Aqueous dispersion of fructan-containing particles, method of preparation and use

Abstract

An aqueous dispersion of fructan-containing particles, wherein the D.sub.50 of the fructan-containing particles lies between 2 μm and 50 μm and the solids content of the aqueous dispersion lies between 61 wt. % and 80 wt. %. Also described is a process for the preparation of an aqueous dispersion of fructan-containing particles comprising: bringing fructan and water together to form a mixture; optionally hydrolyzing a portion of the fructans in the mixture, such that at the end of this step between 5 wt. % and 25 wt. % of all fructans in the mixture are essentially non-soluble at room temperature; optionally bring the mixture into contact with a purification agent, followed by removal of the purification agent from the mixture; and concentrating the mixture such that the solids content lies between 61 and 80%.

Claims

1. A process for preparation of an aqueous dispersion of fructan-containing particles, comprising: a) the step of bringing fructans including fructans in solid particle form having a D.sub.50 of between 2 μm and 50 μM and water together to form a mixture; b) a hydrolysis step, wherein a portion of the fructans in the mixture is hydrolyzed, such that at the end of this step b) between 5 wt. % and 25 wt. % of all fructans in the mixture are in solid particle form and essentially non-soluble in the water at room temperature; c) a concentrating step, wherein the mixture is concentrated, such that a solids content lies between 61 and 80%; and d) during or subsequent to step c) apply shear to the mixture whereby an aqueous dispersion is formed.

2. The process according to claim 1, wherein in step c) an inoculating compound is added to the mixture.

3. The process according to claim 2, wherein during or immediately after step b) the temperature is brought to a level below 40° C.

4. The process according to claim 1, wherein shear step d) is executed in a stirred vessel and for a period of time of between 5 minutes and 48 hours.

5. The process according to claim 2, wherein during step c) a shearing step d) is done, wherein shear is applied to the mixture.

6. The process according to claim 3, wherein subsequent to step c) a shearing step d) is done, wherein shear is applied to the mixture.

7. The process according to claim 1, further comprising a purification step, between step a) and step b), wherein the mixture is brought into contact with a purification step followed by removal of the purification agent from the mixture.

8. The process according to claim 7, wherein the purification agent contains an ion-exchange resin and/or activated carbon.

9. A process for preparation of an aqueous dispersion of an aqueous dispersion of fructan-containing particles, comprising: a) the step of bringing fructans including fructans in particle form having a D.sub.50 between 2 μm and 50 μm and water together to form a mixture; b) a hydrolysis step, wherein a portion of the fructans in the mixture is hydrolysed, such that at the end of this step b) between 5 wt. % and 25 wt. % of all fructans in the mixture are in particle form and essentially non-soluble in the water at room temperature; c) a purification step, wherein the mixture is brought into contact with a purification agent, followed by removal of the purification agent from the mixture; d) a concentrating step, wherein the mixture is concentrated, such that a solids content lies between 61 and 80%; and e) during or subsequent to step d) apply shear to the mixture whereby an aqueous dispersion is formed.

10. The process according to claim 9, wherein in step d) an inoculating compound is added to the mixture.

11. The process according to claim 10, wherein during or immediately after step d) the temperature is brought to a level below 40° C.

12. The process according to claim 9, wherein shear step e) is executed in a stirred vessel and for a period of time of between 5 minutes and 48 hours.

13. The process according to claim 9, wherein step c) is executed and whereby the purification agent contains an ion-exchange resin and/or activated carbon.

14. The process according to claim 10, wherein during step d) and shearing step e) is done, wherein shear is applied to the mixture.

15. The process according to claim 11, wherein subsequent to step d) a shearing step e) is done, wherein shear is applied to the mixture.

16. The process according to claim 10, wherein step c) is executed and whereby the purification agent contains an ion-exchange resin and/or activated carbon.

17. The process according to claim 11, wherein step c) is executed and whereby the purification agent contains an ion-exchange resin and/or activated carbon.

18. The process according to claim 12, wherein step c) is executed and whereby the purification agent contains an ion-exchange resin and/or activated carbon.

Description

(1) The invention will be illustrated by means of the following Figures and Example, without being limited thereto.

(2) In the Figures, FIG. 1 is a photograph of the aqueous dispersion according to Example 1 the invention; this photograph of a sample taken from the top of a container that had stood undisturbed for four months;

(3) FIG. 2 is a photograph of the same aqueous dispersion as in FIG. 1; this photograph, however, is of a sample taken from the bottom of the container;

(4) FIG. 3 presents a Dionex HPAEC (high pressure anion exchange chromatography) chromatogram of the inulin contained in the aqueous dispersion of the invention of Example 1;

(5) FIG. 4 shows a Dionex chromatogram of a native inulin extracted from chicory.

EXAMPLE 1

(6) Measurement of Solid Contents

(7) The determination of solids content was done via measuring the weight difference of a sample before and after vacuum drying. The as such known procedure comprised the following steps: Provision of a small amount of sea sand; Putting the sea sand in a vacuum dryer at 70° C. and at a vacuum of 3500 Pa during 4 hours; weighing of the sea sand, the result being P1 Adding the sample of which the solids content is to be determined to the sea sand; Weighing the thus prepared sample, the result being P2, and putting it in the vacuum dryer at 70° C. and at a vacuum of 3500 Pa during 20 hours; Weighing the sample after drying, the result being P3; Calculating the solids content according to the formula: 100×(P3−P1)/(P2−P1)
Viscosity Measurements

(8) The viscosity was measured in a Rheometer Bohlin CV O50 apparatus. The shear stress was controlled at 1.5 Pa unless noted otherwise. The measurement was conducted at a temperature of 25° C., with no pre-shear being applied and after one hour and a half stabilisation time before measurement.

(9) Measurements of Particle Size

(10) The determination of particle size was done by means of a Mastersizer 2000 apparatus (supplier: Malvern), with Scirocco dry powder feeding unit or a Hydro 2000S unit for liquid samples. The sample was first diluted to a solids content of 60 wt. % and then centrifuged for 90 min at 13000 rpm to separate the suspended particles. After removal of the supernatans, the particles are re-suspended in water to a refractive index of 1.39 and used directly for particle size measurement. The Mastersizer is capable of determining sizes in the 0.02 μm to 2000 μm. As is common in this apparatus, a measurement result is an average of 5,000 measurements done over a period of 5 seconds.

(11) Preparation of Mixture and Aqueous Dispersion

(12) A mixture was formed by bringing 840 kg of inulin—product Orafti GR, supplier Beneo-Orafti—in water such that the inulin was present in 20 wt. %. Inulin GR was characterised by having a number-averaged DP of 12; 70 weight % of the inulin GR had a DP of 11 or more.

(13) The temperature of the mixture was brought to 60° C. The mixture was subjected to a UHT step at 140° C. for 30 seconds.

(14) For the purpose of executing a hydrolysis step, the mixture was then fed into a reactor; the temperature was brought to 60° C., and the pH was lowered to 5.4 by means of H.sub.2SO.sub.4. Subsequently, 280 ml of an endo-inulinase enzyme (Novozymes® 960, batch KNN105) was added. At these conditions, the mixture was allowed to react for 20 hours. The reaction was brought to an end by first raising the pH to 8 with NaOH, then the temperature to 90° C. for 15 minutes; these conditions led to de-activation of the enzymes.

(15) The mixture was cooled to 20° C., in order to execute the purification step: this was done by guiding the mixture through a column with a fixed-bed anion exchange resin type XA100RSCL. Subsequently the pH of the mixture was brought to 6 and the mixture was led over activated carbon (Norit® ROX 0.8) and filtered (0.2-0.4 μm hole size).

(16) The concentration step was executed on the mixture by using a falling film evaporator, in 4 steps, until a solids content of 72% was achieved. In doing so, the aqueous dispersion was formed and immediately cooled to 22° C. with a tube and shell heat exchanger.

(17) Analysis of Aqueous Dispersion

(18) An analysis on the aqueous dispersion as prepared showed that it had the following properties: Solids content: 72% Viscosity: 60 Pa.Math.s D.sub.10: 2.3 μm D.sub.50: 8.0 μm 16 wt. % of carbohydrates, i.e. 11.5 wt. % of the dispersion as a whole, had a DP 11 or more, as measured via Gas Chromatography DP: 6. See also FIG. 3, whereby it is noted that the peak at retention time of 20.0 minutes corresponds to a DP of 10. Stability: very stable; no sedimentation or agglomeration after 4 months of standing, see also FIGS. 1 and 2 where both the absence of agglomeration can be seen as well as the non-occurrence of sedimentation. No gel formation was observed, the aqueous dispersion was—and remained—pumpable

EXAMPLE 2

(19) An aqueous dispersion according to the invention was prepared in the same fashion as in Example 1, with however the following differences: The amount of enzyme added was reduced from 280 ml to 150 ml; Subsequent to the concentration step, the aqueous dispersion was transferred to a vessel equipped with a stirrer and there stirred for 24 hours (shearing step e)).

(20) The aqueous dispersion had the following characteristics: Solids content: 70% D.sub.10: 1.5 μm D.sub.50: 6.0 μm 25 wt. % of the carbohydrates in the aqueous dispersion had a DP of 11 or more as measured via Gas Chromatography Stability: very stable No gel formation was observed, the aqueous dispersion was—and remained—pumpable

EXAMPLE 3

(21) An aqueous dispersion according to the invention was prepared in the same fashion as in Example 1, with however the following differences: The amount of enzyme added was reduced from 280 ml to 130 ml; Subsequent to the concentration step, the aqueous dispersion was transferred to a vessel equipped with a stirrer and there stirred for 24 hours (shearing step e)).

(22) The aqueous dispersion had the following characteristics: Solids content: 70% 30 wt. % of the carbohydrates in the aqueous dispersion had a DP of 11 or more as measured via Gas Chromatography Viscosity: 12500 Pa.Math.s, whereby the viscosity measurement was done with a higher shear stress of 10 Pa (instead of 1.5 Pa) due to the high viscosity of the aqueous dispersion Stability: very stable No gel formation was observed, the aqueous dispersion was—and remained—pumpable