Activated Charcoal Extraction Process for Food and Beverage Ingredients

Abstract

The present disclosure provides a novel extraction (filtration) system, extraction medium, and continuous extraction process for effectively removing low molecular weight compounds, particularly the compound 4-MeI, produced during the commercial production of edible caramel color. In one aspect, the method can include the steps of ultrafiltration to provide a retentate solution and a permeate solution, and contacting the permeate solution with granular activated carbon for a contact time sufficient to provide a purified permeate solution having a substantially reduced concentration of 4-MeI. Optionally, the purified permeate solution can be combined with the retentate solution and reused.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 485,367, filed February 16, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to purification processes for reducing the amount of low molecular weight species from food and beverage ingredients. [Background technology]

[0003] Caramel color compositions are widely used to impart desired colors to food and beverage products. These food color compositions are generally produced by controlled heating of carbohydrates, such as sugars and corn syrup, alone or in the presence of other ingredients. Caramel colors produced by these processes can range in color from light yellow to red, or reddish-brown to dark brown, and typically contain a complex mixture of compounds.

[0004] The International Technical Caramel Association (ITCA) classifies caramel colors into four classes based on production method, composition, and functional properties. One element of the color classification system is whether the color is produced by heating carbohydrates in the presence or absence of compounds such as ammonia, ammonium compounds, or sulfite compounds. Each production method produces its own complex impurities, and subsequent processing is typically used to remove or reduce the concentration of certain components.

[0005] Therefore, there remains a significant challenge in developing new and improved processes that can efficiently remove certain low molecular weight species produced during the commercial production of edible caramel colors. Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides new and improved processes and methods for effectively and efficiently removing certain low molecular weight species, including compounds such as 4-methylimidazole (4-MeI or 4-MEI), produced during the commercial production of edible caramel colors used in food and beverage applications. For example, U.S. Patent Application Publication No. 2010 / 0003383 and U.S. Patent No. 4,416,700 disclose methods for producing caramel colors with reduced 4-MeI content, but there is a need for improved separation, filtration, and / or extraction methods for removing 4-MeI from such color components.

[0007] Generally, edible caramel color compositions are prepared by heating carbohydrates, including commercially available food-grade nutritive sweeteners, alone or in the presence of food-grade acids, alkalis, or salts. The acids, alkalis, and / or salts function as catalysts that impart the characteristic color and functional properties of caramel. Edible caramel color compositions prepared without the use of acids, alkalis, and / or salts are commonly labeled "burnt sugar" and are used as incidentally colored flavors rather than as strict colorants.

[0008] Edible caramel compositions are divided into four general classes. Class I compositions, also known as plain or caustic caramel, are prepared by heating carbohydrates with acid or alkali, but without the use of ammonium or sulfite compounds. Class II caramel, also known as caustic alkali sulfite caramel, is prepared by heating carbohydrates with acid or alkali in the presence of sulfite compounds, but without the use of ammonium compounds. Class II caramel generally has a reddish color and is stable in acids above a pH of about 2.5 to 3. Class III caramel, also known as ammonia caramel, ammonia-processed caramel, closed-cycle ammonia-processed caramel, open-cycle ammonia-processed caramel, baker's caramel, confectionery caramel, or beer caramel, is prepared by heating carbohydrates with acid or alkali in the presence of ammonium compounds, but without the use of sulfite compounds. Class IV caramel, also known as sulfite ammonia caramel, is prepared by heating carbohydrates with acid or alkali in the presence of both sulfite and ammonium compounds. Generally, Class IV caramels have a brown or black color and are generally stable in acids above a pH of about 1.5.

[0009] Compounds such as 4-MeI and other methylimidazoles can arise as by-products from the manufacture of caramel colors using ammonia as a reactant. Thus, in one embodiment, the methods of the present disclosure are particularly useful for Class III or Class IV caramel colors. 4-Methylimidazole, the structure of which is depicted here, may be produced, for example, as a by-product of a manufacturing process that uses ammonia as a reactant. [ka] [Means for solving the problem]

[0010] In one embodiment of the present disclosure, ultrafiltration is used to remove as much low molecular weight compounds as possible, including 4-MeI, from the caramel color composition, and the ultrafiltration yields a permeate containing not only the low molecular weight compounds but also a significant amount of solids, most of which can be recycled, except for the 4-MeI compound.

[0011] Another aspect of the present disclosure provides a continuous extraction process using activated carbon adsorbents, which can remove low molecular weight compounds, such as 4-MeI, from the aqueous permeate fraction with a high removal efficiency of approximately 90% to 99%, allowing the remaining compounds, such as glucose and sucrose, to be recovered and reused. The ability to return the recovered solids to the retentate solution from the ultrafiltration process may provide finer and more stable components, as well as a more consistent taste profile. Developing such a continuous extraction process using activated carbon adsorbents required identifying adsorbents, discovering various factors that can affect the separation of low molecular weight compounds, enabling solids recovery, and understanding how modifying the adsorbents and factors could improve the separation and recovery process.

[0012] Thus, in one aspect, the present disclosure provides: (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution by an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) contacting the permeate solution with granular activated carbon for a contact time sufficient to provide a purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; The present invention provides a process for purifying a caramel color solution, comprising:

[0013] In one aspect, the granular activated carbon can be contained within a filter bed through which the permeate solution flows at a constant rate. This type of filter bed, such as an activated carbon column, provides a convenient continuous process. According to a further aspect, the purified permeate solution is combined with a retentate solution to provide a purified caramel color solution, and residual compounds, such as glucose and sucrose, can be recovered and recycled.

[0014] Thus, the present disclosure: (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution by an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) passing the permeate solution through a first granular activated carbon filter bed at a flow rate sufficient to provide a first purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; Also provided is a continuous process for purifying a caramel color solution, comprising:

[0015] In another aspect, the process described above comprises: (d) passing the first purified permeate solution at a predetermined flow rate through a second granular activated carbon filter bed in fluid communication with the first granular activated carbon filter bed to provide a second purified permeate solution having a third concentration of low molecular weight species that is lower than the second concentration.

[0016] These and other features, embodiments and aspects of the processes, methods, and compositions are described in more detail in the detailed description and claims, as well as in the further disclosure, such as the examples provided herein. [Brief explanation of the drawings]

[0017] [Figure 1] A plot of 4-MeI extraction efficiency (%) versus bed volume number is shown for a 3.5% Brix solution to demonstrate the effect of flow rate on extraction efficiency. [Figure 2] For a 3.5% Brix solution, we provide a plot of residual 4-MeI versus bed volume number and demonstrate that a bed contact time of 18 to 36 minutes (flow rates of 0.5 to 1 L / h) is the minimum contact time for efficient extraction of 4-MeI. [Figure 3]The change in pH of the eluted purified permeate solution as a function of bed volume at flow rates of 0.5 L / h and 1 L / h is shown, demonstrating that the initial increase in pH stabilizes at a value close to pH 7, the starting pH of the permeate solution. [Figure 4] The change in Brix of the eluted purified permeate solution as a function of bed volume at flow rates of 0.5 L / h and 1 L / h is illustrated, demonstrating that the initial decrease in Brix stabilizes at a value close to the starting Brix of the permeate solution. [Figure 5] The change in absorbance of the eluted purified permeate solution as a function of bed volume at flow rates of 0.5 L / h and 1 L / h is shown, demonstrating significant adsorption of color bodies from the permeate solution in the early fractions, trending linearly towards the starting absorbance of the permeate solution. [Figure 6] 1 shows the effect of permeate pH on 4-MeI extraction efficiency (%) for a permeate of 3.5% Brix as a function of bed volume plotted for pH 3 and pH 7 at flow rates of 0.5 L / h and 1 L / h. [Figure 7] The effect of % Brix on the extraction efficiency of 4-MeI is illustrated by plotting extraction efficiency (%) against bed volume for high Brix (approximately 7%), medium Brix (2.7-3.5%), and low Brix (0.8-1%) permeates. [Figure 8] To illustrate the effect of contact with activated carbon on pH changes, plots of effluent pH versus bed volume are made for high Brix (approximately 7%), medium Brix (2.7-3.5%), and low Brix (0.8-1%) permeates. [Figure 9] To illustrate the effect of contact with activated carbon on the change in % Brix, plots of % Brix against bed volume are made for high Brix (approximately 7%), medium Brix (2.7-3.5%), and low Brix (0.8-1%) permeates. [Figure 10] To illustrate the effect of contact with activated carbon on the change in absorbance, plots of absorbance versus bed volume are made for high Brix (approximately 7%), medium Brix (2.7-3.5%), and low Brix (0.8-1%) permeates. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following definitions are provided to more clearly define the terms used herein, and are applicable throughout this disclosure unless otherwise stated or otherwise required by context. If a term used in this disclosure is not specifically defined herein, the definition in the IUPAC Compendium of Chemical Terminology, Second Edition (1997) may be applied, unless that definition conflicts with other disclosures or definitions applicable herein and would not obscure or invalidate the claims to which that definition applies. To the extent that any definition or usage provided by any document incorporated by reference herein conflicts with the definition or usage applied herein, the definition or usage applied herein shall control.

[0019] The terms "low molecular weight species" and "high molecular weight species," referring to components of a caramel color solution, are relative terms and may vary depending on the molecular weight cutoff of the particular membrane used in a particular filtration process, such as ultrafiltration. Thus, for all membranes, filtering a caramel color solution by ultrafiltration or other size exclusion process provides a retentate solution enriched in high molecular weight species and a permeate solution enriched in or concentrated with low molecular weight species present in the original solution. In an ultrafiltration process such as that used in the present disclosure, molecules such as 4-methylimidazole (4-MeI), 2-methylimidazole (2-MeI), 5-hydroxy-2-methylpyridine, 2-hydroxypyridine, 2-hydroxy-6-methylpyridine carboxylic acid, glucose, and sucrose may be concentrated in the permeate solution, while other large molecules, oligomers, and polymers, such as larger oligosaccharides, may be concentrated in the retentate solution. In one aspect, the disclosed ultrafiltration process can employ a membrane having a molecular weight cut-off (MWCO) of about 800 Da (Daltons), with species having molecular weights greater than about 800 Da being retained in the retentate.

[0020] Where numerical ranges are disclosed, Applicant's intent is to separately disclose or claim each numerical value reasonably encompassed by such range, including not only the endpoints of the ranges but also any subranges and combinations of subranges encompassed therein, unless otherwise specified. For example, by disclosing a temperature of 70°C to 80°C, Applicant's intent is to separately recite 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, and 80°C, including any subranges and combinations of subranges encompassed therein, and these methods of describing such ranges are interchangeable. Applicant reserves the right to exclude any individual value, range, or subrange that could be claimed according to the range if, for any reason, Applicant chooses to claim less than the full scope of the disclosure.

[0021] Values ​​or ranges may be expressed using the term "about," and when such values ​​or ranges are expressed, other disclosed embodiments include the recited particular value from the one particular value and / or to the other particular value. In one aspect, use of the term "about" can be substituted with ±15% of the stated value, ±10% of the stated value, or ±5% of the stated value.

[0022] In one aspect, the present disclosure provides new and improved processes and methods for effectively removing low molecular weight compounds, particularly the compound 4-MeI, produced during the commercial production of edible caramel color. (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution by an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) contacting the permeate solution with granular activated carbon for a contact time sufficient to provide a purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; The present invention provides a process for purifying a caramel color solution, comprising:

[0023] The caramel color solution is an aqueous solution or composition. The low molecular weight species described in this process include the compound 4-methyl-imidazole (4-MeI), but may also include other compounds such as 2-methyl-imidazole (2-MeI), 5-hydroxy-2-methylpyridine, 2-hydroxypyridine, 2-hydroxy-6-methylpyridinecarboxylic acid, or combinations thereof.

[0024] The low molecular weight species 4-MeI is particularly present when the caramel color is selected from Class III caramel colors or Class IV caramel colors. Therefore, the process developed in this disclosure and further described in the Examples focuses on the 4-MeI compound.

[0025] Thus, the ultrafiltration process removes these low molecular weight compounds, particularly 4-MeI, from the caramel color composition as selectively as possible, although many higher molecular weight compounds, such as glucose and sucrose, may also pass through the membrane and be present in the permeate. This carbon filtration process allows for the selective removal of low molecular weight compounds from the permeate, thereby allowing the purified permeate to be added back to the retentate to produce a finer, more stable composition and a more closely consistent taste profile.

[0026] While the activated carbon step can be performed batchwise, the present disclosure also provides an efficient continuous extraction process using activated carbon adsorbent to remove compounds such as 4-MeI from the aqueous permeate fraction with high removal efficiencies of approximately 90% to 99%, allowing the remaining compounds, such as glucose and sucrose, to be recovered and reused. The steps of identifying the compounds to be removed, identifying activated carbon as a suitable filtration medium or adsorbent, discovering various factors that can affect separation effectiveness and enable desired solids recovery, and understanding how the adsorbent and factors can be modified to improve the separation and recovery process provided unexpected results, such as unexpected combinations of features that can improve separation efficiency.

[0027] The ultrafiltration process removes low molecular weight compounds from the caramel color solution and provides a retentate and permeate containing these compounds. The activated carbon purification process separates low molecular weight components from high molecular weight components, such as glucose and sucrose, in the permeate solution, and the purified permeate solution can be recycled and reused. For example, the purified permeate solution can be combined with the retentate solution to provide a purified caramel color solution.

[0028] Thus, in one aspect, the present disclosure provides: (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution by an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) contacting the permeate solution with granular activated carbon for a contact time sufficient to provide a purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; The present invention provides a process for purifying a caramel color solution, comprising:

[0029] In this embodiment, the granular activated carbon may be contained in a filter bed through which the permeate solution flows at a constant rate, thereby allowing the process to be run as a continuous process.

[0030] According to a further aspect, once the purified permeate solution with reduced concentrations of low molecular weight compounds is recovered, the purified permeate solution can be combined with a retentate solution to provide a purified caramel color solution. In the disclosed process, several low molecular weight species and various types of low molecular weight species can be removed from the permeate. Examples of low molecular weight species include, but are not limited to, 4-methylimidazole (4-MeI), 2-methylimidazole (2-MeI), 5-hydroxy-2-methylpyridine, 2-hydroxypyridine, 2-hydroxy-6-methylpyridine carboxylic acid, or combinations thereof. This methodology specifically targets the compound 4-MeI (4-methylimidazole), and the examples provide quantitative data regarding its removal under various conditions.

[0031] One aspect of the present disclosure provides sufficient contact time between the permeate solution and the granular activated carbon to provide a purified permeate solution containing low molecular weight species. The contact time varies depending on the flow rate of the permeate through the bed or column of activated carbon, but in embodiments, the contact time can be from about 15 minutes to about 2 hours, from about 20 minutes to about 1.5 hours, or from about 25 minutes to about 1 hour. The flow rate required to achieve these contact times depends on the size and shape of the activated carbon bed. In one aspect, a 300 cm 3 A laboratory-scale column having a carbon bed volume (bed volume) of 0.1 L / h to 1.2 L / h, or 0.3 L / h to 1 L / h, is used, and the permeate solution passes through the filter bed at a flow rate of 0.1 L / h to 1.2 L / h, or 0.3 L / h to 1 L / h.

[0032] Using the disclosed process, particularly when operated at low flow rates to provide sufficient contact time as described herein, approximately 90% or more of the low molecular weight species 4-MeI can be removed when the permeate solution is contacted with granular activated carbon to obtain a purified permeate solution. For example, when the permeate Brix is ​​approximately 3.5%, a 4-MeI concentration of approximately 500 ppb (parts per billion by weight) in the permeate solution can be reduced to a 4-MeI concentration of approximately 50 ppb in the purified permeate solution. In some embodiments, at low flow rates and sufficient contact times (e.g., 18-36 minutes), activated carbon can be used to remove approximately 98% of the low molecular weight species 4-MeI, thereby reducing a 4-MeI concentration of approximately 500 ppb in a 3.5% Brix permeate solution to a 4-MeI concentration of approximately 10 ppb in the purified permeate solution. Examples of contact times and flow rates are provided in Example 3.

[0033] In one aspect, contacting the permeate with activated carbon resulted in a change or shift in the pH, % Brix, and color of the permeate effluent compared to the permeate itself, as detailed in Example 4. As the permeate solution eluted from the column, the initial or first fractions of the effluent were observed to exhibit a higher pH, lower Brix, and lower UV-Vis absorbance compared to the starting permeate solution. The pH, Brix, and absorbance values ​​of the effluent approached or tended to approach those of the starting permeate solution as the bed volume increased.

[0034] It was also observed that the Brix % of the permeate affected the pH, Brix % and color of the initial or first fraction of the eluate, as well as their progression over time and bed volume, as tested in Example 7. The initial change in eluate pH from the starting pH of the permeate solution was significant, with the pH of the eluate approaching the starting value of the permeate solution as more bed volumes were eluted; see Example 7.

[0035] The natural pH of the permeate from an ultrafiltration process is typically about pH 3±0.5 or about pH 3±0.25. While activated carbon removal of small molecular weight compounds is possible at this pH, it has been found to be less efficient at pHs around 3 than at higher pH values; see Example 5. The data in Example 5 demonstrate that while activated carbon saturates more quickly at pH 3 compared to pH 7, slowing the flow rate and increasing the contact time can significantly improve performance at pH 3 and reduce residual 4-MeI concentrations. In one embodiment, a retentate having a pH of about 3 can be treated with a base, such as an alkali metal hydroxide, to raise the pH and improve the efficiency of activated carbon removal of small molecular weight compounds. Thus, in one embodiment, the pH of the permeate can be adjusted to a pH of about 6.5-7.5 or a pH of about 7 before contacting the permeate with granular activated carbon.

[0036] In one aspect, as demonstrated in Example 6, the permeate Brix % was also observed to affect the extraction efficiency of 4-MeI. 4-MeI content was also found to vary with Brix. Permeate samples with various % Brix values ​​ranging from 1% to 7% were tested using high Brix (approximately 7%), medium Brix (2.7-3.5%), and low Brix (0.8-1%) permeate samples. Permeate Brix values ​​greater than 4% were found to result in higher activated carbon consumption due to the higher 4-MeI content. At higher Brix values, the concentration of 4-MeI in the permeate increased, leading to higher 4-MeI uptake. However, at these higher Brix values ​​and uptake rates, the carbon bed saturated more quickly, leading to increased carbon consumption.

[0037] As described in Example 8, the effect of permeate temperature on an extraction process using activated carbon was investigated. Bacterial growth within the activated carbon bed can be problematic, and microbial accumulation over several days of use can lead to problems within the activated carbon unit. In these tests, temperatures above 60°C may mitigate bacterial growth, and therefore elevated temperatures of approximately 60°C to 80°C may be useful for mitigating microbial growth in the carbon bed during extraction. No adverse effects of elevated temperatures (60°C to 80°C) on the extraction of 4-MeI were observed. Therefore, contact of the permeate solution with granular activated carbon can be carried out at temperatures between 55°C and 85°C, or between 60°C and 80°C, without adverse effects.

[0038] Example 9 describes the testing of activated carbon regenerated by removal of adsorbed low-molecular-weight compounds. Regenerated carbon, produced by washing used activated carbon with organic solvents such as ethyl acetate or acetic acid, exhibited activity in removing 4-MeI and could minimize waste through the recycling of activated carbon. The removal performance of 4-MeI was lower compared to virgin carbon. Regeneration with ethyl acetate reduced the extraction efficiency of 4-MeI. Regeneration with acetic acid reduced the extraction efficiency of 4-MeI.

[0039] In Example 10, the effectiveness of two activated carbon beds connected in series was tested. Dual columns may be used in applications requiring frequent adsorbent changes or high carbon consumption rates, such as high Brix permeates. Tests were conducted at temperatures of 60°C and permeate concentrations of 3-4% Brix with permeate flow rates of 0.3-0.5 L / h (residence times of 36-40 min). The carbon beds did not saturate in these tests, and extraction efficiencies for 4-MeI remained high (>99%) for up to 50 bed volumes tested.

[0040] In one aspect, the initial change in pH, color body loss, and Brix change of the early-eluting permeate fraction may be reduced or minimized by pre- and post-treating the activated carbon bed using a series of so-called "sweetening-on" and "sweetening-off" steps. This "sweetening-on" step uses an initial backflow of cold water to remove fines and particulates, followed by a backflow of a solution similar in Brix and pH to the permeate but lacking 4-MeI until the Brix and pH of the outlet solution are equivalent to those of the inlet solution. This pretreatment column can be used for continuous extraction of the permeate until breakthrough of low molecular weight compounds is observed. A post-treatment "sweetening-off" step can be performed using a countercurrent hot water flush of 2-3 bed volumes to remove sugars adsorbed to the carbon bed. Cooling the carbon bed before the sweetening-off process is complete can induce solidification, making it difficult to remove salts and regenerate the carbon.

[0041] Thus, in one aspect, a combination of conditions useful for the disclosed process can include: (i) the Brix of the permeate is 3-4% and the pH of the permeate is adjusted to 6.5-7.5; (ii) the contact time is 15 minutes to 3 hours, 30 minutes to 2 hours, or 40 minutes to 1.5 hours; and (ii) the permeate solution is contacted with granular activated carbon at a temperature of 55°C to 85°C or 60°C to 80°C.

[0042] In a further aspect, a combination of conditions useful in the disclosed process can include: (i) a permeate Brix of 5-7% and a pH of 2.5-3.5; (ii) a contact time of 1-4 hours; and (ii) the permeate solution and granular activated carbon are contacted at a temperature of 55°C-85°C or 60°C-80°C.

[0043] Another aspect of the disclosure is (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution by an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) passing the permeate solution through a first granular activated carbon filter bed at a flow rate sufficient to provide a first purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; The present invention provides a continuous process for purifying a caramel color solution, comprising:

[0044] This process is (d) passing the first purified permeate solution at a predetermined flow rate through a second granular activated carbon filter bed in fluid communication with the first granular activated carbon filter bed to provide a second purified permeate solution having a third concentration of low molecular weight species that is lower than the second concentration.

[0045] In another aspect, the immediately preceding disclosed process may further include combining the first purified permeate solution, the second purified permeate solution, or both with the retentate solution to provide a purified caramel color solution. In embodiments, the permeate solution is passed through a first granular activated carbon filter bed and the first purified permeate solution is passed through a second granular activated carbon filter bed, the flow rate of the filter beds being between 0.3 L / hour and 1 L / h, and the flow rate being between 0.3 and 0.5 L / h. [Example]

[0046] The examples of the present disclosure illustrate the effectiveness of filtration or extraction methods using activated carbon extraction media to remove low molecular weight compounds in certain ingredients of food or beverages, including the compound 4-MeI (4-methylimidazole).

[0047] The activated carbon used in the examples was obtained from Chemviron and had an average particle size of 1.2-1.4 mm. The activated carbon was produced as granular carbon by prior agglomeration and steam activation of selected grades of bituminous coal, and pretreated by acid washing and neutralization.

[0048] Example 1 Continuous Flow Extraction System A simple continuous-flow extraction system was constructed and used in small molecule extraction experiments to identify and develop process aspects. The continuous-flow extraction system included a permeate reservoir (permeate reservoir) in fluid communication with a dosing pump, which was used to deliver the permeate from the reservoir to a column containing activated carbon at a set dosing rate. The pump used was a positive displacement, solenoid-driven pump manufactured by HANNA® Instruments, with an adjustable flow rate of up to 15.2 L / h (liters per hour) at 1 bar pressure.

[0049] A dosing pump collected permeate from the permeate reservoir and delivered it to the top of the activated carbon column using a foot valve assembly fitted with a filter. The flow rate at the column outlet was controlled by a tap at the bottom of the column, and the filtered fraction of the purified permeate was collected for analysis.

[0050] Example 2 Conditions used in the extraction experiment The conditions used in the extraction experiments were based on the results obtained in the initial test. Liquid-phase isotherms were used to demonstrate the relationship between adsorbent (carbon) loading and residual concentrations of low molecular weight compounds. This relationship was modeled using an empirical Freundlich isotherm for a non-uniform surface. This data was obtained by adding increasing amounts of activated carbon to different flasks containing a fixed volume of permeate. An empty flask containing no carbon-containing liquid served as a control. The flasks were stirred at a constant temperature for 24 hours until equilibrium was reached. The contents of the flasks were then filtered, and the liquid was analyzed for residual low molecular weight compounds. The data from the isotherm test can be used to determine the amount of granular carbon (carbon consumption) required to achieve treatment objectives. The isotherm test generated estimates of continuous process parameters based on permeate samples at 5% Brix and pH 7. The amount of carbon used was 140 g / bed. The volume of treated liquid was approximately 20–25 L, the flow rate was 4 L / h, and the estimated test time was approximately 5–7 hours.

[0051] In a particular experiment, the total bed volume (BV) to be processed is approximately 80–85 BV for 24–25.5 L. The bed volume corresponds to the volume of the carbon bed, which is 300 cm for the lab-scale column setup implemented in this study. 3 It was.

[0052] A small sample can be taken every n BV for analysis. Because the filtered permeate is expected to be free of 4-MeI during the initial BV, sampling is initially performed at intervals, and then more frequently once breakthrough is observed at the outlet. Breakthrough is monitored by TLC analysis and confirmed by LCMS-MS analysis. Breakthrough curves are then generated, plotting the 4-MeI concentration (%) at the outlet against the number of bed volumes processed. These plots helped identify the point at which performance significantly declines and the permeate volume the carbon bed can handle.

[0053] These conditions were used in the continuous flow experiments shown in the Examples below to investigate and determine the effect of contact time (linear velocity), pH, % Brix, temperature, activated carbon regeneration, and the series connection of activated carbon columns (beds) on the extraction process.

[0054] Example 3 Effect of contact time (linear velocity, flow rate) on extraction efficiency To identify the highest flow rate at which sufficient extraction could be achieved, allowing for shorter processing times, the effect of permeate contact time in the activated carbon column on extraction efficiency was investigated. These experiments were performed with permeate at 3.5% Brix and pH 7.

[0055] The following flow rates were tested and the contact time of the permeate with the activated carbon bed at each flow rate is shown in the table along with the starting concentration of 4-MeI.

[0056] [Table 1]

[0057] The effect of contact time (linear velocity or flow rate) on the extraction of 4-MeI is shown in Figure 1 in a plot of extraction efficiency (%) versus bed volume number for 4-MeI extraction of a 3.5% Brix solution.

[0058] This study demonstrated that by using flow rates of 1 L / h or less, no breakthrough was observed within the first 15 bed volumes. At flow rates above 1 L / h, the contact time was insufficient to efficiently extract 4-MeI. While not intending to be bound by theory, 4-MeI breakthrough (a decrease in extraction efficiency) was observed earlier, likely due to lower 4-MeI concentrations (ppb) in the permeate. The data below demonstrate that when operated at low flow rates, residual 4-MeI concentrations are low, indicating that good extraction performance can be achieved with contact times of 18 to 36 minutes; see Table 1. Thus, Figure 2 plots residual 4-MeI versus bed volume number for a 3.5% Brix solution, demonstrating that a bed contact time of 18 to 36 minutes (flow rates of 0.5 to 1 L / h) is the minimum contact time for efficiently extracting 4-MeI. Thus, for contact times between 18 and 36 minutes, very low residual concentrations of 4-MeI (approximately 10 ppb) were observed for the first 14 bed volumes, with reduction efficiencies of over 98% for both 4-MeI species. At higher flow rates (2-4 L / h), the contact time between the permeate and carbon was insufficient, resulting in reduced extraction efficiency.

[0059] These experiments demonstrated that longer contact times improved extraction efficiency. A minimum contact time of 18 to 36 minutes was identified as effective for efficient extraction of 4-MeI. Therefore, a minimum contact time of approximately 40 minutes was used in the experiments.

[0060] Similar analysis of the 1% Brix permeate solution also showed that longer contact times (eg, 18 minutes or more) could achieve removal of 4-MeI even at very low starting concentrations.

[0061] Example 4 Effect of activated carbon contact on pH, Brix, and color changes of perfusate As the permeate passed through the column and filtered, changes in pH, Brix, and color of the permeate were observed. These initial changes from the starting pH, Brix, and color were observed with the initial fractions of eluate exhibiting higher pH, lower Brix, and lower UV-Vis absorbance compared to the starting permeate solution. In each case, the pH, Brix, and absorbance values ​​of the eluate approached or tended to approach the starting values ​​of the permeate solution as the bed volume increased.

[0062] An initial increase in pH was observed, which then stabilized at a value close to the starting pH of the permeate, as shown in Figure 3. The control line in Figure 3 represents the pH of the permeate loaded onto the carbon bed before contacting the activated carbon. While not intending to be bound by theory, this observation may result from a variety of factors. For example, some anion exchange or chemical reaction with anions of weak acids or cations of weak bases may occur on the surface of the carbon, resulting in salt formation and affecting the pH. Additionally, the soluble ash content of acid-washed carbons such as those tested here may affect the pH to some extent, although this factor may be less significant due to the relatively low ash content.

[0063] A larger increase in the pH of the initial fractions of eluate was observed for the permeate at pH 3 compared to pH 7. This change in pH appears to be largely independent of the flow rate used, as no significant difference was observed between the flow rates of the pH 3 and pH 7 permeates, as shown in Figure 3.

[0064] Some solids are retained or adsorbed by the activated carbon bed during elution and may be recovered by washing the bed with water. Permeate Brix was also observed to change during the elution process. This progression of Brix measurements of the filtered permeate suggests that initial adsorption of other soluble solids in the permeate occurs, followed by stabilization as the carbon becomes saturated with these soluble solids. Color bodies were also retained by the carbon bed, resulting in a loss of color in the initial fraction of the eluate. Color substances from the permeate were also adsorbed, but compared to the change in Brix, color body adsorption occurred more linearly as a function of bed volume. These effects are demonstrated in the data shown in Figures 4 and 5. The control lines in Figures 4 and 5 indicate the pH of the permeate loaded onto the carbon bed before contacting the activated carbon.

[0065] The extent of color extraction from the permeate and adsorption of solids by the carbon also appears to be largely unaffected by the pH value of the permeate and the flow rate used. As the pH of the permeate increases from pH 3 to 7, the permeate darkens, but the extent (%) of color body extraction is similar at both pH 7 and pH 3. Furthermore, the progression of Brix is ​​similar when the permeate pH and contact time are varied.

[0066] It has been discovered that pH changes, color body losses, and Brix changes may be reduced or minimized by pre-treating and post-treating activated carbon beds using a series of so-called "sweetening-on" and "sweetening-off" procedures.

[0067] Example 5 Effect of permeate pH on extraction efficiency The effect of the pH of the permeate solution on the extraction or removal efficiency of low molecular weight species was investigated. These tests were performed on a permeate solution with a Brix of 3.5%.

[0068] At a permeate pH of 3, close to the natural pH of the permeate, removal efficiency was reduced compared to permeate adjusted to pH 7. This effect was most pronounced for 4-MeI removal, where removal at pH 7 showed better performance compared to pH 3. However, extraction of 4-MeI at pH 3 improved with longer contact times (longer than 36 minutes, corresponding to 0.5 L / h or less). Therefore, removal at pH 3 with longer contact times (e.g., longer than 40 minutes) is expected to provide viable removal efficiency. These results are shown in Figure 6.

[0069] One advantage of performing extraction at pH 3 is that it is approximately the natural pH of the permeate, eliminating the need for additional processing steps such as neutralization or re-acidification. Therefore, removal at pH 3 requires higher carbon consumption and higher operating costs to achieve removal efficiencies comparable to pH 7.

[0070] These data also show that the residual concentration of 4-MeI after column passage is lower at pH 7 compared to pH 3. At pH 3, the carbon becomes saturated more quickly compared to pH 7, so the 4-MeI adsorption capacity of the carbon may be lower at pH 3. However, by slowing the flow rate and increasing the contact time, the performance at pH 3 can be significantly improved, significantly reducing the residual 4-MeI concentration.

[0071] These tests suggested that extraction performance at pH 7 was superior to that at pH 3. However, increasing the contact time between the permeate solution and activated carbon significantly improved performance at pH 3. To achieve similar performance at pH 3 as observed at pH 7, extraction at pH 3 likely required higher carbon consumption.

[0072] Example 6 Effect of % Brix on extraction efficiency The effect of soluble solids in the permeate on extraction efficiency was investigated. The 4-MeI content was also found to vary depending on the Brix. Permeate samples obtained from pilot studies had Brix values ​​ranging from 1% to 7%. These were classified into three groups according to the permeate: high Brix (approximately 7% Brix), medium Brix (2.7-3.5% Brix), and low Brix (0.8-1% Brix). Permeate Brix values ​​above 4% were found to result in higher 4-MeI content, resulting in higher activated carbon consumption. As shown in the following table, at higher Brix values, increasing the 4-MeI concentration in the permeate also resulted in higher 4-MeI uptake.

[0073] [Table 2]

[0074] The uptake of 4-MeI was found to increase (approximately 7%) with higher Brix values, likely due to its higher concentration in the permeate. However, at these Brix values ​​and uptake rates, the carbon bed saturated more quickly, leading to increased carbon consumption. For medium and low Brix samples, no performance degradation was observed across the tested bed volumes at 18 minutes of contact time. However, at high Brix, a significant decrease in performance was observed due to the presence of high concentrations of 4-MeI and other compounds in the permeate. These factors are observed in Figure 7 for 4-MeI. At higher Brix, increasing the mass transfer area for adsorption, for example, by using multiple columns in series to increase contact time, would improve performance and extraction efficiency.

[0075] Thus, in general, under the experimental conditions used, high levels of extraction efficiency were observed for samples below 4% Brix, and therefore, 4-MeI breakthrough dominates the carbon bed life.

[0076] Example 7 Permeate pH, Brix, and color in contact with activated carbon as a function of Brix As the permeate eluted from the column, early fractions of the eluate were observed to change from the starting pH, Brix, and color, exhibiting higher pH, lower Brix, and lower UV-Vis absorbance compared to the starting permeate solution. In each case, the pH, Brix, and absorbance values ​​of the eluate approached or tended to approach those of the starting permeate solution as bed volume increased.

[0077] While not intending to be bound by theory, it is believed that the changes in permeate pH and Brix are due to the adsorption of sugars and salts from the initial bed volume of the eluate. Pretreating the carbon bed, as described herein, can reduce these changes in both pH and % Brix. These effects were found to vary as a function of the Brix of the starting permeate, as shown in Figure 8. In Figure 8, the starting pH values ​​of the eluate before elution were as follows: 0.8-1% Brix, pH 7.4; 2.7-3.5% Brix, pH 7.07; and approximately 7% Brix, pH 7.14.

[0078] As shown, the initial change in effluent pH from the starting permeate pH was large, and as the elution bed volume increased, the effluent pH approached the starting value of the permeate. A lower degree of change in initial effluent pH was observed for the high and medium Brix permeates compared to the low Brix permeates, likely due to the higher concentrations of salts and buffers present in the high and medium Brix permeates compared to the low Brix permeates, which mitigated this change. All samples showed a decrease in pH with increasing bed volume, with the lower Brix values ​​exhibiting a higher initial pH and a more gradual decrease in pH, likely due to the lower concentration of buffers in the low Brix samples. As described herein, a pretreatment step can be applied to precondition the activated carbon bed to reduce or minimize these changes in pH and solids retention.

[0079] The initial change in permeate Brix observed as sugars and salts from the initial bed volume are adsorbed onto the carbon is believed to be due to the activated carbon becoming saturated with sugars and salts from the permeate over approximately 5-10 bed volumes, after which the Brix of the effluent returns to the permeate input value. Figure 9 demonstrates the progression of Brix as a function of the initial permeate Brix.

[0080] Low, medium and high Brix permeates were tested at pH 7. The Brix % of the samples as received and the Brix % of the control (Brix after neutralization to pH 7) are shown in the table below.

[0081] [Table 3]

[0082] Each sample showed an initial decrease in Brix from the starting permeate, followed by an increase in Brix as the bed volume increased. Permeates with higher initial % Brix values ​​exhibited a more rapid increase over a wider % Brix range due to earlier saturation of the carbon bed.

[0083] In contrast, color body extraction or adsorption was observed to vary more linearly with bed volume, as opposed to the asymptotic changes observed with pH and Brix. As shown in the figure, all samples showed an increase in absorbance as larger volumes of permeate passed through the column, and the higher the concentration of color bodies in the high-Brix permeate, the more rapidly the absorbance increased with bed volume number. For Figure 10, the absorbance levels of the control (unfiltered) at each Brix level (500 nm) were as follows: 0.8-1% Brix: 0.327, 2.7-3.5% Brix: 0.501, and approximately 7% Brix: 1.035.

[0084] Example 8 Effect of temperature on the extraction process Bacterial growth within the activated carbon bed can be a problem, and microbial buildup over several days of use can lead to problems within the activated carbon unit. Extractions were tested at temperatures of approximately 20°C ("room temperature"), 60°C, and 80°C. When testing a 3.5% Brix permeate solution with a pH of 7 at these different temperatures, essentially no decrease in extraction efficiency of 4-MeI was observed over approximately 18 bed volumes when tested at a flow rate of 1 L / h and a residence time of 18 minutes.

[0085] In these studies, high temperatures (above 60°C) may mitigate bacterial growth, and therefore the use of elevated temperatures of about 60°C to 80°C may be useful to mitigate microbial growth in the carbon bed during extraction. No adverse effects of elevated temperatures (60-80°C) on the extraction of 4-MeI were observed, so continuous extractions may be performed at temperatures of about 60°C to 80°C.

[0086] Example 9 Activated carbon regeneration test An initial evaluation was conducted to determine whether spent activated carbon could be regenerated. Regenerating spent carbon allows for the carbon bed to be recycled and minimizes waste. These tests were performed as follows: the spent carbon was first washed with two bed volumes of water to release the trapped sugars, followed by a one bed volume dynamic solvent wash using either ethyl acetate or acetic acid, and finally a three bed volume water wash. The regenerated carbon bed was then tested to compare its performance for 4-Mel extraction to that of virgin carbon.

[0087] The table below provides data comparing the extraction efficiency of a used carbon bed before regeneration, after regeneration when washed with either ethyl acetate or acetic acid, and compared to the 4-MeI extraction efficiency of a virgin bed.

[0088] [Table 4]

[0089] These initial tests indicate that regenerated carbon can extract 4-MeI, but at a lower performance than virgin carbon. Therefore, there is potential for the carbon to be regenerated using solvent extraction methods and used for extraction, either alone or in combination with virgin carbon.

[0090] Example 10 Use of two activated carbon columns (beds) in series In applications requiring frequent replacement of the adsorbent or where the carbon consumption rate is high, dual columns can be used, and the use of two columns in series was considered.

[0091] Two columns were connected in series, and breakthrough curves were recorded for each column versus the total bed volume treated. Test conditions included a temperature of 60°C, a permeate flow rate of 0.3-0.5 L / h (residence time of 36-40 min) for a 3-4% Brix permeate. When operated at laboratory scale under these specified conditions, the carbon bed did not saturate in these tests. Extraction efficiency for 4-MeI remained high (>99%) for up to 50 bed volumes tested.

[0092] Studies with shorter contact times have shown that 4-MeI extraction performance is reduced. Therefore, using columns in series can be effective for removing 4-MeI when operated at high Brix (>5%).

[0093] Example 11 Pre- and post-treatment of activated carbon columns Based on the above experimental data showing that solids loss (% Brix change) and pH change (increase) occurred during the initial bed volume of extraction, the following pre- and post-treatment processes for the carbon bed can be developed as follows: These pre- and post-treatment processes are referred to as the "sweetening-on" and "sweetening-off" steps.

[0094] The first cold water wash is performed by passing cold water through the column in a countercurrent mode, with the cold water entering the column from the bottom and exiting from the top. Because cold water is more viscous than hot water, this countercurrent cold water wash effectively removes any remaining fines or particulates. This cold water wash is followed by a hot water countercurrent wash, which warms the bed and minimizes sugar crystallization.

[0095] A pretreatment "sweetening-on" step is then performed using a solution with Brix and pH similar to the permeate but without low molecular weight species (e.g., 4-MeI). This sweetening solution is passed through the column at a rate of 2 L / h from the top until the Brix % and pH at the outlet are the same as those at the inlet. The column is now pretreated, and continuous extraction of the permeate is performed until breakthrough of low molecular weight compounds is observed.

[0096] A post-treatment "sweetening-off" process is performed at the end of the carbon bed's life as follows: A countercurrent hot water flush of 2-3 bed volumes is performed to remove sugars adsorbed to the carbon bed. If the bed cools before the sweetening-off process is complete, solidification can be induced, making it difficult to remove salts and regenerate the carbon. Because a 90-100% recovery of solids is expected from the sweetening-off solution, the sweetening-off fraction can be recycled to condition a new carbon bed during the sweetening-on process.

[0097] Example 12 Changes in permeate composition during extraction As fractions were collected from the ultrafiltration process, changes in the permeate composition occurred, with the Brix and 4-MeI concentration gradually decreasing in the later collected fractions. Changes in permeate composition during extraction were found to have a negative impact on the sustained operation and lifespan of the carbon bed. For example, high levels of 4-MeI in the early permeate fractions could lead to premature breakthrough and reduced extraction performance in medium and low Brix permeates, potentially resulting in desorption of the adsorbed compound (4-MeI) as the Brix progresses to medium and low Brix.

[0098] To avoid these problems, a feed tank can be used to collect multiple fractions of the permeate produced from the ultrafiltration process. This feed tank can be used to supply the permeate to the carbon bed. This process keeps the composition of the permeate supplied to the carbon bed relatively constant, allowing the carbon bed to function efficiently and sustainably. This also preserves the life of the carbon bed, which is affected by significant changes in composition (such as Brix and 4-MeI concentration). Additionally, the use of a recovery tank after extraction can provide a more consistent quality of permeate.

Claims

1. (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution using an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) contacting the permeate solution with granular activated carbon for a contact time sufficient to provide a purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; 1. A process for purifying a caramel color solution, comprising:

2. 10. The process of claim 1, wherein the granular activated carbon is contained within a filter bed through which the permeate solution flows at a constant flow rate.

3. 3. The process of claim 1 or claim 2, wherein the contact time is from 15 minutes to 2 hours, from 20 minutes to 1.5 hours, or from 25 minutes to 1 hour.

4. 4. The process of claim 2 or claim 3, wherein the permeate solution is passed through the filter bed at a flow rate of from 0.1 L / h to 1.2 L / h, or from 0.3 L / h to 1 L / h.

5. 5. The process of any one of claims 1 to 4, further comprising combining the refined permeate solution with the retentate solution to provide a refined caramel color solution.

6. 6. The process of any one of claims 1 to 5, wherein the low molecular weight species comprises 4-methylimidazole (4-MeI), 2-methylimidazole (2-MeI), 5-hydroxy-2-methylpyridine, 2-hydroxypyridine, 2-hydroxy-6-methylpyridinecarboxylic acid, or a combination thereof.

7. The process of any one of claims 1 to 6, wherein the low molecular weight species comprises 4-MeI (4-methylimidazole).

8. 8. The process of any one of claims 1 to 7, wherein the caramel color is selected from Class III caramel colors or Class IV caramel colors.

9. 9. The process according to any one of claims 1 to 8, wherein the molecular weight cut-off of the ultrafiltration process is about 800 Da.

10. 10. The process of any one of claims 1 to 9, wherein the permeate solution from the ultrafiltration step has a pH of about pH 3±0.5 or about pH 3±0.

25.

11. 11. The process of any one of claims 1 to 10, wherein the pH of the permeate solution is adjusted to a pH of about 6.5 to 7.5 or to a pH of about 7 prior to contacting the permeate solution with granular activated carbon.

12. 12. The process of any one of claims 1 to 11, wherein the pH of the permeate solution is between 3 and 4% Brix, and the pH of the permeate solution is adjusted to a pH of about 6.5 to 7.5 prior to contacting the permeate solution with granular activated carbon.

13. 13. The process of any one of claims 1 to 12, wherein contacting the permeate solution with the granular activated carbon is carried out at a temperature of from 55°C to 85°C or from 60°C to 80°C.

14. 14. The process of any one of claims 1 to 13, wherein the % Brix of the permeate solution is from about 1% to about 7% before contacting the permeate solution with granular activated carbon.

15. 15. The process of any one of claims 1 to 14, wherein the low molecular weight species comprises 4-MeI and at least 90% of the 4-MeI concentration in the permeate solution is removed by contacting the permeate solution with granular activated carbon to provide a purified permeate solution.

16. 16. The process of any one of claims 1 to 15, wherein the purified permeate solution comprises 4-MeI at a concentration of 50 ppb (parts per billion by weight).

17. (i) the permeate has a Brix of 3-4% and the pH of the permeate is adjusted to 6.5-7.5; (ii) the contact time is from 15 minutes to 3 hours, from 30 minutes to 2 hours, or from 40 minutes to 1.5 hours; (ii) contacting the permeate solution with the granular activated carbon is carried out at a temperature of from 55°C to 85°C or from 60°C to 80°C; The process according to any one of claims 1 to 2.

18. (i) the permeate has a Brix of 5 to 7% and a pH of 2.5 to 3.5; (ii) the contact time is between 1 hour and 4 hours; (ii) contacting the permeate solution with the granular activated carbon is carried out at a temperature of from 55°C to 85°C or from 60°C to 80°C; The process according to any one of claims 1 to 2.

19. (a) providing a caramel color solution comprising low molecular weight species and high molecular weight species; (b) filtering the caramel color solution using an ultrafiltration process to obtain a retentate solution comprising high molecular weight species and a permeate solution comprising low molecular weight species at a first concentration; (c) passing the permeate solution through a first granular activated carbon filter bed at a flow rate sufficient to provide a first purified permeate solution having a second concentration of low molecular weight species that is less than the first concentration; 1. A continuous process for purifying a caramel color solution, comprising:

20. (d) passing the first purified permeate solution at a predetermined flow rate through a second granular activated carbon filter bed in fluid communication with the first granular activated carbon filter bed to provide a second purified permeate solution having a third concentration of low molecular weight species that is less than the second concentration.

20. The process of claim 19, further comprising:

21. 21. The process of any one of claims 19-20, further comprising combining the first purified permeate solution, the second purified permeate solution, or both, with a retentate solution to obtain a purified caramel color solution.

22. 22. The process of any one of claims 19 to 21, wherein the low molecular weight species comprises 4-MeI (4-methylimidazole).

23. 23. The process of any one of claims 19 to 22, wherein the permeate solution is passed through the first granular activated carbon filter bed, and the first purified permeate solution is passed through the first granular activated carbon filter bed at a flow rate of 0.3 L / h to 1 L / h, or 0.3 to 0.5 L / h.

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