JPH0145349B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing soluble coffee by spray drying a concentrated aqueous coffee extract obtained from roasted and ground coffee.

Work by Hjuste et al., US Pat. No. 3,345,182, shows that volatile retention through spray drying is improved by increasing the solids concentration of the aqueous coffee extract. However, because it is economical to operate the percolator at high withdrawal rates to give high yields, low concentration extracts are produced. Therefore, more effective methods of concentrating extracts are desirable. However, the capture and retention of volatile coffee flavor and aroma compounds is also important.

The present invention is based on Schulimpton's U.S. Patent No.
This method is an improvement and modification of the method disclosed in No. 4107339. According to the method described in the patent, a small fraction of the evaporation is carried out by bulk evaporation;
Produces highly concentrated extract. The condensate from the first evaporation is then re-added to the concentrate and then spray dried.

The method as described in that patent is influenced by three factors related to flavor and aroma capture and retention. The first is a small proportion of evaporation, where removal of the compound is facilitated by its relatively high volatility (relative to water). The relative volatility (α) is
Defined as K ₁ /K ₂ , where K is the ratio of vapor concentration to liquid concentration, K ₁ refers to that of the flavor and aroma compounds that are distilled, and K ₂ refers to that of water. Compounds with relative volatility α' below 40% are not removed satisfactorily. Second, condensation favors low α' compounds. Compounds with high α' result in losses. Third, any compounds that are not removed by small-rate evaporation are then removed by large-rate evaporation and discarded.

If all flavor compounds are important, there are two areas in which the method disclosed in the aforementioned US Pat. No. 4,107,339 needs improvement. The first region is a small percentage of evaporation. Although high rate evaporation can remove heavier volatiles (low α'), the increased loading of water dilutes the product. Therefore, means such as a distillation column are required to separate and concentrate the volatiles before re-addition. Second, the condenser is improved by providing a means to capture highly volatile compounds that would normally be lost.

The present invention uses absorption towers to capture and retain volatile coffee flavor and aroma compounds;
The invention relates to the absorption of the compound into a cooled coffee extract. “Cooling” is approximately 10℃−15
C. and has a solids concentration of about 10%-40%, preferably about 35%. The use of an absorption column as a treatment step allows desirable coffee flavor and aroma compounds to be transferred from the exhaust gas stream to the coffee extract product liquid stream. These flavor and aroma volatiles can then be further processed and retained in the final product obtained by spray drying the concentrated extract. The gaseous aroma fluid may be obtained from any source of volatile aroma, such as a vent from a condenser, a percolator vent, a mill, etc. The volatile aroma compounds are preferably non-condensed flavor and aroma compounds from the condenser. Absorption columns are designed to operate at atmospheric or slightly elevated pressure, but if gaseous aroma compounds are produced in vacuum, a hermetic gas compressor, such as a membrane pump, is used, e.g. The fluid is compressed at normal pressure without contamination.

The present invention is based on the discovery that highly volatile coffee flavor and aroma compounds have a strong affinity for coffee chilled extracts.

The present invention is designed to prevent loss of desirable flavor and aroma volatiles during processing.
For details, see, for example, Schulimpton's patent no.
In the method as in No. 4107339, it solves the problem of flavor loss during extract evaporation due to high volatile flavors and insufficient condensation of aroma compounds in the aroma compound condenser. It is also used to solve the problem of loss due to insufficient condensation of volatile vapor aroma compounds in methods such as steam stripping of roasting and ground coffee and of grinder gas aroma compound collection for jar or brew aroma compounds. can be used for

A further advantage of the present invention is that previous devices for gaseous aroma collectors are high quality items such as liquid nitrogen condensers or pline-cooled wipe film vapor-fluid contactors such as Votators. However, it does involve the use of relatively low cost equipment. A further advantage of the present invention is its versatility for use in processes where it is desirable to capture non-condensable gaseous flavor and aroma compounds to retain them in the final product.

A method has now been discovered to produce soluble coffee by spray drying a concentrated aqueous coffee extract obtained from roasted and ground coffee, which captures volatile coffee flavors and aroma compounds and
(a) evaporating the coffee aqueous extract to produce a flavor and aroma aqueous solution; (b) evaporating the coffee flavor and aroma aqueous solution in a distillation column to 100-500 mm mercury absolute; (c) condensing the steam stripping product in a condenser; (d) stripping the flavor and aroma compounds at pressure; (c) condensing the steam stripping product in a condenser; (d) stripping the flavor and aroma compounds.
compressing from steps (a) and (c); (e) passing the compressed gaseous non-condensed flavor and aroma compounds through an absorption column; and (f) supplementing a portion of the concentrated concentrated extract of step (a). (g) passing the concentrated extract of step (f) countercurrently through said absorption column to absorb the compounds of step (e); (h) the steam-stripping product of step (c); a) the remainder of the stripped concentrated extract of the process; and (g)
Mixing a portion of the concentrated extract containing the flavor and aroma compounds of step (i) spray drying the combined stripping product and extract of step (h).

Preferably, the extract of step (f) is maintained at a temperature of about 10-15°C, a solids concentration of 10%-40%, typically 35%, and 70-150 cps as it passes through the absorption column. Ru.

The evaporative concentration of step (a) can be carried out in a single-effect evaporator or a multiple-effect evaporator, such as a Centritherm.

The solids concentration of the mixed stripping product and extract of step (h) fed to the spray dryer is approximately 35%-
60%, preferably 40%-45%.

The present invention therefore encompasses the use of a mildly viscous liquid (70-150 cps), typically at a 35% solids concentration, as the absorption medium in the gas absorption tower. Absorption columns generally do not operate with viscous liquids. Previous attempts to absorb gaseous aroma compounds into viscous liquids such as concentrated coffee extract have also failed due to poor handling and foaming, or have not been considered economically viable. A unique aspect of the present invention is the use of both gas and liquid fluids as continuous phases in the column, thus preventing the formation of foaming, yet affecting mass transfer of volatiles from gas to liquid. and the liquid. The entire process uses coffee extract at an initial rate of 10%-20%.
% to 35%-60% solids to minimize loss of flavor and aroma compounds.

The entire process, including the initial evaporation step, is carried out in a single effect evaporator and is carried out by two recovery systems. The condensed fluid from the single effect evaporator is sent to a distillation step where volatiles are separated and concentrated. The non-condensable fluid has a viscosity of 70-150 cps and a temperature of about 10-15°C in the absorption tower.
It is recovered by contacting it with a concentrated, odorless extract having a temperature of . The volatile-rich fluid is mixed with the extract-rich fluid prior to spray drying.

The step of steam stripping the flavor and aroma aqueous solution resulting from concentration/condensation of the extract is carried out in a distillation column. The volatiles are removed in the lower part of the distillation column, called the stripping or discharge section. In this zone a large amount of liquid is evaporated and a number of stages are provided to allow removal of volatiles. In the upper part of the distillation column, called the concentration or rectification section, the volatiles are refluxed to the column again.
Concentration is achieved by providing a sufficient number of stages to achieve the desired concentration.

Approximately 75% of the extract fed to the evaporator is evaporated. In this step, the largest amount, perhaps 90%, of volatiles is removed from the concentrate. The extract leaving the evaporator is at a concentration of approximately 52% solids. To achieve this concentration it is necessary to apply an evaporator. More efficient evaporators such as multi-effect evaporators are available to accomplish evaporation in bulk.

The distillation column is designed to recover compounds with a lower limit of relative volatility of 3-15. The actual number of shelves can be determined using standard design methods. The advantage of using distillation columns as separation and concentration devices is their flexibility. By changing the design and/or operating parameters, compounds with other relative volatilities can be recovered, thus changing the flavor of the final product.

The non-condensable vapors from both the evaporator and distillation column were analyzed and found to contain large amounts of volatiles that affected flavor. The recovery for the absorber was over 95% for the carbon compound.

Spray drying uses a highly concentrated extract (43% solids), high spray nozzle pressure (70.3 Kg/cm ² , 1000 psi), and low temperature drying conditions (205°C in, 105°C out, 400° in, 220° in).
It is carried out using

The spray-dried products produced according to the present invention are described as being similar to freeze-dried products. Flavor reviews for the product were winey, buttery, aromatic, powdery, smooth, and well refined.

EXAMPLES The present invention is adapted for efficient recovery of non-condensable gaseous flavor and aroma compounds exiting a condenser in an evaporator and distillation column.

1 The raw extract (15% solids) from a percolator-scale tank was evaporated under vacuum (125-
evaporated to 55% concentration (150mm mercury absolute).

2 The steam was condensed in the tower water condenser.

3 The non-condensable gaseous aroma compounds were then compressed to atmospheric pressure and fed to the bottom of the absorption column.

4 Flavor and aroma condensates from step 2 are
Under vacuum (360mm mercury absolute pressure) in a 20-stage distillation column
Concentrated into

5. The non-condensable gaseous aroma compounds from the vacuum distillation column were compressed to atmospheric pressure and fed to the bottom of the absorption column.

6 A portion of the concentrated extract (10% solids weight from step 1) was again diluted to 35% solids concentration and fed to the top of the absorption column. Operation was continuous and countercurrent.

7 The aroma compound-enriched absorber column product was then mixed with the liquid aroma compounds from the distillation column and the remainder of the concentrated extract.

8 The combined distillate and extract were then spray dried.

Gas chromatography analysis of the gas fluid was performed. A taste comparison of the absorber feed and absorber product describes the product as wine-like, buttery, and rich in aroma. It was shown to mainly contain significantly high levels of coffee flavor characteristics.
The gas chromatogram further showed that essentially all of the gaseous aroma compounds were recovered from the gaseous fluid fed to the absorption column.

For product evaluation purposes, the following product studies were then conducted:

1 Commercially available freeze-dried coffee products 2 Coffee products spray-dried according to the method of the invention (high Colombian content) 3 Coffee products spray-dried according to the method of the invention (medium Colombian content) 4 Commercially available freeze-dried coffee Products A total of 576 judgments were conducted among respondents who used either decaffeinated freeze-dried coffee or ground freeze-dried coffee.

No differences were found between the two user groups (freeze-dried and freeze-dried, both users). The results of this test showed equal selectivity between the product produced by the method of the invention and the commercially available freeze-dried coffee product.

Claims (1)

[Claims] 1. A method for producing soluble coffee by spray drying a concentrated aqueous coffee extract obtained from roasted and ground coffee, comprising: (a) evaporating the aqueous coffee extract to remove flavor and aroma; producing an aqueous solution; (b) subjecting the coffee flavor and aroma aqueous solution to steam stripping in a distillation column at 100-500 mm mercury absolute pressure to strip the flavor and aroma compounds to obtain a concentrated aqueous solution of the flavor and aroma; (c) condensing; (d) compressing the gaseous non-condensed flavor and aroma compounds from steps (a) and (c); (e) compressing the compressed gaseous non-condensed flavor; and aroma compounds are passed through an absorption tower, (f) a portion of the stripped concentrated extract of step (a) is collected, and (g) the concentrated extract of step (f) is passed through the absorption tower in countercurrent. (h) the steam stripping product of step (c), the remaining amount of the stripped concentrated extract of step (a) and
(g) mixing a portion of the concentrated extract containing flavor and aroma compounds; and (i) spray drying the combined stripping product and extract of step (h). A method for producing soluble coffee. 2. When the extract in step (f) passes through the absorption tower, approximately
The method of claim 1, wherein the temperature is maintained at 10-15°C and the viscosity is 70-150 cps. 3. The method of claim 2, wherein the evaporative concentration step of (a) is carried out in a single effect evaporator. 4. The method of claim 2, wherein the evaporative concentration step of (a) is carried out in a multiple effect evaporator. 5. The method of claim 2, wherein the solids concentration of the mixed strip product and extract of step (h) is 40-45%.