METHOD FOR PRODUCING DECAFFEINATED RAW COFFEE BEANS, DECAFFEINATED ROASTED COFFEE BEANS OR PREPARATIONS PRODUCED THEREFROM, CORRESPONDING DECAFFEINATED RAW COFFEE BEANS, DECAFFEINATED ROASTED COFFEE BEANS AND PREPARATION PRODUCED THEREFROM, CORRESPONDING USES AND CORRESPONDING SYSTEMS
20230071419 · 2023-03-09
Assignee
Inventors
Cpc classification
A23F5/206
HUMAN NECESSITIES
A23F5/02
HUMAN NECESSITIES
A23L3/32
HUMAN NECESSITIES
International classification
A23F5/02
HUMAN NECESSITIES
Abstract
A process for producing decaffeinated green coffee beans, decaffeinated roasted coffee beans or preparations produced therefrom is described, wherein one process step comprises the PEF (pulsed electric field) treatment of (optionally presoaked) green coffee beans. Also described is a decaffeinated green coffee bean, a decaffeinated roasted coffee bean, and a preparation produced therefrom, and also the use of a PEF device for the treatment of (optionally presoaked) green coffee beans. A system for decaffeinating green coffee beans is additionally described.
Claims
1. A process for producing decaffeinated green coffee beans, decaffeinated roasted coffee beans or preparations produced therefrom, comprising the following steps: (b) subjecting green coffee beans to PEF treatment, with the result that PEF-treated green coffee beans are obtained, (c) extracting of caffeine from the PEF-treated green coffee beans using an extraction liquid, with the result that decaffeinated, PEF-treated green coffee beans are obtained.
2. The process as claimed in claim 1, comprising the following steps: (a-v) presoaking of green coffee beans with swelling liquid, with the result that presoaked green coffee beans are obtained, preferably presoaked green coffee beans having a predetermined moisture content, (b-v) subjecting the presoaked green coffee beans to PEF treatment, with the result that PEF-treated, presoaked green coffee beans are obtained, (c-v) extracting of caffeine from the PEF-treated, presoaked green coffee beans using an extraction liquid, with the result that decaffeinated, PEF-treated, presoaked green coffee beans are obtained.
3. The process as claimed in claim 2, wherein the swelling liquid is an aqueous swelling liquid.
4. The process as claimed in claim 1, wherein the extraction liquid is selected from the group consisting of: liquid carbon dioxide, supercritical carbon dioxide, dichloromethane, dichloroethane, ethanol, trichloromethane, trichloroethane, acetone, ethyl acetate, methyl acetate, methanol, coffee oil, and water, preferably selected from the group consisting of: water, ethyl acetate, liquid carbon dioxide, supercritical carbon dioxide, and dichloromethane particularly preferably selected from the group consisting of: liquid carbon dioxide and dichloromethane.
5. The process as claimed in claim 1, comprising the following additional step: (d) drying of the decaffeinated, PEF-treated green coffee beans, preferably decaffeinated, PEF-treated, presoaked green coffee beans, with the result that dried, decaffeinated green coffee beans are obtained, preferably dried, decaffeinated green coffee beans having a predetermined moisture content.
6. The process as claimed in claim 5, wherein the drying of the decaffeinated, PEF-treated, green coffee beans, preferably the drying of decaffeinated, PEF-treated, presoaked green coffee beans, is carried out by means of a process selected from the group consisting of: fluidized-bed processes, vacuum-drying processes, vibration drying, freeze drying, hot-air drying, microwave drying, infrared drying, and combinations thereof, and that is preferably selected from the group consisting of: fluidized bed processes, vacuum drying processes, and combinations thereof, wherein the drying process preferably comprises at least fluidized-bed drying, particularly preferably in combination with vacuum drying, and wherein the vacuum drying is very particularly preferably carried out first, followed by the fluidized-bed drying.
7. The process as claimed in claim 1, wherein the PEF treatment creates irreversible pores in the cell membranes and cell walls of the green coffee beans.
8. The process as claimed in claim 1, wherein the green coffee beans, preferably the presoaked green coffee beans, have after the PEF treatment a smaller number of coliform bacteria than before the PEF treatment, in each case determined in accordance with ISO 4832.
9. The process as claimed in claim 1, wherein during the PEF treatment of the green coffee beans in step (b) or of the presoaked green coffee beans in step (b-v) a pulse field strength of at least 0.2 kV/cm, preferably at least 1.0 kV/cm, particularly preferably at least 1.5 kV/cm, very particularly preferably at least 2.7 kV/cm, most preferably a pulse field strength within a range from 0.5 kV/cm to 3 kV/cm, is applied, and or an actual energy input of at least 5 kJ/L, preferably at least 15.0 kJ/L, takes place, and or the green coffee bean is exposed to at least 5 pulses of the pulsed electric field, preferably at least 10 pulses, particularly preferably at least 18 pulses, very particularly preferably at least 20 pulses, most preferably at least 25 pulses, preferably within a range from 5 to 100 pulses, particularly preferably within a range from 5 to 50 pulses, and or the green coffee beans at least initially have a moisture content of at least 10%, preferably at least 20%, particularly preferably at least 30%, very particularly preferably at least 40%, preferably a moisture content within a range from 10 to 50%, particularly preferably within a range from 20 to 45%, determined in accordance with ISO 6673.
10. The process as claimed in claim 2, wherein presoaking of green coffee beans with soaking liquid in step (a-v) is accompanied by absorption of at least 10% by weight of soaking liquid, preferably at least 20% by weight, particularly preferably at least 30% by weight, based on the total mass of the green coffee beans before presoaking.
11. A decaffeinated green coffee bean, decaffeinated roasted coffee bean or preparation produced therefrom, producible by a process as claimed in claim 1, wherein the PEF treatment of green coffee beans results in changes to the cell walls and cell membranes in the green coffee beans.
12. The use of a PEF device for the PEF treatment of green coffee beans.
13. The use as claimed in claim 12, wherein the PEF treatment is carried out before decaffeination, and or before and/or after presoaking, and or before and/or after drying, and or before roasting and or to reduce the microorganism content of the green coffee beans and or to improve the caffeine extractability of the green coffee beans.
14. A system for decaffeinating green coffee beans in a process as claimed in claim 1, comprising at least: a device for the PEF treatment of green coffee beans, a device connected downstream thereof for decaffeinating the PEF-treated green coffee beans, a device for drying the decaffeinated green coffee produced, wherein the drying of the decaffeinated, PEF-treated green coffee beans is carried out by means of a process selected from the group consisting of: fluidized bed processes, vacuum drying processes, and combinations thereof.
15. The system as claimed in claim 14, further comprising a device for presoaking green coffee beans connected upstream or downstream of the device for PEF treatment and or a device for removing adhering water from green coffee beans, preferably comprising a spiral dryer and/or a blower, that is connected downstream of the device for PEF treatment and or a device for the transfer and/or transport of the decaffeinated green coffee produced.
Description
FIGURES
[0191] The invention is elucidated in more detail hereinbelow with reference to figures.
[0192]
[0193] In a first step 102 of the process 100, the employed green coffee beans 101 are presoaked with swelling liquid, with the result that presoaked green coffee beans 103 are obtained. In the process according to the invention, it is particularly advantageous when the presoaking of the employed green coffee beans with soaking liquid takes place in an inventive system in which a device for presoaking green coffee beans (as described above, preferably as referred to above as preferred) is connected upstream of the device for PEF treatment.
[0194] In a second step 104 of the process 100, the presoaked green coffee beans 103 thus obtained are subjected to PEF treatment, with the result that PEF-treated, presoaked green coffee beans 105 are obtained. In the process according to the invention, it is particularly advantageous when the PEF treatment of the employed green coffee beans takes place in an inventive system that includes a device for the PEF treatment of green coffee beans (as described above, preferably as referred to above as preferred).
[0195] In a further step 106 of the process 100, the caffeine is extracted from the PEF-treated, presoaked green coffee beans 105, with the result that decaffeinated, PEF-treated, presoaked green coffee beans 107 are obtained. In the process according to the invention, it is particularly advantageous when the extraction of caffeine (decaffeination) takes place in an inventive system that includes a device for the PEF treatment of green coffee beans and, connected downstream thereof, a device for decaffeinating the PEF-treated green coffee beans (as described above, preferably as referred to above as preferred).
[0196]
[0197] In a next step of the process 200, the caffeine is then extracted from the presoaked green coffee beans 106, with the result that decaffeinated, presoaked green coffee beans 107 are obtained. PEF treatment does not take place in this noninventive comparative example.
[0198]
[0199] Green coffee beans having a moisture content of approx. 8-12% 301 are presoaked with aqueous swelling liquid 302 to a moisture content of 45%, with the result that presoaked green coffee beans 303 are obtained. It is particularly advantageous when the presoaking of the employed green coffee beans having a moisture content of approx. 8-12% with aqueous soaking liquid to a moisture content of 45% takes place here in an inventive system wherein a device for presoaking green coffee beans (as described above, preferably as referred to above as preferred) is connected upstream of the device for PEF treatment.
[0200] In a next step 304 of the process 300, the PEF treatment of the presoaked green coffee beans takes place, with the result that PEF-treated, presoaked green coffee beans having adhering water 305 are obtained. It is particularly advantageous when the PEF treatment of the employed green coffee beans takes place here in an inventive system that includes a device for the PEF treatment of green coffee beans (as described above, preferably as referred to above as preferred). In a next step 306 of the process 300, the adhering water is removed by means of a spiral dryer and a blower, with the result that PEF-treated, presoaked green coffee beans 307 are obtained. It is particularly advantageous when the removal of the adhering water from the PEF-treated green coffee beans takes place here in an inventive system wherein connected downstream of the device for PEF treatment there is a device (as described above, preferably as referred to above as preferred) for removing adhering water from green coffee beans, comprising a spiral dryer and a blower.
[0201] In a next step 308 of the process 300, the caffeine is extracted from the PEF-treated, presoaked green coffee beans using liquid CO.sub.2, with the result that decaffeinated, PEF-treated, presoaked green coffee beans 309 are obtained. It is particularly advantageous when the extraction of caffeine (decaffeination) takes place here in an inventive system that includes a device for decaffeinating the PEF-treated green coffee beans (as described above, preferably as referred to above as preferred).
[0202] In a further step 310 of the process 300, the decaffeinated, PEF-treated, presoaked green coffee beans undergo vacuum drying to a moisture content of 20-25%, with the result that decaffeinated, PEF-treated, presoaked green coffee beans 311 are obtained. It is particularly advantageous when the vacuum drying takes place here in an inventive system that includes a device for (vacuum) drying the decaffeinated green coffee that has been produced.
[0203] In a next step 312 of the process 300, the decaffeinated, PEF-treated, presoaked green coffee beans undergo fluidized-bed drying to a residual moisture content of 9-13%, with the result that dried, decaffeinated, green coffee beans 313 are obtained. It is particularly advantageous when the fluidized-bed drying takes place here in an inventive system that includes a device for drying the decaffeinated green coffee that has been produced.
[0204]
[0205] In a first step 402 of the process 400, green coffee having a moisture content of 8-12% 401 undergoes presoaking with a swelling liquid to a moisture content of approx. 45%, with the result that presoaked green coffee beans 403 are obtained.
[0206] In a further step 404 of the process 400, the presoaked green coffee beans 403 pass through a switched off PEF apparatus, with the result that PEF treatment does not take place and presoaked green coffee beans having adhering water 405 are obtained.
[0207] In a further step 406 of the process 400, the water adhering to the presoaked green coffee beans having adhering water is removed by means of a spiral dryer and a blower, with the result that presoaked green coffee beans 407 are obtained.
[0208] In a further step 408 of the process 400, the caffeine is extracted from the presoaked green coffee beans using liquid CO.sub.2, with the result that decaffeinated, presoaked green coffee beans 409 are obtained.
[0209] In a further step 410 of the process 400, the decaffeinated, presoaked green coffee beans undergo vacuum drying to a residual moisture content of 20-25%, with the result that decaffeinated, presoaked green coffee beans 411 are obtained.
[0210] In a further step 412 of the process 400, the decaffeinated, presoaked green coffee beans undergo fluidized-bed drying to a residual moisture content of 9-13%, with the result that dried, decaffeinated, green coffee beans 413 are obtained.
[0211]
[0212] In a first step 502 of the process 500, green coffee having a moisture content of 8-12% 501 is hydrated and presoaked in a glass reactor using 150-250 g of steam per 500 g of coffee, with the result that presoaked green coffee beans 503 are obtained.
[0213] In a further step 504 of the process 500, the presoaked green coffee beans 503 are subjected to PEF treatment, with the result that PEF-treated, presoaked green coffee beans having adhering water 505 are obtained.
[0214] In a further step 506 of the process 500, the water adhering to the PEF-treated, presoaked green coffee beans having adhering water is removed by means of a spiral dryer and a blower, with the result that PEF-treated, presoaked green coffee beans 507 are obtained.
[0215] In a further step 508 of the process 500, caffeine is extracted from the PEF-treated, presoaked green coffee beans with dichloromethane in a Soxhlet apparatus, with the result that decaffeinated, PEF-treated, presoaked green coffee beans 509 are obtained.
[0216] In a further step 510 of the process 500, the decaffeinated, PEF-treated, presoaked green coffee beans are dried in a hot-air sample dryer to a moisture content of 20-25%, with the result that decaffeinated, PEF-treated, presoaked green coffee beans 511 are obtained.
[0217] In a further step 512 of the process 500, decaffeinated, PEF-treated, presoaked green coffee beans are dried in a fluidized-bed dryer to a moisture content of 9-12%, with the result that dried, decaffeinated, green coffee beans 513 are obtained.
[0218]
[0219] In a first step 602 of the process 600, green coffee having a moisture content of 8-12% 601 is hydrated and presoaked in a glass reactor using 150 g of steam per 500 g of coffee, with the result that presoaked green coffee beans 603 are obtained.
[0220] In a further step 604 of the process 600, the presoaked green coffee beans 603 pass through a switched off PEF apparatus, with the result that PEF treatment does not take place and presoaked green coffee beans having adhering water 605 are obtained.
[0221] In a further step 606 of the process 600, the water adhering to the presoaked green coffee beans having adhering water is removed by means of a spiral dryer and a blower, with the result that presoaked green coffee beans 607 are obtained.
[0222] In a further step 608 of the process 600, caffeine is extracted from the presoaked green coffee beans with dichloromethane in a Soxhlet apparatus, with the result that decaffeinated, presoaked green coffee beans 609 are obtained.
[0223] In a further step 610 of the process 600, the decaffeinated, presoaked green coffee beans are vacuum dried to a moisture content of 20-25%, with the result that decaffeinated, presoaked green coffee beans 611 are obtained.
[0224] In a further step 612 of the process 600, decaffeinated, presoaked green coffee beans are dried in a fluidized-bed dryer to a moisture content of 9-12%, with the result that dried, decaffeinated, green coffee beans 613 are obtained.
[0225] The invention is elucidated in more detail hereinbelow with reference to examples referring to further figures:
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[0236] The solid black bars represent here and in
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EXAMPLES
Example 1: Decaffeination of Test Coffee With Liquid Carbon Dioxide in Production
[0238] The selection of substances in this example is exemplary only and different coffee beans, different soaking liquid, and different extractants may mutatis mutandis also be used by the person skilled in the art.
[0239] Raw green coffee beans of the “Robusta” and “Arabica” test coffees shown in Table 1 were used by way of example.
TABLE-US-00001 TABLE 1 Sample material—Raw green coffee beans B C D Moisture content Caffeine Caffeine (in DM) A [% by weight] [% by weight] [% by weight] Robusta 11.8 2.18 2.48 Arabica 10.7 1.11 1.24
[0240] The moisture content of the raw green coffee beans was determined in accordance with
[0241] ISO 6673; corresponding percent values refer to g/100 g green coffee beans (w/w). The caffeine content of the raw green coffee beans was determined in accordance with ISO 20481; corresponding percent values relate to g/100 g green coffee beans. The caffeine content in the dry matter (in DM, column D) of the raw green coffee beans was calculated from the moisture content and the caffeine content; corresponding percent values refer to g/100 g dry matter of the green coffee beans (w/w).
[0242] The green coffee beans used were hydrated with direct steam (150 g direct steam to 500 g coffee) until presoaked green coffee beans having a moisture content (coffee moisture content) of about 32% were present.
[0243] Half of the green coffee beans presoaked in this way were placed in the PEF treatment cell, which was filled with water and stirred with a spoon to degas it. The mixture of water and green coffee beans was subjected to PEF treatment carried out using the parameters shown in Table 2. The other half of the green coffee beans presoaked as described above were processed further without PEF treatment as a reference sample, by exposing them to a corresponding amount of water for a period corresponding to the PEF treatment time (but without PEF treatment).
TABLE-US-00002 TABLE 2 Parameters for PEF treatment Field Mass (green Mass Mass Energy Energy Specific Voltage strength coffee beans) (water) (in cell) [J] [J/kg] energy Pulse [kV] [kV/cm] [g] [g] [g] per pulse per pulse [kJ/kg] 1 20 30.0 3.00 400.00 432.00 832.00 450 538.92 10.817 2 20 30.0 3.00 400.00 417.00 817.00 450 550.80 11.016
[0244] The resulting PEF-treated, presoaked green coffee beans were decaffeinated in sample cages on the existing production line using liquid CO.sub.2 as extractant. The non-PEF-treated, presoaked green coffee beans were likewise decaffeinated in sample cages on the existing production line using liquid CO.sub.2 as extractant as a reference sample under identical conditions.
[0245] After decaffeination had been carried out, the PEF-treated, presoaked green coffee beans and the non-PEF-treated, presoaked green coffee beans serving as a reference sample were taken out of the sample cages and dried in the laboratory in drying trays in the ambient air with regular turning to a moisture content of 11±1%. The moisture content was determined in accordance with ISO 6673. The caffeine content was then determined in accordance with ISO 20481.
[0246] After decaffeination, the decaffeinated, PEF-treated, presoaked Robusta green coffee beans had a residual caffeine content that was 25.1% below the residual caffeine content of the non-PEF-treated, presoaked Robusta green coffee beans (cf. information for Robusta in Table 3 and
[0247] After decaffeination, the decaffeinated, PEF-treated, presoaked Arabica green coffee beans had a residual caffeine content that was 16.6% below the residual caffeine content of the non-PEF-treated, presoaked Arabica green coffee beans (cf. information for Arabica in Table 3 and
[0248] Results of the experiments from example 1 are summarized in Table 3 and shown in graph form in
TABLE-US-00003 TABLE 3 Selected batches of green coffee beans PEF Reference Difference Moisture Caffeine Moisture Caffeine Caffeine difference Caffeine content Caffeine in DM content Caffeine in DM (Reference − PEF) difference [% by [% by [% by [% by [% by [% by [% by relative weight] weight] weight] weight] weight] weight] weight] [%] Robusta 11.2 0.2273 0.256 11.0 0.304 0.342 0.086 25.1 Arabica 11.6 0.0458 0.052 11.1 0.055 0.062 0.010 16.1
Example 2: PEF Treatments and Decaffeination With Liquid CO.SUB.2
[0249] The selection of substances in this example is exemplary only and different coffee beans, different soaking liquid, and different extractants may mutatis mutandis also be used by the person skilled in the art.
[0250] The batches of green coffee beans described in more detail in Table 4 were selected by way of example.
TABLE-US-00004 TABLE 4 Selected batches of green coffee beans Robusta content Caffeine Moisture content No. Batch [% by weight] [% by weight] [% by weight] 1 T171 15 1.299 11.4 2 T270 100 1.99 11.1 3 T384 0 1.115 10.3
[0251] From the production process for decaffeinating green coffee with liquid CO.sub.2, 6 samples of 400 g to 500 g each of each of the selected batches of green coffee beans were taken directly after hydration (i.e. after presoaking) with an aqueous swelling liquid and each subjected to PEF treatment as individual samples. In addition, corresponding reference samples were taken, which were processed further without PEF treatment.
[0252] The parameters used for PEF treatment are summarized in Table 5.
[0253] For each of the selected batches, 2 sample cages were each filled with 3 of the 6 collected samples of 400 g or 500 g, so that each sample cage contained 1200 g to 1300 g of green coffee.
[0254] For decaffeination, the sample cages containing the PEF-treated, presoaked green coffee beans and the sample cages containing the reference samples (non-PEF-treated, presoaked green coffee beans) were transferred to the same CO.sub.2 decaffeination system (production system), where they were decaffeinated with liquid CO.sub.2 together with the respective production batch (from which they had previously been taken).
TABLE-US-00005 TABLE 5 PEF parameters Field Mass Mass Mass Energy Specific Voltage strength (coffee) (water) (in cell) Energy [(J/kg)/ energy Sample Batch Pulse [kV] [kV/cm] [g] [g] [g] [J/pulse] pulse] [kJ/kg] cage number T171 20 30.0 3.00 400.00 435.00 835.00 450 538.92 10.778 3 T171 20 30.0 3.00 400.00 417.00 817.00 450 550.80 11.016 3 T171 20 30.0 3.00 400.00 423.00 823.00 450 546.78 10.936 2 T171 20 30.0 3.00 400.00 422.00 822.00 450 547.45 10.949 2 T171 20 30.0 3.00 500.00 393.00 893.00 450 503.92 10.078 3 T171 20 30.0 3.00 500.00 400.00 900.00 450 500.00 10.000 2 T270 20 30.0 3.00 400.00 423.00 823.00 450 546.78 10.936 0 T270 20 30.0 3.00 400.00 421.00 821.00 450 548.11 10.962 0 T270 20 30.0 3.00 400.00 416.00 816.00 450 551.47 11.029 4 T270 20 30.0 3.00 400.00 431.00 831.00 450 541.52 10.830 4 T270 20 30.0 3.00 500.00 362.00 862.00 450 522.04 10.441 0 T270 20 30.0 3.00 500.00 374.00 874.00 450 514.87 10.297 4 T384 20 30.0 3.00 400.00 412.00 812.00 450 554.19 11.084 3 T384 20 30.0 3.00 400.00 422.00 822.00 450 547.45 10.949 3 T384 20 30.0 3.00 400.00 450.00 850.00 450 529.41 10.588 4 T384 20 30.0 3.00 400.00 430.00 830.00 450 542.17 10.843 4 T384 20 30.0 3.00 500.00 372.00 872.00 450 516.06 10.321 3 T384 20 30.0 3.00 500.00 380.00 880.00 450 511.36 10.227 4
[0255] The sample cages were removed separately when emptying the decaffeination system. Approx. 500 g of decaffeinated, presoaked green coffee beans was taken from each of the sample cages. In the laboratory, the moisture content of the decaffeinated, presoaked green coffee beans was determined directly by NIR analysis (near-infrared spectroscopy). After drying, the caffeine content was determined in accordance with ISO 20481.
[0256] The results of these experiments are summarized in Tables 6a and 6b and plotted in graph form in
TABLE-US-00006 TABLE 6a Results for example 2 PEF Reference Batch cut Moisture Caffeine Moisture Caffeine Moisture Caffeine content Caffeine in DM content Caffeine in DM content Caffeine in DM [% by [% by [% by [% by [% by [% by [% by [% by [% by weight] weight] weight] weight] weight] weight] weight] weight] weight] T171 54.2 0.0345 0.075 50.2 0.044 0.088 11 0.069 0.078 T270 51.2 0.2885 0.591 51.1 0.306 0.626 11.5 0.476 0.538 T384 45.3 0.0338 0.062 45.6 0.037 0.068 10 0.063 0.070
TABLE-US-00007 TABLE 6b Results for example 2 Caffeine Caffeine difference difference (Reference − PEF) relative [%] [%] T171 0.013 14.6 T270 0.036 5.7 T384 0.006 9.1 Mean 9.8
[0257] The decaffeinated, PEF-treated, presoaked green coffee beans in each case have a lower caffeine content than the decaffeinated, non-PEF-treated, presoaked green coffee beans of the same batch (with otherwise identical treatment).
Example 3: Batchwise PEF Treatment
[0258] For use in the decaffeination of green coffee with liquid CO.sub.2, a PEF unit was by way of example directly integrated into the existing industrial process for decaffeination. Using this test setup, entire coffee batches of approx. 4000 kg of presoaked green coffee were PEF-treated and compared with reference batches that had not been PEF-treated.
[0259] The green coffee was hydrated in a hydration tank with an aqueous swelling liquid to a moisture content of 42 to 45% and then fed directly into a stream of water that was fed through the PEF treatment cell. For the PEF-treated batches, the PEF apparatus was switched on and PEF treatment (according to the parameters in Table 7) carried out; for the reference batches, the cell was not switched on, consequently these underwent the same process path without PEF treatment.
TABLE-US-00008 TABLE 7 PEF parameters Moisture Mass Treatment Coffee Actual Actual energy Pulse field content after (coffee) time flow flow input strength Voltage Power [%] [kg] [h] [kg/h] [kg/h] [kJ/L] [kV/cm] [%] [%] T288 45 5208 2.12 2460.5 — — 2.9 90 80 T333 45 4864 2.15 2262.3 — — 2.8 90 80 T358 45 4862 2.23 2177.0 — — 2.9 90 80 T675 45 4870 2.03 2395.1 6377 14.9 2.9 90 80 T698 42 4636 2.22 2091.4 6218 15.4 2.9 90 80 T731 42 4612 2.12 2178.9 6128 15.5 2.8 90 80 T745 42 4620 1.95 2369.2 5769 16.4 2.9 90 80 T762 42 4626 2.10 2202.9 6269 15.3 2.9 90 80
[0260] The adhering water was then separated from the coffee beans with a spiral dryer and a blower and returned to the upstream tank, whereas the coffee was transported directly to the decaffeination column. In the decaffeination column, caffeine was extracted with liquid CO.sub.2 as extractant.
Example 4: Batchwise Drying
[0261] After decaffeination as described in example 3 had been carried out, the coffee first underwent vacuum drying to a residual moisture content of 30 to 38% and was then dried by fluidized-bed drying to a residual moisture content of 9 to 12%, polished, and removed from the apparatus.
[0262] The drying rates of the two drying steps for the PEF-treated batches and the reference batches were calculated from drying loss and drying time and compared; the results are summarized in Table 8 and shown in graph form in
TABLE-US-00009 TABLE 8 Drying rates for example 4 Drying rate Drying rate Vacuum drying Fluidized-bed drying [kg/min] [kg/min] PEF Reference PEF Reference T675 2.93 2.91 4.13 3.57 T745 3.38 2.88 4.54 3.91 T762 2.85 2.65 4.25 2.81
[0263] The drying rates in the vacuum drying (here drying from approx. 45% moisture to approx. 35% moisture) show a slight increase in drying rate in the PEF-treated, presoaked, decaffeinated green coffee beans (under otherwise identical drying conditions) compared to the respective reference samples.
[0264] The drying rates in the fluidized-bed drying (here drying from approx. 35% moisture to approx. 11% moisture) show an advantageous increase of approx. 0.7 kg/min in drying rate for the PEF-treated decaffeinated, presoaked green coffee beans (under otherwise identical drying conditions). Such an advantageous increase in drying rate allows more swift drying and thus gentler treatment of the coffee and associated advantageous taste properties. In addition, less energy is needed for the same drying result. In addition, less time is required for drying the PEF-treated, presoaked green coffee beans, which means that a higher overall production output can be achieved for the system.
Example 5: Caffeine Content of Batches of Green Coffee Beans Decaffeinated According to Example 3 and Dried According to Example 4
[0265] The caffeine content of green coffee beans PEF-treated and decaffeinated according to example 3 and dried according to example 4 was determined in each case in accordance with ISO 20481; corresponding reference samples that had undergone the same process except for the PEF treatment were measured as reference samples, likewise in accordance with ISO 20481. Results are summarized in Table 9 and shown in graph form in
TABLE-US-00010 TABLE 9 Results of batchwise PEF treatment Caffeine Caffeine Difference in Difference content content caffeine content in caffeine Reference PEF (Reference − PEF) content [% by weight] [% by weight] [% by weight] relative [%] T358 0.063 0.055 0.008 .sup. 12.7.sup.15 T333 0.063 0.044 0.019 30.7 T288 0.320 0.217 0.103 32.1 T762 0.059 0.053 0.006 10.2 T745 0.063 0.05 0.013 20.6 T731 0.053 0.042 0.011 20.8 T698 0.054 0.042 0.012 22.2
[0266] The PEF-treated batches were (under otherwise identical conditions) decaffeinated more strongly and compared in each case to roasted coffee beans of the same type and batch that had previously undergone the same process steps, but without PEF treatment; the arithmetic mean over all batches shows an improvement of 16.6%.
[0267] More efficient decaffeination is felt to be extremely beneficial in the field of the present invention. This allows lower caffeine values to be achieved more easily or allows, with shorter extraction times, such advantageous decaffeination results to be achieved for PEF-treated green coffee beans for which longer extraction times are necessary in the case of non-PEF-treated green coffee beans; here too, PEF treatment allows a higher overall production output to be achieved for the corresponding system.
Example 6: PEF Treatment Prior to Decaffeination With Dichloromethane
[0268] First, green coffee beans of the “Robusta” and “Arabica” types were in a glass reactor hydrated with steam (150 g steam for 500 g coffee beans) to approx. 32%, with the result that presoaked green coffee beans were obtained. The presoaked green coffee beans then underwent PEF treatment with approx. 10 kJ/kg in the water-filled treatment cell of a stationary laboratory PEF device, with the result that PEF-treated, presoaked green coffee beans were obtained. The PEF treatment parameters used are shown in Table 10. A reference sample of the same batch of presoaked green coffee was during this time kept in a water bath without PEF treatment to ensure comparable test conditions for the reference batch.
TABLE-US-00011 TABLE 10 Parameters for PEF treatment Field Mass Mass Mass Energy Energy Specific Voltage strength (coffee) (water) (in cell) [J] [J/kg] energy Pulse [kV] [kV/cm] [g] [g] [g] per pulse per pulse [kJ/kg] Robusta 20 30.0 3.00 400.00 431.00 831.00 450 538.72 10.820 Arabica 20 30.0 3.00 400.00 427.00 827.00 450 550.91 11.021
Example 7: Caffeine Extraction With Dichloromethane as Extractant
[0269] 10 g of PEF-treated, presoaked green coffee beans or of non-PEF-treated, presoaked green coffee beans were weighed out of coffee beans pretreated according to example 6 and transferred to a Soxhlet extraction thimble.
[0270] A Soxhlet extraction with 70 mL of dichloromethane was then initiated at 60° C., 70° C., or 80° C. Soxhlet extraction is a common continuous extraction technique in which soluble constituents are extracted from solid extraction material according to the drain siphon principle in cycles with fresh solvent, in this case dichloromethane. After defined extraction times, the extraction was in each case terminated. A number of test series were carried out for the PEF-treated, presoaked green coffee beans and for the reference samples (non-PEF-treated, presoaked green coffee beans) at 60° C. and 70° C.
[0271] The residual caffeine content in the extracted coffee beans and the extracted caffeine content in the extract were then determined. For this, the extracted coffee beans were dried in a hood at room temperature to a moisture content of approx. 11% (+1- 1%) and the caffeine content was determined in accordance with ISO 20481. The extract was concentrated in a rotary evaporator and taken up quantitatively in double-distilled water. The caffeine content of the aqueous solution thus obtained was determined in accordance with ISO 20481.
[0272] Example results are summarized in Table 11. In addition, data points for an extraction of a Robusta coffee over 380 min at 70° C. are shown by way of example in
TABLE-US-00012 TABLE 11 Caffeine content after Soxhlet extraction with dichloromethane Caffeine content Total in the coffee bean Extraction extraction Average Min. Max. Temperature time difference difference difference [° C.] [min] [%] [%] [%] Robusta 60 120 13.8 8.9 18 Arabica 60 120 16.8 7.9 26 Robusta 70 360 21.9 2.4 36.6 Arabica 80 360 14.9 3.1 27.4
[0273] Through prior PEF treatment it was possible to extract from the “Robusta” and “Arabica” test coffee beans examined here by way of example under otherwise identical conditions an average of 16.9% more caffeine compared to the corresponding non-PEF-treated reference samples. Dichloromethane was chosen here as the extractant purely by way of example; the person skilled in the art will here select a suitable extractant according to the needs in the individual case.
[0274] More efficient decaffeination is felt to be extremely beneficial in the field of the present invention. This allows lower caffeine values to be achieved more easily or allows, with shorter extraction times, such advantageous decaffeination results to be achieved for PEF-treated green coffee beans for which longer extraction times are necessary in the case of non-PEF-treated green coffee beans; here too, PEF treatment allows a higher overall production output to be achieved for the corresponding system.
Example 8: Drying in a Drum Dryer
[0275] 3 kg of a sample of PEF-treated green coffee decaffeinated according to example 3 and 3 kg of a reference sample decaffeinated according to example 3 (sample and reference sample were taken from a batch of green coffee) were each placed in a drum dryer for drying and dried at 90° C. and 15 Hz . Particularly with drying times of one hour or more and with moisture contents of less than approx. 30%, no significant difference is observed between the PEF-treated sample and the reference sample that had not been subjected to PEF treatment; corresponding data points are plotted in
Example 9
[0276] The water-soluble extractables content (WSE) in green coffee beans and roasted coffee beans of PEF-treated samples and non-PEF-treated comparison samples was determined by way of example for various samples in accordance with DIN 10775-1 (roasted coffee beans) or in accordance with DIN 10775-2 (green coffee beans). The water-soluble extract fraction in green and roasted coffee is understood as meaning the fraction of extractable substances that can be determined gravimetrically by extraction with water and subsequent drying at 103° C. Table 12 shows by way of example the values determined for the water-soluble extract fraction in percent by weight.
[0277] Overall, the PEF treatment is surprisingly found to have no significant influence on the water-soluble extract fraction.
TABLE-US-00013 TABLE 12 Water-soluble extract fraction Robusta Arabica PEF Reference PEF Reference Water-soluble extract fraction of green coffee in % (WSE [%]) WSE [%] 22.9 21.3 22.7 23.5 Water-soluble extract fraction of roasted coffee in % (WSE [%]) WSE [%] 30.6 30.9 26.7 27.7
Example 10: Variation of the Specific Energy Introduced
[0278] In a process according to example 6, the specific energy (kJ/kg) in the PEF treatment was varied according to Table 13 via the number of pulses at constant field strength for Arabica and for Robusta green coffee beans.
TABLE-US-00014 TABLE 13 PEF parameters for variation of the specific energy introduced Field Mass Mass Mass Energy Energy Specific Voltage strength (coffee) (water) (in cell) [J]/ [J/kg]/ energy Pulse [kV] [kV/cm] [g] [g] [g] pulse pulse [kJ/kg] Arabica 10 30.0 3.00 315.00 450.00 765.00 450 588.24 5.882 Arabica 20 30.0 3.00 300.00 422.00 735.00 450 538.92 10.949 Arabica 40 30.0 3.00 310.00 480.00 790.00 450 569.62 22.785 Robusta 10 30.0 3.00 30.600 550.00 856.00 450 525.70 5.257 Robusta 20 30.0 3.00 300.00 517.00 817.00 450 550.80 11.016 Robusta 40 30.0 3.00 307.00 530.00 837.00 450 537.63 21.505
[0279] Caffeine was then extracted from the treated beans with dichloromethane in a Soxhlet apparatus according to the procedure of example 7. The extraction times were likewise varied; values for the residual caffeine content in the coffee bean after extraction times of 60 minutes and 120 minutes are shown by way of example in
Example 11: Sensory Characteristics and Cupping
[0280] After decaffeination according to example 3 and drying according to example 4 had been carried out, the decaffeinated green coffee (PEF-treated batches and reference batches) was roasted using the same roasting curve to a coffee color value (CV) of 100 (±5). The roasting parameters are shown in Table 14 for some samples by way of example.
TABLE-US-00015 TABLE 14 Roasting parameters Initial End Product Air Air Roasting Color weight weight temperature temperature supply time value Sample [g] [g] [° C.] [° C.] [Hz] [s] [LRU] T288 Reference 100 85 218 240 40 155 103 T288 PEF 100 85 219 240 40 155 102 T333 Reference 100 85 217 240 40 155 99 T333 PEF 100 84 215 240 40 155 100
[0281] A difference in roasting behavior between the PEF-treated batches and the non-PEF-treated reference batches was not detected.
[0282] To examine the sensory characteristics of the roasted coffee beans, for each sample 11 g portions of the roasted coffee beans were in a triplicate determination ground with a coffee grinder (Mahlkonig VTA6S, grinding level 7) directly into a test vessel (V=200 mL). Fresh tap water was heated to 95° C. in a kettle and poured onto the ground coffee without stirring. After a brewing time of 5 min, the so-called crust was skimmed off and the coffee underwent sensory tasting by a trained sensory panel. More particularly, this was done by assessing the (i) taste, (ii) smell, (iii) acidity, and (iv) body of the infusion. The sensory assessment was carried out in accordance with DIN 10975.
[0283] Example results of the tasting are summarized in Table 15. No differences were observed compared to the respective reference samples.
TABLE-US-00016 TABLE 15 Sensory characteristics and cupping Sensory characteristics and Sample cupping—Result T288 reference T288 PEF No difference T333 reference T333 PEF No difference T698 reference T698 PEF No difference T745 reference T745 PEF No difference T762 reference T762 PEF No difference
Example 12: NMR Analysis
[0284] The .sup.1H-NMR analysis of the organic phase and of the aqueous phase of decaffeinated PEF-treated samples and corresponding reference samples showed a high degree of comparability.
Example 13: Coliform Bacteria
[0285] As part of our own investigations, a process according to the invention was carried out and the contamination of the green coffee beans before step (b-v) (PEF treatment of presoaked green coffee beans) and after step (b-v) (PEF treatment of presoaked green coffee beans) was examined on the basis of the colony-forming units after incubation.
[0286] The investigation was carried out in accordance with DIN EN ISO 4833-1.
[0287] In each case, a smaller number of colony-forming units was found after the PEF treatment than before the investigation.