Process of compacting a microporous fat powder and compacted fat powder so obtained
The invention relates to a process of compacting a microporous fat powder, notably a microporous fat powder that can suitably be used as an oil structuring agent. The process comprises feeding said fat powder into the feed zone of an extruder having a forwarding screw and a barrel within which the forwarding screw is centrally positioned; rotating the forwarding screw to advance the fat powder feed through a compacting zone of the extruder, where the barrel comprises a plurality of venting openings having a shorter dimension that exceeds the volume weighted average diameter of the fat powder feed and that is less than 10 mm; and expelling the compacted fat powder from the extruder; wherein the temperature of the fat powder during passage through the extruder is maintained below 40° C. and wherein the compaction factor achieved exceeds 1.5.
1. A process for compacting a microporous fat powder in an extruder, said microporous fat powder having the following characteristics:
a fat content of at least 50 wt. %;
a solid fat content at 20° C. (N 20 ) of at least 10 wt. %;
a freely settled density in the range of 10 to 200 g/l;
a particle size distribution with at least 90 vol. % of the particles having a diameter in the range of 3 to 400 μm;
said process comprising:
feeding the fat powder into the feed zone of an extruder having a forwarding screw and a barrel within which said screw is centrally positioned;
rotating said forwarding screw to advance said fat powder feed through a compacting zone of the extruder where the barrel comprises a plurality of venting openings having a shorter dimension that exceeds the volume weighted average diameter of the fat powder feed and that is less than 10 mm; and
expelling the compacted fat powder from the extruder;
wherein the temperature of the fat powder during passage through the extruder is maintained below 40° C. and wherein a compaction factor achieved exceeds 1.5.
2. The process according to claim 1 , wherein an amount of solid fat that is molten during extrusion does not exceed 30% by weight of the fat powder.
3. The process according to claim 1 , wherein at 20° C. the fat powder has a solid fat content of at least 20 wt. %.
4. The process according to claim 1 , wherein the fat powder has a melting point in excess of 40° C.
5. The process according to claim 1 , wherein the compaction factor achieved in the process is in the range of 1.5 to 10.
6. The process according to claim 1 , wherein the shorter dimension of the venting openings exceeds 50 μm.
7. The process according to claim 1 , wherein the venting openings represent 3-60% of the surface area of the barrel in the compacting zone.
8. The process according to claim 1 , wherein the compacted fat powder has a freely settled density of at least 90 g/l.
9. The process according to claim 1 wherein the freely settled density is in the range of 20 to 150 g/l.
10. The process according to claim 1 wherein the particle size distribution is with at least 90 vol. % of the particles having a diameter in the range range of 5 to 300 μm.
11. The process according to claim 2 wherein the amount of solid fat that is molten during extrusion does not exceed 15% by weight of the fat powder.
12. The process according to claim 5 wherein the compaction factor achieved in the process lies in the range of 1.7 to 6.
13. The process according to, claim 8 wherein the compacted fat powder has a freely settled density of 120 to 600 g/l.