Process for the production of a powdered composition, the powdered composition obtained thereby and uses thereof

Abstract

The present invention relates to a process for the production of a powdered composition from a liquid composition comprising fat, protein or both, to the powdered composition obtained thereby and products containing said powdered composition.

Claims

1. A process for the production of a powdered composition from a liquid composition comprising fat, protein or both, which process comprises: a) a first atomizing step comprising: i. feeding a mixture of gas and steam into a mixing chamber, and ii. feeding the liquid composition into the mixing chamber containing the mixture of gas and steam by spraying the liquid composition through an inlet nozzle into the mixing chamber so as to obtain a mixture, wherein the liquid composition is atomized through the inlet nozzle, and wherein the mixture of gas and steam creates a non-evaporative zone in which the feeding of the liquid composition into the mixing chamber takes place without simultaneous evaporation, b) a second atomizing step, comprising: i. spraying the mixture out of the mixing chamber through an outlet nozzle and into a drying chamber, wherein the mixture is atomized through the outlet nozzle and c) drying the mixture in the drying chamber, so as to obtain the powdered composition.

2. The process according to claim 1, wherein the gas is air.

3. The process according to claim 1, wherein the liquid composition has a dry matter content from 55 to 70 weight % based on total weight of the liquid composition.

4. The process according to claim 1, wherein the liquid composition has a temperature from 55 to 90 C. when sprayed into the mixing chamber.

5. The process according to claim 1, wherein the weight/hour ratio of gas:steam in the mixing chamber is from 1:0.5 to 1:25.

6. The process according to claim 1, wherein the weight/hour ratio of gas:steam:liquid composition in the mixing chamber is 0.5 to 5:2 to 15:100.

7. The process according to claim 1, wherein the equilibrium temperature in the mixing chamber is from 90 to 155 C.

8. The process according to claim 1, wherein the liquid composition is sprayed into the mixing chamber at a flow-rate from 250 to 700 kg/hour.

9. The process according to claim 1, wherein the mixing chamber has a length of 2 to 10 cm.

10. The process according to claim 1, wherein the pressure in the mixing chamber is 2 to 10 bar.

11. The process according to claim 1, wherein the liquid composition comprises fat, protein and carbohydrates.

12. The process according to claim 1, wherein the liquid composition has a fat content of 20 to 35 weight % based on dry weight of the liquid composition and a protein content of 10 to 25 weight % based on dry weight of the liquid composition.

13. A powdered composition, wherein the powdered composition is obtained according to the process of claim 1.

14. The powdered composition according to claim 13, wherein the powdered composition has a particle size distribution D (v, 0.5) of 80 to 320 m.

15. The powdered composition according to claim 13, wherein the powdered composition has a particle size distribution D (4.3) of 80 to 350 m.

16. The powdered composition according to claim 13, wherein the powdered composition has a bulk density of 0.4 to 0.6 g/ml.

17. A nutritional product comprising the powdered composition according to claim 13, where the nutritional product is a food or feed product.

18. The process according to claim 1, further comprising: collecting the powdered composition from the drying chamber through a recovery outlet.

19. A process for the production of a powdered composition from a liquid composition comprising fat, protein or both, which process comprises: spraying the liquid composition through an inlet nozzle into a mixing chamber containing a mixture of gas and steam having a gas:steam weight ratio of from 1:0.5 to 1:25, wherein the mixture of gas and steam creates a non-evaporative zone in which the spraying of the liquid composition into the mixing chamber takes place without simultaneous evaporation, and wherein the liquid composition is atomized through the inlet nozzle and heated by the mixture of gas and steam to generate a mixture; spraying the mixture out of the mixing chamber through an outlet nozzle and into a drying chamber, wherein the mixture is atomized through the outlet nozzle; and drying the mixture in the drying chamber to generate the powdered composition.

20. The process according to claim 1, wherein feeding a mixture of gas and steam into the mixing chamber comprises separately feeding the gas and steam into the mixing chamber, the steam having a temperature of 164 C. into the mixing chamber at a rate of 21.2 kg/hour and the air having a temperature of 170 C. into the mixing chamber at a rate of 3.8 kg/hour.

21. The process according to claim 1, wherein the gas comprises about 78 vol. % nitrogen, and about 21 vol. % oxygen.

Description

(1) The invention will be further described by way of the non-limiting examples at the accompanying figures.

(2) It is shown in

(3) FIG. 1 a schematically overview of the process according to the present invention;

(4) FIG. 2 the steam and air flow at different equilibrium temperatures in the mixing chamber;

(5) FIG. 3 the bulk and particle density of powdered compositions produced according to the present invention and according to the state of the art as function of the equilibrium temperatures in the mixing chamber resulting form different steam/air ratios and

(6) FIG. 4 SEM pictures of powdered compositions produced according to the present invention and according to the state of the art.

EXAMPLES

Example 1

(7) FIG. 1 shows a schematically overview over the process according to the present invention. FIG. 1 shows an apparatus 100 to conduct a process according to the present invention. The apparatus 100 comprises a mixing chamber 1, an inlet nozzle 2 and an outlet nozzle 3. Furthermore, the apparatus 100 comprises feed pipes 4 to feed a mixture of steam S and gas, in this example air A from a gas chamber 5 into the mixing chamber 1. The apparatus 100 also comprises a drying chamber 6 for drying a mixture coming through the outlet nozzle 3.

(8) A liquid composition LC comprising fat and protein having a temperature from 55 to 90 C. is sprayed in a first atomizing step through the inlet nozzle 2 into the mixing chamber 1. The mixing chamber 1 is also fed with a mixture of overheated steam and air so that a pressure of 5 to 10 bar, for example around 6 bar, is present in the mixing chamber 1. The steam/air mixture creates a non-evaporative zone, where atomization of the liquid composition sprayed through the inlet nozzle 2 which can be for example a pressure nozzle, into the mixing chamber 1 takes place without simultaneous evaporation. This enables atomization at higher viscosities and thus higher dry matter contents. Therefore, the liquid composition can have for example a dry matter content of around 60 to 68%-weight based on total weight of the liquid composition. The small product droplets resulting from atomization are very quickly heated by condensation of the steam on their surfaces. The driving force for this heat transfer is a temperature difference between the liquid composition and the steam. An equilibrium temperature is reached when the liquid composition has reached the steam temperature, which is determined by the steam pressure in the mixing chamber 1. However, the inventors found that a minimum pressure of around 6 bar in the mixing chamber 1 is helpful to get a good second atomization step using the outlet nozzle 3. However, a pressure of 6 bar would result in a steam saturation temperature of 159 C. when using pure steam. This high temperature can lead to product damage.

(9) When both steam and air are present, the steam saturation temperature depends on the partial steam pressure in the mixing chamber 1, which is proportional to the mole fraction of steam in the steam/air mixture. In the steam/air mixture fed into the mixing chamber 1 the actual amount of air can be very low, but when a large part of the steam condenses in the mixing chamber 1, the mole fraction of steam and air start to approach each other and the partial steam pressure decreases. At the point where the declining saturation temperature of the steam meets the increasing product temperature, the equilibrium temperature is reached and heat transfer stops. This point can be determined from the ingoing flows by iterative calculation, so that the equilibrium temperature is known also when no temperature sensor is present in the mixing chamber 1.

(10) Even a very small fraction of steam in the steam/air mixture still provides a non-evaporative zone, enabling atomization at high dry matter. In tests with water the inventors found that a spray coming out of outlet nozzle 3 using pure air instead of steam is much coarser and contains much larger droplets than when a very small amount of steam is added. This indicates the steam effect on atomization.

(11) By choosing a specific weight ratio of air to steam in the mixing chamber 1 and a specific temperature of the overheated steam a specific equilibrium temperature in the mixing chamber 1 can be set resulting in a specific temperature of the liquid composition present in the mixing chamber 1. Suitable equilibrium temperatures in the mixing chamber 1 can be from 90 C. to 155 C. By spraying the liquid composition through the inlet nozzle 2 into the mixing chamber 1 and heating the sprayed liquid composition to the said equilibrium temperature, a first mixture FM is obtained. This first mixture is sprayed through the outlet nozzle 3. At this point a second atomization takes place. A force is created by the gas accelerating in the exit nozzle further breaking up the first mixture into a fine spray which enters the drying chamber 6. The total mass flow through outlet nozzle 3 is dependent from the pressure in the mixing chamber 1 and the gas mass flow fraction.

(12) By spraying the first mixture through the outlet nozzle 3 a second mixture SM is obtained which can be dried by known means, for example by a heated air flow in the drying chamber 6 resulting in the evaporation of the liquid from the second mixture and the accumulation and shaping of a powdered composition. The powdered composition can be obtained through an outlet 7.

Example 2

(13) The apparatus and process shown in FIG. 1 and described in example 1 is used with following parameters:

(14) The mixing chamber is fed with 21.2 kg/hour steam at a temperature of 164 C. and 3.8 kg/hour air at a temperature of 170 C. A liquid composition having a temperature of 81.1 C. is sprayed into the mixing chamber in an amount of 326 kg/hour. The resulting pressure in the mixing chamber is 6.5 bar. The partial pressure of the steam in the mixing chamber is 5.85 bar. The resulting equilibrium temperature present in the mixing chamber is 132 C.

Example 3

(15) Test of Different Steam/air Ratios

(16) A range of steam/air ratios was tested, starting from 100% air and ending at 100% steam. A liquid composition and process settings as defined in table 1 were used:

(17) TABLE-US-00001 TABLE 1 liquid composition and process settings used in the example Fat % 28.3 Protein % 17.8 pH 6.5 Temperature of the liquid composition C. 78 Flow of the liquid composition kg/h 332.0 powder production kg/h 228.0 Dry matter content of the liquid % 67.2 composition

(18) The steam, air and composition flows data where registered for each setting and from these values the equilibrium temperature inside the mixing chamber was calculated. The product flow was found to be between 304 and 337 kg/hour and the dry solids concentration of the emulsion was 67%.

(19) FIG. 2 shows the steam and air mass flows plotted at the calculated equilibrium temperatures. In other trials where the equilibrium temperature was not calculated, but measured inside the mixing chamber similar results were found. This strengthens the reliability of using calculations for the determination of the equilibrium temperature.

(20) When approaching 100% steam, as it was used in the state of the art, it was found that it becomes more difficult to dry the powdered composition correctly. The powdered composition got sticky and some lumps were formed at the fluid bed.

(21) FIG. 3 shows that the steam/air ratio has no strong influence on the bulk and particle density of the powdered composition. However, higher equilibrium temperatures lead to higher bulk and particle densities. The explanation of the trend is the fact that at lower temperatures, more air is present in the gas mixture inside the mixing chamber and this air can be incorporated in the product droplets during the second atomization at the outlet nozzle. When using 100% steam there is no air at all present in the chamber. This results in droplets without included air, resulting in higher densities. However, it is visible from FIG. 3 that using the steam/air mixture according to the present invention results also in satisfying bulk and particle densities without the negative side effects occurring when using steam only and the according high temperatures.

(22) Furthermore, the producing rate for the powdered composition is much higher when using a steam/air mixture due to higher dry matter contents being possible in the liquid composition.

Example 4

(23) The process according to the present invention results in a powdered composition with a desired quality which can be produced in increased amounts.

(24) Furthermore, the obtained powdered composition has specific features making it distinguishable from powdered compositions produced by processes according to the state of the art.

(25) FIG. 4 shows SEM pictures of the powdered composition according to the present invention (FIG. 4a) and of a conventional powdered composition (FIG. 4b).