Note: Descriptions are shown in the official language in which they were submitted.
Case 2986
DESCRIPTION
PRODUCTION OF A MANNA OLIGOMER DROLLEST
TECHNICAL FIELD
The present invention relates to a method of
05 hydrolyzing a coffee extraction residue material.
More particularly, the invention involves hydrolyzing
a coffee extraction residue material, such as the
spent grounds from a commercial coffee percolation
system, in a reactor in the presence of an acid
catalyst. A tubular plug flow reactor is convenient,
although any reactor providing for the relatively
high temperature, short time reaction will suffice.
The hydrolysa-te so produced is a manna oligomer
mixture having oligomers ranging from DO 1 to DO 10.
The specific conditions selected for the reactor
determine the distribution of the manna oligomers
between DO 1 and about DO 10. The manna oligomer
hydrolysate is useful for increasing the soluble
coffee solids content in combination with an aqueous
extract of roasted coffee, for example.
BACKGROUND ART
hydrolyzing coffee material, particularly
partially extracted coffee grounds, to obtain an
increased solids yield is well known in the art.
For example, US. Pat. No. 2,573,406 to Cough et
at. discloses a process for producing a soluble
coffee which involves atmospherically extracting
.
-- 2 --
about 20% of the weight of the coffee, hydrolyzing a
portion of the grounds it a suspension of about 1%
sulfuric acid at 100 for about one hour, adjusting
the pi of the hydrolysa-te, filtering the hydrolysate,
05 combining the same with the atmospheric extract and
drying the combined extract. In another, similar
process described in US. Pat. No. 2,687,355 to
Bender et at., phosphoric acid is used in place of
sulfuric acid. In still another process, disclosed
in US. Pat. No. 3,224,879 to Downward et at., either
alkaline or cold hydrolysis is carried out directly
in the extraction train on coffee grounds that have
been at least atmospherically extracted. Hydrolysis
directly in the extraction train eliminates the
separate hydrolysis step of the prior art processes
and provides for adsorption of the alkaline or acid
catalyst in the mass of spent coffee grounds.
As to the Cough et at. and Bender et at.
processes, the batch hydrolysis reactions at rota-
pa lively low temperatures require about one hour to complete, limiting the practicality of said pro-
cusses on a commercial scale. Moreover, both Cough
et at. and penner et at. essentially aim for whatever
hydrolysate results from operating at 100C for one
hour. Neither disclosure describes a method for nor
the desirability of manipulating the hydrolysis
conditions so as to affect the composition of the
resulting hydrolysate. A similar deficiency is
noted with respect to the Downward disclosure.
It is also widely recognized in the art that
cellulosic material containing predominantly carbon
hydrate polymers and lignins may be hydrolyzed with
an acid catalyst under short time high temperature
conditions. However, if the cellulosic material is
not relatively pure the hydrolysis reaction will
produce undesirable by-products. For that reason,
the art dealing with acid hydrolysis of primarily
cellulosic material is generally limited to the
hydrolysis of waste paper and paper by-products or
05 agricultural wastes such as corn hulls, husks or
cobs. For example, US. Pat. No. ~,201,596 to
Church et at. discloses a continuous process for the
saccharif1catlon of cellulosic materials in a tubular
reactor with an acid catalyst. The object of the
Church et at. process is the conversion to glucose,
furfural and Zulus of cellulosic waste materials
such as saw dust, wood waste, corncobs, etc. Along
the same lines, the kinetics of the conversion of
cellulosic wastes -to monosaccharides in a plug flow
lo reactor are described in Thompson, David R. and
Grethlein, James E. "Design and Evaluation of a
Plug Flow Reactor for Acid Hydrolysis of Cellulose."
In. Erg. Chum. Prod. Rest Dew., Vol. 18, No. 3,
pup 166-169 (1979). The authors of said article are
specifically interested in hydrolyzing cellulose-rich
material to monosaccharides. The authors do not
disclose a method of hydrolyzing only to oligomers,
much less to a specific mug of oligomers. Another
disclosure, US. Pat. No. 4,316,747 to Rung e-t at.,
describes a process for hydrolyzing cellulosic waste
to glucose using an acid catalyst in a twin screw
extrude.
Though the art discloses much about the short
time, high temperature acid hydrolysis of
cellulose-rich materials, the art does not disclose
such treatment of materials in which cellulose is
not a major component, such as a coffee extraction
residue material, particularly the spent grounds
from a commercial percolation system. The major
hydrolyzable carbohydrate in coffee extraction
.
~'?~ 6 3
residue material is manna, not cellulose. Moreover,
the products of manna hydrolysis degrade under
cellulose hydrolysis conditions, destroying any
desirable manna oligomer intermediates that are
05 produced.
It is an object of the present invention to
provide a method of hydrolyzing a coffee extraction
residue material in which manna is the major carbon
hydrate.
Another object of -the invention is to provide a
method of hydrolyzing a coffee extraction residue
material to produce a manna oligomer mixture having
oligomers from DO 1 to about DO 10.
Still another object of the invention is to
provide a method for producing a manna oligomer
mixture with the desired distribution of oligomers
between DO 1 and about DO 10.
DISCLOSURE OF THE INVENTION
It has now been found that the objects of the
invention are met by a method of hydrolyzing a
coffee extraction residue material in a reactor in
the presence of an acid catalyst. The coffee extraction
residue material, preferably spent grounds from a
commercial percolation system, is slurries in water
and the pi adjusted to between pi 1 and 4 by the
acid catalyst. The slurry is then fed through a
reactor at a temperature between 160C and 260C in
about 6 to 60 seconds. After discharge, the hydrolyzed
coffee extraction residue material is separated from
the manna oligomer mixture having oligomers from
DO 1 to about DO 10. The distribution of the manna
oligomers between DO 1 and DO 10 depends on -the
specific conditions selected for a given reactor.
It lo also possible to hydrolyze the manna initially
present in the coffee extract residue material
completely to the monosaccharide muons (hereinafter
referred to as a manna o]igomer having DO 1).
The present invention takes advantage of several
05 properties of the coffee extraction residue material
not widely recognized in the art. Firs-t, most of
the art dealing with coffee grounds focuses on the
cellulosic content of said grounds, not emphasizing
that there is actually more mailman than cellulose
present in the grounds. Moreover, the inventors
herein unexpectedly found that said manna is
substantially separately hydrolyzable from the
cellulose. That is to say that the conditions under
which manna and cellulose in coffee material
hydrolyze are sufficiently separated so that an
essentially pure manna hydrolysate is produced.
Finally, it has been found that the manna need not
be hydrolyzed completely to a monosaccharide as is
the object of most cellulose hydrolysis work (although
it is possible to do so), but the manna may be
hydrolyzed to produce a manna oligomer solution
having any desired distribution of oligomers between
DO 1 and about DO 10.
Before proceeding to a detailed description of
the invention, it is necessary -to define some relevant
terms:
"Mailman" as used herein refers broadly to any
polysaccharide consisting of d-mannose units. The
monosaccharide muons is an aldohexose and an
isomer of d-glucose, differing only by having the
opposite spatial arrangement of the hydroxyl group
nearest the carbonyl. The manna found in the
coffee extraction residue material may have up to 40
muons units in the polysaccharide.
.
Similarly, "cellulose" refers broadly to the
polymer consisting of syllabus units which, in
turn, may be hydrolyzed to -two glucose units. Thus,
cellulose yields the monosaccharide glucose upon
05 complete hydrolysis. Cellulose makes up much of the
structural material of plants. A more complete
discussion of cellulose and its proper-ties is found
in Canaanite, J. and Blat, A. The Chemistry of Organic
Compounds. NAY., Macmillan, 1947. pp. 295-299.
"01lgomer" is untended to mean a polymer come
prosed of a relatively few number of monosaccharide
units. Specifically, as used herein, oligomer
refers to polymers consisting of less than 10 Mooney
saccharine units. Muons is referred to as an
oligomer of DO 1 for convenience, although strictly
speaking, an oligomer is typically comprised of more
than one constituent unit.
"Degree of polymerization" or "DO" refers to
the number of monosaccharide units that make up a
given oligomer. Thus, a manna oligomer of DO 4,
for example, consists of 4 muons units.
"Coffee extraction residue material" is intended
to mean a roast and ground coffee material that has
been partly extracted, preferably at least atmospherically
extracted. Coffee that has been partly thermally
hydrolyzed in order to hydrolyze the less stable
polysaccharides such as arabinogalactan is portico-
laxly useful as coffee extraction residue material.
The spent grounds from a commercial percolation
system is an example of coffee that has been atoms-
phonically extracted and partly thermally hydrolyzed.
In a commercial coffee percolation system,
roast and ground coffee is extracted in a multi-
section, countercurrent extraction battery in which
fresh water at a temperature in excess of about
175C enters the section containing the most spent
coffee (the coffee that has undergone the greatest
extraction). Concentrated coffee extract is with-
drawn from the section containing the freshest
05 coffee. Said coffee obviously undergoes a compost-
tonal change Turing percolation. Table 1 shows the
approximate composition of roast and ground coffee
whereas Table 2 shows the composition of spent
grounds obtained from a commercial extraction system.
lo While the overall percentage of carbohydrates remains
approximately constant, the thermally hydrolyzed
arabinogalactans are seen to be mostly removed. So,
the preferred coffee extraction residue material is
composed of about 45% by weight carbohydrates, of
which over half is manna.
TABLE 1
Approximate Composition of Roasted Coffee
Component % By Weigh-t (dry basis)
polymeric carbohydrates 41
arablnogalactan 13
manna 20
cellulose 8
protein 13
caramel and browning products 13
lipids 11
inert material 9
acids 6
ash 4
caffeine 2
trigonelline
TABLE 2
Approximate Composition of Spent Grounds
Component % By Weight (dry basis)
polymeric carbohydrates 45
arabinogalactan 5
manna 25
cellulose 15
lipids 25
inert material 20
protein 10
3 3
As to the details of the instant method, the
coffee extraction residue maternal is first slurries
in a liquid, typically water, prior to being fed to
a plug flow reactor. The slurry should be between
05 5% by weight and 20% by weight of the dry basis
coffee extraction residue material in order to
insure sufficient solids content in said reactor for
efficient hydrolysis. Moreover, the slurry should
be uniform, that is, the residue material should be
distributed evenly throughout. If the slurry is
made up in batch beforehand, steps should be taken
to insure uniformity such as recirculation by means
of a slurry pump. In the event a different reactor,
such as an extrude, is used, it is not necessary to
dilute the slurry as much. For example, spent
grounds from a conventional percolation system
typically containing between about 50% and 60% by
weight liquid may be fed directly to such an extrude
without further dilution.
An acid catalyst is then added to the slurry in
order to adjust the pi to the suitable level. The
acid catalyst is typically added at between about
0.05% by weight and 2.0% by weight of the slurry.
It has been found that a slurry pi between 0.5 and 4
is desired to catalyze the short time, high temper-
azure hydrolysis of manna to manna oligomers. The
phi in combination with a given reaction time and
temperature determines the distribution of the
different degrees of polymerization of manna oligomeLs
A lower pi combined with higher temperature and
perhaps longer reaction time) tends to provide
oligomers of lower degree of polymerization or, in
the l]mitlng case, the monosaccharide muons.
Conversely, a higher pi tends to favor manna oligomers
of higher DO.
36~
Specific acid catalysts contemplated for use in
the present invention include both inorganic acids
and organic acids. A strong inorganic acid, such as
sulfuric acid, is particularly suitable for use
05 herein because of the relatively small amount of the
acid needed to reach the desired phi Sulfuric cold
is easy to precipitate out from the final hydrolysate
and the acid enjoys wide application in the food
industry. Other inorganic acids, such as phosphoric
acid, nitric acid, and hydrochloric acid are also
suitable, as is a combination of acids, such as
phosphoric acid combined with sulfuric acid.
Organic acids alone or in combination, such as acetic
acid, citric acid, tartaric acid, mafia acid, adipic
acid and fumaric acid, also make acceptable cold
catalysts although generally being weaker, relatively
greater amounts of organic acid are needed to achieve
the desired pi adjustment.
After the acid catalyst has been added to the
slurry, said slurry is fed to a reactor. Suitable
continuous reactors include those capable of promoting
relatively high temperature, short time reactions,
such as single or double screw extrudes or plug
flow tubular reactors. A suitable batch reactor is
a so-called explosion puffer wherein the coffee
extraction residue material is mixed with the acid
catalyst, placed in the reactor vessel which is then
pressurized, as with steam. The pressure is suddenly
and explosively released, discharging the contents
from the reactor vessel. The manna oligomer mixture
having oligomers ranging from DO 1 to about DO 10 lo
then leached from the material so discharged from
said reactor vessel. The plug flow tubular reactors
are especially convenient. A plug flow tubular
reactor is essentially a cylindrical length of pipe
363
- 10 -
in which a reaction can take place. on orifice lo
placed on the discharge end of the reactor in order
to control the pressure in the reactor as well as
the rate of discharge from said reactor. "Plug
05 flow" refers to the velocity profile of the slurry
flowing through the reactor. Normally, a fluid
exhibits a parabolic profile velocity wherein the
fluid in the center of a conduit has a higher velocity
than fluid flowing closer to the wall. In a plug
flow reactor, the velocity profile is flat, arising
from the geometry of the vessel and the nature of
the fluid.
The elevated temperature is achieved in the
reactor in any of several ways. For example, the
slurry may be passed through a heat exchanger prior
to entering said reactor. Temperature may then be
maintained by simply insulating the reactor. Alter-
natively, high pressure steam may be injected directly
into the reactor as a means of raising the temperature.
Although the steam may dilute the slurry somewhat,
such heating is extremely rapid, permitting short
time reactions. Selection of the preferred heating
method, as well as sizing of the diameter of the
reactor and orifice are all within the skill of a
worker in the art, based on standard design principles.
The conditions maintained within the reactor
are, of course, critical in insuring that essentially
only -the manna is hydrolyzed and that the desired
distribution of manna oligomers lo achieved. It
has been found that the reaction temperature should
be between 160C and 260C, preferably from 190C to
220C, in order to hydrolyze the manna and minimize
the degradation of the manna oligomers so produced.
Such temperatures correspond generally to a pressure
in said reactor between 6 atmospheres and 35
atmospheres, which is about the saturation pressure
of the water in the slurry fed to the reactor. In
general, a higher temperature promotes the product
ton of manna oligomers of a lower degree of polyp
05 merizatlon (depending on the pi and the length of reaction) and the converse is also generally true.
The preferred reaction time has been found to be
between 6 seconds and 60 seconds. Below about
6 seconds, the equipment is limiting as it is very
difficult to heat the slurry and insure uniformity
of the reaction. On the other hand, if the reaction
is carried on for much longer than about 60 seconds
in the presence of the acid catalyst, the manna
oligomers (and the small amount of Arabians and
galactose that may be present) begin to degrade,
causing off flavors, limiting the useful yield and
making purification of the hydrolysate difficult.
As herein before noted, the discharge end of the
reactor has an orifice thereon to control pressure
within the reactor and control the rate of discharge.
Passing the slurry through the orifice rapidly
reduces the pressure to which the slurry is subjected
to about atmospheric. Such a rapid reduction of
pressure causes expansion and evaporative cooling of
the slurry thereby "quenching" or immediately term
noting the hydrolysis reaction. By so quenching the
reaction, it is possible to control the reaction
time to within the prescribed 6 seconds to 60 seconds
with great reliability.
Once the slurry is discharged from the plug
flow tubular reactor, said slurry is cooled further
and may then be separated into the manna oligomer
solution and the remaining hydrolyzed coffee extract
lion residue material. It is also preferable -to
neutralize -the discharged slurry by known techniques,
- 12 -
such as precipitation of the acid with a salt,
evaporation of a volatile acid or the use of an ion
exchange resin. The neutralization may be either
before or after the separation of the manna oligomer
05 solution and the hydrolyzed coffee extraction residue
material. Separation may be by any method of solid-
liquid separation known in the art. For example,
said slurry may be filtered in order to remove the
hydrolyzed coffee extraction material therefrom.
lo Alternatively, the slurry may be separated by eon-
trlfuging the slurry, as in a basket centrifuge.
After separation, the hydrolyzed coffee extraction
residue is disposed of, most preferably burned for
fuel.
An alternative embodiment of the present invention
is one in which carbon dioxide gas lo used as the
acid catalyst. The carbon dioxide gas may be dissolved
in the slurry prior to entering the reactor by
pressurizing the slurry under a head space of carbon
dioxide gas while agitating said slurry. The slurry
is then fed to the reactor as hereinbe~ore described.
Alternatively, rather than add the catalyst to the
slurry prior to entering the reactor as herein before
described, the carbon dioxide gas is injected directly
into the plug flow tubular reactor wherein the
carbon dioxide gas dissolves in the slurry, lowering
the pi to less than about pi 4. The surprising
aspect of using carbon dioxide gas is that injection
of said gas is able to sufficiently alter the pi of
the slurry so as to still catalyze the short time,
high temperature hydrolysis reaction. The acid
catalysts previously discussed are all relatively
strong acids, certainly stronger than the acid
resulting from dissolving carbon dioxide gas in the
slurry. It was unexpectedly found that said acid,
~2~3~3
- 13
despite its relative weakness, is able to catalyze
the hydrolysis of the manna in the coffee extraction
residue material.
Whichever embodiment is used, the instant
05 method provides for production of a manna oligomer
solution having oligomers from DO 1 to about DO 10.
Moreover, the specific conditions selected for the
reactor determine the distribution of the manna
oligomers between DO 1 and about DO 10. The control-
lying principle lo that "harsher" conditions, Thetis, higher temperatures, longer reaction times and
lower slurry oh's, favor the production of oligomers
with lower degrees of polymerization (with the
limiting case being the production of the moo-
saccharides muons). Conversely, hydrolysis at temperatures towards the lower end of the range, for
shorter periods of time and at higher slurry pews
favors a solution with a distribution of oligomers
having higher degrees of polymerization. Table 3
shows the distribution of the manna oligomers in
hydrolysates produced at the different conditions
listed. The reactor used was a plug flow tubular
reactor with provision for direct steam injection.
The acid catalyst in each case was sulfuric acid
and the reaction time was about 6 seconds. The
overall yield based on the starting weight of the
coffee extraction residue material and the amount of
oligomers produced was about 30%. The manna oligomer
distribution was determined by high performance
liquid chromatography (HPLC) with the percentage
indicated being the relative percentage of the total
peak area for the manna oligomers.
I
- 14 -
TABLE 3
acid catalyst
level % temp. Distribution of manna oli~omers (OWE)_ _
by weight C DPl Pi DP3 DP4 DP5 DP6 Pi
05
0.25 240 98.6 1.4
0.25 220 95.5 4.5
0.10 220 34.0 25.9 19.011.0 6.5 2.7 0.9
0.10 240 47.1 27.6 1~.76.6 2.6 1.1 0.3
As can be seen from Table 3, the higher acid catalyst
concentration (and lower slurry phi combined with
the higher hydrolysis temperature favors oligomers
with lower degrees of polymerization whereas oli~omers
from DO 1 to DO 7 are produced at lower acid catalyst
concentration and the lower hydrolysis temperature.
The manna oligomer mixture having oligomers
ranging from DO 1 to about DO 10 produced by the
method of the present invention has numerous apply-
cations and the specific distribution of oligomersin the mixture may be tailored to any given end use.
One of the more important uses is the addition of
said mixture to a conventional coffee extract in
order to increase the amount of soluble coffee
produced from the starting roasted and ground coffee.
Inasmuch as the manna oligomer mixture is itself
produced from coffee, and a conventional extract
typically contains a quantity of manna oligomers,
the resulting coffee extract is not especially
different from the conventional coffee extract. For
this particular application, it is preferable to
have a majority of the manna oligomers distributed
between about DO l and DO 6. The manna oligomer
mixture may be added to the conventional coffee
extract prior to drying said extract or the manna
I
- 15 -
oligomer mixture may be dried and then combined with
a soluble coffee produced from a conventional extract.
Drying may be by any means known in the art, such as
freeze drying or spray drying. Alternatively, the
05 mixture can be heavily distributed towards muons
(an "oligomer" of DO 1 as hereinabove defined),
which mixture might then be simply converted to
minutely by known methods, providing an inexpensive
source of minutely, a sweetener widely used in the
food industry. Other uses of the manna oligomer
mixture having oligomers ranging from DO 1 to DO 10
include adding said mixture to an aqueous coffee
extract used in decaffeinating coffee beans so as to
infuse the beans with the oligomers, wenching the
roasting reaction with the mixture so as to infuse
the oligomers in roasted coffee beans and agglomerating
spray-dried coffee along with the dried manna
oligomer mixture so as to produce superior agglomerates.
Still other uses of the manna oligomer mixture
having oligomers ranging from DO 1 to DO 10 are
apparent to a worker skilled in the art and are not
limited to the applications described herein.
The following examples illustrate certain
embodiments of the present invention. The examples
are not meant to limit the invention beyond what is
claimed below.
EXAMPLE 1
A series of runs was conducted using essentially
the same procedure but varying the acid catalyst,
the reaction temperature and the reaction time. The
procedure was as follows:
Spent coffee grounds from a commercial percolation
process were dispersed in water and milled using a
3~3
- 16 -
Gifford Wood W-200 Killed Mill to a particle size
well below 0.8 mm (the orifice size of plug flow
reactor) to give a slurry of 4.68% by weight solids.
The slurry was then placed in the hopper of a plug
05 flow reactor at room temperature and kept agitated
to prevent settling. The slurry was then pumped
using a Mooney pump into the plug flow reactor having
about 113 ml volume. Just prior to feeding the
slurry into the reactor, a previously calibrated
quantity of 94% by weight sulfuric acid was pumped
into the slurry stream with a small variable stroke
piston pump to give the desired acid concentration.
The reactor consisted of a heating section in which
steam was injected directly into the slurry and a
reaction section which was essentially a length of
tubing. After the slurry entered said reactor, the
temperature was rapidly raised my condensation of
steam injected into the slurry. The temperature of
the reactor was changed by varying the steam pressure
by means ox a valve and was monitored with a thermos
couple. Residence time of the slurry in the reactor
could be varied by changing -the pumping speed of the
Mooney pump. After passing from the reactor through
-the orifice of the reactor, the slurry dropped back
to atmospheric pressure and the temperature core-
spondingly dropped to about 100C, quenching the
reaction. The slurry and any condensate were further
cooled to about room temperature by passing the same
through a water cooled heat exchanger. The hydrolyzed
slurry was then neutralized with calcium carbonate,
and the residue was filtered therefrom.
The resulting hydrolyzate containing the manna
oligomer mixture was analyzed to determine both
composition and the distribution of the manna
oligomers between about DO 1 and DO 10. The purity
- 17 -
of the manna ollgomer mixtures in this and the
following examples were typically in excess of 80%,
indicating that essentially only the manna and very
little cellulose was hydrolyzed.
05 High performance liquid chromatography (H.P.L.C.
was used for the analysis, with the percentage
indicated being the relative percentage of the total
peak area for the manna oligomers. The analysis
was carried out on a Waters Carbohydrate Analysis
column (part number 84038) with a solvent of 70/30
acetonitrile/water. The temperature was maintained
at about 17C and the solvent flow rate was about
2 ml/mln. The peaks were monitored with a Waters
differential refractive index detector.
Table 4 shows the results for sulfuric acid.
Table 5 shows the results for phosphoric acid and
Table 6 shows the results for acetic acid.
TABLE 4 - Sulfuric Acid Catalyst
acid
catalyst
level % temp.time Distribution of manna oligom us (%~ _
25 by weight C sec. DPl DP2 DP3 DP4 DP5 DP6 DP7 DP8 DP9
. .
0.25 200 8 51.9 20.9 13.5 8.3 2.6 I 0.7 0.7
0.10 220 8 36.3 23.0 15.4 10.2 6.7 4.3 2.7 1.3
0.05 ~20 8 1~.5 15.8 15.7 14.3 13.1 11.5 8.2 4.8 2.1
30 0.025 240 8 12.6 14.0 14.9 14.7 14.3 12.7 8.9 4.7 3.3
AYE 3
- I -
TABLE 5 - Phosphoric Acid Catalyst
acid
catalyst
05 level % temp.time Distribution of manna oligomers (%)
Dye weight C sex. DP1 DP2 DP3 Pi DP5 DP6 DP7 DP8 DP9
.
0.25 240 30 100 - - - - - - - -
0.25 220 30 58.2 22.7 11.8 4.4 2.0 0.9 - - -
10 0.25 200 30 25.4 21.7 17.4 13.0 9.8 6.5 4.0 2.3
0.25 180 30 22.3 20.6 15.3 12.8 13.4 10.0 5.7 - -
1.0 200 30 68.8 15.6 6.8 5.2 2.1 1.6 1.9 - -
TABLE 6 - Acetic Acid Catalyst
acid
catalyst
level % ~emp.time _ Distribution of manna oligomers (%)
20 by weight C sec. DPl DP2 DP3 DP4 DP5 DP6 DP7 DP8 DP9
. . _ . .
1.0 220 30 14.3 15.1 15.0 15.0 14.6 12.1 8.5 5.5
1.0 200 30 12.6 13.5 11.2 12.2 13.6 15.4 9.1 12.3 -
0.25 240 30 14.0 15.0 15.2 14.9 13.1 12.4 9.1 I -
25 0~25 220 30 14.2 12.8 13.6 14.0 13.5 13.7 11.0 2.1
0.25 200 30 23.0 13.6 11.2 12.2 13.6 15.4 9.1 12.3 -
Examination of -the above tables indicates that
varying distributions of the manna oligomers are
obtainable by varying the acid catalyst, the reaction
temperature and the reaction time. The general
trend is for oligomers of lower degree of polymeric
ration for increasing acid concentration, increasing
temperature and increasing reaction time.
, . . .
3~3
-- 19 --
EXAMPLE 2
Carbon dioxide was fed as a gas into the reactor
through the same opening used to pump the sulfuric
05 acid. The carbon dioxide pressure was maintained
above that of the steam introduced into the reactor
by adjusting the regulator valve on the carbon
dioxide cylinder. The amount of carbon dioxide
flowing into -the reactor could also be varied by
opening the valve on the COY regulator. Carbon
dioxide levels were estimated to be about 1% by
weight resulting in a pi of about 3.4. Different
runs were conducted at higher and lower carbon
dioxide flow rates. The valve on the COY regulator
was opened about one-half of the way for the higher
carbon dioxide flow rate and only about one-quarter
of the way for the lower carbon dioxide flow rate.
The effluent coming out of reactor after cooling to
room temperature consisted of a loose foam (COY gas
plus hydrolysate and spent grounds residue). A-t
240C, the high and low COY flow rates gave comparable
oligosaccharide distributions.
The results are shown in Table 7 below
TABLE 7 - Carbon Dioxide Catalyst
C2 tempt C02 Distribution of Manna oligomers (%)
30 press a flow DPl DP2 DP3 DP4 DP5 DP6 DP7 DP8 DP'3
(elm) rate
41 200 low 55.8 35.7 Trace --
48 240 low 10.8 12.8 l4.5 15.9 17.2 13.7 9.7 5.4
35 48 240 high 11 7 13.6 15.4 15.8 15.1 13.7 9.0 3.0 2 8
.
63
- 20 -
Examination of Table 7 indicates that varying
distributions of the manna oligomers are similarly
obtainable with carbon dioxide as the acid catalyst.
05 EXAMPLE 3
An experiment was run with two modified Wenger~
single screw extrudes, produced by Wenger Menu-
lecturing Company of Sabbath, Kansas, which were
used as high pressure screw conveyors to hydrolyze
commercially produced spent coffee grounds of thick
consistency (about 60-70% moisture). Spent grounds
(approx. 70% moisture) were placed in a live bottom
circular bin and fed via two corotating screws into
the first extrude (SX-80). This first extrude was
used to develop high pressure and preheat the grounds.
The output of the SX-80 was then fed into the second
extrude (SX-llO) and heated further. Sulfuric acid
was injected into the front end of the SX-llO at the
point where the spent grounds had reached the reaction
temperature using a small pump. The temperature
remained constant while the slurry was in the reaction
zone. The material exited the SX-llO through a
hydraulically activated orifice whose opening was
controlled by hydraulic pressure. Neither the
temperature nor the residence time were accurately
measurable. The thermocouples in the extrude
appeared to read only the metal barrel temperature.
The barrel temperature ranged from 107C to about
200C. Due to surging, the residence time varied.
H.P.L.C. analysis again indicated the presence of
manna oligomers.
The results are shown in table 8 below.
2 I
TABLE 8 - Wenger Extrude
acid moisture
catalyst of spent barrel
05 level % grounds temp. Distribution of manna oligomers (%)
by weight (C) DPl DP2 DP3 DP4 DP5 DP6 DP7
_ _
1.0 70 121 76.4 11.3 5.3 4.0 3.1 - -
0.2 70 121 15.3 14.9 15.6 14.9 16.7 16.1 6.5
10 0.3 60 150 45.6 21.6 13.3 8.8 6.6 4.1
Inasmuch as control was not as precise for the
extrude, it was not possible to obtain the range of
the manna oligomers between DO 1 and about DO 10
but it was possible to produce a distribution of
manna oligomers nonetheless.
EXAMPLE 4
An hydrolysate was prepared from spent grounds
by hydrolysis in the plug flow reactor at 220C,
with 0.05% sulfuric acid and a residence time of
about 7 sec. The hydrolysate was concentrated under
vacuum to about 22% by weight solids and mixed with
a conventional coffee extract (about 25% solids) at
20% by weight of the extract. The mixture was spray
dried in a Nero spray drier at about 160C inlet
temperature 80C outlet temperature. A control
consisting of conventionally prepared coffee extract
was spray dried under similar conditions, the two
samples were dehydrated at the 1% level (1 g/100 cc
hot water) and tasted. No major differences were
observed in taste of the product. The product
containing the hydrolysate was slightly more turbid
due to some suspended solids and was in that respect
more like home brewed coffee.
