Process for processing coffee and corrected coffee

Abstract

The present disclosure relates to a process for correcting the acidity and / or bitterness of coffee infusions, de-acidified coffee infusions, de-acidified coffee powders and pods or capsules containing the de-acidified coffee powders obtained therefrom.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application No. 63 / 252,644, filed October 6, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a process for correcting the acidity and / or bitterness of coffee infusions, de-acidified coffee infusions, de-acidified coffee powders and pods or capsules containing the de-acidified coffee powders obtained therefrom. [Background technology]

[0003] Robusta coffee gets its name from the robustness and hardiness of the plant. It grows very quickly, making this type of coffee easier to cultivate than Arabica. The main countries producing Robusta coffee are Indonesia, Uganda, Côte d'Ivoire, India and Vietnam.

[0004] Robusta produces grains with twice the caffeine of Arabica, but is characterized by fewer complex aromas and a more acidic and bitter taste.

[0005] Traditionally, producers of commercial coffee have reduced acidity by chemical means, such as using buffers to neutralize the acidity, which may result in expected aging of stored coffee, while also imposing additional labeling requirements under certain legislation. Furthermore, buffering methods tend to adversely affect the delicate aroma profile of coffee, which may in any event be further masked by a more acidic coffee infusion (e.g., pH below about 5). Summary of the Invention [Problem to be solved by the invention]

[0006] There is a need to improve the acidity / bitterness profile while preserving as much of the coffee's aromatic character as possible. [Means for solving the problem]

[0007] A process for deacidifying coffee is provided, comprising the steps of providing a coffee infusion from ground coffee and eluting the coffee infusion onto a weak anion exchange resin to provide a deacidified coffee infusion after elution.

[0008] In one embodiment, the volume (BV) of the coffee infusion provided is from about 100 to about 200 BV for a coffee infusion having a Brix of from about 2 to about 5, or the BV is from about 2 to about 50 BV for a coffee infusion having a Brix of from about 10 to about 20.

[0009] In one embodiment, the coffee infusion provided has a concentration index of between 2 and 10 degrees Brix.

[0010] In a further embodiment, the coffee infusion provided is concentrated.

[0011] In another embodiment, the concentrated coffee infusion has a concentration index of from about 10 to about 20 Brix.

[0012] In one embodiment, the process described herein further comprises a step of pre-treating the coffee infusion.

[0013] In a further embodiment, the coffee infusion is eluted onto a weak anion exchange resin at a circulation flow rate of between 5 BV / hr and 250 BV / hr.

[0014] In one embodiment, the weak anion exchange resin is made from acrylic, styrene or phenol-formaldehyde polycondensates.

[0015] In another embodiment, the weak anion exchange resin is made from acrylic.

[0016] In a further embodiment, the weak anion exchange resin comprises tertiary amine functional groups on the resin.

[0017] In one embodiment, the weak anion exchange resin has a particle size of 300 to 600 μm.

[0018] In certain embodiments, the weak anion exchange resin is made of beads or non-spherical granules.

[0019] In a further embodiment, the weak anion exchange resin is LEWATIT S5221 resin, Purolite PPA847 resin, Dowex FPA53 resin, Diaion WA10 resin, Lanxess MDSS4368 resin, DOWEX 66 resin or Duolite A568 resin.

[0020] In one embodiment, the coffee infusion provided has a pH value of about 5 to about 6.

[0021] In a further embodiment, the deacidified coffee infusion has a pH value of from about 6 to about 7.5.

[0022] In one embodiment, the process encompassed herein further comprises the step of removing water from the de-acidified coffee infusion to form a de-acidified coffee powder.

[0023] In one embodiment, the water is removed by freeze drying or spray drying.

[0024] There is also provided a deacidified coffee infusion obtainable by the process encompassed herein.

[0025] Further provided is a capsule containing the deacidified coffee powder encompassed herein.

[0026] In one embodiment, the capsule contains about 5-7 g of deacidified coffee powder. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 shows pH change and BV / hr as a function of time for coffee infusion processed on a resin according to one embodiment. [Diagram 2] FIG. 1 is a comparative example showing the pH change of coffee infusion and the capacity of resin as a function of BV. [Diagram 3] FIG. 1 shows the pH change and BV / hr as a function of time for coffee infusion processed on a resin according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] "BV" is an acronym for "bed volume", i.e. the volume of resin in a column. In fact, in the technical field of coffee infusions carried out in columns packed with ion exchange resins, it is very common to express the circulation (or in other words through) flow rate of the coffee infusion in the column in BV / hour. This has the advantage of indicating the flow rate in a normalized way, i.e. independently of the volume of the column. For this reason, in the following description, the circulation flow rate of the coffee infusion will be expressed in particular in BV / hour.

[0029] Thus, during the deacidification methods provided herein, the circulation flow rate of the coffee infusion in the column containing the anion exchange resin may be varied between 5 BV / hr and 250 BV / hr, or between 10 BV / hr and 200 BV / hr.

[0030] In one embodiment of this method, the volume (BV) of coffee infusion used in the process varies depending on the initial pH, the required pH output and the concentration of the deacidified coffee. For example, the BV can be from about 100 to about 200 BV for a coffee infusion having a Brix of from about 2 to about 5, or the BV can be from about 2 to about 50 BV for a coffee infusion having a Brix of from about 10 to about 20.

[0031] The deacidified coffee infusions useful herein may be concentrated or non-concentrated and may have, for example, a concentration index which may comprise between 2 and 10 degrees Brix, preferably from about 2 to about 5 for non-concentrated infusions and from about 10 to about 20 for concentrated infusions.

[0032] In one embodiment, the process further comprises the step of pre-treating the coffee infusion to be deacidified.

[0033] This pretreatment step has the advantage of preventing clogging of the column.

[0034] In the method provided herein, an anion exchange resin is used to deacidify the coffee infusion. Without being bound by theory, it is believed that the resin may capture some organic acids, resulting in an increase in pH, which may release "basic" compounds such as pyridines and pyrazines, which may otherwise be in the form of hydrochloric acid at lower pH. Depending on the ionic strength of the medium, an increase in molecules responsible for the taste of coffee may also be observed.

[0035] Preferably, the resin is a weak anion exchange resin. For example, the weak anion exchange resin is neutral at a pH above 10 and contains a tertiary amine functional group that is ionized at a pH below 10. As a result, it is understood that the weak anion exchange resin refers to a resin that dissociates cationic function based on the pH of the solution.

[0036] Weak anion exchange resins have the advantage that they are very specific for weak and polyacids, and, as explained above, the coffee infusion to be deacidified contains organic acids that are weak acids.

[0037] In the context of the present invention, a "weak acid" refers to an acid that does not completely dissociate in water. The higher its pKa, the weaker the acid.

[0038] Preferably, the anion exchange resin is an acrylic, styrene or phenol-formaldehyde polycondensate type exchange resin. Advantageously, the anion exchange resin is an acrylic type anion exchange resin. The resin preferably has tertiary amine functional groups on the resin. The capacity of the acrylic type anion exchange resin is preferably in the range of 1.1 to 3.2.

[0039] The particle size of the resin varies between 300 and 600 μm. For example, the anion exchange resin may be beads (uniformity of about 1.7 or less, or preferably about 1.2) or non-spherical granules.

[0040] An example of an acrylic type weak anion exchange resin is LEWATIT S5221 resin from LANXESS Co. Further examples of related acrylic type resins include Purolite PPA847, Dowex FPA53 and Diaion WA10.

[0041] Further examples of resins with different polymer supports can also be used, as they have similar pKa's, including Lanxess MDSS4368 (acrylic), DOWEX 66 (polystyrene), Duolite A568 (formaldehyde-phenol).

[0042] In one embodiment of the present disclosure, the coffee infusion (to be deacidified) has a degree of Brix of about 2 to about 20 Brix, or preferably about 3 to about 15 Brix.

[0043] In one embodiment of the present disclosure, the pH value of the coffee infusion (to be deacidified) ranges from about 5 to about 6, preferably from about 5.3 to about 5.7.

[0044] In one embodiment of the present disclosure, the pH value of the coffee infusion to be deacidified ranges from about 6 to about 7.5, preferably from about 6.5 to about 7.0, and more preferably from about 6.5 to about 6.7.

[0045] In one embodiment of the present disclosure, the pH value of the coffee infusion increases by 0.5 to 2 pH units, preferably 1 to 2 units, more preferably 1-1.2 to 1.5 units under the process.

[0046] The deacidified coffee infusion, or coffee reconstituted from the deacidified coffee powder disclosed herein and water, may preferably have a pH of about 6.5 to about 6.7.

[0047] The de-acidified coffee infusion may be further processed to remove water by conventional processes, such as by either freeze drying or spray drying methods known to those skilled in the art, to provide a de-acidified coffee powder (also called soluble coffee, or coffee crystals), which may be used to reconstitute drinkable coffee.

[0048] The deacidified coffee infusion, coffee powder or pods or capsules disclosed herein do not contain any additional / external acidity / pH adjusting or masking compounds such as sodium polyphosphate, dipotassium phosphate, bases, chelating agents, or buffers.

[0049] Coffee capsules can be any shape and size, but are often cylindrical and intended for single use. They are also generally vacuum packed in plastic or aluminum capsules, suitable for use in infusion coffee machines compatible with the capsules for infusing coffee powder. Coffee pods are generally rounded pods filled with a predetermined amount of coffee placed within a filter (e.g. compressed within two filter sheets such as a material similar to a tea bag). A coffee pod may contain about 7g of coffee, while a coffee capsule may contain about 5-7g of coffee. EXAMPLES

[0050] coffee An infusion was prepared from private label Robusta ground coffee sold under the trade name ECO by E. Leclerc.

[0051] Preparation of leachate: Five litres of demineralised water were heated to 90°C, 500g of ground coffee were added and the mixture was gently stirred for 2 hours. The suspension was pre-filtered through a fabric cone and the discarded coffee grounds were manually pressed to extract further infusion. After filtration through a 30μm Büchner system the Brix of the infusion was approximately 3.6°B.

[0052] The infusions were repeated three times using the same batch of commercially available ground coffee.

[0053] [Table 1]

[0054] [Table 2]

[0055] [Table 3]

[0056] The pH of the resulting (initial) coffee infusion is about 5.5. Infusion #1 was filtered through a 30 μm filter and used without concentration to perform the high volumetric flow deacidification process.

[0057] Leachates #2 and #3 were not 30 μm filtered but were concentrated in a vacuum rotavapor at approximately 14° B and then centrifuged to remove suspended solids.

[0058] Table 1 below summarizes the physicochemical properties of the resulting leachates.

[0059] [Table 4]

[0060] It should be noted that the pH of the concentrated leachate does not change compared to the initial leachate, despite the concentration factor being approximately 4. EXAMPLES

[0061] High volume flow deacidification - non-concentration The resin is cut into 3.14 cm sections. 2 The solution was packed in a glass column of 100 ml. A pH meter was placed in the glass measuring cell at the outlet of the column. The solution was fed into the system by a peristaltic pump at 6–600 rpm (1–100 ml / min).

[0062] The process was carried out at room temperature (i.e., approximately 20-25 degrees Celsius) with flow rates of 150-6 BV / h. The product was circulated in a loop in a feed beaker to the resin bed with stirring until the target pH was adjusted. The system was then switched to straight through to promote and accelerate the deacidification. The entire product resin was rinsed with 2 BV of demineralized water.

[0063] The coffee infusion loading (liters of infusion / liters of resin or BV) was calculated as follows, for example, for a target pH of 7.5:

[0064]

number

[0065] In the following examples, free acidity was measured by titration with 1 eq / l (1 mol / l) of sodium hydroxide.

[0066] [Table 5]

[0067] This process, carried out on unconcentrated coffee infusions, was carried out to recover deacidified coffees with pH 5.9, 6.4, and 7.2. The following table summarizes some relevant physicochemical properties.

[0068] [Table 6]

[0069] In Table 2, it can be seen that as the pH increases, the Brix and dry matter of the leachate decrease slightly.

[0070] The determination of organic acids was performed by HPLC; Column: BIORAD HPX87H 7.8 * 300mm; Mobile phase: H at 0.6 ml / min 2 SO 4 8 mM, 50°C.

[0071] [Table 7] EXAMPLES

[0072] High volume flow rate deacidification-concentration The same process was used as described above for the non-concentrated leachate, but with a concentrated leachate of approximately 14°B (i.e., a concentration factor approximately four times higher than in the previous test method), and the system was therefore sized accordingly.

[0073] This process produced deacidified coffees at pH 6.7 (i.e. +1.2 units), pH 7.0 (i.e. +1.5 units) and pH 7.5 (i.e. +2.0 units).

[0074] [Table 8]

[0075] As shown in Figure 1, this process made it possible to reach an average pH of 6.7.

[0076] The competitive effect on the column was likely caused by the high concentration of substances in the infusion solution, which could reduce the exchange capacity of the resin. Therefore, to produce a higher pH coffee, the amount of resin was increased and the corresponding loading was reduced to about 8.25 BV, resulting in the desired pH of 7.5.

[0077] Comparative Example: Slow Dissolution with Concentrated Leachate (Comparative Process) In this test method, a concentrated leachate was used, and the product was now injected into the lower section of the column at a lower flow rate (i.e., about 2 BV / h).

[0078] Resin 0.79cm 2 The resin was packed in a glass column of 1000 ml. Two adjustable pistons (with PTFE sintered body with porosity of 30 μm) at both ends of the column allowed the adjustment of the resin settling level. The system was driven by a peristaltic pump at 6 to 600 rpm. The pH was measured directly at the column outlet in a test tube.

[0079] This test is considered as a benchmark for the ion exchange process: low speeds cause strong pH fluctuations during production.

[0080] [Table 9]

[0081] Figure 2 shows that under these operating conditions the effluent reached an average pH of 7.5. Strong pH fluctuations were observed (i.e. pH 9.7 at the start of production and pH 6.2 at the end). The maximum loading is 30.4 BV or 92.1% of the loading based on free acidity measurements and resin manufacturer's data. The output pH at the end of the test was not at the pH level of the feed solution, indicating that the resin still has exchange capacity. EXAMPLES

[0082] High volumetric flow deoxidation - staged loading In this process, the process was carried out using the above setup, except that the concentrated leachate loading was gradually increased.

[0083] The process started with a loading of 3.6 BV (11% of the resin's available capacity), and then the flow rate was reduced while adding concentrated leachate in 50 ml increments. The output pH and average pH curves were coincident at a certain point. After 50 minutes of loop operation, the system was switched to conventional parallel flow to complete the deacidification operation.

[0084] [Table 10]

[0085] As shown in Figure 3, the concentrated deacidified leachate stabilized at the target pH of 7.48. Thus, any strong pH fluctuations were limited while optimizing the exchange capacity of the resin. The total amount of leachate added was 200 ml or 43% of the resin capacity. EXAMPLES

[0086] Coffee infusion tasting Deacidified coffee samples were obtained according to the process of Example 2 above (high volumetric flow deacidification-concentration). The concentrated deacidified coffee was then diluted to a substantially constant value of 4 Brix for tasting.

[0087] The testers were rather amateurs of "fine" coffee. The coffees were tasted unsweetened at room temperature (approximately 20°C). We asked the testers to rate certain aspects of the coffee (i.e., acidity, bitterness, roundness and burntness) on a scale of 1 to 8, where 1 represents the lowest or even mediocre quality level and 8 represents the highest perceived quality.

[0088] Testers were also asked to comment generally on their assessment, using traditional descriptions of coffee: whether they considered the aroma and taste to be negative ('strong, powerful, unbalanced, burnt, bitter, sour, pungent, soapy, earthy, etc.) or positive ('fruity, nutty, 'lightly roasted', lingering in the mouth, mellow, 'green', etc.).

[0089] [Table 11]

[0090] Considering the above observations, we conclude that there is a fairly clear gradation in perceived quality with stepwise increases in pH, which is primarily a demonstration of the advantages provided by the process of the present invention.

[0091] The pH 7.5 deacidified coffee was not tasted by itself, but was used to combine with a pH 5.5 raw coffee to evaluate the possible positive effect of introducing such a deacidified coffee into raw acidic coffee. Surprisingly, even such a combination was able to improve the tasting score of the resulting coffee.

[0092] [Table 12]

[0093] Coffee that has been deacidified by classical ion exchange loses its roundness and characteristic coffee aroma.

[0094] As discussed above, and in marked contrast, coffee deacidified according to the process of the present invention had an increased characteristic coffee aroma. EXAMPLES

[0095] Quantitative analysis of selected compounds in leachates The following quantitative analyses were carried out using the deacidified coffee described in Example 4 above.

[0096] It is now well known that coffee contains a large number of aromatic compounds that contribute to its characteristic odor and taste, some negative, others positive. It was decided to use analytical methods to assess the content of certain pyridine and pyrazine compounds.

[0097] The equipment used was a headspace coupled to a GC-MS.

[0098] Gas chromatography Headspace: Oven: 100℃; Sample loop: 150℃; Transfer line: 200℃; Total / injection volume: 20mL / 10mL; Gas chromatography : HP5-MS column: 30 meters * 250μm * 0.25μm 50°C (3 min), 5°C / min to 150°C, 10°C / min to 250°C (7 min) Helium at a constant flow rate of 1 ml / min. Mass spectrometry: Ions 79 (pyridine), 94 (methylpyrazine), 108 (dimethyl / ethylpyrazine), 121 (trimethyl, ethyl / methylpyrazine) and 135 (tetramethylpyrazine) were acquired in selected ion monitoring (SIM) mode. Acquisition in SIM mode allowed for increased sensitivity as the molecules were not concentrated.

[0099] 10 ml of coffee infusion (adjusted to 10° B with water) was injected.

[0100] The following Table 9 shows a summary of the analysis, expressing the results in terms of relative intensities (i.e. not weight or volume amounts) obtained by integration of the resulting curves and peaks.

[0101] [Table 13]

[0102] [Table 14] Pyridine gives a perceived "burnt" flavor and is detectable at 10 g / ton. It can therefore be considered a negative "note". The detection threshold for pyrazine molecules is 0.01 g to 1 g / ton. Certain pyrazines, such as 2-methylpyrazine, 2,5-dimethylpyrazine and 2,6-dimethylpyrazine, impart green, hazelnut, coconut, oily and slightly toasty notes similar to ethyldimethylpyrazine. On the other hand, ethylmethylpyrazine compounds provide a harsher character, such as those associated with baked or roasted potatoes. On the other hand, 2-ethyl-3,(5- or 6-)dimethylpyrazine imparts a fruity and green sensation.

[0103] The above analytical results show that the pyridine content increases up to pH 6.7, which corresponds to the bitter taste sensation in the tasting described above, and then decreases above that pH.

[0104] A significant increase was observed for the desirable pyrazines, and it is hypothesized that due to the relatively low detection threshold of pyrazines, these "good molecules" are prioritized over the less desirable earthy compounds. Thus, at pH values ​​above 6.5 / 6.7, it is possible to detect desirable fruity notes that would no doubt be hidden in the "green" coffee (before it was deacidified).

[0105] Thus, the increase in certain pyrazine compounds that partially mask the bitterness of pyridine, and the concomitant decrease in said pyridine (e.g. when increasing pH) may in part explain the observations outlined in the tasting results above.

[0106] Without wishing to be bound by theory, an increase in pH may release "basic" compounds such as pyridines and pyrazines, which may otherwise be in the form of acidic salts at lower pH. Depending on the ionic strength of the medium, it may also be possible to observe an increase in molecules involved in coffee taste. Thus, the process disclosed herein not only changes the pH of the infusion to a less acidic one, but also makes it possible to correct the balance of aromatic compounds, resulting in a better overall coffee taste.

[0107] While the disclosure has been described in relation to specific embodiments thereof, it will be understood that further modifications are possible, and this application is intended to cover any variations, uses, or adaptations including departures from the disclosure that fall within the scope of known or customary practices in the art, which may also apply to the essential features described above and the following appended claims.

Claims

1. 1. A process for deacidifying coffee, comprising the steps of: - Providing a coffee infusion from ground coffee; - eluting said coffee infusion on a weak anion exchange resin to provide a deacidified coffee infusion after elution; The process includes:

2. 10. The process of claim 1, wherein the volume (BV) of the coffee infusion provided is from about 100 to about 200 BV for a coffee infusion having a Brix of from about 2 to about 5, or said BV is from about 2 to about 50 BV for a coffee infusion having a Brix of from about 10 to about 20.

3. 3. The process of claim 1 or 2, wherein the provided coffee infusion has a concentration index of 2 to 10 degrees Brix.

4. 3. The process of claim 1 or 2, wherein the provided coffee infusion is concentrated.

5. 5. The process of claim 4, wherein the concentrated coffee infusion has a concentration index of from about 10 to about 20 Brix.

6. 10. The process of claim 1, further comprising the step of pre-treating the coffee infusion.

7. 2. The process of claim 1, wherein the coffee infusion is eluted onto the weak anion exchange resin at a circulation flow rate of between 5 BV / hr and 250 BV / hr.

8. 10. The process of claim 1, wherein the weak anion exchange resin is made from acrylic, styrene, or phenol-formaldehyde polycondensates.

9. 10. The process of claim 1, wherein the weak anion exchange resin is made from acrylic.

10. 10. The process of claim 1, wherein the weak anion exchange resin comprises tertiary amine functional groups on the resin.

11. 2. The process of claim 1, wherein the weak anion exchange resin has a particle size of 300 to 600 μm.

12. 10. The process of claim 1, wherein the weak anion exchange resin is made from beads or non-spherical granules.

13. 2. The process of claim 1, wherein the weak anion exchange resin is LEWATIT S5221 resin, Purolite PPA847 resin, Dowex FPA53 resin, Diaion WA10 resin, Lanxess MDSS4368 resin, Dowex 66 resin, or Duolite A568 resin.

14. 10. The process of claim 1, wherein the provided coffee infusion has a pH value of about 5 to about 6.

15. 10. The process of claim 1, wherein the deacidified coffee infusion has a pH value of from about 6 to about 7.

5.

16. 10. The process of claim 1, further comprising removing water from the de-acidified coffee infusion to form a de-acidified coffee powder.

17. 17. The process of claim 16, wherein the water is removed by freeze drying or spray drying.

18. A deacidified coffee infusion obtained by the process of claim 1.

19. 19. The deacidified coffee infusion of claim 18, wherein the deacidified coffee infusion is a powder.

20. 20. A capsule containing the deacidified coffee powder of claim 19.

21. 21. The capsule of claim 20, comprising about 5 to 7 g of deacidified coffee powder.

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