METHOD AND EQUIPMENT FOR THE CONTINUOUS PRODUCTION OF A POROUS POWDERED PRODUCT

Abstract

The present invention relates to a method for producing a powdered porous product from at least one starting powdery and/or viscous product, characterised in that it comprises the continuous following steps without exposing the product to open air: a) preparing the starting product in order to make it viscous; b) in a thermo-mechanical machine (10) for continuously realising transport and/or mixing functions of viscous products or dry-material rich products, lowering the viscosity of the viscous product without changing its dry-material content, by intimate mixing with a gas injected into the processing machine (10) and simultaneously initiating the porosity in the viscous product; c) continuously with the processing machine (10), statically or dynamically intensifying the intimate mixture of the viscous product with a gas in order to obtain an aerated and porous mass; and d), dividing said mass in order to obtain aerated and porous particles.

Claims

1. (canceled)

2. Method according to claim 26, wherein in step a), the starting product is pulverulent, having a of dry matter content of from 70 to 98% by weight and wherein step a) includes one or more of: mixing the pulverulent starting product with at least one ingredient in the thermomechanical treatment machine, and shearing the pulverulent starting product in the thermomechanical treatment machine, and thermos-treating the pulverulent starting product in the thermomechanical treatment machine.

3. Method according to claim 26, in step a), the starting product is pulverulent, having a dry matter content of from 70 to 98% by weight and wherein step a) includes mixing the pulverulent starting product with an added product, that is viscous.

4. Method according to claim 26, wherein in step a) the starting product is, viscous, and wherein step a) includes one or more of: mixing the viscous stating product with at least one ingredient in the thermomechanical treatment machine, shearing the viscous starting product in the thermomechanical treatment machine, and thermo-treating the viscous starting product in the thermomechanical treatment machine.

5. (canceled)

6. Method according to claim 3 wherein the viscous added product has a viscosity greater than 100 mPa.Math.s and a dry matter content of from 50 to 90% by weight.

7. Method according to claim 26, wherein the method further comprises a step d) in which the porous powdered product is further dried.

8. Method according to claim 7 wherein at the end of step d), the porous powdered product has a dry matter content of the order of 96% by weight.

9. Method according to claim 26 wherein the first gas is identical with the second gas mixed.

10. Method according to claim 26, wherein the first gas is carbon dioxide, air, steam, nitrogen or a nitrogen oxide.

11. (canceled)

12. Method according to claim 26 wherein the first gas represents at least 10% of the total of the first gas and the second gas mixed.

13. Method according to claim 26 wherein the viscous product of step a) is milk, powdered milk thereby being obtained as the porous powdered product.

14. Method according to claim 26 wherein the viscous product of step a) is a natural or modified starchy product based on cereal flours, potato flour, potato granules, potato flak, tapioca flour or a mixture thereof, the starting product being in the form of a mixture of the solution, suspension or emulsion type in an aqueous medium.

15. Method according to claim 26 wherein the viscous product of step a) is a natural or modified protein product selected from milk casein, wheat gluten, maize zein, soybean proteins, legume proteins, proteins of oleaproteaginous crops or a mixture thereof, the starting product being in the form of a mixture of the solution, suspension or emulsion type in an aqueous medium.

16. Method according to claim 26 wherein the viscous product of step a) is a milk fractionation co-product obtained by fractionating milk by centrifugation, filtration, nanofiltration, ultrafiltration and/or reverse osmosis, a milk fractionation by-product obtained by fractionating milk by centrifugation, filtration, nanofiltration, ultrafiltration and/or reverse osmosis, a co-product obtained by coagulation of milk, or a mixture thereof.

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

26. Method for producing a porous powdered product, the method comprising: a step a) in which a viscous product is prepared from a starting product that is viscous or pulverulent, so that at the end of step a), the viscous product has a viscosity greater than 100 mPa.Math.s, a step b) in which the viscous product of step a) is treated in a thermomechanical treatment machine into which a first gas is injected and then in a static or dynamic aeration device into which a second gas is injected, the step b) including two successive sub-steps b1) and b2) which are performed continuously and without exposing the ongoing treated product to the open air both during and between the sub-steps b1) and b2), and wherein: in sub-step b1), the viscous product of step a) and the first gas are mixed in the thermomechanical treatment machine to obtain an intermediate mixture having a dry matter content that is unchanged from the viscous product of step a), so that at the end of sub-step b1), the intermediate mixture has a viscosity that is lower than the viscosity of the viscous product of step a) and porosity is initiated in the intermediate mixture, and in sub-step b2), the intermediate mixture of sub-step b1) and the second gas are mixed in the aeration device to obtain a treated product in the form of an aerated and porous mass, and a step c) in which the treated product of sub-step b2) is spray dried to obtain the porous powdered product, so that at the end of step c), the porous powdered product has particles having a dry matter content of from 50 to 90% by weight and a particle size less than or equal to 3 mm.

27. Method according to claim 3, wherein step a) further includes one or more of: before mixing the pulverulent starting product with the viscous added product, mixing the pulverulent starting product with at least one ingredient in the thermomechanical treatment machine, after mixing the pulverulent starting product with the viscous added product, shearing the pulverulent starting product mixed with the viscous added product in the thermomechanical treatment machine, and after mixing the pulverulent starting product with the viscous added product, thermo-treating the pulverulent starting product mixed with the viscous added product in the thermomechanical treatment machine.

28. Method according to claim 4, wherein the viscous starting product has a viscosity greater than 100 mPa.Math.s and a dry matter content of from 50 to 90% by weight.

29. Method according to claim 26, wherein the first gas is different from the second gas.

30. Method according to claim 26, wherein the second gas is carbon dioxide, air, steam, nitrogen or a nitrogen oxide.

31. Method according to claim 26, wherein at the end of step a), the viscous product has a viscosity greater than 200 mPa.Math.s.

32. Method according to claim 14, wherein the cereal flour is wheat flour, oat flour, maize flour, barley flour or a mixture thereof

33. Method according to claim 26, wherein the thermomechanical treatment machine is an extrusion machine having two co-rotating and co-penetrating screws which are driven in rotation at a speed of from 50 to 1200 rpm, and wherein each screw has a part in which sub-step b1) is performed, which has a length representing between 3 and 12 times of a diameter of the screw.

34. Method according to claim 26, wherein at the end of step a), the viscous product has a dry matter content of from 10 to 90% by weight.

Description

[0043] Other features and advantages of the invention will become apparent from the following description, which is given with reference to the accompanying drawings, in which:

[0044] FIG. 1 is a front view, in diagrammatic form, of equipment for the production of a porous powdered product from a starting product in the viscous state, according to the invention,

[0045] FIG. 2 is a front view, in diagrammatic form, of equipment for the production of a porous powdered product from a pulverulent starting product with mixing with a viscous product, according to the invention,

[0046] FIG. 3 is a curve showing the change in the viscosity of a product, for example skimmed milk.

[0047] FIGS. 1 and 2 show, in diagrammatic form, equipment for the continuous production of a porous powdered product from at least one pulverulent and/or viscous product, which equipment comprises two main elements located one after the other, a thermomechanical treatment machine designated as a whole by the reference numeral 10, and a static or dynamic aeration device designated by the general reference numeral 20 for mixing the product leaving the thermomechanical treatment machine 10 with a gas, as will be seen hereinbelow.

[0048] The thermomechanical treatment machine is preferably constituted by an extrusion machine 10 having two co-rotating and co-penetrating screws.

[0049] In that case, and in a known manner, the extrusion machine 10 comprises two screws (not shown) which are driven in rotation about their axes by a motor and a reduction gear, which are designated by the general reference numeral 11, inside an elongate vessel forming a sleeve 12 which envelops them. The screws of the extrusion machine 10 are equipped especially with helical threads or other elements for treating the product introduced into the sleeve 12 and which engage with one another. The helical threads or the elements forming the screws of the extrusion machine 10 determine different treatment zones for the product introduced into the sleeve 12.

[0050] The starting product is constituted by: [0051] a viscous product having a content of dry matter of from 50 to 90% and a viscosity greater than 100 mPa.Math.s and preferably greater than 200 mPa.Math.s (FIG. 1), said viscous product being from the same family as the product to be obtained, or [0052] at least one pulverulent product which has a content of dry matter of from 70 to 98% and is mixed with a viscous product having a content of dry matter of from 50 to 90% and a viscosity greater than 100 mPa.Math.s and preferably greater than 200 mPa.Math.s (FIG. 2), or [0053] at least one pulverulent product having a content of dry matter of from 70 to 98%.

[0054] The sleeve 12 is equipped at its upstream end, relative to the direction of flow of the product indicated by the arrow F, with a feed orifice (not shown) surmounted by means 13 for introducing the product to be treated into the extrusion machine 10.

[0055] In general, the starting product undergoes various treatments and various modifications in the extrusion machine 10 and in the aeration device 20 in order to obtain a porous powdered product which is in the form of aerated and porous particles.

[0056] Referring now to FIG. 1, the equipment 10 will be described in the case where the starting product is a viscous product from the same family as the final product obtained. In this case, the starting product in the viscous state is prepared before it is introduced into the extrusion machine 10.

[0057] The extrusion machine 10 is composed of a plurality of zones comprising, according to the nature of the starting product: [0058] a first zone A1 which is a transport zone for the product or rich in dry matter and/or a zone for mixing with at least one ingredient and a heat treatment zone, [0059] a second zone B1 which is a transport zone for the product in the viscous state obtained in zone A1, zone B1 is a transport, shearing and heat treatment zone for the product, [0060] a third zone C1 in which the viscosity of the product in the viscous state is lowered and porosity is simultaneously initiated in the product in the viscous state, the third zone C1 likewise being a heat treatment zone for the product.

[0061] In zone A1 of the extrusion machine 10, different ingredients I can be introduced through one or more orifices provided in the sleeve 12, for example lecithin and/or water and/or flavorings and/or colorings and/or other appropriate ingredients, in order to mix them with the starting product.

[0062] In zone C1, the sleeve 12 of the extrusion machine 10 has at least one orifice for injecting into said sleeve 12 a gas G which is intimately mixed with the product in the viscous state in order to lower the viscosity of the product in the viscous state without changing its content of dry matter.

[0063] Simultaneously with the lowering of the viscosity of the product in the viscous state, porosity is initiated in the product in the viscous state by the injection of the gas. Intimate mixing of the product in the viscous state and the gas is facilitated by the working of the product in the co-penetrating and co-rotating screws of the extrusion machine 10.

[0064] The gas injected into zone C1 of the extrusion machine 10 is, for example, carbon dioxide, air, steam, nitrogen or an oxide thereof.

[0065] By way of example, the screws of the extrusion machine 10 are driven in rotation at a speed of from 50 to 1200 rpm and zone C1 has, for example, a ratio L/D between the length L of zone C1 and the diameter D of the screws of the extrusion machine of from 3 to 12.

[0066] The product at the outlet from the thermomechanical treatment machine has a concentration of dry matter of from 50 to 90%.

[0067] At the outlet from the extrusion machine 10, the product in the viscous state, the viscosity of which has been lowered in zone C1 of the extrusion machine 10, is transferred directly and continuously, and without being exposed to the open air, to the static or dynamic aeration device 20.

[0068] In the aeration device 20, the intimate mixing of the product in the viscous state with a gas is intensified in order to obtain an aerated and porous mass.

[0069] In the device 20, the gas injected is, for example, carbon dioxide, air, steam, nitrogen or an oxide thereof.

[0070] In the case of a static aeration device, the device 20 is constituted, for example, by a helical mixer, and in the case of a dynamic aeration device, the device 20 is constituted by a device equipped with agitator blades.

[0071] The totality of the treatment of the product in the viscous state in the extrusion machine 10 and in the aeration device 20 is carried out continuously and without exposing the product to the open air.

[0072] Accordingly, the device 20 is located directly at the outlet of the extrusion machine 10 or is connected to the outlet of the extrusion machine 10 by a joining element constituted, for example, by at least one leak-tight and continuous tube.

[0073] At the outlet from the device 20, the equipment comprises a means for separating the aerated and porous mass so obtained in order to obtain aerated and porous particles which are smaller than 3 mm and preferably smaller than 2 mm. The separation means is constituted, for example, by orifices provided at the outlet from the device 20.

[0074] The percentage of gas in total injected into the extrusion machine 10, expressed as percent by volume based on the dry mass of the product treated in said machine 10, is from 0.01 nl.kg.sup.1.mn.sup.1 to 10 nl.kg.sup.1.mn.sup.1, the volume of gas being expressed under normal temperature and pressure conditions.

[0075] The gas injected into zone C1 represents from 30 to 60% of the total amount of gas injected into the equipment, and the gas injected into the device 20 represents from 40 to 70% of the total amount of gas injected.

[0076] The particles so obtained have a concentration of dry matter of from 50 to 90%, a solubility greater than 90% and an internal porosity greater than 50%.

[0077] At the outlet from the aeration device 20, the equipment can comprise a device for drying the aerated and porous particles, and the drying device is formed by at least one fluidized-bed dryer or by at least one atomizing tower or by a counter-current vertical dryer or by a conveyor dryer. After this additional drying, the particles have a concentration of dry matter of the order of 96%.

[0078] Referring now to FIG. 2, the equipment 10 will be described in the case where the starting product is at least one pulverulent product.

[0079] The extrusion machine 10 is composed of a plurality of zones comprising, according to the nature of the starting product: [0080] a first zone A1 which is a transport zone for said at least one pulverulent product and/or a zone for mixing with at least one ingredient and/or a heat treatment zone in which the product is brought to a temperature of from 20 to 80 C., [0081] a second zone A1 which is a zone for mixing of the product obtained in zone A1 with a viscous product from the same family as the final product to be obtained and for heat treatment of the mixture brought to a temperature of from 40 to 200 C., said viscous product having a content of dry matter of from 50 to 90% and a viscosity greater than 100 mPa.Math.s and preferably greater than 200 mPa.Math.s, [0082] a third zone B1 which is a transport and shearing zone for the product in the viscous state and in which the product in the viscous state is maintained at a temperature of from 40 to 200 C., and [0083] a fourth zone C1 in which the viscosity of the product in the viscous state is lowered and porosity is simultaneously initiated in the product in the viscous state while maintaining the product at a temperature of from 40 to 200 C.

[0084] The sleeve 12 is equipped at the start of zone A1 with a feed orifice (not shown) surmounted by means 13a for introducing the product to be treated into the extrusion machine 10.

[0085] In zones A1 and A1 of the extrusion machine of FIG. 2, different ingredients I can be introduced through one or more orifices provided in the sleeve 12, for example lecithin and/or water and/or flavorings and/or colorings or other appropriate ingredients, in order to mix them with the starting product.

[0086] Analogously to zone C1 of the first embodiment shown in FIG. 1, the sleeve 12 of the extrusion machine of the second embodiment shown in FIG. 2 has at least one orifice for injecting into said sleeve a gas G which is mixed intimately with a product in the viscous state in order to lower the viscosity of the product in the viscous state without changing its content of dry matter.

[0087] The gas injected into zone C1 of the extrusion machine 10 is, for example, carbon dioxide, air, steam, nitrogen or an oxide thereof.

[0088] The speed of rotation of the screws of the extrusion machine 10 is identical with that of the preceding embodiment, and the characteristics of the screws are analogous.

[0089] At the outlet from the extrusion machine 10, the product in the viscous state, the viscosity of which has been lowered in zone C1 of the extrusion machine 10, is likewise transferred directly and continuously, and without being exposed to the open air, to the static or dynamic aeration device 20, which is identical with that of the preceding embodiment.

[0090] In the aeration device 20, the intimate mixing of the product in the viscous state with a gas is intensified in order to obtain an aerated and porous mass.

[0091] In the device 20, the gas injected is, for example, carbon dioxide, air, steam, nitrogen or an oxide thereof.

[0092] The gas injected into zone C1 of the embodiment of FIG. 2 represents from 10 to 80% of the total gas injected into the equipment, and the gas injected into the device 20 represents from 20 to 90% of the total amount of gas injected.

[0093] At the outlet from the device 20, the particles so obtained have a temperature of from 20 to 90 C. and a particle size less than or equal to 3 mm.

[0094] The equipment can also comprise a device for drying the aerated and porous particles at the outlet from the aeration device 20, and the resulting particles have a concentration of dry matter of the order of 96%.

[0095] The gas injected into the extrusion machine 10 can be identical with or different from the gas injected into the device 20.

[0096] In general, a first operation of mixing the product in the viscous state with a gas is carried out in the thermomechanical treatment machine 10, and a second operation of mixing the product in the viscous state with a gas is carried out in the aeration device 20. The second mixing operation in the aeration device 20 is carried out under pressure.

[0097] According to a first example, the product in the viscous state is milk, powdered milk thereby being obtained.

[0098] According to a second example, the product in the viscous state is a natural or (physically and/or chemically) modified starchy product based on cereal (wheat, oat, maize, barley, etc.) flours, potato flour, potato granules, potato flakes and/or tapioca flour, the product initially being in the form of a mixture of the solution, suspension or emulsion type in an aqueous medium, the method yielding the product in pulverulent form.

[0099] According to a third example, the product in the viscous state is a natural or (physically and/or chemically) modified protein product selected from milk casein, wheat gluten, maize zein, soybean proteins, legume proteins, in particular pea proteins and/or proteins of oleaproteaginous crops, in particular sunflower or rape, the product initially being in the form of a mixture of the solution, suspension or emulsion type in an aqueous medium, the method yielding the product in pulverulent form.

[0100] According to a fourth example, the product in the viscous state is a milk fractionation co-product/by-product obtained by fractionating milk by centrifugation, filtration, nanofiltration, ultrafiltration and/or reverse osmosis, or a co-product obtained by coagulation of milk.

[0101] In general, the method according to the invention carried out using the equipment which combines an extrusion machine, in which the viscosity is lowered and porosity is initiated, and a static or dynamic aeration device, in which the increase in the porosity of the product is continued, therefore makes it possible to work very viscous products and to aerate them while structuring their porosity, which is not the case with the methods used hitherto.

[0102] In fact, as is shown by way of example in FIG. 3, which shows the change in the viscosity of a product such as skimmed milk as a function of its percentage of dry matter, it will be seen that the viscosity of the product increases exponentially from a content of 50% dry matter. For other products, the curves may be different but show the same exponential increase, with a marked reversal point corresponding to a content of dry matter which is generally from 10 to 90%, depending on the nature and composition of the solutions, suspensions or emulsions under consideration.

[0103] The technological solutions known hitherto, which allow the product to be treated below the reversal point of the curve, are not suitable beyond that point.

[0104] In the case of skimmed milk, for example, it will be seen that a technological jump must be imagined and implemented in order to be able to transport, mix, aerate that product at a content of dry matter greater than 50% owing to its viscosity, which becomes very high.

[0105] The method and equipment according to the invention therefore allow very viscous products having a concentration of dry matter of from 50 to 90% to be handled and treated, and aerated and porous particles having good characteristics of porosity, wettability, instant solubility and apparent density to be obtained.

[0106] Depending on the nature of the product, the content of dry matter can vary from 10 to 90% with a viscosity greater than 100 mPa.Math.s.

[0107] Moreover, the method and equipment according to the invention allow productivity to be improved while energy costs are reduced.

[0108] According to a variant, the starting product can be constituted by at least one pulverulent product having a content of dry matter of from 70 to 98% without being mixed with a product in the viscous state. In this case, the equipment is identical with the equipment of FIG. 2.

EXAMPLES

A. Powdered Milk

[0109] Starting product: concentrated milk with a concentration of dry matter of 65% and a viscosity greater than 1000 mPa.Math.s [0110] Extrusion machine 10: [0111] zone A: optional mixing with lecithin [0112] zone C: injection of 50% of the total amount of gas [0113] temperature of the product below 50 C. [0114] Aeration device 20 [0115] injection of 50% of the total amount of gas [0116] temperature of the product below 50 C. [0117] Resulting particles smaller than 2 mm with a concentration of dry matter of from 65 to 85%.

B. Instant Drinks

1 ST EXAMPLE

[0118] Starting product: oat flour 55%sugar 37%chocolate powder 8% [0119] Extrusion machine [0120] zone A: mixing with water [0121] temperature of the product from 120 to 150 C. [0122] zone B: viscous product with a concentration of dry matter of from 60 to 70% [0123] temperature of the product from 120 to 150 C. [0124] zone C: injection of carbon dioxide 80% of the total amount of gas [0125] temperature of the product of the order of 70 C. [0126] Aeration device 20 [0127] injection of carbon dioxide 20% of the total amount of gas [0128] temperature of the product of the order of 60 C. [0129] Resulting particles smaller than 3 mm with a concentration of dry matter of from 60 to 80 A.

2 ND EXAMPLE

[0130] Starting product: maize flour 91.5%cassava starch 8%calcium carbonate 0.5% [0131] Extrusion machine [0132] zone A: mixing with water [0133] temperature of the product from 60 to 100 C. [0134] zone B: viscous product with a concentration of dry matter of from 60 to 80% [0135] temperature of the product from 120 to 150 C. [0136] zone C: injection of carbon dioxide 90% of the total amount of gas [0137] temperature of the product from 150 to 200 C. [0138] Aeration device 20 [0139] injection of carbon dioxide 10% of the total amount of gas [0140] temperature of the product of the order of 90 C. [0141] Resulting particles smaller than 3 mm with a concentration of dry matter of from 70 to 90%.