

15. The method according to claim 1, wherein the disintegrated material is dried with a drying gas at a speed of 7.5 m.s−1 to 9.5 m.s−1 and a temperature of 25° C. to 55° C. until attaining a moisture content below 30% by weight in dried material.

16. The method according to claim 1, wherein the method is repeated successively in the process 1 to 20 times, with the particle size of the mass being reduced each time.

17. The method according to claim 16, wherein the material is in a first stage disintegrated to particles with an average surface area of a particle being in the range of 20 cm2 to 600 cm2, and then the material disintegrated in this manner is dried until the liquid water has been fully evaporated from the particle's surface area, and subsequently the particles are repeatedly disintegrated so that the total average surface area of the material is increased by at least 5% to 1000% against the original average particle area of the material from the first stage where the area of individual particle in each degree of disintegration is always reduced; the material disintegrated in these manner is repeatedly dried in the same way as in the first stage and this process is repeated until the total content of dry matter in the material reaches at least 70% by weight.

18. The method according to claim 1, wherein the temperature of the drying gas flow is 90° C. to 110° C.

19. The method according to claim 1, wherein the flow rate of the drying gas is 6.5 m.s−1 up to 15 m.s−1.

Description

EXAMPLES OF EMBODIMENTS

Example 1

[0065] Sugar beet roots with a moisture content of 78% by weight were grated into particles with a cross-section dimension of approximately 4×3 mm and a length of 40 to 120 mm, the particles of this size formed approximately 85%-90% of the obtained material. The temperature of the material was about 20° C., immediately after grating on an industrial grater the material was transferred to a quarter-operation drum dryer and dried for a maximum of 5 minutes in an air flow with a flow rate of 8.5 ms.sup.−1±0.5 ms.sup.−1 at a temperature of 90° C.±5° C. throughout the process. The air flow in the dryer during the process was from 1750 m.sup.3/h to 1900 m.sup.3/h. The material was dried in a drum dryer with the inner shell of the drum dryer rotating perpendicularly to the direction of drying air flow at a speed of 65 rpm and thus rotating the material during a drying time of 120 minutes. Following the expiry of this drying time, the dry matter content in the material reached a level of 9%±2% by weight. The material after drying was beige-yellow to light green in colour, with no signs of degradation. The particles, which contained the tissues of the outer skin of the sugar beet roots, the epidermis, were, at the place of the epidermis, darker and locally coloured in brown shades with occasional dark spots below the epidermis, which, however, did not generally damage the quality of the material. After drying, the material was stable in atmospheric air also during its storage. The flavour and aroma of the material was typical for sugar beet.

Example 2

[0066] Identically with Example 1, the sugar beet material was disintegrated and dried in the same method, but in the space for disintegrating the sugar beet roots as well as throughout the drying process the electromagnetic radiation of wavelengths from 200 nm to 420 nm was reduced to 0.003 mW.cm.sup.−2 and to 50 mJ.cm.sup.−2. The material was found to be less prone to discolouration and the degradation reactions slowed compared to the processes when the material was dried in Example 1. The effects of radiation reduction were significantly more noticeable when drying temperature was reduced to 55° C. and the drying time was extended from 120 minutes to 300 minutes.

[0067] After the expiry of the drying time, the final moisture content of the material reached a level of 16%±2% by weight. The material was lighter in colour with no black or grey spots apparent in the epidermis as in Example 1. Other features of the dried materiel were similar to Example 1. In a repeated experiment, the material was dried in a flow of nitrogen and carbon dioxide under the same conditions but at a gas flow rate of 5 ms.sup.−1, where the oxygen content was measured by a probe at the outlet of the device and during drying did not exceed 6% by volume in the gas mixture. In the atmosphere of gases, the material was dried with the same result, with no visible degradation, but the resulting colour was lighter and the aroma of the material was assessed as less marked by typical sugar beet odours.

Example 3

[0068] The sugar beet was disintegrated on cutting knives into particles with a cross-section of approximately 3×8 mm and a length of 50 to 100 mm, which formed at least 80% by weight of disintegrated material. The material prepared in this manner was dried in a cabinet tray dryer at an air flow rate of 8.0 m.s.sup.−1 where the tray was made of stainless steel mesh. The material was layered on the trays to a maximum height of 40 mm so that it was loosely poured onto the tray so that the layer be passable for the drying air flow during drying. The material layered in this manner was dried at 65° C. for 5 hours to give the resultant 14% by weight of humidity; the resulting quality of the material was similar to the quality of material obtained in Example 1, but the drying rate was lower in this method. In a repeated experiment, the material after disintegration was cut with a knife calibre of 3×4 mm (cross section) with a length of particles (slices) of up to 70 mm. The material disintegrated in this manner was dried in a flow of air at a flow rate of 9 to 10 m.s.sup.−1 at a temperature of 40° C. for about 280 minutes to a humidity value of 14%±2%. The material was of light green colour without any marks of damage by degradation (without colour changes towards black hues). The flavour and aroma of the material was typical for sugar beet.

Example 4

[0069] The sugar beet was disintegrated into particles with a cross section of 15×8 mm and a length of up to 120 mm, which were dried in a flow of air at a temperature of 35° C. with a flow rate of 15.0 m.s.sup.−1, after 30 minutes the material still contained about 60% by weight of moisture, but the surface of the material was dried and when placed on cellulose filter paper, the particles did not leave a wet surface on the paper. Subsequently, the material was repeatedly disintegrated by grating on a disc grater where more than 75% of particles gained cross-sectional dimensions of approximately 15×8 mm and the length of slices up to 30 mm. The material disintegrated for the second time in this manner was dried fora further 120 minutes, whereby the humidity dropped by about 22% by weight. Subsequently, the material was disintegrated again into particles measuring approximately 10×8×10 mm, and the air temperature was set at 50° C., at which the material was fully dried to the resultant dry matter content of 92% by weight. During the whole process, electromagnetic radiation with wavelengths of 200 nm to 420 nm was reduced so that the radiation energy during drying did not exceed 100 mJ.cm.sup.−2. The material dried in this manner had a lighter colour than the material in Example 1, had a lighter yellow-green colour and a typical aroma of sugar beet, without colour changes to shades of dark or black.

Example 5

[0070] As in Example 4, the sugar beet was fluid dried, but the roots were only quartered and air dried at 25° C. with a flow rate of 12.0 ms.sup.−1 for 30 minutes, after which parts of the roots were cut into parts with an average surface area of particles of about 40 cm.sup.2 and further dried for 30 minutes. By repeated cutting of the particles after drying their surface, their average surface area shrank to about 10 to 15 cm.sup.2, during 60 minutes of drying under unchanged process conditions. Subsequently, the temperature of the drying air was raised to 60° C., the air flow was reduced to 8.0 m.s.sup.−1, and the material was dried for a further roughly 80 minutes, when the dry matter content reached was about 74% by weight. In the last step, the material, cut on knives with a cutting cross-section of 3×3 mm to particles with a surface area of 2.5 cm.sup.2 to 8 cm.sup.2, was dried at 68° C. and an air flow rate of 8.0 to 9.0 m.s.sup.−1 to a dry matter value below 80% by weight. The material had comparable qualities without a sign of degradation as was the case of material in Example 4. Throughout the process the radiation intensity in the space was below 0.005 mW.cm.sup.−2.