Method for producing instant-solving coffee powder

Abstract

FIELD: coffee industry.SUBSTANCE: method is carried out as follows. Water extract of coffee is provided. Roasted coffee with a CMU color greater than 100 is provided. Roasted coffee is maintained in a substantially oxygen-free processing chamber containing less than 2% oxygen by volume at a temperature of 70 to 120 °C for 30 minutes to 50 hours to produce roasted coffee with reduced acrylamide content. The processing chamber is flushed with inert gas before use and the roasted coffee is stored and poured into the chamber under the influence of inert gas. The aqueous coffee extract is dried to produce instant coffee powder. Roasted coffee powder with reduced acrylamide content is added to the aqueous coffee extract before the drying step or to the soluble coffee powder obtained in the drying step to obtain an instant coffee powder containing soluble coffee and from 1 wt.% to 20 wt.% roasted and ground coffee, by weight of the instant coffee powder. The method reduces acrylamide concentrations by at least 30%. The instant coffee powder has an acrylamide content of less than 900 ppb, consists of instant coffee and from 1 wt.% to 20 wt.% of roasted and ground coffee by weight of the instant coffee powder, wherein the roasted and ground coffee has a roast color according to CMU of more than 100, preferably more than 120 and more preferably more than 130, wherein the roasted and ground coffee is uniformly distributed in the instant coffee.EFFECT: enabling the creation of instant coffee containing an additive of roasted and ground coffee, with a reduced acrylamide content and a wider range of flavor and aromatic notes.20 cl, 6 dwg, 1 tbl

Description

[0001] The present invention relates to a method for producing an instant coffee powder that has a reduced acrylamide content or a different flavor profile without increased acrylamide content. In particular, the invention relates to an instant coffee powder containing soluble coffee supplemented with roasted and ground coffee particles.

[0002] The extraction of roasted and ground coffee with water to produce a liquid coffee concentrate with a high content of coffee solids is well known. Furthermore, drying such a concentrate, for example, by spray or freeze drying to produce an instant beverage, is well known. The instant beverage can then be reconstituted at the consumer's discretion with hot (or cold) water to produce a coffee beverage. It is well known that roasted and ground coffee powder is added to such products, which improves the product's flavor and aroma.

[0003] Industrial production of liquid coffee concentrates for soluble or "instant coffee" products involves higher temperatures and pressures than those used in coffee shop brewing systems. This allows for a higher yield of beans and less waste, but has the side effect of potentially introducing undesirable flavors and aromas into the coffee.

[0004] Food products exposed to high temperatures during processing often contain high levels of acrylamide. These temperatures can be reached during the first few minutes of the coffee roasting process, when acrylamide levels have been reported to be highest. Because acrylamide is a potential carcinogen, the food industry has joined forces to reduce acrylamide concentrations in foods. Therefore, it is advisable to take measures to reduce acrylamide levels that accumulate during coffee production.

[0005] Asparagine is converted to acrylamide, among other products, through a chemical reaction at elevated temperatures. Unlike most other foods, acrylamide content in coffee decreases with increasing processing time (roasting). This effect occurs in all foods with sufficient heat, but under normal processing conditions, most foods do not convert all of their asparagine to acrylamide; thus, longer processing typically results in higher acrylamide concentrations. However, in coffee, all of the asparagine is depleted before processing is complete, after which acrylamide concentrations begin to drop. The most likely mechanisms for acrylamide loss are polymerization, decomposition, or reaction with other food components. Therefore, in the case of roasted and ground coffee, the problem is primarily with lighter roasts, as acrylamide decomposes under harsher roasting conditions.Lighter roasts can be associated with different flavor profiles and higher yields.

[0006] Accordingly, to obtain roasted and ground coffee with low acrylamide levels, it is necessary to roast the coffee relatively dark. The darker the roast, the lower the observed acrylamide concentrations, but the coffee's flavor profile suffers. The sale of coffee products is regulated by strict sanitary standards, requiring commercial products to have low acrylamide levels.

[0007] The roast level of coffee beans can be assessed by analyzing the color of the roasted beans. This is based on the color reflectance, so darker beans are associated with a lower Colorette Number (CMU). A CMU of less than 90 is associated with a relatively dark roast, while a CMU of around 120 corresponds to a relatively light roast. The color measurement system and its meaning are discussed below.

[0008] It is known from the prior art that acrylamide concentrations in roasted and ground coffee decrease very gradually during storage; Guenther et al., Food Additives & Contaminants, Vol. 24(sup1), p60 (2007). However, long-term storage of coffee is associated with a loss of freshness and flavor, so that the product no longer meets consumer expectations.

[0009] It is therefore desirable to create a new coffee product with the desired low acrylamide concentrations, but with a different flavor profile, or even a product with a standard flavor profile having lower acrylamide concentrations, and / or to solve at least some of the problems associated with the prior art, or at least to provide a commercially viable alternative thereto.

[0010] GB 2514138 refers to the pre-extraction of coffee solids from roasted and ground coffee powder before using it as an additive in instant coffee.

[0011] EP 3087845 relates to instant coffee comprising: a dried coffee extract; and a fine powder of roasted coffee beans, wherein the instant coffee has a mass ratio of acetic acid (B) to malic acid (A), [(B) / (A)], equal to 2.9 or less.

[0012] GB 2006603 relates to a coffee product consisting of highly free-flowing agglomerates containing soluble coffee particles and finely ground roasted coffee, said finely ground roasted coffee being present in an amount of from 2 to 20% by weight based on the weight of the two coffee components and having a particle size such that 90% by weight of the ground coffee passes through a 75 micron mesh.

[0013] JP 2008048728 relates to a method for producing coffee beans, including feeding an extracted coffee solution that suppresses the production of hydrogen peroxide in the body after consumption.

[0014] JP 2011055716 relates to a method for producing purified roasted coffee beans, which enables the production of a coffee extract having not only a high chlorogenic acid dimer content ratio and a low hydroxyhydroquinone to chlorogenic acid content ratio, but also excellent taste.

[0015] According to a first aspect, a method for producing instant coffee powder is provided, comprising:

[0016] (i) providing an aqueous extract of coffee;

[0017] (ii) providing roasted coffee;

[0018] (iii) holding the roasted coffee in a substantially oxygen-free processing chamber at a temperature of from 70 to 120°C for at least 30 minutes to produce roasted coffee with reduced acrylamide content; and

[0019] (iv) drying an aqueous extract of coffee to obtain soluble coffee powder; wherein either:

[0020] a) the roasted coffee obtained in step (ii) is a roasted coffee powder, wherein step (iii) produces a roasted coffee powder having a reduced acrylamide content; or

[0021] b) the method further comprises the step of grinding the roasted coffee with reduced acrylamide content obtained in step (iii) to obtain a roasted coffee powder with reduced acrylamide content;

[0022] and, wherein the method further includes:

[0023] (v) adding a reduced acrylamide roasted coffee powder to an aqueous extract of coffee before the drying step (iv) or adding a reduced acrylamide roasted coffee powder to the soluble coffee powder obtained in step (iv), thereby producing an instant coffee powder containing soluble coffee and from 1 wt. % to 20 wt. % of roasted and ground coffee, by weight of the instant coffee powder.

[0024] Acrylamide is formed primarily during coffee roasting at temperatures between 140 and 180°C, and begins to decompose at temperatures above 180°C. For coffee extraction processes (i.e., bringing roasted coffee into contact with a hot aqueous solvent), limiting the temperature below 140°C will result in low yields during industrial processing. Meanwhile, prolonged exposure to temperatures above 180°C, which can reduce acrylamide content, will lead to overextraction and the development of off-flavors.

[0025] Roasting coffee at temperatures below 140°C does not produce acrylamide, and the coffee is not roasted sufficiently to produce the desired flavor. At temperatures above 180°C, acrylamide levels begin to decrease. Typical roasting profiles involve temperature gradients that pass through the acrylamide formation range and then remain for some time in the acrylamide degradation range. The longer the coffee remains above the acrylamide formation range, the darker the roast color.

[0026] Roasting coffee to a darker roast is not always desirable, as it affects the flavor and aroma characteristics, and the associated temperatures lead to material loss during roasting. Lighter roasts offer a wider range of available flavor and aroma characteristics and are indeed better extracted when exposed to hot water during traditional extraction. Furthermore, since lighter roasts experience less roasting loss, higher yields (relative to the original green bean mass) can be achieved. However, using a lighter roast means that the beans contain more acrylamide, which can result in products with unacceptable acrylamide levels.

[0027] As is well known, instant coffee products contain roasted and ground coffee material mixed with instant coffee granules or embedded within the instant coffee granules. However, during the manufacturing of these products, there are limits on the acrylamide content of the finished coffee granules. To meet these requirements, darker roasted and ground coffee is added, for example, to a color value of 80-90 CMU.

[0028] The inventors have discovered that the processing process described herein can reduce the acrylamide content of the roasted and ground coffee component and, optionally, the soluble coffee component, allowing for the use of lighter roasted and ground coffee. This means that reducing the acrylamide content of the product components allows for the use of lighter roasted coffee, thereby broadening the flavor range and simultaneously increasing the yield of the roasted and ground coffee used.

[0029] In the context of roasted and ground coffee with added instant coffee, this is particularly important, as roasted and ground coffee contains unextracted coffee aroma components that are only released upon reconstitution in water during beverage preparation (compared to a conventional product containing only instant coffee). This means that the present invention allows for the capture of additional flavor and aroma notes that are otherwise not observed in products with added roasted coffee due to the required dark roasting necessary to meet low acrylamide regulations. Without the present invention, these flavor notes would only be observed if the products also had undesirably high acrylamide levels, for example, greater than 900 ppb.

[0030] It should be understood that the processing methods described herein for reducing acrylamide concentrations in roasted and ground coffee components, as well as in soluble coffee components, affect the flavor of the final product. The desired final flavor achieved in each specific case will determine the extent to which the processing can be applied to the entire product or to its components. While the present method certainly opens up opportunities for creating a wider range of products, a balance must be struck between acrylamide concentrations and the desired product characteristics.

[0031] According to a further aspect, there is provided an instant coffee powder comprising instant coffee and from 1% by weight to 20% by weight of roasted and ground coffee, by weight of the instant coffee powder, wherein the roasted and ground coffee has a roast color according to CMU of more than 100, preferably more than 120 and more preferably more than 130, and wherein the instant coffee powder has an acrylamide content of less than 900 ppb;

[0032] Preferably, the roasted and ground coffee is evenly distributed in the instant coffee.

[0033] Detailed Description

[0034] The present invention relates to the production of instant coffee powder. Instant coffee powders are well-known commercial coffee products manufactured by a number of different companies. Instant coffee powders are such that when hot water is added, for example at a temperature above 85°C, preferably from 85 to 95°C, the instant coffee powder dissolves and a coffee beverage is obtained. Instant coffee powder contains soluble coffee, which is usually in the form of granules. Spray-dried soluble coffee is typically characterized by the presence of round, spherical granules, while coffee obtained by freeze-drying is typically characterized by sharp, shard-shaped granules, which are generally slightly larger than the granules of coffee obtained by spray-drying.Instant coffee powders may additionally contain other components, such as insoluble particles of ground coffee or soluble components such as creamer and / or sweeteners.

[0035] The instant coffee powder obtained according to the present method contains soluble coffee and (insoluble) particles of roasted and ground coffee. The instant coffee powder contains soluble coffee and from 1 to 20% by weight of roasted and ground coffee by weight of the instant coffee powder. Preferably, the instant coffee powder contains from 12 to 18% by weight of roasted and ground coffee. Preferably, the instant coffee powder consists of soluble coffee and particles of roasted and ground coffee. The particles of roasted and ground coffee can be uniformly distributed in the soluble coffee or can be dry-mixed with the soluble coffee particles after their formation. Uniform distribution is easily achieved due to the fact that the material from the roasted and ground coffee is present in the liquid coffee extract before it is dried.

[0036] The method includes the step of (i) obtaining an aqueous coffee extract. Methods for producing an aqueous coffee extract are well known in the art, with the most common commercial approach involving multiple sequential extraction columns. Hot water, passing through roasted and ground coffee beans, extracts soluble coffee matter into the hot water, forming a solution of soluble coffee solids. A preferred aqueous coffee extract contains from 35 to 65% by weight of soluble coffee solids, more preferably from 45 to 55% by weight of soluble coffee solids. That is, if the extract were completely dehydrated, the remaining solids would constitute 45-55% by weight of the original mass.

[0037] The method includes the step (ii) of providing roasted coffee. Methods for roasting coffee beans are well known in the art, and the method is suitable for all degrees of roasting. As described below, the roasted coffee can be provided in the form of whole beans or in the form of ground or ground coffee beans. Preferably, the roasting process is carried out on whole beans, but the roasted beans can then be ground or ground before subsequent steps of the process described herein. Preferably, the roasted coffee obtained in step (ii) has been roasted to a color according to the CMU greater than 100, preferably greater than 120, and more preferably greater than 130.

[0038] Preferably, the roasted coffee obtained in step (ii) is obtained at a temperature below 50°C, preferably at room temperature. This means that the process is preferably carried out on pre-roasted and cooled roasted coffee. The processing described herein constitutes a separate processing step and is not part of the initial roasting stage.

[0039] Stage (iii)

[0040] For reducing the acrylamide content in roasted coffee, the method comprises the step (iii) of holding the roasted coffee in a substantially oxygen-free treatment chamber at a temperature of from 70 to 120°C for at least 30 minutes to obtain roasted coffee with a reduced acrylamide content.

[0041] This heating hold step is based on the inventors' work on reducing acrylamide formation during the extraction process, understanding the formation pathways and identifying critical pathways. By understanding the mechanisms that cause acrylamide reduction in later roasting stages, during storage of roasted and ground coffee, and the observed increase in acrylamide during the preparation of instant coffee from roasted and ground coffee beans, the inventors were able to develop strategies to minimize adverse acrylamide changes during instant coffee production.

[0042] In the authors' work, a number of precursors (free amino acids, reducing sugars), intermediates (3-aminopropionamide (3-APA)) and reaction products (acrylamide, pyrazines and pyrroles) were monitored during the extraction of five different types of roasted and ground coffee: very light roast, light roast, medium roast, and dark roast Robusta, and medium roast Arabica. Samples of green beans, roasted beans, and samples obtained from primary, secondary, and tertiary extracts were analyzed.

[0043] Green beans contain sugars and free amino acids, which react during roasting to produce color, flavor, and acrylamide. After roasting, these precursors are greatly depleted, and there is no evidence of significant amounts of the intermediate 3-APA. At darker roasts, asparagine is not detectable. The deeper the roast, the more depleted the Maillard reaction precursors are, the more flavor compounds such as pyrazines and pyrroles are formed, but also the more acrylamide is degraded.

[0044] During the three stages of the extraction process, free amino acids, including asparagine, are formed at all stages, but at the end of the tertiary process, asparagine is again depleted. Importantly, during tertiary extraction, the breakdown of galactomannans leads to a significant increase in the content of reducing sugars, glucose, and mannose. This stage is characterized by the accumulation of free amino acids, a significant increase in reducing sugars, and high temperature. It is here that most of the acrylamide is formed in situ.

[0045] Thus, the results showed an increase in free amino acids during all stages of extraction, and, most importantly, asparagine, the main precursor of acrylamide, was detected in all primary and secondary extracts. However, acrylamide formation also requires a source of reducing sugars. The results showed that at the highest temperature stage, when the temperature is high enough to destroy galactomannans in coffee, a significant increase in glucose and mannose was observed. Thus, in the high-temperature tertiary phase, relatively high sugar concentrations and an accumulation of free amino acids, including asparagine, are observed, which also contribute to acrylamide formation. Under these conditions, a significant increase in acrylamide content was observed, with concentrations in the accumulated extracts reaching 1200 ppb.

[0046] The direct correlation between glucose content and acrylamide formation provides compelling evidence that this is the primary pathway for acrylamide formation during the production of instant coffee from roasted and ground coffee. A key factor in reducing the formation of new acrylamide during the tertiary extraction process is preventing the breakdown of galactomannans. One possible solution is to conduct the bulk of the extraction at temperatures below those required for galactomannan breakdown. Alternatively, the high-temperature extraction time could be extended, but this would impact the flavor profile of the final product, particularly the last two, likely resulting in a significantly increased burnt appearance.

[0047] However, the present inventors also found that acrylamide concentrations were higher than could be explained simply by the presence of conditions favorable for the formation of new acrylamide. They hypothesized that acrylamide chemically or physically bound to coffee may also be released. Without being bound by any theory, the most likely candidate for this reversible acrylamide uptake appears to be melanoidins in coffee. These heterogeneous nitrogen-containing brown pigments are formed in roasted coffee and other cooked foods during the final stage of the Maillard reaction. They are formed by cyclization, dehydration, rearrangement, and condensation of low-molecular-weight Maillard reaction products. The chemical composition of melanoidin structures is largely unknown due to the complexity of the products.However, their composition will depend on the polysaccharides (galactomannans and arabinogalactans), amino acids, proteins, and phenolic compounds (chlorogenic, caffeic, or ferulic acids) contained in the coffee beans. The nature of the binding may be physical, such as incorporation into the complex structure of melanoidin (for example, the incorporation of small molecules into maltodextrins), or may involve covalent bonds between acrylamide and melanoidins. Acrylamide is known to undergo Michael addition to thiol or amino groups, and this can lead to acrylamide loss during thermal processing. Although this reaction was previously thought to be an irreversible pathway for acrylamide reduction, the inventors discovered that the reaction can be reversible.If Michael addition is reversible under the high pressure and high humidity conditions used for coffee extraction during instant coffee processing, this could explain the elevated acrylamide levels in instant coffee.

[0048] The inventors discovered that if acrylamide is released at high temperatures, there are process steps that can be implemented to promote the reuptake of acrylamide by coffee melanoidins, trapping the acrylamide within the beans rather than within the coffee extract. It is hypothesized that the mechanism that promotes acrylamide reuptake may also be responsible for the loss of acrylamide during storage of roasted coffee beans and ground coffee. Consequently, they developed a method for optimally promoting the uptake of acrylamide by coffee melanoidins, resulting in reduced acrylamide concentrations in roasted and ground coffee.

[0049] Without being limited by any theory, it is understood that heat treatment causes acrylamide in coffee beans to bind to the melanodins contained in the beans. Therefore, the present invention consists of trapping acrylamide formed during roasting of coffee beans in the bean material so that it is not released under typical extraction conditions at home or in a coffee shop (i.e., in water at temperatures up to 100°C). The inventors therefore realized that heat treatment can increase the amount of acrylamide naturally trapped in the beans so that it is not so easily released. This means that although acrylamide is still present, the amount of acrylamide released during extraction is reduced.

[0050] The method includes holding roasted coffee in a substantially oxygen-free processing chamber at a temperature of 70 to 120°C for at least 30 minutes to obtain roasted coffee with a reduced acrylamide content. At this stage, they are preferably held in a dry state. At a temperature below 70°C, the processing time is too long for commercial viability, while at a temperature of about 120°C, the processing itself can lead to the formation of additional acrylamide. Preferably, the processing is carried out at a temperature of 100 to 120°C, preferably from 101 to 120°C, more preferably from 110 to 120°C. Preferably, the roasted coffee beans are held at a temperature of 70 to 120°C (or in narrower ranges) for from 1 to 50 hours, preferably from 2 to 10 hours.

[0051] By the term substantially oxygen-free, it is meant that oxygen levels are maintained below atmospheric levels, such that the atmosphere contains less than 2% by volume of oxygen, preferably 1% by volume of oxygen, and more preferably less than 0.1% by volume of oxygen. The processing chamber is preferably flushed with an inert gas, such as nitrogen, before use to remove oxygen, and the beans can be stored and poured into the chamber under the influence of an inert gas. Other suitable inert gases include carbon dioxide, which can be produced as a byproduct of coffee roasting, and noble gases such as argon. During processing, the beans are maintained in a gaseous environment. For the avoidance of doubt, a substantially oxygen-free processing chamber does not contain added water or coffee extract. That is, the beans are not immersed in water or coffee extract in the substantially oxygen-free processing chamber.

[0052] Coffee aroma compounds can be added to the atmosphere to enhance the flavor characteristics of the beans and reduce aroma loss. Suitable sources of coffee aroma include coffee oils or gases captured from the coffee grinder.

[0053] As noted above, prior art indicates that acrylamide concentrations decrease very gradually during roasted coffee storage. The inventors discovered that this decrease accelerates significantly with increasing storage temperature. At high temperatures, significant reductions can be achieved within a few hours. However, this also poses a problem. Tasting revealed that hot storage significantly reduces the flavor of roasted whole beans due to aroma loss.

[0054] However, the inventors have discovered that this impact on flavor and aroma can be reduced by conducting heat treatment, as described herein, under conditions that prevent the loss of aroma compounds. For example, if beans are heated in a sealed vessel with minimal air space, the aroma balance shifts toward the beans, both during warm / hot storage and afterwards, when the temperature is reduced again. Nitrogen flushing removes oxygen, which is another source of aroma degradation at higher temperatures. Some pressure is created in a sealed vessel either during the nitrogen flush, the increase in temperature, or due to gas loss from the coffee, so the processing vessel must be capable of withstanding slightly higher pressure (i.e., be a pressure vessel) or be flexible, as this allows for increased headspace.

[0055] Accordingly, in one embodiment, the processing chamber is a sealed, pressurized chamber. The chamber is loaded with beans or ground coffee in an oxygen-free environment. Preferably, the processing chamber is filled substantially entirely with roasted coffee. Preferably, the processing chamber is flushed with an inert gas before loading. During heat treatment, the pressure in the vessel increases, but the pressure chamber is capable of withstanding this.

[0056] In one embodiment, the processing chamber comprises a gas circulation system for circulating an oxygen-free process gas or gases. That is, the grain processing chamber may comprise at least one inlet and at least one outlet, with the heated oxygen-free gas stream used to heat / cool the grains, and the gas stream continuously recirculated through a heating / cooling device located outside the chamber. During heat treatment, the pressure in the vessel will not increase, as it will be controlled by the gas circulation system.

[0057] Preferably, the method reduces acrylamide concentrations by at least 30%, more preferably by at least 40%, and most preferably by at least 75%. Reductions of 80% and even 95% can be achieved, as shown in the examples. However, the method may have some impact on the product's flavor, as higher levels of acrylamide reduction lead to a stronger impact on flavor.

[0058] Preferably, before opening the processing chamber, the processed coffee is cooled or allowed to cool to a temperature below 30°C. This helps prevent the loss of aroma and volatiles. Preferably, after processing, the chamber is kept sealed at a temperature below 20°C, preferably below 10°C, and more preferably below 5°C, for at least 1 minute, preferably at least 10 minutes, and more preferably at least 1 hour. Surprisingly, this step of holding the coffee at a low temperature appears to cause the coffee to reabsorb additional flavor compounds, altering the flavor of the product.

[0059] If the roasted coffee was provided as whole beans in step (ii), then after step (iii) they must be ground or crushed.

[0060] Preferably the roasted coffee powder with reduced acrylamide content has a particle size of D 50from 5 to 100 µm, preferably from 10 to 50 µm and preferably has D 90 less than 120 µm, preferably less than 80 µm. This particle size may be determined by providing the roasted coffee in step (ii) with such a particle size distribution or, alternatively, by grinding the roasted coffee after step (iii). This grinding may represent a further size reduction if the roasted coffee has already been ground before step (ii), or may represent the first grinding of whole coffee beans.

[0061] Stage (iv)

[0062] The method then includes step (iv) of drying the aqueous coffee extract to form a soluble coffee powder. Suitable drying methods are well known in the art, the most common being spray drying and freeze drying. Preferably, step (iv) of drying the aqueous coffee extract is a spray drying or freeze drying step. Any steps commonly used in the production of such products may be employed here, including the addition of gases for foaming and reducing the density of the product, as well as the addition of roasted and ground coffee particles or other beverage ingredients, such as whitener or sugar.

[0063] These methods are preferably so-called gas-injected spray drying or gas-injected freeze drying methods, which involve adding an inert gas such as carbon dioxide or nitrogen before drying to adjust the powder density. This can improve the solubility and properties of the product.

[0064] As discussed above, the roasted and ground coffee with reduced acrylamide content can either be mixed with the aqueous coffee extract before the drying step (iv), or it can be mixed with the final soluble coffee powder. In either case, an instant coffee powder is provided containing both soluble coffee and roasted and ground coffee.

[0065] Roasted and ground coffee is added to instant coffee to produce an instant coffee powder containing instant coffee and 1 to 20% by weight of roasted and ground coffee, based on the weight of the instant coffee powder.

[0066] The aqueous coffee extract preferably has a solids content of 35 to 65% by weight before drying, more preferably 45 to 55% by weight. It should be noted that this includes the solids of the roast and ground coffee additive in those embodiments where it is added before drying.

[0067] Water coffee extract

[0068] This document describes two optional additional approaches that can further reduce acrylamide levels. In the first approach, the roasted coffee itself, which is used to produce the soluble coffee portion of the final instant coffee product, is subjected to the same thermal treatment described above (all aspects discussed above apply equally to this method).

[0069] That is, preferably, the aqueous coffee extract in step (i) is obtained by a method comprising:

[0070] (I) Providing roasted coffee:

[0071] (II) holding the roasted coffee in a substantially oxygen-free processing chamber at a temperature of from 70 to 120°C for at least 30 minutes to obtain a roasted coffee with a reduced acrylamide content;

[0072] moreover, or:

[0073] a) the roasted coffee obtained in step (I) is a roasted coffee powder, wherein step (II) produces a roasted coffee powder with a reduced acrylamide content; or

[0074] b) the method further comprises the step of grinding the roasted coffee with reduced acrylamide content obtained in step (II) to obtain a roasted coffee powder with reduced acrylamide content;

[0075] and the method further comprises:

[0076] (III) extracting the powder from the roasted coffee having reduced acrylamide content with water to form an aqueous coffee extract.

[0077] Preferably, the roasted coffee obtained in step (I) has been roasted to a color according to CMU greater than 100, preferably greater than 120, and more preferably greater than 130.

[0078] Preferably, step (III) is carried out at a temperature of at least 140°C, preferably at least 175°C.

[0079] According to an alternative method, preferably the aqueous coffee extract in step (i) is obtained by a method comprising:

[0080] (I) Providing roasted and ground coffee powder;

[0081] (II) extracting the roasted and ground coffee powder with water to form an aqueous coffee extract precursor; and

[0082] (III) contacting the aqueous coffee extract precursor with spent coffee grounds at a temperature of 70 to 120°C for at least 30 minutes to form an aqueous coffee extract.

[0083] Preferably, step (II) is carried out at a temperature of at least 140°C, preferably at least 175°C.

[0084] The method of this alternative embodiment includes contacting an aqueous coffee extract containing acrylamide with spent coffee grounds at a temperature of 70 to 120°C for at least 30 minutes to form a coffee extract with a reduced acrylamide content. Thus, the aqueous coffee extract to be treated is maintained with spent coffee grounds at a temperature of 70 to 120°C for at least 30 minutes. The maintaining may include the use of a storage tank, filtration through a bed of spent coffee beans, optionally with a recirculation process, or the use of a slurry processing system. When filtration through a bed, the recirculation system can ensure that the extract remains at an acceptable temperature for an acceptable time while in contact with the beans.

[0085] The extract is brought into contact for a period of time and then stopped. This separates the spent coffee grounds from the coffee extract, allowing the coffee extract to be used as usual (e.g., to produce instant coffee powder). The spent coffee grounds can be easily removed from the extract by screening or decanting. A variety of methods and devices are known for separating coffee extracts from roasted coffee beans. The spent coffee grounds can thus be reused for further processing of the extract until they become enriched in acrylamide and can be excluded from the process.

[0086] Preferably, after the step of bringing the acrylamide-containing aqueous coffee extract into contact with the spent coffee grounds, there follows an additional step of recovering the spent coffee grounds from the aqueous coffee extract to obtain a treated aqueous coffee extract with a reduced acrylamide content. This step will preferably remove at least 90 wt.%, more preferably at least 95 wt.%, and most preferably at least 99 wt.%, or substantially all of the spent coffee grounds.

[0087] Spent coffee grounds are a well-known product in the field of instant coffee extraction. Generally, as long as roasted and ground coffee still contains any extractable material that can be recovered through an additional extraction step without the need for high temperatures that would cause undesirable levels of off-flavor formation, it will undergo further processing and is not considered spent. Thus, spent coffee grounds are roasted and ground coffee material remaining after aqueous extraction, where it would normally be disposed of or burned for energy production.

[0088] In the context of the present invention, the spent coffee grounds have at least been subjected to aqueous extraction at a temperature of 175°C or higher, preferably 200°C or higher, and more preferably from 205°C to 240°C. Preferably, the spent coffee does not contain additional useful extractable coffee solids.

[0089] The acrylamide-containing aqueous coffee extract is contacted with spent coffee grounds at a temperature of at least 70°C, since the rate of acrylamide reduction below this temperature is too low for commercial use. A temperature below 120°C is used to prevent the release or formation of additional acrylamide in the extract. The processing time is at least 30 minutes to achieve sufficient acrylamide reduction at these temperatures. Preferably, the acrylamide-containing aqueous coffee extract is contacted with spent coffee grounds at a temperature of 100 to 120°C. Most preferably, the temperature is 110 to 120°C.

[0090] The preferred processing time is between 30 minutes and 50 hours, preferably between 1 hour and 24 hours, and more preferably between 2 hours and 10 hours. These time periods provide an optimal balance of reduction without compromising flavor and aroma properties and compatibility with industrial instant coffee production. After this period, the spent coffee grounds are removed from the aqueous coffee extract.

[0091] The amount of spent coffee grounds required for the process depends on the amount of coffee extract to be processed. Generally, to process 100 kg of coffee extract, based on the weight of soluble coffee solids in the coffee extract (i.e., on a dry matter basis), at least 1 kg of spent coffee grounds can be used, more preferably at least 10 kg of spent coffee grounds, and preferably 20 to 100 kg of spent coffee grounds per 100 kg of coffee extract.

[0092] This holding stage, which involves bringing the coffee extract into contact with the coffee material at a temperature lower than the previous extraction stage, is not performed in traditional industrial processing. This is because the primary goal of traditional processing is to increase yield by increasing temperature steps and then quickly obtain a dried powder product, thereby minimizing space consumption and avoiding holding times that could lead to product quality loss.

[0093] The method enables the production of a coffee extract with reduced acrylamide content. Preferably, it contains less than 400 ppb acrylamide, more preferably less than 200 ppb acrylamide, more preferably less than 100 ppb acrylamide, and most preferably substantially no acrylamide. Preferably, the method reduces acrylamide concentrations by at least 30%, more preferably by at least 40%, and preferably by more than 75%. Reduction levels can be greater than 80%, such as 95%, when using higher temperatures and longer processing times, as shown in the examples. However, the method may have some consequences on the taste of the product, since higher levels of acrylamide reduction lead to a stronger effect on the taste.

[0094] Preferably, an aqueous coffee extract containing acrylamide is passed through spent coffee grounds in a continuous process. This is industrially efficient and allows for the continuous production of dried coffee products.

[0095] Preferably, the spent coffee grounds are provided in the form of a spent coffee grounds layer. The use of water percolation through coffee grounds layers is well known in the art, so it is straightforward to adapt existing equipment to the processing method described herein.

[0096] Preferably, the spent coffee layer is maintained in a sealed chamber, which may optionally be maintained at a pressure greater than atmospheric pressure. Preferably, it is at least 1 bar above standard atmospheric pressure, for example, from 1 to 500 bar, preferably from 2 to 25 bar. This helps prevent the loss of volatile flavor and aroma compounds during processing.

[0097] Preferably, the aqueous coffee extract obtained in step (III) has a solids content of 35 to 65% by weight, more preferably 45 to 55% by weight.

[0098] Instant coffee powder

[0099] According to a further aspect, there is provided an instant coffee powder comprising instant coffee and from 1% by weight to 20% by weight of roasted and ground coffee, by weight of the instant coffee powder, wherein the roasted and ground coffee has a roast color according to CMU of more than 100, preferably more than 120 and more preferably more than 130, and wherein the instant coffee powder has an acrylamide content of less than 900 ppb, preferably less than 700 ppb and most preferably less than 400 ppb.

[0100] Preferably, the roasted and ground coffee is evenly distributed throughout the instant coffee. This means that the roasted and ground coffee is preferably contained in the coffee water extract before it is dried, rather than added in dry form afterward.

[0101] Preferably, the instant coffee powder can be produced by the method described herein. This product will be noticeably different from traditional coffee products due to its low acrylamide content and the comparatively lighter roast color of the added roasted and ground coffee component.

[0102] The instant coffee powder described herein may contain additional ingredients, such as creamer and / or sweeteners. Preferably, these are simply dry-mixed with the instant coffee powder after it has been manufactured in accordance with the present invention. An exemplary three-in-one product would contain coffee powder, creamer, and a sweetener such as sugar in a single-use sachet. This allows the consumer to prepare a complete beverage simply by adding hot water to the contents of the sachet.

[0103] The invention will now be described with respect to the following non-limiting figures, with Figures 1-6 showing a flow chart of the main steps of the method according to the invention. As mentioned elsewhere, the exact point at which the coffee is ground may vary. In each figure, wet mixing and dry mixing are generally considered alternatives, although in principle both types of mixing can be performed.

[0104] Measurement methods

[0105] Size

[0106] Particle size measurements are now commonly used in the art to determine the particle size distribution of ground coffee. Particle size distribution and corresponding D values 50 and D 90 determined using laser diffraction.

[0107] The diffraction of a laser beam depends on the size of the particles passing through it. A suitable detector and computer system convert the beam diffraction pattern into a particle size distribution. For measurements, a Sympatec Helos laser diffraction particle size measurement system with a RODOS dry dispersion unit for powders and a computer interface, as well as hardware for running data recording and calculation software, can be used.

[0108] The procedure and settings used corresponded to the manufacturer's recommendations for the type and size range of the product being measured. The sample size incorporated into the dispersion system was approximately 10-20 g. A lens with a focal length of 1000 mm was used, suitable for particle sizes ranging from 9 to 1759 microns.

[0109] Data recording, calculation, and presentation are performed by software provided by the manufacturer. It is designed to calculate and present values ​​for "Q3"—the normalized particle volume distribution—and its first derivative, q3—the particle volume distribution density. For the purposes of this calculation, the program assumes that roasted and ground coffee particles are spherical. This reasonable assumption is based on a thorough examination (using microscopy) of the ground coffee powder. Values ​​for VMD and fines can be obtained directly from the output.

[0110] Color

[0111] Color can be measured using the Probat Colorette 4. The Colorette 4 measures the color and intensity of ground roasted coffee in the visible light spectrum. The instrument operates on the reflectance principle. The Colorette illuminates the sample with a pulsed LED and measures the light reflected from the sample. Output values ​​are reported as color values ​​in CIE L*ab and Colorette Units (CMU). The instrument is calibrated before use in accordance with the standard operating instructions for the instrument.

[0112] It is important that the sample is truly representative, so the minimum sample volume is 100g.

[0113] Standard color measurements are based on a grind size of X50 (450 µm ±30 µm). Whole beans are ground to this size before color measurement. If color measurement is required for roasted and ground coffee with a different grind size, the value can be accurately determined using calibration curves. This means that color measurements of coarser or finer ground coffee can be calibrated to determine the color of the same coffee ground to 450 µm, and therefore a comparable CMU value can be determined.

[0114] Examples

[0115] The invention will now be described with reference to the following non-limiting examples.

[0116] Roasted and ground coffee were stored in a sealed chamber under an inert atmosphere. Their acrylamide concentrations were measured before and after treatment. The observed reduction is presented in the table below.

[0117]

[0118] Although preferred embodiments of the invention have been described in detail herein, it will be understood by those skilled in the art that changes can be made therein without departing from the scope of the invention or the appended claims.

Claims

1. A method for producing instant coffee powder having an acrylamide content of less than 900 ppb, comprising: (i) providing an aqueous extract of coffee; (ii) providing roasted coffee roasted to a CMU colour greater than 100; (iii) holding the roasted coffee in a substantially oxygen-free processing chamber containing less than 2% by volume of oxygen at a temperature of from 70°C to 120°C for from 30 minutes to 50 hours to produce roasted coffee having a reduced acrylamide content, wherein the processing chamber is flushed with an inert gas before use and the roasted coffee is stored and filled into the chamber under the influence of an inert gas; and (iv) drying the aqueous coffee extract to obtain soluble coffee powder; and either: a) the roasted coffee obtained in step (ii) is a roasted coffee powder, wherein step (iii) produces a roasted coffee powder having a reduced acrylamide content; or b) the method further comprises the step of grinding the roasted coffee with reduced acrylamide content obtained in step (iii) to obtain a roasted coffee powder with reduced acrylamide content; and, in this case, the method additionally includes: (v) adding a reduced acrylamide roasted coffee powder to the aqueous extract of coffee prior to the drying step (iv) or adding a reduced acrylamide roasted coffee powder to the soluble coffee powder obtained in step (iv), thereby producing an instant coffee powder comprising soluble coffee and from 1% by weight to 20% by weight of roasted and ground coffee, by weight of the instant coffee powder, wherein the method reduces acrylamide concentrations by at least 30%.

2. The method according to claim 1, wherein the processing chamber in step (iii) is a sealed pressure chamber and / or comprises a gas circulation system for circulating oxygen-free process gases.

3. The method according to claim 1 or 2, wherein the processing chamber in step (iii) is pre-flushed with nitrogen before loading the roasted coffee beans to be processed.

4. The method according to any one of the preceding claims, wherein in step (iii) the roasted coffee beans are maintained in a processing chamber at a temperature of from 100 to 120°C.

5. The method according to any one of the preceding claims, wherein step (iii) the roasted coffee beans are maintained at a temperature of from 70 to 120°C for from 1 to 50 hours, preferably from 2 to 10 hours.

6. The method according to any one of the preceding claims, wherein after step (iii) and before step (v), the roasted coffee with reduced acrylamide content is cooled or allowed to cool to a temperature of less than 30°C before opening the processing chamber.

7. The method according to any one of the preceding claims, wherein the instant coffee powder contains from 12 to 18% by weight of roasted and ground coffee.

8. The method according to any one of the preceding claims, wherein the step (iv) of drying the aqueous coffee extract is a spray drying or freeze drying step.

9. The method according to any one of the preceding claims, wherein the powder from roasted coffee with reduced acrylamide content has a particle size of D 50 from 5 to 100 µm, preferably from 10 to 50 µm and preferably has D 90 less than 120 µm, preferably less than 80 µm.

10. The method according to any one of the preceding claims, wherein the roasted coffee obtained in step (ii) has been roasted to a CMU colour greater than 120 and more preferably greater than 130.

11. A method according to any one of the preceding claims, wherein the roasted coffee obtained in step (ii) is obtained at a temperature of less than 50°C, preferably at room temperature.

12. A method according to any one of the preceding claims, wherein the aqueous extract of coffee in step (i) is obtained by a method comprising: (I) Providing roasted coffee: (II) maintaining the roasted coffee in a substantially oxygen-free processing chamber at a temperature of from 70 to 120°C for at least 30 minutes to obtain a roasted coffee with reduced acrylamide content; and either: a) the roasted coffee obtained in step (I) is a roasted coffee powder, and step (II) produces a roasted coffee powder with a reduced acrylamide content; or b) the method further comprises the step of grinding the roasted coffee with reduced acrylamide content obtained in step (II) to obtain a roasted coffee powder with reduced acrylamide content; and the method further includes: (III) extracting the powder from the roasted coffee with reduced acrylamide content with water to form an aqueous coffee extract.

13. The method according to claim 12, wherein the roasted coffee obtained in step (I) has been roasted to a CMU color greater than 100, preferably greater than 120, and more preferably greater than 130.

14. A method according to any one of the preceding claims, wherein the aqueous extract of coffee in step (i) is obtained by a method comprising: (I) providing roasted and ground coffee powder; (II) extracting the roasted and ground coffee powder with water to form an aqueous coffee extract precursor; and (III) contacting the aqueous coffee extract precursor with spent coffee grounds at a temperature of 70 to 120°C for at least 30 minutes to form an aqueous coffee extract.

15. The method according to claim 14, wherein step (II) is carried out at a temperature of at least 140°C, preferably at least 175°C.

16. The method according to claim 14 or 15, wherein the precursor of the aqueous coffee extract is brought into contact with the spent coffee grounds at a temperature of from 100 to 120°C.

17. The method according to any one of claims 14 to 16, wherein the aqueous coffee extract precursor is brought into contact with the spent coffee grounds for a period of from 1 to 50 hours, preferably from 2 to 10 hours.

18. The method according to any one of claims 14-17, in which the spent coffee grounds are presented as waste after aqueous extraction of roasted and ground coffee at a temperature of at least 175°C.

19. The method according to any one of claims 14 to 18, wherein the roasted and ground coffee powder obtained in step (I) has been roasted to a colour according to CMU greater than 100, preferably greater than 120 and more preferably greater than 130.

20. An instant coffee powder comprising instant coffee and from 1% to 20% by weight of roasted and ground coffee, by weight of the instant coffee powder, wherein the roasted and ground coffee has a roast color according to CMU greater than 100, preferably greater than 120, and more preferably greater than 130, and wherein the instant coffee powder has an acrylamide content of less than 900 ppb; In this case, the roasted and ground coffee is evenly distributed in the instant coffee.

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