Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a process for producing a
soluble coffee product which, when reconsti-tuted, possesses an
improved cup appearance and also has desirable cup aroma and
flavor.
Numerous attempts have been made over the years to
enhance or improve the appearance, aroma and flavor of ins-tant
coffee products. ~mong the efforts made to improve the appear-
ance of instant coffee products have been techniques for making
the reconstituted brew prepared from the soluble coffee product
appear more like freshly brewed coffee prepared from roasted and
ground coffee. A principal objective has been that of attempt-
ing to obtain a more turbid appearance in ~'he brew prepared from
a reconstituted soluble coffee product. U.S. Patent No.
3,652,292 to Bach et al. describes a 1-echnique for adding col-
loidal particles of roasted coffee to an aqueous coffee extract
so as to obtain a soluble cof~ee product containing approxi-
mately 3 to ~0% of colloidal coffee partic].es. ~Iowever, a
disadvantage to the Bach et al. method is that some sedimenta-
tion is noted to occur in the reconstituted brew thereby dimin-
ishing the dèsired turbidity effec-t. Moreover, the flavor does
not appear to be optimum and some "oiling off" is observed,
The incorporation of fine particles of roas-ted coffee
to a coffee extract so as to improve the aroma and flavor of a
dried soluble coffee product prepared from the extract is also
described in U.S. Patent No. 3,26l,689 to Ponzoni. However, the
process there described appears to be specific to the use o~
carbon dioxide in the grinding operation with the result that
the fine particles of roasted coffee may lose some of their
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aromatic and flavorful notes by virtue of such notes being
released during sublimation of the carbon dioxide.
The utilization of ni-trogen as a cryogenic grinding
aid in grinding processes for roasted and ground coffee is dis-
close~ in U.S. Patent ~lo. 3,965,267 and U.K. Pa-tent Specifica-
tion 1,424,264 However, the size to which the roasted coffee
beans is ground by the process described in each of these
patents is generally in the order of finer than 70 mesh and
finer than 20 mesh, respectively. However 9 a-t -these particles
sizes the roasted and ground coffee, if incorporated wi-th
difficulty in~o a coffee extract which is s~bsequently dried or
if blended wi~h a dried soluble coffee product, would have a
tendency to settle to the bot,om of a cup in which the soluble
coffe product would be reconstituted. Thus, the desired turbid
appearance would be lost and at the same time the sought-after
flavor and aroma characteristics would be minimized.
A process has nGw been discovered for the production
of a soluble coffee product which, when recons-tituted, gives an
improved turbid appearance oE the brew in the cup and at the
same time the reconstituted brew has desired aroma and flavor
characteristics. Broadly, ~he process of the present inven-tion
involves air cooling freshly roasted coffee beans followed by
quenchin~ the beans with liquid nitrogen and freezing the beans.
The frozen beans are then subjected to a grinding operation to
produce a colloidal coffee product having a particle size less
than 45 ~. The frozen colloidal product is then added to a
chilled coffee extract prepared by conventional methods and is
blended with the extract using a homogenizer. The coffee
extract containing the colloidal coffee product is then spray-
dried or freeæe-dried to produce a soluble coffee powder. The
soluble coffee powder is fo~md to contain regular coffee
aromatic notes and possesses a regular coffee flavor.
An essential feature of the process of this invention
is the dry cryogenic grinding of the air-cooled freshly roasted
beans. It has been found that a stable colloidal product may be
prepared by dry grinding the frozen roasted beans in -the
presence of liquid nitrogen. The colloidal product when added
1~ to ~he coffee extract and spray-dried or freeze-dried is found
to retain its uniformity and aromatic character. Moreover, when
the dried soluble coffee product is reconstituted with hot
water, flocculation does not occur. The reconstituted soluble
coffee product is found to have regular cofee aromatic notes
and is similar to a r~gular coffee in that a turbid appearance
is observed. By cryogenically dry grinding the roasted coffee
it appears that the flocculation phenomenon which has been found
to exist with a soluble coffee product as prepared following the
teaching of the above-referred-to Bach et al. process, U.S.
Patent No. 3,652,292, is avoided. This flocculation phenomenon
seems to be caused principally because of the hydrolysis of
polysaccharides, hydrolysis of some proteins, protein denatur-
ation during the grinding stage and extraction of soluble
compounds such as sugars. Moreover, the oil content of the
finely ground coffee particles appears to increase thereby
giving rise to an undesirable appearance in -the c-up when the
soluble coffee product of Bach et al. is reconstituted.
A principal critical feature of the process of this
invention is the roasting operation. Aromatic retention in the
beans may be maximized using low charge weight, dark roast and
no water quench roasting techniq-ue. Preferably, mild beans such
as Colombians are employecl.
After the beans have been air cooled, they are im-
mediately quenched, using liquid nitrogen and ground. The
beans may be preground using J for example, a Gump* grinder.
From this stage on a Fitz-Mill~' grinder (model 6D) may
be used to grind the coffee in three stages. Screens of lO0,
200 and 3~5 mesh (U.S. Sieve) are used respectively to grind the
coffee ~o colloidal size. However, o-ther equipmen-t such as pre-
coolers and hammer mills may be employed.
Liquid nitrogen is used during -the Fitz-Mill~ grinding
operation to preserve the retention of aromatics and also to
minimize temperature rise of the product while grinding. The
ground coffee is reduced to less than 45 ~ in size~ about 25% of
Lhe particles being less than lO~ in size. A Coulter* Counter
(Mode:L Z~ Mz) may be used to analyze the particle size~
To reduce vola-tile losses and preserve aromatics, cold
extract at 4C to 10C (40F. to 50F.) is blended with the col-
loid coffee product. A Polytron* Mixer homogenizer is used to
disperse the colloid particles in the extract. However, the
colloidal product may also be dispersed in cold water (1 part
colloid to 1 parts of water by weigh-t) and then the resultant
liquor may be homogenized with the extract.
The level of colloidal co~ee to be added to the ex-
tract may range ~rorn about 1% to about 15%. The colloidal
addition level is expressed by the ollowing formulae:
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P X
s + X
= SP
1 - P
P = % of colloid in solids
S = Amount of solids in extract batch
X = Amount of colloid to be added
After the mixing stage the product is spray-dried or
freeze-dried using conventional spray-drying or freeze-drying
conditions.
If desired, the spray-dried product may -then be
agglomerated employing conventional conditions. In agglomerat-
ing spray-dried soluble coffee powder containing colloidal cof-
fee product prepared by the process of this inventlon the
agglomerated product is found to have a density and color
comparable to a conventional agglomerated spray-dried soluble
coffee powder.
The product prepared by the process of the present
invention in the spray-dried or freeze-dried form containing the
colloidal coffee product is different in taste and cup appear-
ance than commercially available soluble coffee. Thus, soluble
coffee containing 1 to 15% level of colloidal coffee product is
found to have regular coffee characteristics. When evaluated by
a taste profile panel, samples judged to have the best roasted
and ground notes were composed of a dark roast extract blend
with 10% colloidal addition (Colombians or mild type beans
usually at 40 or 35 roast color). A high -turbidity level is
considered desirable for cup appearance of reconstitwted soluble
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coffee. Cup turbidity is found to increase with increasing
level of colloidal addition. Turbidity is caused by the
particles which are 10~ and less.
The following indicates the effect on turbidity of
varying the level of colloidal coffee:
Turbidity
(J.T.V. Value)
Commercial Soluble Coffee Control 1.7
2% Colloid 1.9
l~% ~ 2.8
6% " 4.0
8% " 6.0
10% " 6.7
Turbidity was meas-ured using Hach* Meter 2100.
In addition to turbidi-ty the colloidal coffee cup may
have a sediment. At a 5% level of added colloidal coffee
product, the sediment is about the same as found in a cup of
percolator prepared regular coffee. The sediment may be eli-
minated if desired if all the colloidal particles are less than
10 ~.
Typical distribution of colloidally ground coffee
(-325 mesh U.S~ Sieve size) was as follows:
_rticle Size RangeCumulative %
Larger than 40 ~ 0%
30-40 ~ 8%
2Q-40 ~ 28%
10-/~0 ~41%
1-10 ~ 24%
100%
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Standard deviation on the particle size was +10%.
Two methods, using the Coulter Counter TA model were
used to determine the dis-tribution of particle size of the
colloidal coffee products.
The first method, using the lithium chloride electro-
lyte solution, was usecl to analyze the soluble coffee particles
in water.
The second method, using the isotone electrolyte solu
tion, was used to analyze the regular coffee or insoluble coffee
products in water.
The analyses on colloidal coffee were carried out
using lO0 ~ aperture size and isotone electrolyte solution.
In order to illustrate the present invention the
following non-limiting Example is furnished:
EXAMPLE
Colombian beans were roasted to 40 Roast Color, ai.r
cooled and liquid nitrogen quenched.
The beans were then preground using a Hobart~ grinder.
The frozen beans were then subjected to three passes through a
Fitzmill* grinder utilizing 100, 200 and 325 mesh (U.S. Sieve)
screens respèctively in -the presence of liquid nitrogen.
To 50 parts of chilled 4C. (40F.) extract 2S%
concentration, 1.39 parts of dry cryogenically ground frozen
colloidal cof~ee (10%) was then added and homogenized using a
Sonic Nixer - Polytron~. The extract was then held at ~C. ~^
(40F.) for a minimum of one hour for volatile diffusion to
take place.
The extract was -then spray dried using the following
spray drying conditions.
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Extract concentration 25.5%
Inlet Temperature 232C (450F.)
Outlet Temperature ' 107C (225F.)
Nozzle Pressure 300 P.S.I.G.
A dry soluble coffee product was obtained. When the
product was reconstituted, the coffee beverage was found to have
improved cup appearance and improved cup aroma and flavor.
Flocculation in the cup was not apparent when hot water is added
to the dry soluble coffee product and the beverage was noted to
contain regular coffee aromatic notes similar to those found in
a freshly brewed cup of coffee.
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