KR920007406B1 - Production of a mannan oligomer hydrolysate - Google Patents

Abstract

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Description

Method of producing oligomeric hydrolyzate

The present invention relates to a process for hydrolysis of coffee extract residues. More specifically, the present invention relates to a process for hydrolyzing coffee extract residues, such as coffee grounds, extracted with conventional coffee percolation systems in reactors with acid catalysts. It is convenient to use a tubular plug flow reactor in the present invention, but any reactor can be used as long as it can perform a relatively high temperature short time reaction. The hydrolyzate thus produced is a full-stage oligomer mixture containing oligomers of DP 1 to DP 10. The specific conditions applied to the reactor determine the oligomeric distribution of DP 1 to about DP 10. Oligomeric hydrolysates encountered are useful, for example, for increasing the solids content of soluble coffee mixed with extracts of roasted coffee.

It is already known in the art to hydrolyze coffee extraction residues, in particular partially extracted coffee grounds, to increase solids yield. For example, U.S. Patent No. 2,573,406 to C1ough et al. Extracts about 20% of the coffee weight under atmospheric pressure, and some of the residue left after extraction at 100 ° C in about 1% sulfuric acid suspension. After hydrolysis for about 1 hour, the pH of the hydrolyzate is adjusted, and then the hydrolyzate is filtered and mixed with the extract extracted under atmospheric pressure, followed by drying the combined extract, revealing a process for producing soluble coffee. In addition, US Pat. No. 2,687,355 to Benner et al. Describes a method similar to the above method in which arithmetic is used instead of sulfuric acid. Alternatively, US Pat. No. 3,224,879 to DiNardo et al. Found that alkali or acid hydrolysis of coffee grounds extracted at least under atmospheric pressure occurred directly in the extraction train. Direct hydrolysis in this extraction train eliminates the need for a separate hydrolysis step as before, and the alkali or acid catalyst adsorbed in the mass of coffee grounds used.

In methods such as clogs and beners, it takes about one hour to terminate the batch hydrolysis reaction at a relatively low temperature, so there is a limit to the practicality of the process on a commercial scale. They are essentially all hydrolyzates obtained by treatment at 100 ° C. for 1 hour, and do not reveal the method and necessity of the hydrolysis conditions to affect the composition of the hydrolyzate obtained. A similar flaw is seen in Dinard's method.

It is also well known in the art that cellulosic materials, mostly carbohydrate polymers and lignin, can be hydrolyzed under high temperature and short time using acid catalysts. However, when the cellulosic material is relatively impure, hydrolysis reactions produce undesirable byproducts. In this regard, acid hydrolysis treatment of primary cellulose materials has generally been limited to hydrolysis of waste paper and paper by-products, or agricultural waste such as corn husks, pods or cobbs. For example, US Pat. No. 1,201,596 to Church et al. Discloses a continuous process of saccharifying cellulosic material with an acid catalyst in a tubular reactor. The purpose of this process is to convert cellulosic materials such as sawdust, wood by-products, corncobs etc. into glucose, furfural and xylose. The same process for converting cellulosic waste to monosaccharides in a plug flow reactor is described in 1nd.Eng.Chem.Prod.Res.Dev, Vol. 18, No. 3, pages 166-69 (1979). "Design and Evaluatlon of a P1ug Flow Reactor for Acld Hydr1" 1ysis of Cellu1ose by David R.Tompson and James E.Grethlein Design and evaluation). The authors have paid particular attention to the hydrolysis of cellulose-rich substances into monosaccharides, but they also can be obtained only by oligomers, except for hydrolysis, which yields a specific mixture of oligomers. Decomposition has not been revealed. Meanwhile, US Pat. No. 4,316,747 to Rug et al. Discloses a method for hydrolyzing cellulose waste to glucose using an acid catalyst in a twin screw extruder.

As mentioned above, although several documents have disclosed a method of acid hydrolysis of cellulose-rich materials under high temperature and short time, cellulose is not a main component, for example, coffee extract residues, especially obtained from conventional percolation apparatus. A method of treating coffee grounds and the like by acid hydrolysis is not described. The main carbohydrates that can be hydrolyzed in coffee residues are not cellulose. Moreover, the mandatory hydrolysis products are degraded under cellulose hydrolysis conditions, thus making any desired mandatory oligomer intermediates obsolete.

It is an object of the present invention to provide a method of hydrolyzing a coffee extract residue wherein mannan is the main carbohydrate.

It is a further object of the present invention to provide a process for producing a full-stage oligomer mixture having an oligomer of DP 1 to about DP 10 by hydrolyzing the coffee extraction residue.

It is another object of the present invention to provide a process for preparing a full oligomeric mixture having a suitable oligomer distribution between DP 1 and about DP 10.

It has been found that the object of the present invention is achieved by a method of hydrolyzing a coffee extract residue in the presence of an acid catalyst in a reactor. The coffee extract residues, especially the extracted debris obtained from conventional percolation equipment, are sulliated in water and the pH is adjusted between 1 and 4 with an acid catalyst. This slurry is then passed through a reactor at 160 ° C. to 260 ° C. for about 66 to 60 seconds. Upon exiting the reactor, the met oligomer mixture with oligos of DP 1 to about DP 10 is separated from the hydrolyzed coffee extraction residue. The full oligomer distribution of DP 1 to about DP 10 depends on the specific conditions applied to a given reactor. It is also possible to completely hydrolyze mandan, which is initially present in the coffee extract residue, with mannose monosaccharides (hereinafter referred to as “manufactured oligo” of DP 1).

The present invention has been made using several properties of coffee extraction residues that are not widely recognized in the art. First, most of the conventional techniques for processing coffee grounds were concerned only with the cellulose content of the coffee grounds, rather than focusing on the fact that these residues are actually more present than cellulose. However, the inventors have unexpectedly discovered that the above all can be hydrolyzed from cellulose to actually separate it. That is, mandala and cellulose in the coffee material are sufficiently separated under hydrolysis conditions to yield essentially pure mandala hydrolyzate. Finally, it is not necessary to completely hydrolyze mandan to the monosaccharides desired by most cellulose hydrolysis operations (although it is of course possible to do this), but the mannan is hydrolyzed to produce the desired oligomer distribution of DP 1 to about DP 10. It has been found that a full-stage oligomer solution can be prepared.

-만노스 단위로 이루어지는 임의의 다당체를 포괄적으로 나타내는 것이다.

-만노스 단당체는 알도육탄당과

-글루코스의 이성체이며, 이들은 카르보닐기에 가장 인접한 히드록실기의 공간 배치가 서로 대향하고 있다는 것만이 다른 점이다. 커피 추출 잔류물에세 발견되는 만난은 다당체에 최대 40개의

-만노스 단위체를 가질 수있다.In order to explain the present invention in more detail, related terms are described as follows. "Meet" is

A generic representation of any polysaccharide consisting of mannose units.

Mannose monosaccharides are the

-Isomers of glucose, except that they are spaced apart from each other in the hydroxyl groups closest to the carbonyl group. Encounters found in coffee extract residues can contain up to 40 polysaccharides.

Can have mannose monomers

"Cellulose" refers generically to polymers consisting of cellobiose units, which can be hydrolyzed into two glucose units. Thus, cellulose produces glucose monosaccharides upon complete hydrolysis. Cellulose is a substance that forms most of the plant's structures. A more detailed description of cellulose and its properties is described in Conn and Blatt's "The Chemistry of Organic Compounds" (Macmillan, 1947), pp. 295-299. It is.

"Oligomer" means a polymer consisting of relatively few monosaccharide units. In particular, the oligomer in the present invention means a polymer consisting of less than m monosaccharide units. Strictly speaking, the oligomer is one whose structural unit number exceeds 1, but for convenience, mannose is referred to as oligomer of DP l.

"Degree of polymerization" or "Degree of Polymerization" means the number of monosaccharide units constituting a given oligomer. Therefore, the met oligomer of DP 4 consists of four mannose units.

"Coffee extraction residue" means roasted and ground coffee that has been partially extracted (preferably, extracted at least under atmospheric pressure). Particularly useful coffee extraction residues are coffees that have been partially hydrolyzed by heat to hydrolyze relatively less stable polymeshes such as arabingalactan. Residues obtained from conventional percolation equipment are, for example, coffee that has been partially hydrolyzed by extraction under heat and heating.

In a typical percolation apparatus, roasted powdered coffee is extracted with a multisection countercurrent extractor, which is supplied with fresh water above about 175 ° C in a section filled with almost used coffee (maximum extraction). do. The concentrated coffee extract is drawn from the section filled with the freshest coffee. The coffee changes in composition during percolation. Table 1 shows the approximate composition of the roasted powdered coffee, and Table 2 shows the composition of the extraction dregs obtained with a conventional percolator. The total percentage of carbohydrates is almost constant, but most of the pyrolyzed arabinogalactan was removed. Therefore, the preferred coffee extraction residue contains about 45% by weight of carbohydrates that have met at least 1/2.

TABLE 1

[Composition of Roasted Coffee]

TABLE 2

[Composition of Extraction Residue]

The present invention can be described as follows. The coffee extract stream is first slurried in a liquid (usually water) before being fed into the plug flow reactor. In order to obtain a sufficient concentration of solids in the reactor for effective hydrolysis, the slurry should be about 5% to 20% by weight of the dry weight of the coffee extract. Also, this slurry must be homogeneous. That is, the residues must be uniformly distributed. If the slurry is formed prior to treatment in a potted reactor, a homogenization step is necessary, such as recycle treatment with a slurry pump. If different reactors such as extruders are used, it is not necessary to dilute the slurry excessively. For example, extraction residues with about 50% to 60% by weight of liquid obtained from conventional percolation apparatus can be fed directly to the extruder without the need for further dilution.

An acid catalyst is then added to the slurry to adjust the pH of the slurry to an appropriate level. Typically the acid catalyst is added at about 0.05% to 2.0% by weight of the slurry. In order to accelerate the high temperature short time hydrolysis reaction of the mannan to obtain the met oligomer, the pH of the slurry is preferably 0.5 to 4. The pH is combined with a given reaction time and temperature to determine the degree of polymerization of the oligomers encountered. At low pH (combined with high temperature prolonged reactions), oligomers of relatively low degree of polymerization may be produced or, in limited cases, mannose monosaccharides. Conversely, at high pH, higher oligomers are produced.

Particular acid catalysts used in the present invention include inorganic and organic acids. Strong inorganic acids, such as sulfuric acid, are particularly suitable because they reach an appropriate pH even with relatively small amounts of acid. Sulfuric acid is widely used in the food industry because it is easy to precipitate and separate out in the final hydrolyzate. Other inorganic acids such as phosphoric acid, nitric acid and hydrochloric acid are also suitable, and also such as mixtures of sulfuric acid and phosphoric acid. Organic acids such as acetic acid, citric acid, tartaric acid, malic acid, adipic acid and fumaric acid alone or mixtures of foreign substances are generally weak acids, so relatively large amounts should be used to obtain a proper pH, but are also suitable as acid catalysts.

After the acid catalyst is added to the slurry, the slurry is fed to the reactor. Suitable continuous reactors include those capable of promoting relatively high temperature short time reactions, such as single or twin screw extruders or plug flow tubular reactors. Suitable as batch reactors, so-called explosion puffers, are suitable, in which the coffee extraction residue is mixed with an acid catalyst charged into the reaction vessel followed by a vapor pressure. This pressure is released quickly and explosively to drain the contents from the reactor. The met oligomer mixture having oligomers in the range of DP 1 to DP 10 is thus obtained by filtration from the material exiting the reactor. Plug flow tubular reactors are particularly convenient. Plug flow tubular reactors basically have to have the cylinder length of the pipe long enough for the reaction to take place. An orifice is installed at the outlet end of the reactor to control the pressure in the reactor as well as the rate of discharge from the reactor. "Plug flow" means the flow rate profile of a slurry flowing through a reactor. Typically, the fluid exhibits a parabolic flow rate profile where the fluid velocity at the conduit center is faster than the fluid flowing close to the wall. In a plug flow reactor, the flow rate profile is uniform, which results from the geometry and fluid properties of the conduit.

Various optional methods allow the internal temperature of the reactor to become high. For example, a slurry is passed through a heat exchanger before entering the reactor. The high temperature can then be maintained by simply isolating the reactor. As another method of temperature rise, high pressure steam can be injected directly into the reactor. Although steam may somewhat dilute the slurry, this heating raises the temperature rapidly, allowing the reaction to complete in a short time. The choice of preferred heating method as well as the diameter of the reactor and orifice are also included within the technical scope based on standard design principles in the art.

The internal conditions of the reactor are essentially important for hydrolyzing only mannans and obtaining full-stage oligomers with the required degree of polymerization distribution. In order to hydrolyze manganese and minimize the decomposition of the met oligomers thus produced, the reaction temperature should be 160 ° C to 260 ° C, preferably 190 ° C to 220 ° C. This temperature is such that the pressure in the reactor generally corresponds to 6 to 35 atmospheres, which is close to the saturation pressure of the water in the slurry supplied to the reactor. In general, high temperatures promote the production of low oligomers (depending on pH and reaction duration) and the inverse of them. Preferred reaction times are between 6 and 60 seconds. In about 6 seconds or less, it reveals an apparatus limitation that it is difficult to heat the slurry and make the reaction occur uniformly. In contrast, if the reaction lasts for more than about 60 seconds in the presence of an acid catalyst, the oligomers encountered (also a small amount of arabinose and galactose that may be present) begin to decompose with an unpleasant flavor, thus limiting the amount of available production and hydrolyzate Purification becomes difficult.

As described above, the discharge end of the reactor is provided with an orifice for adjusting the pressure inside the reactor and controlling the discharge rate. Rapidly passing the slurry through the orifice can reduce the pressure the slurry receives to atmospheric pressure. This rapid pressure drop causes expansion and evaporative cooling of the slurry, such that the slurry is "quenched" or the hydrolysis reaction ends immediately. Such quenching makes it possible to adjust the reaction time within a predetermined 6 to 60 seconds, which method is highly reliable.

Once the slurry is discharged from the plug flow tubular reactor, the slurry can be further cooled and then separated into met oligomer solution and hydrolyzed coffee extraction residue. It is also a good idea to neutralize the discharged slurry by known methods such as precipitation of the acid with a salt, evaporation of volatile acids, or the use of ion exchange resins. Neutralization can be both before or after separation of the full oligomeric solution and the hydrolyzed coffee extraction residue. Separation can be carried out by any solid-liquid separation method known in the art. For example, the slurry can be filtered to remove the hydrolyzed coffee extraction residue from the slurry. As another chamber, the slurry can also be separated by centrifugation, such as in basket centrifugation. After separation, the hydrolyzed coffee extract residues are most preferably treated by incineration.

Another embodiment of the invention is a method of using carbon dioxide gas as an acid catalyst. The carbon dioxide gas may dissolve the carbon dioxide into the slurry by compressing the slurry under the headspace of the carbon dioxide gas while stirring the slurry before injecting the slurry into the reactor. This slurry is then fed to the reactor as described above. Alternatively, the carbon dioxide gas is injected directly into a plug flow tubular reactor which dissolves carbon dioxide gas into the slurry, rather than adding the catalyst to the slurry before the slurry is injected into the reactor as described above. At this time, the pH of the slurry is lowered to less than about 4. In using carbon dioxide gas, it is surprising that by injecting carbon dioxide gas, the pH of the slurry can be sufficiently changed so that the high temperature short time hydrolysis reaction is continuously promoted. All of the acid catalysts described above are relatively strong acids, much stronger than acids due to the dissolution of carbon dioxide gas into the slurry. However, while the acid from carbon dioxide is a relatively weak acid, it was unexpectedly found that this acid could promote full hydrolysis of the coffee extract residue.

The present invention provides a process for the preparation of manno oligomer solution having an oligomer of DP 1 to about DP 10, using any method of the above embodiments. In addition, the particular conditions chosen for the reactor determine the full oligomer distribution of DP 1 to about DP 10. That is, the more severe the conditions, the higher the temperature, the longer the reaction, and the lower the pH of the slurry, the better the degree of polymerization of oligomers (if limited to the production of mannose, the monosaccharide). In contrast, the lower the temperature, the shorter the reaction time, and the higher the pH of the slurry, the more the hydrolysis reaction carried out under these conditions yields a solution containing a higher degree of polymerization. Table 3 shows the peak oligomer distribution in the hydrolyzate produced under the different conditions described above. The reactor used was a plug flow tubular reactor built for direct steam injection. In each case the acid catalyst was sulfuric acid and the reaction time was about 6 seconds. The overall yield based on the weight of starting material of the coffee extraction residue and the amount of oligomer produced was 30%. The oligomer distributions encountered were expressed in percentage by HPLC, which represents the relative percentage of the total peak area for the oligomers.

TABLE 3

As shown in Table 3, higher acid catalyst concentrations (and lower slurry pH), and higher temperatures result in lower oligomers, while oligomers between DP 1 and 7 produce acid catalyst concentrations. Lower yields and lower hydrolysis temperatures resulted in higher yields.

Full-stage oligomer mixtures having oligomers between DP 1 to 10 produced by the present invention can be used in various applications, and the specific distribution of oligomers in the mixture can be adjusted according to the end use purpose. One of the more important uses may be to add the above mixture to conventional coffee extracts in order to increase the amount of soluble coffee produced in roasted ground coffee. The coffee extract obtained is not particularly different from conventional coffee extracts, since the met oligomeric mixture itself is produced from coffee and the conventional extract contains large amounts of met oligomers. As such a specific use, it is preferable to make most the oligomers which have distribution of DP1-DP6 exist. The met oligomer mixture may be added to a conventional coffee extract prior to drying the extract, or may be mixed with soluble coffee produced from the conventional extract after drying the met oligomer mixture. Drying can be carried out by methods known in the art, such as lyophilization or spray drying. Alternatively, the mixture can be distributed mostly to mannose (“oligomer” of DP 1 as described above), and low cost of mannitol, a sweetener widely used in the food industry, can be obtained by simply converting to mannitol by a known method. have. Another use of met oligomer mixtures having oligomers in the range of DP 1 to 10 is to add the mixture to the coffee extract aqueous solution used to remove caffeine from the beans, mix the oligomers with the coffee beans and roast the mixture with the distillate ( The quenching of the roastlng reaction) infiltrates the oligomers into the roasted coffee beans and agglomerates the spray dried coffee with the oligomeric mixtures that meet the dry to produce good bulk coffee. Other uses of met oligomer mixtures having oligomers in the range of DP 1 to 10 are clear to those skilled in the art and are not limited to the applications described in this specification.

The following examples are intended to illustrate embodiments of the invention, but the invention is not limited to these examples.

Example 1

Basically the same method was used, but a series of processes were performed, varying an acid catalyst, reaction temperature, and reaction time. The method is as follows.

The coffee grounds obtained in the conventional percolation process were dispersed in water and ground to a particle size of 0.8 mm or less (orifice size of the plug flow reactor) using Gifford Wood W-200 Colloid Mil1 to obtain 4.68% by weight solid slurry. Prepared. This slurry was then placed in a hopper of a plug flow reactor at room temperature and stirring continued to prevent sinking. This slurry was injected into a plug flow reactor of about 113 ml volume using a Moyno pump. Immediately before feeding the slurry to the reactor, a 94 weight percent sulfuric acid, previously weighed, was injected into the slurry stream using a small variable stroke piston pump until the required acid concentration was obtained. The reactor consists of a heating section into which steam is directly injected into the slurry and a reaction section consisting of a tube of a certain length. After the slurry was injected into the reactor, the temperature rose rapidly by condensation of the steam injected into the slurry. The temperature of the reactor was changed by changing the vapor pressure with a valve operation and sensed with a thermocou-ple. The slurry residence time in the reactor could be changed by changing the pumping speed of the Moyno pump. After the slurry passed through the reactor through the orifice of the reactor, the slurry pressure dropped back to atmospheric pressure and the temperature was lowered to about 100 ° C., causing the reaction to stop. The slurry and concentrate were further cooled to room temperature through a water cooled heat exchanger. The hydrolyzed slurry was then neutralized with calcium carbonate and the residue was filtered off.

The hydrolysates with met oligomer mixtures were analyzed for met oligomer distribution and composition between DP 1-10. The purity of the met oligomer mixtures in this example and the following examples typically exceeded 80%, indicating that essentially only metmann was hydrolyzed and cellulose was only hydrolyzed in traces.

The distribution of met oligomers was analyzed by HPLC and expressed as a percentage, representing the relative percentage of total peak area for met oligomers. The analysis was performed on a Waters Carbohydrate Analysis column (part number 84038) using 70/30 acetonitrile / water solvent. The temperature was maintained at about 17 ° C. and the solvent flow rate was about 2 ml / min. Peaks were detected with a Waters differential refractive index detector.

Table 4 below shows the results for sulfuric acid, Table 5 shows the results for phosphoric acid, and Table 6 shows the results for acetic acid, respectively.

TABLE 4-Sulfate Catalyst

Table 5-Phosphate Catalyst

TABLE 6 Acetic Acid Catalyst

The tests in the table show that varying distributions of met oligomers can be obtained by varying the acid catalyst, reaction temperature and reaction time. As a general trend, lower polymerisation oligomers are obtained as the acid concentration is increased and the temperature and reaction time are increased.

Example 2

Carbon dioxide was supplied to the reactor in gaseous form through the same orifice used for sulfuric acid pumping. The carbon dioxide pressure was maintained above the input of steam injected into the reactor by regulating a control valve located in the carbon dioxide cylinder. The amount of carbon dioxide entering the reactor could be varied by opening the valve on the carbon dioxide regulator. The pH was maintained at about 3.4 by injecting carbon dioxide levels at about 1% by weight. Another process was carried out with increasing or decreasing the carbon dioxide flow rate. To increase the carbon dioxide flow rate, the valve of the carbon dioxide regulator was opened about 1/2, and when the carbon dioxide flow rate was to be lowered, about 1/4. After cooling to room temperature, the effluent exiting the reactor was foamy (combined with carbon dioxide gas, hydrolyzate and extracted residue residue). Comparable oligosaccharide distributions were achieved by increasing or decreasing the carbon dioxide flow rate at 240 ° C. The results are shown in Table 7 below.

Table 7-Carbon Dioxide Catalyst

The examples in Table 7 suggest that similar distributions of met oligomers of various distributions can be obtained using carbon dioxide as the acid catalyst.

Example 3

This experiment was conducted using two modified Wenger_single screw extruders from Wenger Menupacking Company, Sabeta, Kansas, as a high pressure screw conveyor, with a high density (60-70% water content). Coffee grounds were hydrolyzed. Extraction debris (water content about 70%) was placed in a working bottom circular bin and fed to the first extruder (SX-80) via two idle screws. The first extractor was used to preheat by applying high pressure to the residue. The discharge of SX-80 was fed to a second extruder (SX-110) and further heated. At the point where the cord residue reached the reaction temperature, sulfuric acid was injected into the front end of SX-110 using a small pump. The temperature was kept constant while the slurry remained in the reaction zone. The discharge was discharged from the SX-110 through a hydraulically controlled orifice. The temperature and residence time of the slurry could not be measured accurately. The thermocouple in the extruder appeared to read only the temperature of the metal barrel. Barrel temperature varied from 107 ° C to 200 ° C. Due to fluctuations, the residence time changed. HPLC analysis confirmed the presence of met oligomer again. The results are shown in Table 8 below.

Table 8-Wenger Extractor

It was not possible to obtain a met oligomer range of DP 1 to 10 because the adjustment was not done correctly in the extruder, but a constant distribution of met oligomer production was possible.

Example 4

Extraction residue was held in a plug flow reactor for about 7 seconds and hydrolyzed at 220 ° C. with 0.05% sulfuric acid to prepare a hydrolyzate. The hydrolyzate was concentrated in vacuo to give about 22% by weight solids, and 20% by weight of the extract was mixed with a conventional coffee extract (about 25% solids). The mixture was spray dried with a Niro spray dryer having an inlet temperature of 160 ° C and an outlet temperature of 80 ° C. Controls of conventional coffee extracts were also spray dried under the same conditions, and the two samples were hydrated again to 1% level (1 g / 100 ° C. hot water) to taste. There was no difference in the taste of the product. The hydrolyzate was more turbid due to some suspended solids, and for this reason the product had the same appearance of home-made coffee.

Claims (18)

A coffee extract residue consisting of coffee grounds extracted under atmospheric pressure and then hydrolyzed by heat to remove most of the arabinogalactan contained therein was obtained by (1) an amount of 5-60% by weight, based on the dry weight of the residue. Slurring in a liquid, (2) adding an acid catalyst to the slurry in an amount sufficient to bring the pH of the slurry to 0.5-4, and (3) adding the slurry to the reactor at a temperature of 160 ° -260 ° C. and 6-35. Supplying at atmospheric pressure for 6-60 seconds to hydrolyze the mannan, (4) discharging the slurry from the reactor through an orifice and rapidly dropping the pressure to atmospheric pressure to terminate the hydrolysis reaction, (5) discharging the discharged slurry Neutralizing and (6) separating the hydrolyzed coffee extraction residue from the met oligomer of about DP 1 to about 10 to obtain a met oligomer having a purity of 80% or greater. Method that is characterized by hydrolyzing a coffee extraction residue for producing a met oligomer of DP 1 to about DP 10 which. The process of claim 1 wherein the slurry is about 5-20% by weight, based on the dry weight of the residue, and the reactor of step (3) is a plug flow tubular reactor. The process of claim 2, wherein the met oligomers of DP1 to about 10 are separated as an aqueous solution from the hydrolyzed coffee extraction residue. The process according to claim 1, wherein the acid catalyst is selected from the group consisting of sulfuric acid, acid, nitric acid, hydrochloric acid, acetic acid, citric acid, tartaric acid, malic acid, adipic acid, fumaric acid and mixtures thereof. The process of claim 2 wherein the temperature in the plug flow tubular reactor is 190 ° -220 ° C. The process of claim 1 wherein the reactor of step (3) is an extruder. The process of claim 1 wherein sulfuric acid as an acid catalyst is added to the slurry in an amount of 0.05-0.5% by weight of the slurry. (1) slurrying 5 to 60% by weight of the coffee extraction residue in the liquid, based on the dry weight of the coffee extraction residue, (2) reacting the slurry for 6-60 seconds in a reactor at 160 ° -260 ° C; Simultaneously injecting carbon dioxide into the reactor as an acid catalyst to maintain the pH of the slurry at less than about 4, (3) discharging the slurry from the reactor through an orifice to rapidly drop the pressure to atmospheric pressure to terminate the hydrolysis reaction immediately; (4) separating the hydrolyzed coffee extract residue from a metnan oligomer solution containing an oligomer of DP 1 to about 10 to hydrolyze the coffee extract residue to meet DP 1 to about DP 10 Process for preparing oligomers. The method of claim 8, wherein the slurry is 5-20% by weight based on the dry weight of the residue, and the reactor of step (2) is a plug flow tubular reactor. The method of claim 8, wherein the reactor of step (2) is an extruder. The method of claim 8, wherein the liquid constituting the slurry is water. The method of claim 8, further comprising drying the met oligomer solution containing oligomers of DP 1 to DP 10. (1) slurrying the coffee extraction residue in a liquid in an amount of 5-60% by weight based on the dry weight of the residue, and (2) adding an acid catalyst to the slurry in an amount sufficient to bring the pH of the slurry to 0.5-4. Adding (3) hydrolyzing the mannan by feeding the slurry to the reactor at a temperature of 160 ° -260 ° C. and 6-35 atm for 6-60 seconds, and (4) evacuating the slurry from the reactor through the orifice to pressure Rapidly dropping to atmospheric pressure to terminate the hydrolysis reaction, (5) neutralizing the discharged slurry, and (6) separating the hydrolyzed coffee extract residue from the met oligomer of about DP 1 to about 10 by 80%. Obtaining an aqueous met oligomer solution having a purity above (7) drying the met oligomer solution and (8) mixing the dried met oligomer solution with soluble coffee A process for producing a dry met oligomer mixture of DP 1 to about DP 10. (1) slurrying the coffee extraction residue in a liquid in an amount of 5-60% by weight based on the dry weight of the residue, and (2) adding an acid catalyst to the slurry in an amount sufficient to bring the pH of the slurry to 0.5-4. Adding, (3) feeding the slurry to the reactor at a temperature of 160 ° -260 ° C. and 6-35 atm for 6-60 seconds to hydrolyze the mannan, (4) draining the sludge from the reactor through the orifice and Rapidly dropping the pressure to atmospheric pressure to terminate the hydrolysis reaction, (5) neutralizing the discharged slurry, and (6) separating the hydrolyzed coffee extract residue from the met oligomer of about DP 1 to about 10 Obtaining an aqueous solution of met oligomers having a purity of at least%, (7) mixing the met oligomer solution containing oligomers of DF 1 to about DP 10 with a conventional coffee extract and (8) drying the mixture Method of producing a met oligomeric mixture, characterized in that consisting of a step. The method of claim 1 wherein the liquid constituting the slurry is water. The method of claim 3, further comprising drying the met oligomer solution containing oligomers of DP 1 to DP 10. (1) slurrying 5 to 60% by weight of the coffee extract residue in the liquid, based on the dry weight of the coffee pouring residue, (2) reacting the slurry for only 6-60 seconds in a reactor at 160 ° -260 ° C. Injecting carbon dioxide as an acid catalyst into the reaction to maintain the pH of the slurry at less than about 1, (3) discharging the slurry from the reactor through an orifice to rapidly drop the pressure to atmospheric pressure to immediately terminate the hydrolysis reaction, ( 4) separating the hydrolyzed coffee extract residue from the met oligomer solution containing oligomers from DP 1 to about 10, (5) drying the met oligomer solution and (6) the dry met oligomer solution with soluble coffee. A process for producing a dry met oligomer mixture of DP 1 to about DP 10, characterized in that it comprises the step of mixing. (1) slurrying 5 to 60% by weight of a coffee stem residue in a liquid, based on the dry weight of the cupper extraction residue, (2) reacting the slurry for 6-60 seconds in a reactor at 160 ° -260 ° C. Injecting carbon dioxide as an acid catalyst into the reactor to maintain a pH of less than about 4, (3) discharging the slurry from the reactor through an orifice to rapidly drop the pressure to atmospheric pressure to immediately terminate the hydrolysis reaction, (4) Separating the hydrolyzed coffee extract residue from the met oligomer solution containing oligomers from DP 1 to about 10, (5) mixing the met oligomer solution with a conventional coffee extract and (6) drying the mixture Method of producing a dry met oligomeric mixture, characterized in that consisting of a step of making.