PROCESS FOR THE PREPARATION OF PELLETS

Abstract

The disclosure provides a process for the preparation of pellets containing wheat gluten, including: A preparatory step, in which a raw material containing at least 50 wt. % wheat gluten is brought to a particle size distribution having a D.sub.90 of at most 175 m, to form a feeding material; and A pelletizing step, in which the feeding material is formed into pellets.

Claims

1. A process for the preparation of pellets containing wheat gluten, comprising: A preparatory step, in which a raw material containing at least 50 wt. % wheat gluten is brought to a particle size distribution having a D.sub.90 of at most 175 m, to form a feeding material; and A pelletizing step, in which the feeding material is formed into pellets. means.

2. The process according to claim 1, wherein the raw material consists essentially of vital wheat gluten.

3. The process according to claim 1, wherein the raw material is brought to a particle size distribution wherein the D.sub.50 is at most 80 m and wherein the D.sub.90 is at least 60 m.

4. The process according to claim 3, wherein the raw material is brought to a particle size distribution such that at least 90 wt. % of the feeding material is at most 150 m, preferably at most 140 m in size.

5. The process according to claim 3, wherein the raw material is brought to a particle size distribution wherein the D.sub.50 is between 30 or 40 m and 80 m, and wherein the D.sub.90 is at least 80 or 100 m and at most 150 or 140 m.

6. The process according to claim 3, wherein the raw material is brought to a particle size distribution wherein the D.sub.75 is at least 50 or 60 m and at most 100 m.

7. The process according to claim 1, wherein the pelletizing step is executed in a pelletizing press.

8. The process according to claim 1, wherein the feeding material is humidified prior to being formed into pellets and/or brought to a temperature lying between 30 and 100 C.

9. The process according to claim 8, wherein the humidification is done by an aqueous liquid and/or an aqueous vapour, such that the water content of the feeding material is between 5 and 20 wt. %.

10. The process according to claim 9, wherein the water content of the feeding material is brought to between 6 and 14 wt. %.

11. The process according to claim 1, wherein the pelletizing step is executed such that the bulk density of the pellets is between 50 and 350 kg/m.sup.3 higher than the bulk density of the feeding material.

12. The process according to claim 11, wherein the pelletizing step is executed such that the bulk density of the pellets is between 100 and 250 kg/m.sup.3 higher than the bulk density of the feeding material.

13. The process according to claim 1, wherein the bulk density of the pellets is between 450 and 700 kg/m.sup.3, preferably between 500 and 650 kg/m.sup.3.

14. The process according to claim 1, wherein the pelletizing step is executed in a pellet press or in an extruder.

15. The process according to claim 1, wherein the pelletizing step is executed such that the resulting pellets have a diameter between 3 mm and 8 mm, and a length between 5 mm and 40 mm.

Description

EXAMPLE 1

[0036] Pellets consisting of vital wheat gluten were produced in an industrial-size Bhler Pellet Mill DPHD with an inner diameter of 650 mm, having die holes of 6 mm wide and 60 mm deep.

[0037] In Example 1, a vital wheat gluten was first milled in order to achieve a feeding material having particle size distribution according to the invention (see Table 1 below). Immediately prior to being subjected to the pelletizing step, the feeding material was humidified by mixing with 5 wt. % steam, after which it had an average temperature of 61 C. and a water content of 11 wt. %. Pelletizing was done with a throughput of 6.1 tonnes per hour. The pellets produced had a water content of 8.7 wt. %.

[0038] The pellet durability index (PDI) of the pellets was determined by means of a Holmen NHP 100 pellet tester. The test length was 60 seconds, the pressure was set at 60 mbar. The PDI was determined in the usual way by measuring the weight of the pellets before and after the test and calculating the percentage of weight remaining:

PDI=100(mass of pellets after the test)/(mass of pellets before the test)

[0039] The average PDI was determined to be 96.4%.

Comparative Experiment A

[0040] Vital wheat gluten from the same batch that was used in Example 1 was, in its un-milled form, used for Comparative Experiment A. Pellets were produced in the same installation as was used in Example 1, at the same throughput and using the same amount of steam.

[0041] The average PDI of the pellets produced was determined to be 94.9%, i.e. 1.5% lower than the average PDI of the pellets of Example 1.

[0042] The size fractions of the feeding material as given in Table 1 were obtained via sieving.

TABLE-US-00001 TABLE 1 Example 1 Comparative Experiment A Milled gluten Unmilled gluten Size fractions (wt. %) (wt. %) Up to 80 m 65 28 80 to 100 m 20 15 100 to 140 m 11 17 140 to 160 m 2 7 160 to 200 m 1 9 200 to 280 m 0.5 11 Rest (280 m and bigger) 0.5 13
From Table 1 it follows that the D.sub.90 of the gluten according to Example 1 lies between 100 and 140 m, whereas the D.sub.90 of the gluten according to Comparative Experiment A has a value greater than 280 m.