Note: Descriptions are shown in the official language in which they were submitted.
SOLUBLE COFFEE COMPOSITION
lZ~08~
Technical F7~1d
This invention relates to a coffee extract or concentrate and
a process for making it and to a soluble coffee composition which
have a flavor s;milar to that of regular roast and ground coffee
lU and less like the flavor of instant or soluble coffees and to a
brewing article for use in conjunction with the soluble coffee
product. The coffee is characteriled by its low furfural content
and high content of pyrazine derivatives.
Background of the Invention
The standard of flavor excellence among many coffee
drinkers is freshly ~rewed roast and ground coffee. This
beverage provides a balanced blend of aroma and flavor notes
contributed by volatile and moderately volatile flavor compounds~
as well as nonvolatile eoffee soli~s. However, for reasons of
20 convenience and economy, many consumers do not prepare freshly
brewed roast and g round coffee for each coffee consumption
experience. Roast and ground coffee Is typically conveniently
brewed in quantities of 5 to l O cups (or more) at a time. For
many consumers, such as single consumers, it is uneconomical to
25 brew a large pot of coffee to consume a single cup. Brewing a
single cup in most common coffeemakers involves the sams
inconvenience as brewing a number of cups. Thus, many
consumers have turned to soluble coffee products as a substitute.
Unfortunately, most soluble coffee produces have serious
30 deficiencies. Many soluble coffee products are lacking in the
volatile and moderately voiatile flavor components which are easily
lost during processing. In addi~ion, the economics of soluble
coffee manufacture forces producers to extract the maximum
possible yield from the;r percolation processes. This typically
35 involves the use of high temperature and pressure extraction
processes to hydrolyze otherwise insoluble coffee ~onsti~uents and
to provide a higher soluble yield. This modifles some of the
existing flavor compounds present in roast and ground coffee,
and it also creates or manufactures addi~ional flavor compounds.
"~
Also, It Is both difficult and uneconomical to package, ship
and s~ll substantial quantitles of watel in coffee products, As a
result, most commercial extracts are reduced tc dryness for
packaglng and sale, typically by thermal evaporative technlques
S which further aggravate tha problem of volatile loss and flavor
deg radation .
As a resule of this processing, most instant coffees are poor
reproductlons of the flavor of freshly brewed roast and ground
coffee . Even where low-boi ling volatiies have been added by
10 aromatization processes, soluble products are often lacking in
moderately volatile aromatics, and, in addition, contain off-flavor
aromatic compounds generated by thermal processing and by
hydrolysis during extraction.
For these reasons, it would be desirable to provlde
15 single-serving convenience in a roast and ground coffee product.
As a result, attempts have been made to package roast and
ground coffee in single-serving brewing packets, like tea bags.
However, the brewing time of such coffee bags is longer than the
time to make an instant coffee, and the extractability can be
20 variable depending on the water temperature, brew time, volume
of water, etc. This has been overcome in some products by the
combination of the roast and grollnd coffee in a packet with
soluble coffe~, including solubles produced by low-temperature
extraction processing. The use of solubles produced by low-
25 temperature processing (I.e., solubles extraction withouthydrolysis3 results in a very acceptable beverageO However, the
low-solids ylelds of low-temperature extraction processes are such
that it is uneconomical to produce the product except for sale at
a premium price. And unfortunately, the combination of roast
30 and ground coffee with conventional instant coffees in a coffee
bag results in a brew that tastes instant-like and foreign to those
accust~med to drinking fresh brewed roast and ground coffee.
Alternatively, it would be desirable to have a soluble co~fee
product whose flavor is a close duplicate of freshly brewed roast
35 and ground coffec solubles and yet economical to produce.
Numerous attempts at production of such a product have been
made. Many such processes have involved strenuous efforts to
~L~
,
-3-
capture, preserve and retain the volatiles present in freshly
brewed coffee.
One such attempt is that described in U.S. 4,277,509, issued
July 7, 1981 to Wouda and assigned to D.E.J. International
Research Company B.V., relates to a process ~or "primary"
extraction of roast and ground coffee. The coffee is exhaustively
extracted at low temperatures with a first quantity of water. The
coffee is then extracted again with a second quantity of water to
remove hydrophobic aroma components. Y~ouda then steam strips
the second extract and collects the aroma components as a small
volume of stripper condensate, which is then added to the first
extract. This process can be continued throughout the fresh
solubles section o~ an extraction train.
Another approach is that described in De~ensive Publication
T920,012, published March 5, 1974 by Pfluger and Bowden,
relates to a method for producing a soluble coffee product. In
this process, the extract drawn offstream from a coffee perco-
lation unit is split into two batches. the first containing higher
quality and higher concentration extract, and the second
containing lower quality and lower concentration extract. The - I
second batch is evaporatively concentrated within a continuous
evaporator and then added to the flrst batch. The combined
extracts are dried in conventional fashion.
U.S. 3,720~518, issued March 13, 1973 to Galdo and assigned
to General Foods, relates to a process for the production of a
high concentration coffee extract containing 30-409~ solids by
weight. The key step in this process is the use of intercolumn
concentration prior to the fresh stage in a percolator train. The
patent describes intercolumn concentration by a variety of
techniques, including flash evaporators and vacuum evaporator~,
as well as membrane separators and other techniques. Like
Wouda, Galdo also describes stripping aroma from the extract,
then adding the aroma back to the concentrate.
4-
Unfortunat~ly, when coupled with conventional commerclal
percolation o~ extractlon processes, these aroma retentlon and/or
aroma add~back processes have the effect of also retaining off- -
flavor volatiles which have been gen@rated durlng the extraction
5 process. As 3 result, current instant sof~ees, both spray dried
and freeze dried, have a characteristic flavor which Ts dTfferent
from the flavor of freshly brewecl roast and ground coffee.
Surpris;ngly, it has becn found that an aromatic soluble
coffee can be made at about 35% to 50% solids yield which retains
10 the moderately volatlle flavor components characteristic of roast
and ground coffee but whlch does not contain the flavor materials
characteristic of soluble or instant coffees which have been
hydrolyzed during processing. The process used to create this
new soluble cof~ee composition involves a conventional extraction
15 and hydrolysis of roast and ground coffee follo~ed by multistage
or countercurrent steam stripping of the hydrolysis extract. The
hydrolysis volatiles are discarde~.
-~ U.S. 4,129,665, issued December 12, 197~ to Clark, and
assigned to Nestle, relates to a process for extracting vegetable
materials in the liquid phase in a group of "cells", divided into
hydrolysis extraction and fresh extraction cells. Extraction water
is run through the cells countercurrently. Extract from the
hydrolysis stage is subjected to a vacuum evaporation or rapid
expansion. Then water is added to the partially evaporated
`ex~ract in a quantity at least equal to the quantity of evaporated
Iiquid, and preferably greater than the quantity of evaporated
llquid, prior to passage of th~ extract through the fresh
extraction cells.
Clark used a countercurrent hydrolysis step for vegetable
materials in U.S. ~,129,665. Unfortunately, he evaporated the
extract instead of steam stripping. Evaporation is not capable of
obtaining the degree of removal, for example, of aqueous furfural
as is countercurrent steam stripping. Moreover, evaporation
involves a heat treatment of the extract which causes thermal
degradation of the aroma and flavor coffee solids. This heating
and concentration also creates or encourages the precipitation of
polymeric ma~erials from solution during evaporation.
--5--
~ 7~3
It is an object of an aspect of this invention to
provide a soiuble cofEee which closely approximates the
flavor of freshly brewed roast and ground coffee and
which is lacking in the off-flavors which are
characteristic of hydrolyzed coffee.
It is an object of an aspect of this invention to
provide a coffee extract or concentrate which has a
flavor and aroma approximating fresh roast and ground
coffee extracts.
It is an object of an aspect of this invention to
provide a soluble coffee which can be manufactured in
high yield for combination with roast and ground coffee
to produce a less bitter coffee brew.
It is an object of an aspect of this invention to
provide a process for producing a coffee extract and a
soluble coffee which closely approximates the flavor of
freshly brewed roast and ground coffee.
It is an object of an aspect of this invention to
provide a process for making a soluble coffee which can
be manufactured in high yield but which does not contain
off-flavors associated with hydrolysis extraction.
It is an object of an aspect of this invention to
provide a process for making a regular or decaffeinated
coffee extract which closely approximates the flavor of
freshly brewed coffee.
It is an object of an aspect of this invention to
provide an infusion device containing a specially
processed soluble coffee in combination with roast and
ground coffee.
These and other objects of the invention will be
evident from the following disclosure.
Summary of the Invention
Various aspects of this invention are as follows:
A coffee brewing article comprising a
water-permeable infusion article containing:
a) roast and ground coffee; and
b) a soluble coffee composition comprising:
1) volatile and non-volatile aroma and
flavor compounds, at least two of said
-5a-
8~6
.
aroma and flavor compounds being furfural
and pyrazine derivatives;
wherein the ratio of furfural to total
pyrazine derivatives is less than 1.5:1,
and wherein the pyrazine derivatives have
a g.c. count of at least 20,000, wherein
said g.c. counts, on a dry solids basis,
are measured on a Freon 11 solution of
separated volatiles by capillary gas
chromatography on a fused silica column;
and
2) wherein the total ash is less than 12% on
a dry solids basis~
A coffee extract comprising: (a) at least 15~, and
preferably at least 35%, coffee solids, said solids
comprising non-volatile and volatile aroma and flavor
compounds, at least two of said aroma and flavor
compounds being furfural and pyrazine derivatives; (b)
wherein the ratio of furfural to total pyrazine
derivatives is less than 1.5:1 and wherein the total
pyrazine derivatives are at least 20,000 corrected g.c.
counts on a dry solids basis, wherein said g.c. counts
are measured on a Freon 11 solution of separated
volatiles by capillary gas
.
.,
-- 6 --
chromatography on a lFused silica column; and (c) wher~ln the
total ash Is less than 12~, on a dry solids basisO
This coffee extract is concentrated in a mann~r which
preserves the coffee volatiles and dried to form a soluble coffee
5 product with essentially the same furfural, pyrazine derivatives
and ash contentO
The process comprises the steps of:
1) forming a hydrolyzed roast and ground coffee extract;
2) mul~istage or countercurrently steam-stripping the
hydrolysis extract to remove hydrolysis volatiles;
3~ discarding said hydrolysis volatiles; and
4) passing the stripped hydrolysis extract through roast
and ground coffee at a temperature of from about 138C
~280F) to about 21C 170F) to produce a final
extract.
This extract is concentrated in a manner which preserves
the low and the mGderately volatile compounds. Preferably,
freeze concentraton is used to produce a concentrated coffee
extract. The concentrated coffee extract can also be dried to
2~, make a soluble co~fee.
The coffee brewing article comprises a water-permeable
infusion article containing:
a) roast and ground coffee; and
b) a soluble coffee composition comprising:
1) volatile and non-volatile aroma and flavor com-
pounds, at least two o~ said aroma and flavor
compounds being furfural and pyrazine deriva-
tives;
wherein the ratio of furfural to total pyrazine
derivatives is less than 1.5:1, and wherein the
pyrazine derivatives have a g.c. count of at least
20,000, wherein said g.c. counts, on a dry solids
basis, are measured on a Freon 11 solution of
separated volatiles by capillary gas
chromatography on a fused silica column; and
2) wherein the total ash is less than 12% on a dry
solids basis.
~2~
Brief Descr ption of the Fi~ures
Figure 1 is a schematlc of the coffee extract and soluble
coffee process.
Figures 2A, 2B, 2C, 3A, 38 and 3C are chromatograms of
s various coffee products.
Figures 2A, 2~3 and 2C are chromatograms of organlc
compounds in the soluble coffee of this invention.
Figures 3A, 3B and 3C are chromatograms of organic
compounds in a commercial spray-dried instant coffee.
Figure 1~ is a drawing of the steam distillation apparatus
used to concentrate the coffee volatiles for the analytical gas
chromatographio method.
Disclosure of the Invention
1. The Coffee Composition
This invention provides an instant or soluble coffiee and a
coffee extract or concentrate which are similar to grouncl roast
coffee in its composition of moderately volatile flavor components.
At the same time, it is di~erent in composition from other soluble
coffees. In particular, the soluble coffee of this invention
contains relatively large c;uantities of moderately volatile
compounds, having normal boiling points of 88C (190F3 to 205C
(401F), and nolmally found in roast and ground coffees, These
quantities are significantly higher than those present in
conventional instant coffees. hloreover, the coffee brew made
from the extract or soluble cof~ee is less bitter than roast and
ground and typical soluble coffees.
All of the specific components of coffee aroma and flavor
volatiles have not been identified. It is estimated that over 250
compounds are present or contribute to the aroma and flavor of
coffee. While it is not possible to say that the compounds
identTfied herein are definitive of ooffee flavor and aroma, it is
believed that these compounds represent the retention of good
flavors and the removal of off-flavors.
These aroma and flavor compounds importantly include
various pyrazines which are ~ormed during coffee roasting and
which are considered herein to be key indicators of roast ans~
~L2~
-- 8 --
ground coffee flavor. Such compounds include, but are not
limited to, pyrazlne; methyl ~yraline 2, 5-dimethyl pyra in~;
2,6-dimethyl pyrazine; 2,3-dimethyl pyrazine; 2-ethyl-6-methyl
pyrazine; 2-ethyl-5-methyl pyrazine; 2,3,5-trimethyl pyrazine;
5 and 2-ethyl-2,5-dimethyl pyrazine.
These coffee aroma and f3avor compounds also include
various other volatiles which are indicators of roast and ground
flavor. Such non-pyrazine compounds include, without limitation,
isobutyraldehyde, methyl ethyl ketone, 2,3-pentanedione,
10 dihydro-2-methyl-3(2H) furanone, acetoacetate, 5 methyl
pyrrole-2-carboxaldehyde, guaiacol, ethyl guaiacol and vinyl
guaiacol ~
Additionally, cof~ee volatiles also include various
sulfur-bearing coffee volatiles which are formed during coffee
15 roasting, and which are also considered to be key indicators of
roast ancl ground flavor. Note that, in general, pyrazines are
volatiles which can be formed during the roasting of most grains.
It is the sulfur-bearing volatiles which help to distinctively
separate coffee from other roasted grain beverages. These
20 sulfur-bearing compounds, as analyzed by the gas chromato-
graphic method described below, are not yet sp~cifically
identified. Yet, the analysis demonstrates that the soluble coffee
of the process of this invention has (1~ a level of these sulfur
volatiles significantly higher than in conventional instant coffee,
25 and (2) a level of these compounds essentially equal to the level
in roast and ground coffee.
The composition of this invention contains less of thè
compounds normally found in high quantities in instant cof~ees,
and referred to herein as hydrolysis volatiles. Furfural is
30 especially prominent among these compounds and is considered
herein as an indicator of the prPsence of hydrolysis volatiles in
general. Furfural is a reaction product from the hydrolysis of
5-carbon sugars. It is present in detectable amounts in regular
roast and ground coffees, but is present in much larger
Q~3'7~ti
g
qu~ntitles ln in~tant coffees, both spray dried and freeze drled,
due to hydroly~ls extraction.
Tho composition of this invention is both a coffee extract
and a soluble coffee product comprising non-volatile coffee solTds
s and volatile aroma and flavor compsunds. This composition has
levels of the key volatiles boiling at atmospheric pressure in the
range of from abollt 88C (190F) to about 205C (401F)
("moderately volatile flavor compounds") which are at least
substantially equivalent to the levels of those same voiatiles in
roast and ground coffee, on a gram for gram basis.
By "at least substantially equivalent to freshly brewed roast
and ground coffee" is meant that the key moderately volatile
compounds of the composition of this invention, on a gram for
g ram basis, average at least 100% or more of the ,ev~ls of the
same volatiles in conventional roast and ground coffee.
Preferably, at least 150% of the level of those volatiles present in
roast and ground cof~ee are present in the coffee of this
invention .
Th~ cof~ee extract and the solubles are further defined by
the content of pyrazine derivatives and the ratio of furfural to
pyrazines. The aroma and fla~vor compounds are steam distilled
and extracted (with Freon 113 from the coffee extract or soluble
coffee product. The relative amounts of the aroma and flavor
compounds are then measured by capillary gas chromatography on
a fused silica column. Each compound can be identifled by its
retention time on the column. Gas chromatography giYes the
relative proportions of the compounds in composition and can be
related to the actuai concentration of the compound in the
composition.
The coffee compositions herein are defined by the minimum
number of gas chromatographlc counts (g.c. counts) of pyrazine
derivativ~s and by the ratio of chromatographic counts of furfural
to pyrazine derivatives. Gas chromatographic counts are the
electronic output of the ga~ chromatograph.
-- 10 --
By pyrazlne derivatives are meant th~ following compounds:
pyrazine, methyl pyrazine, 2 ,5-dimethyl pyrazine, 2 ,6-dllTlethyl
pyrazine, 2,3-dimethyl pyrazine, 2-ethyl-6-methyl pyrazine,
2-ethyl-5-methyl pyrazine, 2,3,5-trlmethyl pyrazine, and
5 2-e~hyl-2, S-dimethyl pyrazine. These derivatives are defin~d by
their retention times using the capilliary gas chromatographic
method as described in the method herein. Figures 2A, 2B, 2C,
3A, 3B and 3C are typical chromatograms. The pyrazine
compounds are denoted on each as follows: pyrazine (2); methyl
pyrazine (4), 2,5-dimethyl pyrazine (6), 2,6-dimethyl pyrazine
(8), 2,3-dimethyl pyrazine (10), 2-ethyl-6-methyl pyrazine (12),
2-ethyl-S-methyl pyrazine (14), 2,3,5-trimethyl pyrazine (16),
and 2~ethyl-2,5-dimethyl pyrazine (18). Fur~ural is identified as
(20) .
The compositions herein have a gas chromatographic count of
at least 20,000 for pyrazine derivatives and pre~rably about
30,000 to about 50,000 counts. Because of the presence of
Freon 11 solvent and other impurities associated with the
analytical method, the concentration of the volatiles is given in
20 g.c. counts rather than percent volatiles. The ratio of furfural
to pyrazine is less than 1.5:1, and preferably from about 0.4:1 to
1 : 1 .
The total sulfur compound le~el is also measured by gas
ehromatography as described below. The level of these sulfur
25 compounds approximates those in roast and ground coffee. The
total sulfur compounds will be about 4,000 to about 15,000 by the
method used herein.
Another characteristic of the coffee extract and cof~ee
solubles is their ash content. Ash is the oxidation product
30 minerals of which are present in the green coffee beans. The
ash is measured by pyrolysis of the coffee sample. The minerals
of the roast and ground coffee are easily extracted. Thus, the
ash content of a soluble coff~e or coffee axtract can be used as a
me~ure of yield of solids from the roast and ground coffee. The
coffee extract and soluble coffee herein has an ash content, on a
dry solids basis, of less than 12~, preferably less than 9%, and
5 most preferably from 5% to 7.5%.
I l . The Process
A. Green Bean Blendin~
The solùble eoffee product of this invention is made by
extraction of conventional roast and ground coffee. Because the
10 product of this invention is designed to duplicate closely the
flavor of freshly brewed roast and ground coffee, it will be
evident that the starting blend of green beans and the roasting
and grinding conditions will contribute importantly to the final
product characteristics. While these parameters are more
15 important than is usual in making soluble coffee, they are not
critical .
Three major types of green coffee beans are blended to
formulate a coffee blend for subsequent roasting. These three
types of coffee are milds, Brazilians, and Robustas. Botanically,
20 the milds and Brazilians are traditionally thought of as Arabicas.
The miids give coffee brews which are fragran~ and acidic.
The Brazilian beans result in coffee brews which are relatively
neutral flavored. The Robusta beans produce brews with strong
distinctive flavors that possess varying degrees of dirty or
25 rubbery notes.
Traditionally, the milds are the most expensive of the three
types of beans, with Brazilians being of intermediate expense,
and Robustas being least expensive.
Since the fiavor of the c~ffee blend is more prominent in the
30 soluble product of this invention than in conventional soluble
products, more care must be taken in formulation of the blend.
For example, conventional instant coffees are often made using
high levels of Robustas, which are less expensive and yield more
solubles but have poorer flavor characteristics. The blend of
35 coffees used in the process of this invention preferably contains
lower levels of Robusta coffees. If it i~ desired to use a major
~,.2~t~
-lla-
proportion of Robustas, th~n at least a portion of the Robustas
should be "upgraded" by techniques known to the art, such as
those described 5n U. S. 3,640,726, i~sued February 3, 1972 to
Bolt et al., and U.S. ~,234,613, issued November 18, 1980 to
5 Lewis. However, some persons prefer a heavier, more robust
coffee flavor and could use a higher level of Robusta~.
~ )ecaffeina~ed beans can be used to make a decaffeinated
soluble coffee or decaffeinated coffee ex~ract. Blends of decaf-
feinated beans with undeeaffeinated or partially decaffeinated
10 beans will provide a low caffeine coffee extract or soluble coffee.
B, Roasting and GrindTn~
A variety of roasting techniques known to the art can be
used to roast the green coffee in the process of this invention.
In the normal operation of preparing conventionai roasted and
15 ground coffee, coffee beans are roasted in a hot gas medium
whereby the coffee bean temperature is raised to a temperature of
from about 176.6C ~350~F) to about 218C (425F) with the time
of roasting being dependent on the flavor characteristics desired
in the coffee beverage when brewed. Where coffee beans are
~ roasted in a batch process, the batch roasting time at the
hereinbefore given temperatures is from about ~ minutes to about~
20 minutes, preferably about 6 minutes. Where coffee beans are
roasted in a continuous process, the residence time of the coffee
beans in the roaster are from about 30 seconds to about 9
25 minutes, preferably about S minutes. The roasting procedure can
involve static bed roasting as well as fluidized bed roasting.
In roasting green coffee for conventional instant coffee
extraction, darker roasts are commonly used. This is done t
develop strong but somewhat harsh flavors which can survive
30 conventional instant coffee processing. Because the process of
this invention provides much better carry-through of roast
flavor, this process does not require darker roasts. Lighter
roasts can preferably be used to provide a flavor that is not
burnt-tasting, yet strong. The lighter roasts also produce
35 clearer, reddish cup colors. Additionally, the lighter roasts do
not develop as much of the dirty, rubbery note in th~ Robusta
coffees as wou!d a darker roast. Thus, the blended beans are
- 1 2 -
roasted to a Hunter "L" color of from about 18 to about 27, but
preferably about 22 to about 26. The Hunter Color "L" scale
values utilized herein to deflne the color of coffee beans and the
degree to which they have been roasted are units of color
measurement in the Hunter Color system. That system ts a
well-known means of defining the color of a given material. A
complete technical description of the system can be found in an
article by R. S. Hunter, "Photoelectrlc Coior Difference Meter",
J. of the Optical Soc. of Amer., 48, 985-95 (1958). Devices
-
specifically designed for the measurement of color on the Hunter
Color scales are described in U.S. Patent No. 3,003,388 to Hunter
et al., issued October 10, 1961. In g~neral, it is noted that
Hunter Color "L" scale values are units of light reflectance
measurement, and the higher the value is, the lighter the color is
since a lighter colored material reflects more light. In particular,
in the Hunter Color system the "L" scale contains 100 equal units
of division; absolute black is at the bottom of the scale lL = 0)
and absolute white is at the top (L - 100). Thus, in measuring
degrees of roast, the lower the "L" scale value the greater the
degree of roast~ since the greater the degree of roast, ~he
darker the color of the roasted bean is. The use of the Hunter
Color "L" scale value provides an accurate and reproducible
means for measurement of degree of roast. The Hunter Color "L"
scale values herein are measured utili~ing ground beans, the
grind size being through 12-mesh U.5. Standard Sieve Series and
more than 75 weight percent on 30-mesh U . S~ Standard Sieve
Series. With roasted beans, the level of moisture in the beans is
adjllsted to below 7 weight percent if not already at that level,
before color measurement.
Grinding of the whole roasted coffee can be done in any of
the ways known to ~hose skilled in the art. In the process of
this invention, finer coffee grinds are preferred to allow the most
efficient fresh extraction possible. Efficient fresh extraction is
impor~ant in this invention to minimize as much as possible the
carryover of low-temperature extractable solubles into the
hydroiysis section of the train. If they are carried into the
3'76
- ~ 3
hydrolysis 5eetion, they will be thermally degraded and produce
inseant coffee off-flavors.
C. Extraction
The roast and ground coffee is extracted with water to form
S a fresh coffee extract. The extracted coffee is hydrolyzed and
extracted to produce an hydrolyzed extract. Any conventional
coffee extraction and coffee hydrolysi5 process can be used
herein. Most commercial extraction processes use a coffee
extraction train and, therefore, this type of process will be used
10 to illustrate the invention.
Water is passed countercurrently through a coffee extraction
train consisting of a series of extraction columns filled with roast
and ground cof~ee. The operation of such a system is well
understood and many modifications and variations will be apparent
15 to those skilled in the art from the description and examples that
fol low .
A plurality of extraction columns filled with roast and
ground coffee are connected in series by piping between the
individual columns. Typicaily, six columns are found In the
20 countercurrent extraction system, and therefore this description
is given with reference to a six-column system. The las~ three
columns, i.e., those containing the most nearly spent coffee
grounds, are referred to collectively as the hydrolysis columns,
while the next two columns which contain coffee grounds of an
2s intermedi~te degree of spentness, together with the first column
which contains the freshest coffee grounds, are referred to as
the fresh extraction columns. As above noted, the extraction
columns are intended to be used with roast and ground coffee;
however, it should be realized that they can be adapted to the
30 extraction of whole coffee beans.
Water enters the column containing the most nearly spent
coffee grounds at the lower extremity of the column and is
discharged at the top of the column. The outlet line from one
column is connected to the inlet line of the next column. The
35 extracting fluid progresses from column to column in the series
entering each column at the bottom and being discharged from the
top. Heat exchangers can be fitted in the lines between the
38~3~3
columns Immediately prior to the extraction liquld inlet to th~
columns. The heat exchangers can be used when required to
achiev~ or to maintain the hydrolysis temperature, i.e., about
30ûF to 380F in the hydrolysis columns of the extraction
5 system. They can also be used in the extraction columns to cool
or to heat the extraction liqlJid to any desired extracting
temperature, i.e., usually within the range of from 37.8C (100F
to 137.8C (280F). Each column is filtted with a means for
charging the column with roast and ground coffee, for
10 discharging the coffee from the co3umn, and for keeping the
coffee in the column during the overall extraction cycle. The
column which the extract liquor enters just prior to being
withdrawn from the system contains the freshest coffee,
In most systems, at least one extra column is provided in
15 each series so that the extraction operation is not interrupted
while the most nearly spent coffee column is being emptied and
refilled~ The extra column is a standby column which is cut into
the system either slightly before or simultaneousiy with the
removal of the most nearly spent coffee column. Additional extra
20 columns are usually avai!able to allow operation of an extraction
train of more than six columns, if desired,
In the operation of a cof~ee extraction system, aqueous
extract is drawn off at a draw-off ratio of about 1 to 3. As is
well known to those skilled in the art, the clraw-off ratio is the
25 amount of extract withdrawn fron3 the fresh extraction column
compared to the average weight of coffee in the individual
columns. Preferably, a draw-off ratio of 1 . 5 to 2 . S is employed
in the process of this invention.
After extract draw~off from the fresh extraction column is
30 complete, a new column containing fresh roast and ground coffee
is cut into the system with the original fresh extraction column
becoming the next succeeding stage, and so on to the point where
the column that originally contained the most nearly spent cof~ee
is removed from the system. The cotumn removed from the
35 system is cleared of the spent coffee grounds and charged with
fresh roast and ground coffee to become the standby fresh
extraction column. The cycle tim~ is defined as the time interv~l
-15-
between successive draw-off~ of final extract. The cycle time of
this process can vary from about 15 minutes to about 1 hour. In
the practlc~ of this invention, a cycle time of about 30 minutes Is
preferred. The cycle time al50 corresponds to the interval
5 between other operating steps besides draw-off; for example, i~
also corresponds to the tirne interval between the exposure of
coffee in one coffee column to hydrolysis, and the exposure of
coffee in the next freshPr column, to hydrolysis temperature.
The fresh extraction temperature profile is preferably
10 relatively steep, i.e., the extraction temperatures should range
from about 50C 1122F) to about 99C (210F), to allow for
efficient fresh extraction. This is generally achieved by starting
extraction at a relatively low temperature and increasing the
extraction temperature to near that of boiling water. The
relatively rnild fresh column temperature 50C (122F) is preferred
to extract heat sensitive components early in th~ extraction
process, to avoid thermal degradation. The steep profile, up to
9â.9C ~210F), in only four columns, is preferred to extract as
much as possible of the fresh solubles. As described in the case
of the use of flner coffee grinds, efficient fresh extraction is
important in this invention to minimize as much as possibl~ the
carry-over of low temperature extractable solubles into the
hydrolysis section of the train.
The hydrolysis extraction temperature profile is preferably
relatiYely mild. That is, the temperatures should be high enough
to effect hydrolysis, generally in the range of from about 154C
(310F) to about 166C (about 330F), but low enough to avoid
excessive thermal degradation of the coffee, which can occur at
hTgher temperatures.
D. Removal of Hydrolysis Volatiles
In the practice o~ this invention, the coffee extract issuing
from the last hydrolysis column of the extraetion train ti.e.,
immediately preceding the fresh extraction columns~ is referred to
as a hydrolysis extract. In making the coffee product of this
invention, the hydrolysis extract is multistage or countercurrently
steam-stripped to thoroughly remove volatiles created during the
hydrolysis stage of the extraction process. The resulting
8~3
-16-
strlpped hydrolysis extract is then passed through the fresh
extractlon columr;s, preferably in a countercurrent manner.
The steam stripping process of this invention can be
practiced in a varlety of ways known to the art. Typically, the
S stripping is accomplished at temperatures of from 38.9C (102F)
to 108.9C (228F) and pressures of 1 to 20 psia. The mass ratio
of steam to extract is from 0.3 to 10, and most preferably from
0.5 to 1.5. Evaporation, which involves boiling the extract, does
not efficiently or effectively remove the volatiles which multistage
10 or countercurrent steam stripping removes. Importantly, this
steam stripping removes furfural very effectivelyO Furfural is
representative of the hydrolysis volatiles. Removal of furfural
indicates that the off-flavors are also being removed.
In a preferred method, hydrolysis extract leaves the
15 hydrolysis section of the extraction train and is sprayed into the
top of a vacuum chamber. The feed temperature of the extract
must be at or above the boiling point of water at the pressure of
the stripping chamber. Otherwise, steam in the chamber will
condense onto the extract droplets and reduce the efficiency of
20 the stripper. As the extract falls through the chamber, it is met
with an upflow of steam introduced into the bottom of the
chamber. The extract is rernoved from the bottom of the
chamber, and the steam, along with the hydrolysis volatiles
stripped from the extract, is drawn from the top of the chamber
25 and collected in a condenser for appropriat~ disposal. It will be
appreciated that in the process described, the steam flows
countercurrent to the extract. This results in highly efficient
and effective removal of hydrolysis Yolatiles from the extract.
In another method, the extract is successively sprayed into
30 and collected from a series of stripping chambers, with fresh
steam introduced into each chamber. In such a process it is not
critical that the steam flow countercurren~ to the extract, because
the gradient for removal of hydrolysis volatiles is re-established
in each successive chamber. This method o~ers certain
35 advantages and is thus also preferred although it is less energy
efficient than a strict countercurrent stripping process. The
stripping process can be conducted at any desired pressure.
-17-
Atmosph~r;c pres~ure Is preferred for simplicity of cquipm~nt
design ~nd op~ra~k~n, but sub- or superatmospherlc pressures
can be used.
In another ~hod, somewha~ less preferred, the extract is
S drawn o~ not be~een the fresh and hydrolysis sections of the
train, but in pOs~ on further ~orwardl in the traln. For example,
an extr~ction trainl with the following profile is being used:
~ydrolysis Fresh
Column P~b. 1 2 3 4 5 6 7
Temp., ~F 330 320 310 210 180 150 12û
The extract steant stripping column would be used to strip the
extract l~aaving CO~mn 4 and entering column 5. AlternativelyJ it
would b~ used to ~strip the extract leaving col~amn 5 and entering
column ~ This rr~location of the stripper has the following
15 advanta~s~ It allows tar-like materials, which emerge from
the hydr~lysis se~::tion along with the hydrolysis extract, to be
filtered ~ut in the~ colder, fresh columns of partially spent roast
and gro~Jmd coffe~, before the materials enter the stripping
column; and (2) Itt allows any volatile off-~lavors produced in the
20 hotter, fir~sh colu~mns to be stripped away.
Th~ number a~ countercurrent contacting stages will have a
marked ~ffect on ~effectiveness of off-flaYor removal in the
stripper~ A mult~stage stripping system is highly preferred.
Other le~ efFlcienst steam stripping methods can be used, but are
25 not pref~rred. ~fter steam stripping, the stripped hydrolysis
extract i~ ~ed cl~u-Jntercurren~ly through the fresh extraction
columns as descri~ed above, and the final extract is drawn off
the fre~best colu~7mn. The distillate or condensate which results
from the steam strripping operation is discarded. By "discarded"
30 is simply~, meant t~at the stripper condensate is not used for
coffee P~cessing.
E- ~oncentrcation of the Extract
-
The fresh 5ssDluble flavor of the soluble coffee of ~his
invention~ is more sensTtive to change and variation than typical
'7~
-lB-
Instant flavol. Therefore, after l~avlng the extraction tralf1, the
coffe~ extract of this inventlon Is processed in a manner which
preserves the volatile compounds, particularly the low and
moderately volatile compounds, and avoids substantial thermal
5 degradation 9f those volatiles. In this context it Is also important
to note the interdependence of the stripping operation and the
post extraction processing. In particular, if the stripping is not
performed to remove hydrolysis-generated off-flavor volatiles, the
careful post-extraction processing will actually produce an inferior
10 coffee by concentrating off-flavor materials in the product.
Conversely, if the stripped extract is processed by conventional
post-extraction techniques, such as thermal evaporative
concentration, the resulting coffee product will be remarkably
flat, since most of the flavor of conventional instant coffees is
15 provided by the hydrolysis volatiles, due to the absence of
authentic moderately volatile compounds which are lost during
conventional processing.
After the extract issues from the extraction train, it is
preferably concentrated to a solids concentration of at least 35~.
20 For the concen~ration step, a concentration techniclue which does
not involve substantial loss of aroma and flavor volatiles is
essential. Freeze concentration is a highly preferred process.
Freeze concentration is accomplished in a manner in which the
water is removed as substantially or essentially pure ice crystals.
25 Adhering or occluded compounds must not be present in the ice
and must not be removed with the ice.
A preferred embodiment of a concentration process involves a
freeze concentrator which has a scraped-wall heat exchanger
connected to an adiabatic recrystallizer tank. The recrystallizer
30 tank allows water to recrystallize and ice crystals to grow in size
under conditions which form pure ice. A filter at the exit of the
tank retains alt crystals of more than 100 microns in size. This
insures that most ice nuclei are retained for recrystallization.
Ths recrystallized Ice is separated from the concentrated extract
35 by the use of a wash column. The wash column rinses any
adhering concentrate from the ice crystals, and expedites removal
of essentially pure jCQ from ths freeze concentra~e. A preferred
- 1 g-
apparatus for use In free~e concentratlon 5s the Grenco freeze
concentration unit. This unit is described in U,S, 3,777,892,
Issued to Thijssen In 1973; U.S. 3,872,009, issued to Thijssen in
1975; and lJ.S. 4,004,896, issued to Thijssen et al. in 1977.
Other freeze concentration approaches that can be used
herein are those which have been developed by CMC Concentra-
tlon Specialists, Inc., and Chicago Bridg~ and Iron Works,
Other concentration methods which Iminimize IOS of volatiles,
such as other free~e concentration processes, membrane concen-
l0 tration, reverse osmosis or sublimation concentration involving
slow freezing and slow water removal, can be used but are less
preferred. Combinations of any of the foregoing concentration
methods can also be used.
As mentioned, concentration of the extract is carried out
lS until the extract has a "solids" content of at least 20~, preferably
at least 35% and most preferably at least 40% by weight. For the
purposes of this invention, the term "solids" is defined to
encompass any and all materials in the extract or concentrate
other than water. It thus includes a number of organic
20 compounds which are volatile liquids under normal conditions of
temperature and pressure. It is important to note that when the
extract has been concentrated to, for example, 6û% solids, water
is actually a minority speeies in the concentrate, Because of the
organic nature of most of the solids, these high solids
concentrates behave more like organic solutions than aqueous
solutions, and this effect enhances volatile retention durin
subsequent processing.
The extract can be decaffeinated either before or after the
extract concentration. Liquidlliquid decaffeination of coffee
extract processes are well known. See, for example, Morrison,
Elder ~ Phillips, U.SO Patent 4,409,~53.
The coffee extract or concentrated cof~ee extract can be
pasteurized, frozen or aseptically packaged. The extract or
concentrate can be aromatized or flavored with natural or arti~lcial
sweeteners, cream or artificial creamers, natural or artificial
flavors, such as herbs and spices. Preservatives such as
~20-
anSioxidants or mold Inhibitors can be added to the extract, as
can be antifoaming agentsr
F~ Preparation of Solubl~ Coffec Product
The extract produced in this Invention can be dried to a
moisture content of from about 1~ to abou~ 8~ by weight, and
preferably from about 3% to about 5% by weight. This is a dry
soluble coffee powder. The extract can be drled in any known
rnanner to provide a dry soluble coffee product. The drying
method should be designed to retain volatlles. Freeze drying or
other known moisture-removal processes whîch preserve volatile
compounds can be used.
If the resultant dry product is not in the form of particles,
it can be broken up by a number of methods to form instant
coffee particles. A preferred economical method for drying the
aqueous extract is spray drying wherein the liquid extract is
sprayed into a tower and simultaneously contacted with a flow of
heated air. Vi~ater is removed from the droplets of the aqueous
coffee extract as they fall through the spray tower and they
emerge from the bottom as porous, spherical particles of instant
coffee containing, for example, from about 1.596 to about 5.0% by
weight moisture. lTypical disclosures of spray drying processes
which can be used to prepare instant coffee particles can be
founJ, for example, in Sivetz ~ Desrosier, " Coffee Technology",
Avi Publishing Co., ~estport, Conn., 1979, pp. 373-~3, and in
U.S. Patents Nos. 2,771,343 to Chase et al., issued on Nov. 20,
1956; 2,750,998 to Moore, issued on June 19, 1956; and 2,~69,553
to Hall, issued on A~ay 10, 1949.)
Preferably, the spray drying Is conduc~ed under conditions
which maximize volatile retention and minimize thermal degradation
or oxidation of the soluble coffee, The extract ~eed temperature
to the drier is preferably in the range of from about 15C (60F)
to about 38C (100F). Air flows and air temperatures which
produce inlet and outlet temperatures of from about 121C (250F)
to about 204C (400F) and from about 82C (180F) to 121C
(250F), respectively, are preferred. An inert gas atmosphere
can be used to minimize possible oxldatlve effects.
-21 -
Freeze drying can produce superior volatlles retention,
compared to spray drylng, but Is also more expen51v~. Typical
disciosures of freeze drylng processes which can be used can be
found in Sivetz and Desrosier, cited above, at pp. 484-524.
After drying, the soluble coffee of thls invention can be
pelletized or agglomerated to improve its handllng and dissolution
characteristics. It can also be aromatized to supply additi~nal
high volatiles, i . e., those boiling at temperatures below about
88C. These volatiles can be supplied by practice of any of the
many aromatl~ation techniques known to the art. Preferred
aromatization techniques include those ~escribed in U.S.
4, 335 ,149, issued June 15, 1982 to Stipp, and Reissue Patent
31,1127, reissued October 25, 1933 to Lubsen et al. Other
arornatization techniques are described at pp. 434 to 483 of the
Sivetz and Desrosier text cited hereinabove.
This soluble product can also be milled into flakes or
agglomerated. U.S. 3,652,293, issued to Lombana et al. (1972)
describes such products. The dried soluble coffee of this
invention can be packaged, with or withou~ agglomeration ancl
with or without aromatization, for use as an instant coffee
product.
111. Coffee Brewing Mixtures
However, a preferred use of the soluble coffee of this
invention is in combination with roast and ground coffee. A
particularly preferred product provides the soluble coffee of this
invention and roast and ground coffee in a soluble: roast and
ground ratio of from 1: 4 to 1:1 by weight. A particularly
preferred product is a permeable bag containing from about 1 to
about 2.5 grams of soluble coffee and from about 1.5 to about 5
grams of roast and ground coffee. Combined in these ratios in
such a product, each component contributes to a positive overall
product perception. The roast and ground portion provides
practically all of the coffee aroma during opening of the package
and before brewing. It also contributes noticeably to the brewing
aroma during preparation and cup aroma. The soluble portion
pro~ldes most of the unique flavor of the solubles of this
2~8~
-22-
Inventlon, and 75% or mors of the product brew sollds and titrat-
able aclds.
In general, finer grlnds of roast and ground coffee will
provide better extraction, although a tradeoff with plugging of
S bag pores must be made whan extremely fine grinds are used. If
desired, the roast and ground coffee component can be flaked or
milled ts increase its extractability. Examples of this can be
found in U.S. 3,615,667, issued in 1971 to Joffe, lJl.S. 3,640,727,
issued in 1972 to Heusinkveld; U.S~ 3,660,106, issued in 1972 to
McSwiggin; U.S. 3,769,031, Issued in 1973 to McSwiggin;
Canadian 939, 246, issued in 1976 to Bergeron and Schlichter;
U.S. 4,110,485, issued in 1978 to Grubbs et al.; U.S. 4,267,200,
issued in 1981 to Klien and Gieseker; and U.S. 4,331,696, issued
in 1982 to Bruce.
The roast and ground coffee component can also be fast
roasted to provide an expanded cellular structure and improved
extractability. U.S. 3,0û8,825, issued in 1963 to Topalian and
Luddington: and U.S~ 3,122,439, issued in 1964 to McAllister an~
Spothaltz, disclose processes for the fast roasting of coffee. The
~439 patent also dlscloses that fast roasted coffee can be flaked.
The coffee articlo of this Invention can bo mad~ of any
water-permeable Infuslon material. A metal eonta~ner with small
holes, such as a "tsa ball", can be used for brewing the soluble
coffee, roast and ground coffee colrbination. Other articles
Include plastic, metal or woodan spoons covered with a water-
permeable infusion material. For ease of manufacture and
economlcal dellvery, the preferred article is a water-permeable
infusion bag.
Also, particularly pra~erred is a brewing article containing
roast and ground coffee and the soluble coffee of this invention
in which the soluble coffee, the roast and ground coffee, or
both, are milled into flakes. Flaking of the coffee squeezes out
air and other gases and makes the coffee more dense. The result
is that a coffee brewing bag using this n-ixtura will be
significantly less buoyant than a coffee bag not containing flaked
-- 23 --
coff~. A lese buoyant bag results in faster brewing ~nd mor~
convenlence during coffe~ preparation. An added benefit i5 that
a mixture of soluble flaked coffee and roast and ground coffee
flows easily when fllling bags on a packing line.
The coff~e can be milled by any means, but a preferred
method is by passing it through a two roll pressurized flake mill
uslng about 400-500 psig pressure and about 20 to 30 rpm at zero
gap between th~ rolls. IJ . S. 4, 267, 200, issued to Klien and
Gieseker, describes milling. The milling method is Incorporated
1( by reference herein. Th~a soluble flaking operation may include
an addition of cof~ee oil to the powder to aid in roll lubrication
and flake strength. Alternately, the soluble coffee and the roast
and ground coffee can be milled together, with the oil coming
from the roast and ground coffee.
When the coffee article is used, most of the fresh solubles
are dissolved after 30-~5 seconds, delivering abol~t 1.0~ solids
concentration in 200 ml of water. Extraction of the roast and
ground coffee continues until a concentration of about 1.15% to
1.30% is reached after about 3 minutes of brewing. With this
product composition, the coffee extraction is non-linear, with
very high extraction rates during the initial 15 seconds or so of
extraction, slower rates for about the next 30 seconds, but then
only sli~ht concentration changes during the ne)~t several
minutes if brewing is continued.
The preferred coffee article of ~his invention can be ~ormed
from both nonwoven and woven fabrics. Included within the class
of nonwoven and woven fabrics are synthetic fabrics made of
rayon, nylon, polyesters, polyacrylic and polypropylene fibers
and natural fibers made of hemp and cotton fibers. In addition,
it will be appreciated that combinations of fibers can be used to
prepare the fabrics suitable for use as the pouch material of the
coffee bag of this invention, e.g., where greater fabric strength
or increased fabric porosity is desired. Particularly preferred
are the nonwoven fabrics comprising fibers of rayon, nylon,
polypropylene, and hemp and mixtures thereof. It is immaterial
for the purposes of this invention the type of fiber used as the
-- 24 --
water-permeable material for forming the pouch so long as it is
chemically inert, essentially taste-fre~ and sufficiently strong to
remain an integral unit throughout normal handling, packaging,
shipping of the coffee bag, brewing of the coffee beverage, and
disposing of the used packet.
It iS essential that the fabric used for preparing the coffee
bag be permeable to water. Yet the pores in the fabric allowing
water permeabTlity should be of such a nature and size that the
roast and ground coffee particles present in the bag do not pass
thr~ugh with the brewing water. The fabric must act as a
filter5ng means to accomplish the objectives of preventing the
formation of sediment in the brewed coffee. The fabric thickness
used can vary but will generally range from about 0.002 in. to
abo-~t 0. 012 in ., preferably from about 0. 003 in . to about
0. 009 in .
The size of the pores in the pouching material used in
makin!3 the coffee article of the present invention can vary in size
from about 5 microns to about 1û00 microns, prefer3bly from
about 20 microns to about 200 microns. If a substantial portion
of the pores are smaller than approximately 5 microns, it may be
impossible, irrespective of time, to extr~ct all of the desired
flavor components and constituents from the coffee in the article
into the brewed beYerage since smaller pore si~es ~end to clog
during brewing of the coffee beverage. Where the pore size is
extremely fine inordinately long brewing times are needed. Pore
openings larger than about 1000 mierons are to be avoided since
they permit passage of coffee fines into the bevera~7e resulting in
a high level of sediment. în addition, pore sizes larger than
about 1000 microns will allow the smaller particles to sift out on
agitation, as for example on shipping, and a dusty cof~ee packet
having an undesirable appearance can result.
A~ least a portion of the coffee article can be an apertured
or formed fllm, rather than a fabric. Such materials, and
methods for making them, are described in U . S. Patents
4,151,240, issued April 24, 1979 to Lucas and VanConey, and
-- 25 --
~,3q2,31q, Jssuad August 3, 1982 to Radei and Thompson. In
general, the crltella ~or selectlon of materlals and aperture sizes
for formed ~ilms are th~ same as those described above as
applicable to fabrics.
The preferred article of this invention is simply and easily
made. All that is necessary is to form a pouch out of the water-
permeable materials hereinbefore described to contain the coffee.
This can be done by "drawstring" means whereby the bag is
gathered at one end or by stitching the material together to form
the bag. A preferred embodiment of this invention involves heat
sealing the water-permeable material to form a bag. In this
preferred embodirnent the heat sealing is accomplished through the
use of a heat-sealing binder. Binders which are acceptable f~r
heat sealing are those binders having a rnelting polnt lower than
l' the softening or charring point of the bag material but a meltTng
point higher than the temperature of boiling water. In addition,
the binder, similar to the bag material, must be chemically inert
and essentially taste-free. It i5 important that the binder be
sufficiently inert and insoluble in hot water so that no adverse
physiological effect from consumption o~ the coffe0 beverage can
result. Examples of suitable binders for heat sealing of the bag
materials described above are the polymeric binders, as for
example, the polymeric binder described in U. S. Patent No.
3,183,096, issued to Hiscock (196S).
The coffee article of this invention can be of any shape that
will contain the roast and ground and soluble coffees. The shape
to be used may be determined to a certain extent by the brewing
method employed. The coffee article of this invention can be
brewed in any type of vessel. After brewing, the coffee article
containing the spent roast and ground coffee particles may be
easily disposed of as a unit.
In addition to packaging the roast and ground coffee and
soluble coffee of this invention in a coffee article, the mlxture of
the two coffees can be pelleted or tableted for convenient
handling. The pellets or tablets are preferably used in a
brewing device with a filter to retain the extracted roast and
ground coffee.
1~4~6
The methods for brewlng coffee wlth the coffee bag of thi~
inventlon are numerous. A coffee beverage can be brewed by
placlng the coffee bag in a cup or pot of wat~r which has been
brought to a boil and allowed to cool just slightly (to about 160F
5 to about 210F) and the cof~ee bag steeped in the hot water for
from about 0. 3 minutes with agitation of the bag to about 6
minutes with little or no agitation of the bag. The bag can then
be removed and disposed of. A coffee beverage can also be
prepared using a suitably shaped coffee bag of thls invention and
~, methods and equipment in ger~eral us~ for ~rewlng a coff~
beverage.
Gas C:hromatographic Method
Capillary Gas Chromatographic Analysis of Volatil~
Coffee Components Separa~ed and Concantrated by
15 Simultaneous Distillation and Extraction ~SDE-CGC)
A. Princip!e
The steam distillationlextraction method of Schultz et al.,
J. Agric. Food Chem., 25, 446-449 (1977) has been applied to the
analysis of volatile components of coffees. The first step i~
20 simultaneous distillation and extraction ~SDE). Figure 4 is a
drawing of the apparatus used for this proc~ss. The volatile
components are steam distilled from a coffee sample. These
votatiles ar~ co-condensed with Freon 11. The volatile
connponents are extracted by th~ Freon l l . The co-condensed
25 water and Freon 11 are aJlowed to separate and returned to their
respective flasks. Thus, the volatile components are extracted
and concentratcd in the Freon 11. After ninety minutes the
voiume of Freon is reduced by evaporation and methylene chloride
(dichloromethane) is added to reduce the loss of extracted
30 volatiles prior to evaporation to a specific volume. The extract is
not allowed to evaporate to dryness.
The extract obtained by SDE is analyzed by capillary gas
chromatography ((~GC) using a I lewlett-Packard 5880A Gas
Chromatograph and fused silica columns. A DB5 column is used
35 with a fiame ionization detector (FID) to detect the carbon and
hydrogen in volatile compounds in the SDE ex~ract. A CP-57-CB
87 ~
column Is used with a flame photometric detector (FPD) to det~ct
sulfur-bearlng volatlle compounds. The injected sample Is spllt
between ~he two columns. Two Hewlett-Packard level four data
~erminals are used to process the data, giving retention times,
peak areas and area percents. The methylene chloride (solvent)
peak is excluded from the data. Additionally, a total of sTx other
peaks which are considered to be "artifacts of the method" are
excluded from the numerical data. However, ~hey do appear on
the chromatogr~ms. Th~y are detectable on a blank analysis. These
1~ peaks represent impurieles in the methyl~ne chloride and Freon 11,
and constltuents of the antifoam.
So far, 27 compounds In th~ separated coffee volatlles have
been identified by the SDE-CC;t: method: isobutyraldehyde,
methyl ethyl ketone, diacetyl, 2, 3-pentanedione, pyrazine,
pyridine, pyrrole, dihydro-2-methyl-3(2H)-furanone, methyl
pyrazine, furfural, furfural alcohol, aceto acetate, 2,5-dimethyl
pyrazine, 2,6-dimethyl pyrazine, 2,3-dimethyl py~azine, 5-methyl
furfurai, furfural acetate, 2-ethyl-6-methyl pyrazine,
2-ethyl-S-methyl pyrazine, 2,3,5-trimethyl pyrazine, 5-methyl
pyrro!e-2-carboxaldehyde, 2-ethyl-2,5-dimethyl pyrazine,
guaia~ol, 2-t2-furan methyl)-5-methyl pyrrole, ethyl guaiacol,
vinyl gualacol.
The data obtained by the SDE-CGC method are sufficiently
accurate and preclse to be valid for a comparison of differences
in composition of coffee samples.
B. mple Preparation
Cof~ee weighing 10.000 + O.OOS grams is placed into a S00
ml. flask~ Two hundred ml. of distilled water is added. Then
3 ml. of in~ernal standard solution and 3 boiling stones are
added. (With instant cof~ee, 3 drops of Antifoam B are also
added. )
C Internal S ndard Preparation
First, 9.0100 ~ .00005 grams of 2-acetyl pyrazine are
weighed and placed Tnto a clean, dry 100 ml. volumetric flask.
Then sufflcient methylene chlorlde is added to fill the flask to
100 ml.
3'7~
28
D. SDE Procedure:
1. The apparatus Is set up as shown In Figure 4 .
The apparatus Includes a sample flask 214 and a solvent
flask 218. The sample flask 214 is hsated by a stirrer-hot plate
222 while flask ~18 is heated by hot plate 224. P~sitloned on top
of flask 21~ and 218 is a steam distillation/extraction (SDE)
column 226 which includes a sample vapor column 228 which
receives vapors from the cof~ee sample and a solvene vapor
column 232 which receives vapors from flask 218. The top
sections of the vapor columns 228 and 232 are joined to condenser
column 244. Mountad on top of condenser column 24~ is a Dewar
condenser 2~8 provided with a cor~ 250 for receiving coolant.
Condenser column 244 Is provided with a w~ter Inlet 252 and
a water outlet 254 for the circulation of water throlJgh a first
cooling system ~56 whlch cools core 258 of column 244. Column
244 is also fitted with a second water inlet 260 and a second
water outlet 262 for circulation of water through a second cooling
system indicated by 264 which cools the periphery 266 of column
244.
Vapors which condense in core 258 and along periphery 266
are c~llected in U-tube 268 connected to the bottom end o~
condenser 24q. Tubing section 272 connects trap 268 to sample
column 228 for passage of condensed vapors to flask 214. Tubing
section 276 connects trap 268 to solvent column 232 for passage of
condensed vapors to flask 218. The cooling water is circulated
through systems 256 and 264 and the Dewar condenser core 250 is
filled with dry ice.
2, The Freon 11 is redistilled before using it. About 150
rnl. of Freon is collected in a 250 ml. fiask 218 to be used as the
extracting solvent.
3. The Freon 11 is draine~ from the U-tube 2~8 when the
liquid level reaches the "~"' part 272 of the U-tube.
4. The coffee sample is prepared while the Freon 11 is
being redistilled.
5. After the Freon redistillation is cornplete, the Freon is
drained until the Jiquid level is in the middle of the "Y" juncticn.
8~76
6. Dlstlll~d water Is add~d through the connectlon 278
wh~r~ thl~ Dewar condenser 25û flts onto the top of the water
condensar 256, untll the water liquid level reaches the bottom of
the large outer water condenser 260.
7, Three boiling stones are added to flask 218 containing
the redistilled Freon.
8. The 500 ml. flask 214 containing the cof~ee solution is
cnnnected .
9. Ice Is added to a plastic reservoir which is then used to
immerse U-tube 268.
10. Distillation is carried out for 1-1/2 hours a~er water
vapor and Freon 11 begin condensing and collecting In U-tube
~68 O
11. The heat to th~ coffee solutlon in flask 214 and tho
Freon 11 in flask 218 is turned off at the end of the distlllatlon
period. After the coffee solution stops boiling, the distlllation
apparatus is disassembled.
12. The Freon 11 is drained out of U-tube 268 until the
liquid level is at the Y-junction of the U-tube 268 and tube 272.
It is then poured into a flask 218 with the rest of the Freon 11.
13. The Freon 11 is evaporated down to about 5 ml. under
nitrogen on a steam bath set at 60C (140F) to 71C (ï60F).
14. ETght ml. of dichloromethane is added to the flask
containing the Freon 11 and swirled.
15. The contents of the flask containing the Freon 11 and
dichlorornethane are evaporated down to about 3 ml.
16. A portion of the extract is transferred into a 2 ml.
reaction vial.
17. The extract in the reaction vial is evaporated down to 1
ml. and portions of extract from the fiask are added to the vial
and partially evaporated to 0.5 ml. until the flask is empty. Two
ml. of dichloromethane are added to the flask and swirled. The
solvent wash from the flask is added to the reaction vTal and
partially evaporated to 0.5 ml. The extract in the reaction vial is
evaporated to 0. 3 ml. if it is to be injected into the gas
~Q~'7~
-- 30 --
cht~matograph; otherwls~, It is evaporated to 0.5 ml. and put
inSo a frl~ezer untll prlor to g.c. InJectlon, at whlch tlm~ It Is
evaporated to the 0.3 ml. Ievel, The extract is not evaporated to
dryness.
S E. Gas Chromatographic Analysis;
Conditions for the HP 5880A Q.C.
Septum purge flow :1 ml.lmin.
Inlet pressure : 26 psTg
Vent flow :30 ml./min,
Make-up carrier flow :30 ml./min.
FID:
Hydrogen flow rate :30 ml./min.
Air nOw rate :400 ml.lmin.
Column flow :3 ml.Jmin.
Spllt ratlo : 1011
FPD:
Hydrogen flow rata :75 ml. Imtn.
Air flow rate :50 ml.lmin.
Oxygen flow rate :40 ml.lmin.
Detector temperature : 200C
Temperature Pro~ram
Oven temperature 25C, limit of 405C. The oven is heated
at 25C ~or 2.6 minutes.
The oven is then programmed to rise 20. ûClmin. to a
2s temperature of 45C. Then the oven rises at 3.0C/min. to a
temperature of 65C. Then the oven rises a~ 2. 0Clmin. to a
temperature of 125C. Finally the oven rises at 3.0C to a
temperature of 220C. The oven is then heated to 230C and
held there for 15 minutes.
The DB5 gas chromatography column used to detec~ and
separate the organic compounds are 60 meter columns of 0. 322
mrn. inner diameter. A film of crosslinked polyethylene glycols
1 micron thick is used. The DB5 column is available from J~-W
Scientifc, Inc., Cardova, CA.
The CP-57-CB column used to separate the organic sulfur
compounds is 25 micron in length and has an inner diameter of
0.33 mn~. The CP-57-CB column is available from Chrompak
~L2~3'7~ - 31 -
Incor~ora~ed, N.J., Cat. No. 7763. ~ fllm of CP~TM-~ax S7,
WSCC)T fused sillca column ~t 1.12 mlcron thlckne~ U51~d.
Th~ chromatograms ar~ analyzed by determinlng area percent
o~ each peak from the ga~ chromat~3raphic counts (electrical
s impulses recorded).
The total gas chromat~raphis counts of the sample as
obtained from the chromatogram are corrected to mak~ all of the
samples on the same basis for compaJison.
The internal standard (2-acetyl pyrazine1 Is assumed to be
3000 counts based on the concentratlon added and the resp~nse
factor. A sample calculation is as follows:
Internal Standard as measured 2737
Pyrazines to~al 21~785
21,785 ~c 3050 = 23,87
2737
Corrected pyrazine count is 23,878.
The furfural count is co~rec~ed in the same mann~r~
The furfural to pyra~ine ratio is obtained by dividlng the
total furfural corrected g.c. counts by the total corrected
20 pyrazlne counts.
The total sulfur-bearing volatiles count is also correcsed to
make all samples on the same basis for comparison.
Ash Measurement
A sample of coffee extract or soluble coffee is weighed into a
25 crucible, The sample is then heated as follows: heated from
20C (68F) to 400C (752F) in one hour; cooled to 200C
(392F) then heated to 1000C (1832F) and kept at that
temperature overnight (about 16-18 hours). The percent ash is
then determTned by taking the weight o~ the final sample ~imes
30 100 and dividing by the weight of the original sample.
.,
3'7~
-32--
Ex?mple 1
Th~ ~ollowing @xampl~ Illustrates the process of this
invention. Unless otherwise stated, all p~rcentages are given on
a weight basi~.
A blend of 25% primes, 25~ Bra2ils, 20% natural Arabicas,
and 30~ Robustas was roasted on a Thermalo roaste~ model 23R5.
The roast slze was 3013 Ib5. green cof~ee, and le was repeated
three times. The results oF the roasts are listed below:
2 3
Roast time, minutes 6.50 6.25 6.33
Final temperature of 442 438 440
roast, F
Water quench le~el, 13.9 13.9 13.9
% of green weigh~
llunter L color 21.1 22.1 21.9
The roasts were blended together to form a single whole
roast lot. The whole roast was held at room temperature for
about 8 hours belFore the start of grinding and extraction.
An 8-eolumn extraction train and extract steam-stripping
20 column, with assoclated pumps, hea~ers, coolers, and piplng, was
utllized. Once begun, the process was operated long enough to
tnsure that a truly countercurrent progression of grounds and
extract liquor exit~d be~ore taking data and test extract
draw-off. This was accomplished by sequentially adding columns
25 to the process until the to~al was seven operating extraction
columns plu~ the extract steam-stripping column. As ~he fresh
column was put on-line into the system, the most spent column
was taken out of the process, emptied, cooled, washed, and
refilled to be ussd again. This procedure is known in the art as
30 "startup".
The extraction col~mns are 0.5 ft. in internal diameter and
4.0 ft. high. As known to those skllled in the art, appropriate
piping for feedwater and extracts is also used. The columns are
also Jacketed w3th a heating oil to prevent heat loss from the
35 columns during operation. The temperature of the oil was
adjusted per column approximately to match the inlet fluid. ~ .
~LZ41D876
-33-
temp~rature, In a temperature proflle as describ~d later in thls
example.
The appropriate piping from and returning to the extraetlon
allowed the us~ of an ex~ract steam-stripping column (6 inches
5 internal diameter, 20 ft. hlgh, steam.inl~t at the bottom, extract
Tnlet at the top, no internal packing, extract enters through a
spray nozzle poTntlng down the column) to strip the hydrolysls
volatiles from the hydrolysis extract. Thus, the stripping column
stripped the extract leaving column 3 and the stripper bottoms
10 became the extract whTch entered column 4. About 130 Ibs. per
hour of steam was fed to the stripping colurnn which operated at
atmospheric pressure. A l~eed temperature o~ about 230F was
used .
Grinding was done on a Gump model 33 coffe~ granuli~er.
15 The following is a typical particle size dis~ributlon:
U.S. Sieve Screen
+~ 8.q
-~+8 41 . 4
-~+1 2 25 .
20-12~16 12.~
-16~20 6.0
-20 6.0
After startup, th~ temperatures in the extraction train
starting with the column containing the most spent coffee grouncls
25 and progressing to the fresh column, as measured at the inlet
and outle~ to each column, were as follows:
2 3 4 5 6 7_ _ _ _
30 Inlet, F 334 319 310 246 1~1 150 119
Outlet, CF 316 307 261 1~5 151 127 131
The average column load of roast and ground was 20.3 Ibs.
The pressure of columns 1, 2 and 3 was 150 psig. The
35 pressure o~ columns 4, 5, 6 and 7 was near at~nospheric. The
~,
-3~ -
draw-of~ ratlo was 2.1 and the average cycle time was 30 mlnutes.
The vap~drs and th~ extract ~rom the fresh column were condensed
and/or cooled to aboue 10C (50F). The fresh extraction column
was exhausted through a chill~d wat~r heat exchanger to an open
weigh tank. The percentage yield of solubles based on the roast
and ground cof~ee was 39. 0%. The resultant extract of this
example contained 1~1. 6~ solubles. ~ sample of the extract was
analyzed by SDE-fllD and the results are contained in Table 1.
The corrected g.c. area for ~he pyrazine derivatives is 12,037
the corrected g.c. area for furfural is 8,251; and the ratio of
furfural to pyrazine derlvatives is 0.64:1.
The extract was then filtered through a spiral wound
cartridge filter rated at 15 micron openings. The fiîtered extract
was chilled to about 2C (35F) and pîaced into a refrigerated
storage tank.
A Grenco model W8 freeze concentration unit was fed from
the refrigerated supply tank. The Grenco system is a closed
system.
The refrigerator unit and recircu3ation pump circulating the
extract from the recrystalllzer through the scraped-wall heat
exchanger were started and the extract was cooled down to about
-1C (30F) and formatlon of recrystalli2ed ice was achleved after
about 2 hours. Removal of Ice via the wash column started about
3 hours later. A concentration of about 40% dissolved solids was
achiev~d after about 20 hours of operation. The unit was then
drained of extract. The drained extract was then immediately
spray drîcd, as described below. The Grenco was then
recharge~ with fresh extract and the process was repeated.
The average age of the extract tfrom draw off to drying)
for the first freeze concentration run was about 36 hours. The
age for the second run was about 2~ hours,
The concentrated ex~ract was dried on a co-current spray
drier. The inlet extract temperature was about 16C (61F).
The inlet air temperature was about 171C 1340F). The outlet
air temperature was about 93C (200F). The dried solids were
collected at a rate of about 40 Ibs. per hourd at a moisture of
3~-
about 4. 5~. This powder would have an ash cont~nt of abou~
7.0%.
A sample of the spray-dried powder was anal3~zed with both
SDE FID (for furfural and pyra~ines3 and SDE-FPD (for sulfur)
5 to yieid the data in Table 1 and Figure 2A, 2B, & 2C. The corrected
g.c. area for the pyrazine deriYatives Is 36,343; the corrected
g.c. area for furfural is 27,gO8; and the ratio of furfurai to
pyrazine derivatives is 0.77:1. The total corrected sulfur
compounds is 10,994.
Example 2
A sample of a commercial freeze-dried premium-priced instant
coffee was analyzed by SDE-FID and SDE-FPD, and the results
are detailed in Table 1. The corrected g.c.
area for the pyrazine derivatives is 12,474; the corrected g.c.
l5 area for furfural is 28,426; and the ratio of furfural to pyrazine
derivatives is 2.28:1. The total corrected sulfur g.c. counts is
2 ,994.
Example 3
A sample of a commercial spray-dried instant coffee was
20 analyzed by SDE-FID and SDE-FPD, and the results are detailed
in Table 1 and Figures 3A, 3B, ~ 3C. The corrected g.c. area for the
pyra~ine derivatives is 12,386; the correcteJ g.c. area for
furfural is 64,428; and the ratio of furfural to pyrazine
derivatives is 5.2:1. The total corrected sul~ur g.c. counts is
4, IJ211 .
Example 4
A sample of roast and ground co~fee was analyzed by
SDE-FID and SDE-FPD, and the results are detailed in Table 1.
The corrected g.c. area for the pyra~ine
30 derivatives is 23,89g; the corrected g.c. area for furfural i~
12,876; and the ratio of furfural to pyrazine derlvatives is
0.54:1. The total corrected sulfur g.c. counts is 12,953.
3'7
~36-
C~ .
Examplo ~ shows th~ nor~ral ratios of furfural to py~azines in
roast and ground coffe~ whlch is consldered to b~ the targ~t
standard of composition for an instant coff~. Thes~ levels of
S furfural and pyrazines in roast and ground coffee have also been
indep~ndently established by outside researchers, ~Nakamichi,
L., "Coffee Flavor", New Food Industry 25, No. 11, pp. 54 59,
1983. ) Example 1 ~hows that an extraet and a powder with a
furfural to pyrazines ratio sllghtly higher than roast and ground
coffee is obtained with the process of this Inventlon. Example 2
shows how a commercial premium freeze-drTed coffee has a much
higher furfural to pyrazines ratio, and l~xample 3 shows an e~en
higher ratlo,
Regarding sulfur volatile Intensities, it is apparent that the
soluble coffee of this inventlon has a significantly higher level of
sulfur volatiles than in conventional instant coffees, and the level
is about equal to that of roast and ground~
Exampl~ 5
A eoffee bag was made by formlng a single chamber bag of
Dextel 25B8 paper of the following specificasions:
1. Heat sealing bTnder on one side of th~ paper.
2. {;rammage: 24.6 g./m.3
3. Alr permeability:
460 Llmin./100 cm2 Q 12.7 mm. 112O P
4. Tensile strength:
dry machine directlon 5300 9./25 mm.
dry cross directlon 1990 9.~25 mm.
wet cross direction ~25 g./25 mm.
5. pH: 5.2
Th2 bags were manufactured on a Hayssen vert5Oal form
filled seal machine~ The dimensions of the bag were 2 inches
wide by 2.75 inches long with a 114 inch heat seal on the bottom
. of the bag. The coff~e las desclibed below) was placed into the
-~ ` bag. A 1/4 inch heat seal was made along the top of ~he bag. A
--37--
1/8 Inch wide by 4~1/8 inch Mylar strip (with paper tag attached)
was attached uslng a heat sealer to the top of th~ bag.
The roast and ground eoffe~ was mad~ from a blend of green
coffee consisting of 55~ milds, 25~ Brazils and 20~ Rcbustas. The
5 cof~ee was roasted on a Probat~Model UG22N batch roaster in a 59
Ib. batch. The coffee was roasted to a Hunter L color readTng of
21. 6 In 8-1/2 minutes at a f3nal roast temperature of 465F. It
was quenched at the end of the roast with water 3t a level of
11.7~ of the initial load of green coffee. The whole roast was
10 aged about 6 hour5 and the ground on a Gump cof~ee granulizer
Model 66. The ~ollowlng is a typical partiele size distributlon:
U. S. Screen Ran~e, Weigh~
on 12 0-2
through 12, on 16 12-20
through 16, on 20 35-ll9
through 20, on 30 18-30
through 30 12-30
The coffee was then screened through a U . S . 1~ mesh
screen ~to remove coarse particles) and on a U.S. 40 mesh screen
20 (to removo flne particles). The coarse and ~n~ fractions were
discarded .
The soluble coffee was prepared much in the sam~ way as in
Exampl~ 1. The soluble coffee was then milled on a Lehman mill
Model 4X8, to form flakes. The ftakes were sized through a U.S.
25 7 mesh screen tto ren ove large flakes) and on a U . S. 30 mesh
screen (to remove fines). The coarse and fines were recycled
through the mill. The flaked and sized solubles were mixed with
the sized roast and ground coffee in a ratio of ~.0 parts solubles
and 3.5 parts roast and ground. The coffea bag was paeked with
30 5 . 5 grams of th~s mixture. The mixture of roast and ground
coffee and drled powder coffee was analyzed by SDE FID and
SDE-FPD, and the results are detailed in Table 1. The corrected
g . c . area for the p~yrazlne derivatives is 27, 857 the correc~ed
. .
37~
-3~-
g.c. area for furfural ts 22,992; and the ratio of ~ur~ural to
pyrazine derlvatives is 0.83:1.
A brew test of the bag was run. The bag was placed in 200
milllliters of 88C (190F) water in a cup for 1 minute. During
5 this period the bag was occasionally dunked, uslng the mylar
strip-tag to raise and lower the bag, The resulting brew
contained 1.3196 solubles. Organoleptic evaluatlon of the brew by
an expert panel showed that, in the absolute, the brew tasted
smooth and flavorful like fresh brew~d coffee.
-39--
U~
X EC ~ ~ ,1 ~ ~ o
,~, E ~ L ~¦ ~` r~ ,~,
Q a~ ~ ~ $
~ x iL a ~ S ~ O-
~ 8~ o` ~` ~
~¦
` ` U~
.
o
Z~
-- 40 --
Example 6
Two samples of hydrolysis extract and a hydrolysis extract
stripper condensate, which were obtained in runs conducted in a
manner similar to that detailed in Example 1, were analy ed by
5 SDE-FI D, and the results are detailed in Table 2, Column A is
the feed extract to the stripping column. Column B is the
stripper extract leaving the bottom of the column. Column ~, a
hydrolysis extract stripper condensate, is a sample w~¢h
typifies the composition of the strippate which Is disclosed.
Table 2
Yolatiles Analysis Results of Hydrolysis
Extracts and Hyd~rsis Condensate
.
Example 6
StripperStripper Stripper
Feed Bottoms Condensate
A B C
FurfiJral 30,205 1,491 30,451
Pyrazines 581 67 638
% furfural 52.0 6.7 57,3
% pyrazines 1.0 0.3 1.2
Total corrected 58,086 22,252 53,143
9 . c. counts
The reslJles in Table 2 show that the hydroly is extract
steam-stripping column removes virtually all of the fur~ral
25 present in the hydrolysis extract. The furfural is contained in
the condensate from the stripping process and discarded. Few
valuable volatiles are present in the feed to the stripping column,
as evidenced by the low pyrazines levels, and thus little besides
furfural is lost. The calculat1On be1Ow estimates the actual degree
30 of removal of furfural:
Feed ~urfural 58,086 x .52 = 30,205
Bottoms furfural 22,25,2 x .067- 1491
100 x ll - (1491/30,205)] = 95.1% remo~al
~,~?t~3'76
-41-
This degree of removal car: obviously, to those skllled in the art,
be improved signifieantly by the use of additional stages in the
countercurrent multiple staga stripperr or by a higher steam to
extract ratio. In Example 1, a tall column spray stripper was
5 used. A taller column wou5d add extra contacting stages, for
example. A 99. 0% or better removal could be achieved. Thus,
the stripping column allows almost total furfural removal from the
hydrolysis extract.
