초록 ▼

The invention describes a low temperature extrusion process and a respective device for an energy-optimized and viscosity-adapted microstructuring of frozen aerated systems like ice cream. Therewith a very finely dispersed microstructure is reached under optimized balance of viscous friction based m

The invention describes a low temperature extrusion process and a respective device for an energy-optimized and viscosity-adapted microstructuring of frozen aerated systems like ice cream. Therewith a very finely dispersed microstructure is reached under optimized balance of viscous friction based mechanical energy dissipation and transfer of dissipation heat and additional phase transition (freezing) heat to a refrigerant up to very high frozen water fraction at very low temperatures. With this new process and device aerated masses are continuously frozen and optimally micro-structured under minimized/optimized mechanical energy input. The microstructure of this-like treated masses supports on the one hand preferred rheological properties which lead to improved shaping, portioning and scooping properties, even at very low temperatures, and on the other hand leads to an improved shelf life (heat shock stability) and mouth feel (e.g. creaminess, melting behavior).

대표청구항 ▼

1. A device for a low temperature extrusion process for energy optimized, viscosity adapted micro-structuring of frozen aerated masses, the device comprising: at least one extruder screw that comprises a screw flight and rotates within an extruder screw channel formed by an inner barrel wall, the ex

1. A device for a low temperature extrusion process for energy optimized, viscosity adapted micro-structuring of frozen aerated masses, the device comprising: at least one extruder screw that comprises a screw flight and rotates within an extruder screw channel formed by an inner barrel wall, the extruder screw channel having an inner diameter and a length,the length of the extruder screw channel divided into at least three zones comprising an inlet zone (I), middle zone (II), and a final third (III), the device configured to perform a mechanical treatment of a partially frozen, aerated mass over the length of the extruder screw channel with respect to its local viscosity, performed such that, in each of a subsequent zone there is a dispersing of air bubbles/air cells and at the same time temperature decrease and related increase of the frozen water fraction is achieved,the device having a variable screw geometry along the length of the extruder screw channel locally adjusted in each of the at least three zones according to a local viscosity with respect to efficient progressive dispersing, simultaneous progressive temperature reduction and related freezing of water, the extruder screw comprising a screw flight height adjusted along the length of the extruder screw channel for mass viscosity wherein, in the inlet zone (I) of the extruder screw channel, the ratio of the screw flight height to the outer screw diameter is adjusted to between 0.03 and 0.07; in the middle zone (II) of the extruder screw channel, the ratio of the screw flight height to the outer screw diameter is adjusted to between 0.1 and 0.15; and in the final third (III) of the extruder screw channel, the ratio of the screw flight height to the outer screw diameter is adjusted to between 0.1 and 0.25. 2. The device of claim 1, wherein the device has a leakage gap width between the screw flight and the inner barrel wall of less than 0.1 mm. 3. The device of claim 1 further comprising a screw flight thickness between 2 and 20 mm and a screw flight front edge inclination relative to the inner barrel wall of 10-45°. 4. The device of claim 1 further comprising a continuously increasing screw flight height over the length of the extruder screw channel such that an unscrewed contour line of a screw root between mass inlet and outlet, with the centre length axis of the screw forms an angle of 0.03 to 0.1°. 5. Device according to claim 1 comprising 3 to 7 screw flights in a first third of the length of the extruder screw channel; 1-4 screw flights in a second third of the length of the extruder screw channel and 1-3 screw flights in a final third of the length of the extruder screw channel in the vicinity of an extruder outlet. 6. Device according to claim 1 comprising a progressive reduction of a number of screw flights over 2-10 equal or variable length segments of the extruder screw, whereas the number of screw flights is continuously reduced by 1-2 screw flights from segment to segment. 7. Device according to claim 1 comprising screw angles in an inlet zone (I) between 35 and 90°, in a middle of the extruder screw channel between 30 and 45°, and in a final third of the length of the extruder screw channel between 20 and 35°. 8. Device according to claim 1 comprising a constant or variable screw angle reduction between 45 and 90° from an extruder inlet zone (I)-to-between 20 to 35° in an extruder outlet zone (III). 9. Device according to claim 1 comprising cuts in screw flights over a first 10 to 30% of the length of the extruder screw channel. 10. Device according to claim 1 comprising more than one screw flight per extruder screw and cuts in the respective screw flights which are shifted axially such that the mass is subjected to scraping/“wiping off” flow at each part of the inner barrel wall. 11. Device according to claim 1 comprising cuts in screw flights where a length of these cuts is 2.5- to 3-fold of a screw channel height and where the non-cut parts of the screw flights have the same dimensions. 12. Device according to claim 1 comprising inbuilt elements connected to the inner barrel wall, intermeshing with cuts in a screw flight during screw rotation. 13. Device according to claim 1 comprising elements connected to the inner barrel wall at 2-10 different positions arranged at a perimeter of the inner barrel wall. 14. Device according to claim 1 comprising more than one screw flight having cuts in the same axial position to allow for intermeshing with inbuilt elements. 15. A single or twin-screw extruder arrangement for low temperature extrusion of frozen, aerated masses and adapted geometry characteristics, the arrangement comprising: at least one extruder screw that comprises a screw flight and rotates within an extruder screw channel formed by an inner barrel wall, the extruder screw channel having an inner diameter and a length, the length of the extruder screw channel divided into at least three zones comprising an inlet zone (I), middle zone (II), and a final third (III),the arrangement configured to perform a mechanical treatment of a partially frozen, aerated mass over the length of the extruder screw channel with respect to its local viscosity, performed such that, in each of a subsequent zone there is a dispersing of air bubbles/air cells and at the same time temperature decrease and related increase of the frozen water fraction is achieved,the device having a variable screw geometry along the extruder length locally adjusted in each of the at least three zones according to a local viscosity with respect to efficient progressive dispersing, simultaneous progressive temperature reduction and related freezing of water, the variable screw geometry comprisinga screw flight height adjusted along the length of the extruder screw channel for mass viscosity wherein, in the inlet zone (I) of the extruder screw channel, the ratio of the screw flight height to the outer screw diameter is adjusted to between 0.03 and 0.07; in the middle zone (II) of the extruder screw channel, the ratio of the screw flight height to the outer screw diameter is adjusted to between 0.1 and 0.15; and in the final third (III) of the extruder screw channel, the ratio of the screw flight height to the outer screw diameter is adjusted to between 0.1 and 0.25. 16. The device of claim 1, wherein the screw flight height is adjusted along the length of the extruder screw channel to mass viscosity whereas in the inlet zone (I) of the extruder the ratio of the screw flight height to the outer screw diameter is adjusted to 0.05, in the middle (length) zone (II) to 0.125 and in the final third (III) of the extruder length between 0.1 and 0.25. 17. Device according to claim 1 comprising screw angles in an inlet zone (I) of 45°, in a middle of the extruder screw channel between 30 and 45°, and in a final third of the length of the extruder screw channel between 20 and 35°.