Liquid espresso concentrate and method for preparing same
Shown is a method of making a coffee concentrate, and a coffee concentrate obtainable by the method. The method involves primary and secondary extraction, with split tapping of the primary extract into a first and second primary draw off. The extraction is conducted under such conditions as to satisfy a minimum mass transfer Fourier number, and a minimum ratio of the extraction yield of the first primary draw-off to the extraction yield obtained in all extraction sections.
1. A method for preparing a coffee concentrate comprising the steps of:
(a) providing ground roasted coffee beans having an average Martin diameter minimal value of from 0.5 to 3 mm;
(b) subjecting the ground roasted coffee beans to primary extraction with water, said primary extraction comprising obtaining a first primary extract with a draw-off factor of at most 2;
(c) drawing off a second primary extract after said first primary extract;
(d) subjecting the primarily extracted ground roasted coffee beans to a secondary extraction with water, so as to obtain a secondary extract;
(e) subjecting the second primary extract and the secondary extract to evaporation and combining the extracts before or after the evaporation, so as to obtain a concentrated extract having a dry solid matter content of from 30 wt. % to 75 wt. %;
(f) combining the concentrated extract with the first primary extract; and
(g) optionally adding water;
so as to obtain a liquid coffee concentrate having a dry solid matter content of from 15 wt. % to 55 wt. %, wherein the primary extraction is conducted under such conditions as to satisfy a mass transfer Fourier number of at least 0.35; and wherein the ratio of the first primary drawn soluble solids yield (Y-PE1) to the total extraction yield for coffee solubles (Y_TE) is in a range of from 0.15 to 1.0.
2. The method according to claim 1 , wherein the Martin diameter minimal value of the ground roasted coffee beans is 0.5 to 2.0 mm.
3. The method according to claim 2 , wherein the average Martin diameter minimal value of the ground roasted coffee beans is 1.4 to 1.9 mm.
4. The method according to claim 1 , wherein the coffee beans have a roasting degree corresponding to a roasting loss of 13% to 20%.
5. The method according to claim 1 , wherein the ground roasted coffee beans of step (a) have been roasted for 7.5 minutes to 15 minutes.
6. The method according to claim 1 , wherein the total extraction yield (Y_TE) ranges from 25% to 45%.
7. The method according to claim 1 , wherein the first primary drawn soluble solids yield (Y-PE1) ranges from 7.5% to 25%.
8. The method according to claim 1 , wherein the ratio of first primary drawn soluble solids yield (Y_PE1) to total extraction yield (Y_TE) ranges from 0.20 to 0.60.
9. The method according to claim 1 , wherein the Fourier number for primary extraction ranges from 0.5 to 1.5.
10. The method according to claim 1 , wherein aroma is recovered by means of steam stripping from the second primary draw-off to obtain a recovered aroma distillate, wherein partial aroma-recovery is applied to 20% to 60% of the total amount of the second primary draw-off, and the recovered aroma distillate is added to the coffee concentrate after evaporation.
11. The method according to claim 1 , wherein the dry solid matter content of the concentrated extract of step (e) after evaporation ranges from 40% solids content to 60% solids content.
12. The method according to claim 1 , wherein the ratio of water-to-coffee bean weight of step (b) is between 2.8 and 15.
13. The method according to claim 1 , wherein the primary extraction is conducted using, as an extraction fluid, water of a temperature between 70° C. and 120° C.
14. The method according to claim 1 , wherein the dry solid matter content of the obtained liquid coffee concentrate ranges from 25 wt. % to 35 wt. %.
15. A coffee concentrate comprising 15% to 55% dry solid matter, obtainable by a method as claimed in claim 1 .
16. A coffee concentrate comprising 15% to 55% dry solid matter, characterized by comprising 1-caffeoylquinic acid lactone (1-CQL) in an amount of at least 450 mg chlorogenic acid equivalents per kg of dry solid matter.
17. The method according to claim 2 , wherein the average Martin diameter minimal value of the ground roasted coffee beans is 1.6 to 1.8 mm.
18. The method according to claim 1 , wherein the ground roasted coffee beans of step (a) have been roasted for 8 to 10 minutes.
19. The method according to claim 1 , wherein the total extraction yield (Y_TE) ranges from 30% to 35%.
20. The method according to claim 1 , wherein the first primary drawn soluble solids yield (Y_PE1) ranges from 10% to 20%.
21. The method according to claim 1 , wherein the ratio of Y_PE1 to Y_TE ranges from 0.30 to 0.40.
22. The method according to claim 1 , wherein the Fourier number for primary extraction ranges from 0.5 to 1.0.
23. The method according to claim 1 , wherein aroma is recovered by means of steam stripping from the second primary draw-off to obtain a recovered aroma distillate, wherein partial aroma-recovery is applied to 20% to 40% of the total amount of the second primary draw-off, and the recovered aroma distillate is added to the coffee concentrate after evaporation.
24. The method according to claim 1 , wherein the ratio of water-to-coffee bean weight of step (b) is between 3 and 10.
25. The method according to claim 1 , wherein the ratio of water-to-coffee bean weight of step (b) is between 4.0 and 8.0.
26. The method according to claim 1 , wherein the primary extraction is conducted using, as an extraction fluid, water of a temperature between 85° C. and 95° C.
27. The coffee concentrate of claim 16 , comprising 1-CQL in an amount of at least 510 mg chlorogenic acid equivalents per kg of dry solid matter.
28. The coffee concentrate of claim 16 , comprising 1-CQL in an amount of at least 590 mg chlorogenic acid equivalents per kg of dry solid matter.