KR960007093B1 - Hydrolysis of a partially extracted roasted and ground coffee - Google Patents

Abstract

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Description

Hydrolysis of partially extracted roasted and ground coffee

The present invention relates to a solubilization method of partially extracted roasted and ground coffee. More specifically, the present invention includes a method of hydrolyzing partially extracted, roasted and ground coffee without using an acid catalyst in a single fixed bed reactor or a series of fixed bed reactors. The hydrolyzate obtained in this way is useful, for example, for mixing with an aqueous extract of roasted coffee to increase the solids of soluble coffee.

In the soluble coffee technology industry, there has been a particular focus on maximizing the yield of soluble solids from roasted and ground coffee by varying the percolation conditions. Prior to World War II, the early days of instant coffee development, soluble solids were leached from roasted and ground coffee with boiling water, yielding less than 25% soluble solids yield. Morganthaler, US Pat. No. 2,324,526, describes that 27% soluble content was obtained using a temperature of 160 ° C. to 175 ° C. (320 ° to 347 ° F.). Sivitz and Desrosier, "Coffee Technology" (Avi Publishing Company, Inc., 1979), page 366, describes the technical details of soluble yields. In this document, the total yield of soluble coffee from roasted and ground coffee is about 40 to 50%, and "higher yields in the strainer, since it compresses the tailings and does not reduce the flow rate, otherwise productivity and quality are compromised. It is impossible to obtain "the quality of the soluble coffee states that at the upper end of the above yield range tar and other inadequate flavors have already been produced and the quality is impaired. From awareness of the limitations of filtration, attention is focused on other ways of increasing the yield of soluble coffee.

Acid catalytic hydrolysis of partially extracted coffee grounds to increase the yield of solids has been tested as a way to increase the yield of soluble solids. For example, US Pat. No. 2,573,406 to Clough et al. Extracts about 20% by weight of coffee from the atmosphere, and fractions of tailings are hydrolyzed in about 1% sulfuric acid suspension at 100 ° C. for about 1 hour, A process for producing soluble coffee is described that includes adjusting the pH of the hydrolyzate, filtering the hydrolyzate, combining it with an extract in the atmosphere, and drying the combined extract. In another similar method described in US Pat. No. 2,687,355 to Benner et al., Phosphoric acid is used instead of sulfuric acid. As another method, DiNardo et al., US Pat. No. 3,224,879, describe a method of alkali hydrolysis or acid hydrolysis directly in an extraction apparatus for at least coffee grounds extracted in air. In the case of the direct hydrolysis in the extraction apparatus, the prior art process can eliminate the hydrolysis step carried out separately and also adsorb the alkali or acid catalyst to the spent tailings.

More recently, U. S. Patent No. 4,508, 745 to Fulger et al. Prepared slurries of spent residue at a concentration of 5 to 60 wt%, adjusted the pH to about 0.5 to 4.0, and adjusted the slurry to 160 ° to 260 ° C. A method for producing met oligomers of DP1 to DP10 by hydrolyzing coffee extract residual material by reacting for 6 to 60 seconds at According to Pooler et al., The process may increase the yield of solubles from about 30% by weight of partially extracted coffee extract residues, such as spent tailings obtained from commercial filtration devices extracted from the atmosphere and thermally partially hydrolyzed. Can be.

However, for example, acid catalyzed reactions may be undesirable or impractical to use to increase the yield of solubles. It is therefore an object of the present invention to provide a method of increasing the yield of solubles by treating roasted and ground coffee without acid catalyst.

Another object of the present invention is to make the process efficient and to ensure that the soluble solids produced by this process have an acceptable flavor quality.

It has been found that the object of the present invention can be met by a method of treating partially extracted roasted and ground coffee in one fixed bed reactor, or a series of fixed bed reactors. According to the present invention, a portion of the arabinogalactan that is inherently present in the roasted and ground coffee by partial extraction, preferably roasted and ground coffee from which most of the arabinogalactan has been removed is fed into a fixed bed reactor. Subsequently, the partially extracted roasted and ground coffee has a weight ratio of water to tailings of about 6: 1 or more, preferably about 8: 1 to about 12: 1 and about 176.7 ° C to about 260 ° C (about 350 ° to about 500). Extraction with water at a temperature of < RTI ID = 0.0 > According to the present invention, the yield of soluble solids is increased, resulting in a total soluble solids yield of about 55 to about 68 weight percent from roasted and ground coffee.

Before the detailed description of the present invention, it is necessary to define some related terms.

As used herein, the term "mannan" refers to any polysaccharide d-mannose that is an isoform of d-glucose, differing only in that it is an aldohexose and the spatial arrangement of the hydroxyl groups closest to the carbonyl group is reversed. It means broadly. Mannan found in coffee extract residues can have up to 40 d-mannose units in the polysaccharide.

"Partially extracted roasted and ground coffee" means a partially extracted roasted and ground coffee material, for example, extracted from the atmosphere. In general, extraction under atmospheric conditions removes caramel and browning products, roasted and ground coffee intact flavors, caffeine, trigonelin, chlorogenic acid, ash, arabinose, protein and coffee acid. "Partially extracted roasted and ground coffee" may also contain some of the extracted arabinogalactan and preferably most of the arabinogalactan extracted therefrom. “Partially extracted roasted and ground coffee” also includes roasted and ground coffee that has been hydrolyzed such that a portion of the mannan contained is hydrolyzed with the hydrolysis of galactose, arabinose, proteins and other heat condensation products. Roasted and ground coffee with reduced encounters of about 1/3 to 1/2 is also included in "partially extracted roasted and ground coffee". This can be done, for example, by limited thermal hydrolysis.

The present invention relates to a method for producing coffee solids of satisfactory quality and hydrolyzing partially extracted roasted and ground coffee in an effective manner to minimize degradation of the solids after production. Compared to the prior art, in particular the methods of Sibitz and Deslozi, the present invention provides a solids yield of at least 55% by weight of the starting and roasted and ground coffee in a fixed bed reactor with minimal loss of soluble solids after production of soluble coffee solids. You can get it.

According to the present invention, it has been found that soluble coffee solids produced by thermal hydrolysis are likely to be a series of decomposition products. Initially, soluble coffee solids can be broken down into a form that can be called soluble coffee solid intermediates such as hydroxymethyl furfural. It can then be further broken down into volatile acids and / or insoluble coffee solids. The present invention has found that after the production of soluble coffee solids, these solids decompose into intermediate soluble coffee solids and are also effective in minimizing their degradation into insoluble coffee solids. Degradation into intermediate soluble coffee solids does not itself reduce the yield of soluble solids, but has been found to cause side effects in coffee flavor due to the relatively increased concentration of intermediate soluble solids. However, the process of the present invention can yield soluble solids yields of at least 55% by weight while the resulting soluble solids are minimally degraded into intermediates and insoluble coffee solids.

Partially extracted roasted and ground coffee that can be suitably used as feed material for the process of the invention can be obtained by any method known in the art. For example, it is suitable to extract the soluble solids so that a part of the arabinogalactan in the roasted and ground coffee in the extraction apparatus, preferably most of the arabinogalactan, is extracted. In addition, extraction of soluble solids such that a portion of the mets, typically one-third to one-half of the mets present in the extraction apparatus, is effective in producing partially extracted roasted and ground coffee.

There is another suitable method of producing partially extracted roasted and ground coffee for use in the present invention. For example, roasted and ground coffee can be extracted by slurrying the coffee with water for a temperature, pressure and time effective to form partially extracted roasted and ground coffee in the container. Similarly, roasted and ground coffee is placed in the reactor and water is passed through the reactor for a temperature, pressure and time effective to produce partially extracted roasted and ground coffee.

According to the invention, the partially extracted roasted and ground coffee is placed in a single fixed bed reactor or a series of fixed bed reactors. The type of single fixed bed reactor is not critical to the invention as long as the reactor can withstand the temperature and pressure conditions described below. Reactor models are well known to those of ordinary skill in the art using engineering principles recognized in the art. However, it should be appreciated that the type of reactor affects working variables such as withdrawal factors as described below. Filtration columns in conventional extraction equipment are examples of fixed bed reactors suitable for use in the present invention. Preferably, two to three fixed bed reactors can be used in series, but the number of reactors is not critical.

Water is fed to the reactor at the top or bottom of the fixed bed reactor containing the partially extracted roasted and ground coffee. Typically, water is fed to the top of the reactor to flow down through the coffee. When using more than one reactor, a stream of water (hereinafter referred to as "extract") containing coffee solids exiting the bottom of the first reactor is fed to the second reactor, typically at the top of the second reactor, and the extract This is done in this series of reactors until it exits the final reactor. The temperature of the water supplied to the first column is important in the practice of the present invention, and the temperature is generally from about 193.3 ° C. to about 232.2 ° C. (about 380 ° to about 450 ° F.), typically from about 201.6 ° to about 218.324 ° C. (about 395 ° to about 425 ° F.). The internal pressure of the reactor or reactors keeps the water in the vessel from instantaneously evaporating at its system temperature. This can typically be accomplished by adjusting the outlet flow to maintain the internal pressure of the reactor as desired.

The relationship between the residence time of the coffee grind and the extraction time of the extract in the reactor has been found to be important for achieving the object of the present invention. It has also been found that the residence time of the extract should be significantly shorter than the residence time of the grind to prevent inadequate concentrations of soluble high blood from being broken down into intermediate soluble coffee solids and / or volatile acids from the insoluble coffee solids. . In conventional filtration, the residence time of the mill is about 225 minutes to 275 minutes for a typical six column operation. About 80% of its residence time is under high temperature, ie, thermal hydrolysis conditions. According to the invention, the residence time of the milled product is from about 30 to about 120 minutes. On the other hand, the residence time of the extract is only about 7 minutes to about 45 minutes, preferably about 30 minutes to about 40 minutes. It has thus been found that shortening the residence time of the extract, in particular compared to the residence time of the milled product, is important for obtaining the yield of the desired solubles and at the same time producing a coffee extract containing the coffee solids of the desired flavor.

Also, the ratio of water or extract to coffee grind, typically referred to as draw factor, is important for the present invention. The withdrawal factor is calculated by dividing the total weight of the coffee extract produced in a given amount of coffee by the weight of the coffee. According to the present invention, in order to achieve the object of the present invention, the withdrawal factor is greater than about 6, preferably about 8 to, in particular, to obtain a soluble solids yield of about 55% to about 70% by weight of the original roasted and ground coffee. It needs to be 10. Soluble yields to some extent depend on the degree of mixing of the coffee being extracted. As is known in the art, for example, Robusta coffee is easier to extract than Arabica coffee.

As the aqueous medium flows through the coffee grounds in the reactor, the surface speed of the medium is important for achieving the object of the present invention. The surface velocity described herein is defined as the velocity of the aqueous medium through the empty column. Surface velocity varies with the geometry of the reactor or reactors used. However, the surface speed to achieve the desired relationship between the residence time of the extract and the residence time of the steaming is essential for the purposes of the present invention. If the surface velocity is too slow for a given geometry of the reactor, the residence time of the extract is too long resulting in the decomposition of soluble solids to an unsuitable degree. However, if the surface velocity is too fast for a given geometry of the reactor, the residence time of the extract is so short that in order for the yield of the desired solubles to exceed 55% by weight, the withdrawal factor needs to be at least 8-10, which is the preferred range. have. In addition, if the surface velocity is too fast, the layer becomes unstable or the layer is squeezed. On the other hand, extremely fast surface velocities may be efficient to achieve the object of the present invention at very high withdrawal factors, but this operation results in a very low concentration of the extract exiting the system, thus increasing the concentration to a useful degree. It is relatively inefficient because a level of evaporation must be performed. The surface velocity is about 0.50 to 1.50, depending on the geometry of the reactor. Suitably, the length to diameter ratio of the reactor is from 2: 1 to 20: 1.

The extract exiting the final reactor of the series of reactors can be dried to form coffee powder. Alternatively, the extract can be added to another coffee extract, such as the coffee extract produced when the roasted and ground coffee is partially extracted, to form partially extracted roasted and ground coffee. In any case, the extract produced by the present invention contains soluble solids with good flavor and fragrance properties, and volatile acids, intermediate solids and insoluble coffee solids at acceptable levels.

Example 1

Roasted and crushed Rothbuta coffee was partially extracted in the extraction apparatus in the following manner. That is, freshly prepared roasted and ground coffee was packed into an extraction column and this column was connected to the end of the extraction apparatus to be the newest column in the line. The extraction apparatus consisted of five columns connected and the extraction water was fed to the most used column at any given time at about 176.7 ° C. (about 350 ° F.). Water flowed upward through the most used columns, passed through the second most used column to reach the newest column, and finally exited as a coffee extract. After about 50 minutes, the first column, the most used column, was removed from the extraction unit and a new clean column was connected to the device end. This process was repeated while connecting clean columns and removing the most used columns from the extraction equipment. After the used column was removed from the extraction apparatus, the roasted and ground coffee in the column was found to be partially extracted roasted and ground coffee. Most arabinogalactan was extracted from roasted and ground coffee and about 40% of the mannan was extracted from it. The yield of soluble solids in the extraction apparatus was about 53% by weight.

A partially extracted roasted and ground coffee was fed into an extraction column with a length to diameter ratio of 2: 1. As extracts, water was fed to the top of the extraction column at a temperature of about 204.4 ° C. (about 400 ° F.). The weight ratio of extract to the original roasted and ground coffee was about 10: 1, which corresponds to a withdrawal factor of 10. The time for which the partially extracted roasted and ground coffee stayed in the extraction column was about 60 minutes, and the residence time of the extracts was about 15 minutes. Extracts with a concentration of about 1% of soluble solids exited the extraction column.

It has been found that the partially extracted roasted and ground coffee hydrolyzed in the extraction column of the present invention was substantially extracted with met. The hydrolyzed roasted and ground coffee contained only about 10% of the mannan present in the original roasted and ground coffee. The yield of soluble solids in the extraction column of the present invention was increased to about 10% by weight. Therefore, the total yield of soluble solids was about 63% by weight based on the original roasted and ground coffee. The extract was evaporated to a concentration of about 25% by weight, re-added to the coffee extract produced in the extraction apparatus, and the mixture was concentrated and dried to produce a soluble coffee product. Sensory evaluation of the final coffee by experts confirmed that it had a suitable flavor.

Example 2

Filled roasted and ground coffee partially extracted into two extraction columns 25.4 cm (10 inches) in diameter and about 5.0 m (16.5 ft) in length. Water was fed to the top of the first column, ie the more used column, at a temperature of about 265.6 ° C. (about 410 ° F.). Water was passed down through the partially extracted roasted and ground coffee, exited to the bottom, and fed to the top of a second extraction column connected at a temperature of about 222.2 ° C. (about 400 ° F.). The total residence time of the extract in the two connected columns was about 27 minutes. After about 42 minutes, the more used column was removed from the series of columns and a new second extraction column containing the partially extracted roasted and ground coffee was connected to the series of columns. Thus, the first second extraction column became the first column of the series, ie the more used column. This process was repeated every 42 minutes. The total residence time for the partially extracted roasted and ground coffee was about 84 minutes. The total withdrawal factor was about 8.

Partially extracted roasted and ground coffee, hydrolyzed in two series of columns, was found to contain substantially about 10% of the mannan inherent in roasted and ground coffee, with substantially no met. Therefore, the yield of soluble solids increased by about 31% by weight, so that the yield of total soluble solids from the original roasted and ground coffee was about 62% by weight. The extracts produced in the two series of columns were found to have a suitable flavor. The extract was evaporated to a concentration of about 55%, mixed with the first extract and then dried to form a soluble coffee product. The coffee product was subjected to sensory inspection by all the sellers to confirm that it was of a suitable flavor quality.

Claims (13)

The partially extracted roasted and ground coffee in a fixed bed reactor at a temperature of 193 ° C. to 232 ° C. (380 ° to 450 ° F.) has a reactor residence time of 30 to 120 minutes and a reactor residence time of water of 7 to 45 minutes. Effective to hydrolyze the partially extracted roasted and ground coffee, effective to remove at least 50% of the fractions encountered, and obtain a soluble solid yield of 55% to 68% by weight based on the roasted and ground coffee A method of solubilizing partially extracted roasted and ground coffee, comprising contacting with water to be effective to minimize degradation of soluble coffee solids produced by decomposition. The method of claim 1, wherein the partially extracted roasted and ground coffee is produced by extracting roasted and ground coffee in an extraction device. The method of claim 1, wherein the partially extracted roasted and ground coffee is air-extracted, roasted and ground coffee original flavor component, caffeine, trigonelin, chlorogenic acid, ash, arabinose, protein, coffee acid and caramel and browning product How to extract it. 3. The method of claim 2, wherein 1/3 to 1/2 of the mannan originally present in the roasted and ground coffee is extracted from the partially extracted roasted and ground coffee. The method of claim 1 wherein said contacting is performed at a temperature between 204 ° C. and 216 ° C. (400 ° to 420 ° F.). The method of claim 1 wherein the contact is effective to obtain a yield of soluble solids of 58% to 65% by weight based on roasted and ground coffee. The method of claim 1, wherein a series of fixed bed reactors is used instead of the fixed bed reactor. 6. The process of claim 5 wherein the series of fixed bed reactors is two fixed bed reactors. 7. The method of claim 6, wherein water is supplied to the second fixed bed reactor at a temperature of 213 ° C. to 218 ° C. (415 ° to 425 ° F.) and then to the first fixed bed reactor from 202 ° C. to about 207 ° C. (395 ° to 405 ° F.). How to feed at the temperature of). The method of claim 1, wherein the draw factor, which is the ratio of extract to coffee, is about 6. 6. The method of claim 1 wherein the withdrawal factor is from 8 to 10. The method of claim 1 wherein at least 75% of the met fractions are removed during hydrolysis. The method of claim 1, wherein at least 90% of the met fractions are removed during hydrolysis.