Note: Descriptions are shown in the official language in which they were submitted.
~039567
This invention relates to a readily soluble sweetening
compositlon containing an edible bulking agent and a dipeptide
sweetening agent. More particularly, it relates to a speci~ic
method of spray drying a low bulk density sweetening composition
which results in a composition having extremely rapid solubility
in water and a bulk density and caloric value per unit of volume
considerably less than that of sucrose.
Previous attempts to produce artificial sweeteners have
involved the use of saccharins and/or cyclamates. Chief among
these have been attempts to produce table sweeteners which have
the appearance, behavior-in-use and sweetening intensity of sucrose
per unit volume such as is taught in United States Patent No.
3,320,074 issued May 16, 1967. Specifically, this Patent teaches
a method of spray drying an aqueous solution of saccharin and/or
cyclamate whereas the solution is aerated with a non-reactive,
non-inflammable gas, the amount of aeration gas defining the bulk
-density of the final product.
Similarly~ United States Patent No. 3,170,801 issued
February 23, 1965 teaches a method of deriving a table sweetener
having the desirable organoleptic properties of sucrose by spray
drying a solution of an artificial sweetener such as saccharin
or cyclamate, a water dispersible edible protein whipping agent
and a slurry of lactose into which a soluble gas has been intro-
duced prior to drying. Problems have arisen with the use oP
these compounds, however, since the saccharins leaves a somewhat
bitter aftertaste in the mouth and the cyclamates are now excluded
from commercial food products as hazardous to human health.
It has recently been found that certain dipeptide com-
pounds possess an intense sweetness level. Examples of these
compounds are set forth in United States Patent Nos. 3,475,403
and 3,492,131. Most suitable among these compounds are the lower
alkyl esters of aspartylphenylalanine wherein the stereochemical
configuration is L-L, DL-DL, DL-L or L-DL. Illustrative o~`the
~3~567
lower alkyl esters are methyl, ethyl, propyl, butyl, pentylg
hexyl, heptyl and the branched chain groups isometric therewlth,
with the methyl ester being the most preferred embodiment.
These dipeptide materials would appear to have great
commercial applications as sweetening agents since they range up
to 200 times the sweetness level of sucrose, have no discernible
unpleasant aftertaste and can be produced from naturally occurring
amino aclds. Problems have arisen, however, with the use of
these compounds in that their rate of solution into water is
markedly slower than sucrose and that the compounds tend to decom-
pose, losing substantially all their sweetness upon heating at
temperatures above about 80C.
It has now been found that the rate of solution of
dipeptide sweetening compounds can be significantly increased by
spray-drying an aqueous solution of an edible bulking agent and
the dipeptide sweetening compound. The specific method utilized
in this invention produces a sweetening composition havin~ at
least as rapid a rate of solubility as a freeze-dried sample on
contact with water and as a result eliminates the tendency of
spray dried sweeteners to float as a cohesive mass on the surface
of beverages. In addition, utilization of this spray-drying
method excludes the need for aerating the sweetener solution with
gases that may affect the taste of the resultant product as well
as cause extensive foaming problems when added to aqueous systems
such as beverages. It has also been found that, surprisingly,
these aqueous solutions may be spray-dried at conditions of
elevated temperatures specifically, at temperatures as high as
~rom 300F. to 500F., without significant adverse effects on the
sweetening level of the dipeptide compounds.
According to the invention there is provided a sweeten-
ing composition containing a finely divided and dispersed lower
alkyl ester of aspartylphenylalanlne having a sweetening power
similar to sucrose in a matrix comprising a spray-dried spherical
--2--
-- ... :
~03951 ;7
light reflec~ve powder of low bulk denslty in relation to that
of sucrose between about 0.12 and 0.14 and a rapid solubility in
water, said powder having as its ma~or bulking agent a dextrinose
enzymatic starch hydrolysate having a dextrose equivalency o~
about 4 to 20 and an irregular distribution of other low sac-
charides which are preponderently hexameric and heptameric.
There is also provided a method for producing a rapidly
soluble sweetening composition comprising the steps of forming an
aqueous solution of an edible bulking agent and L-aspartyl-L-
phenylalanine meth~l ester, said bulking agent being selectedfrom the group consisting of organic acids, hydrolyzed starch
materials and sugars, said aqueous solution containing less than
one part L-aspartyl-L-phenylalanine methyl ester per part of bulk-
ing agent and spray drying the solution at a feed concentration of
not less than about 50% solids in a spray dryer apparatus having
an inlet air temperature of about 350~. to about 500F.
The solid edible bulking agents suitable for use in this
invention may be any of the non-toxic substances or combination
of substances heretofore employed by the prior art for this pur-
pose including the organic acids such as citric, adipic, malictartaric, fumaric acids and the hydrolyzed starch materials such
as dextrins and sugars. Especially suitable among these solid
bulking agents are the dextrins, particularly the low dextrose
equivalent (D.E.) dextrins of the class commonly known as corn
syrup solids. These materials are pre~erred not only because
they are low in caloric content and non-hygroscopic but also due
to the fact that they have a low bulk density which results in a
caloric value per unit of bulk that is less than sucrose though
its sweetness is equivalent to sucrose, the resulting composi-
tion has the crystalline appearance of table sugar and dissolvesrapidly in cold water.
According to one embodiment of this invention, a table
sugar substitute having the appearance of crystalline sucrose may
--3--
. .. . '
~039567
be prepared by forming a uniform aqueous solution o~ a corn
syrup dextrin material and a dipeptide sweetening agent and
spray-drying this solution in a manner so as to yield an expanded
product which may then, if necessary, be ground to size. The
method of spray-drying of this invention concerns introducing an
aqueous solution of the bulking agent and dipeptide swee-tener
preferably maintained at a temperature of about 150F. to 160F.
for reasons of complete dissolution of the dipeptide, into the
spray dryer. Prior to feeding the solution into the spray drier,
the solution is preferably pumped from the container through an
in-line strainer to the dryer feed pump which is equipped with a
homogenizing head. Thus, when the strained feed solution is
sprayed into the dryer itself, the particle size Or undissolved
sweetener particles is further reduced. Accordingly, the feed
solution is pumped and sprayed downward and co-current with the
drying air within the spray dryer. In order that the desired
density of the spray-dried sweetening composition be derived, the
feed concentration and inlet alr temperatures are critical. For
the purposes of producing the table sweetener of this invention
which preferably has a density of from about .12 to about .14, a
feed concentration of usually not appreciably below about 50%
and preferably about 60% on an "as is" solids basis at an inlet
air temperature of about 450F. is preferred. However, inlet air
temperatures of as low as 300F. and as high as 500~. may be
used, the densities varying inversely with temperatures and con-
centration. Inlet temperature of below about 350~., however,
will yield-end products having densities ranging from abo~t 0.2 to
about 0.3. The air outlets, although not critical to this inven-
tion, are preferably maintained at from about 225F. to about
270Fo~ an air outlet of 230F. at a flow of 2400 cpm being most
preferred. Thus, where, for example, a density of 0.35 to 0.25
is desired, the feed concentration is accordingly ad~usted to
about 30% to 40% with an air inlet temperature of about 300F.
--4-- ~ -
- . .
~39567
Modification of thls procedure for variance of densities derived
s~ould be obvious to those skilled in the art.
Since dextrins require great care in drying due to both
fire and explosion hazards, this specific method of spray drylng
results in operation at about half the lower explosion limit.
Thus, it should be obvious to those skilled in the art that further
provisions for explosion supression devices and a high venting
capability in the equipment, i.e., 1 ft.2 venting area per 25-40
cu. ~t., may permit use of higher capacities through use of higher
feed concentration and higher inlet air temperatures with relative
safety. Such conditions, in turn, would tend to produce a product
of even lower denslty.
This method of spray drying was found unexpectedly to
produce a sweetening composition having at least as great a rate
of solubility than even a freeze-dried sample. Freeze-drying is
ordinarily associated with producing dried compositions of such
low density as to make them rapidly soluble but, unfortunately,
is an extremely expensive process. This invention affords a
method of drying whereat the resultant composition is not only at
least as fast dissolving as a freeze-dried sample, but is also
less expensive to produce.
The dextrin material used for the production of these
sugar substitutes must dissolve easily in water to produce a
clear solution and must be non-hygroscopic. In this regard, the
D.E. (dextrose equivalent) of the dextrin material has been found
to be a critical parameter. The dextrin material must have a suf-
ficiently low mo--lecular weight to be easily soluble in water and
to produce a clear solution so that the final product will have
the essential reflecting surfaces in order to give the appearance
of a crystalline product. On the other hand, the molecular weight
of the dextrin material must be high enough so that hygroscoplcity
is avoided.
Accordingly, it has been determined that for the produc-
--5--
.. .. . .
. ~ - .
16~39567
tion of table sugar substitutes, the dextrin material should have
a D.E. in the range o~ about 4 to 20 and preferably in the range
of about 5 to 10. Additionally, it ~as been found that the best
results are obtained if the dextrin material contains an irregular
distribution of the other lower (one to eight saccharide units)
saccharides with a preponderance of the hexamer and heptamer.
Such corn syrup dextrins have been produced by means of enzymatic
hydrolysis of starch and are typified by the products available
from CPC under the name Mor-Rex.
Consequently, the aforementioned specific method of
spray-drying when applied to an aqueous solution comprised of a
dextrin preferably a low D.E. dextrin such as Mor-Rex and a lower
alkyl ester of aspartylphenylalanine, preferably L-aspartyl-L-
phenylalanine methyl ester is the preferred embodiment of this
lnvention. The spray-dried product of this invention consists of
fairly uniform small, white spheres which reflect light in a way
which suggests crystallinity are readily and completely soluble
in water and produce clear aqueous-based solutions.
The processes of this invention are further illustrated
0 but not limited by the ~ollowing examples:
EXAMPLE 1
Three grams of citric acid and one gram of L-aspartyl-
L-phenylalanine methyl ester are dissolved in 50 ml. o~ water
with stirring. The resulting solution is spread on a stainless
steel tray (2.1 sq. ft.) and allowed to dry at ambient conditions
for about two days. The dry material was then scraped from the
tray and ground with a mortar and pestle. One-half gram samples
of this ground material were added, with stirring, to beakers
containing 200 ml. of water at 40F. The material completely dis-
solved in an average time of about 55 seconds yielding solutionswhich were sweet with a slight acid taste.
EXAMPLE 2
A solution was prepared containing 800 grams of water
-6-
-r~D~
... .....
1C1~395~i7
(80F.), 241 grams of 5 D.E. Mor-Rex and 5.95 grams of L-aspartyl
L-phenylalanine methyl ester. This solution was placed in a tray
at a 1.5 inch thickness and freeze dried in a Stokes Freeze Drier~
- for 48 hours. The material was then ground to a fine powder using
a Waring Blende ~at a high speed.
EXAMPLE 3
A solution was prepared according to the method of
Example 2 and this solution was drum dried at a temperature of
130C. on a drier operating at 25 lbs./sq.in and 6.25 rpms.
EXAMPLE 4
A solution containing 384.05 grams o~ water, 241 grams
of 5 D.E. Mor-Rex~and 5.95 grams of L-aspartyl-L-phenylalanine
methyl ester was prepared. This solution was then spray dried in
a Niro Spray Dryer~at an air pressure of 5.2 kg/sq. cm., an air
inlet temperature of 160C. (320F.), an air outlet temperature
of 75C. (167F.) and a rate of solution flow of 15 co/min.
Equal weight samples of the sweetening compositions
of Examples ?, 3 and 4 were dissolved in coffee samples and were
organoleptically determined.to have a substantially equivalent
sweetness level. This sweetness level is not found to signifi-
cantly differ from control coffee samples containing an equal
amount of the untreated dlpeptide material, thus indicating the
absence of any degradation of the ~ipeptide material during the
drying operations. The rate of solubility, however, is appreci-
ably and substant~ally improved.
The solubility rate of the powders from Examples 2, 3
and 4 was evaluated by recording the times required for complete
solution of 1.5 gra~ samples of these powders (containing about
o.o36 grams of sweetener) into 170 ml. of water at a temperature
of 40F., with stirring. The results are summarized in the
table below:
40F (time in seconds)
Example 2 62
Example 3 40
Example 4 60
~k -rR~ y~ _7_
1~39567
As is evident rrom the above data, the specific method
of spray-drying utilized resulted in a product having an equiva
lent rate of solubility as the freeze-drled sample.
When 0.036 gram samples of L-aspartyl-L-phenylalanine
methyl ester are sought to be di~solved in 170 ml. of water at
40F., with s~irring, average times for complete solution run
about 30 minutes.
Additional tests have shown that varying the level of
dipeptide in the sweetening compositions up to the level of about
one part dipeptide per part of bulking agent, does not have any
appreciable or predictable effect on the rate of solution.
It has also been found that the elevated temperatures,
in excess of 100C~g which are employed during the spray drying
operation of this invention does not effect the sweetness of the
final product.
The bulk density of the final sweetening composition
can be controlled by varying the solids concentration of the solu-
tion prior to spray drying. The bulk density may also be con-
trolled by changing the method of drying, by varying the rate of
drying, or by varying the conditions of pressure under which the
solution is dried. Bulk densities ranging as low as about 0.04g/-
cc can be obtained Oy the process of the instant invention.
The addition of a small amount of an anti-caking agent
such as trlcalcium phosphate may also be used to adjust the bulk
density of the final product.
Thus, by exercising proper control over the process, it
is possible to produce a final product which has substantially the
same bul~ density of granulated sucrose or a product which has a
much lower bulk density than granulated sucrose, but which, by ad~
~usting the level of dipeptide sweetening compound, has on a
volume basis the same level of sweetness as sucrose, but a far
less caloric value. More importantly, the resulting spray-dried
product has a substantially greater rate of solubility and greater
--8--
.. . . : . .
. :~ - : -
.
1039S67
absolute solubllity in water.
EXAMPLE 5
A sweetening composition which has on a volume basis the
same sweetening power of sucrose is prepared by spray-drying a
50% solids solution containing 96.5%, 10 D.E. Mor-Rex and 3.5% L-
aspartyl-L-phenylalanine. The drier was equipped with a single
l/lTC Whirl~et nozzle and was operating with a spray pressure of
500 to 700 psig., an inlet air temperature of 400F., an air
flow of 2800 cu. ft./min., an air outlet temperature of 245F. and
a feed temperature of 155F. The spray-dried powder was screened
through a 16 U.S. mesh screen and blended with 0.1% by weight of
tricalcium phosphate. The resultant product has a bulk density
of 0.14 g/cc, has a crystalline appearance, has, on a volume basis,
the same level of sweetness as granulated table sugar and dissolves
rapidly in 40F. water.
The density obtained above can be modified, particularly
increased, by employing suitable agglomeration techniques such as
applying moisture to a falling curtain of material as disclosed in
Patents to Sienkiewicz, et al. or in belt agglomeraters or the
like.
~ ~R~
_g _
- .
. . . - , . .
.. ~ - . .. . .
