Note: Descriptions are shown in the official language in which they were submitted.
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PRODUCTION OF LOW DENSITY MATERIALS
TECHNICAL FIELD
This invention relates to the production of low
density materials possessing physical attributes
which are highly desirable in many commercial appli-
cations. The invention further relates to a method
for producing a highly flowable, low density,
material, as for example a non-dairy creamer, said
method utilizing a multi-fluid nozæle of novel
design. The multi-fluid nozzle provides for gas
entrainment in finely atomized droplets under highly
controlled conditions.
BACKGROUND OF THE INVENTION
It is known that low density spray-dried coffee
powders may be produced by dispersing a gas in an
aqueous coffee extract to produce a foam prior to
the spray-drying step. In U.S. Pat. No. 2,788,276 a
process i5 disclosed involving the introduction of a
flow of gas into a coffee extract under pressure to
form a foam, raising the pressure with a booster
pump, and feeding the foam into a high-pressure
reciprocating pump where the foam is compressed to a
still higher pressure for spray-drying. In U.S.
Pat. No. 3,749,378 a mixing device is disclosed
which comprises an inlet for gas and an inlet for
liquid which lead into a mixing zone. The mixing
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zone is conne~ted to a second zone containing a
plurality of spaced plates through which coarse foam
passes and is discharged as a fine foam. Similarly,
U.S. Pat. Nos. 4,129,624 to Kate~ and 4,160,002 to
05 Janovtchik disclose fluid mixing or injection devices.
However, these references and the art as a whole
fail to provide a system for producing a low density
material with an acceptable level of proces~ control
such that a low density material may be produced
with a consistent and controllable density, particle
size distribution, and flowability. Further, the
prior art systems require downstream handling of a
foamed material, as for example pumping, which is
inherently inefficient and troublesome in a commercial
environment
Several references teach that a non-dairy
creamer may be used in preparing a prelightened
coffee composition. Non-dairy creamers normally
contain fat, protein and carbohydrate. The ingredi-
ents are normally formulated as an emulsion which issubse~uently dried, preferably spray-dried, and
either sold as a bulk powder or further blended with
other ingredients in preparing a final product. Two
such references are Einstman et al. in U.S. Pat.
No. 3,706,572 and Mancuso et al. in U.S. Pat. No.
3,653,911. The Einstman et al. reference teaches
homogeneously blending spray-dried coffee solids and
spray-dried non-dairy lightener solids, grinding the
blend to a particle size range of 90 to 150 microns,
and agglomerating. Mancuso et al. teach blending a
non-dairy lightener and a coffee percolate and then
spray-drying. The improvement advanced by Mancuso et
al. is the incorporation of a part of the buffering
agents normally found in the lightener into the
coffee percolate instead.
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Gardiner in U.S. Pat. No. 4,046,926 teaches a
process for preparing a non-dairy creamer which
exhibits an improved resistance to "feathering",
where feathering describes the precipitation from
05 solution of serum protein in the presence of an
unfavorable acid-salt environment. Gardiner employs
a mixture of sodium carbonate and dipotassium hydrogen
phosphate to achieve this desirable result.
The physical attributes o~ a material such as a
non-dairy creamer are exceedingly important in
applications where the material is blended with
other ingredients so as to produce a final dry-blended
product. Some of the attributes which are particularly
important in this regard are particle size distri-
bution, density, and flowability. Particle sizedistribution is important in producing a dry-blended
product which maintains its homogeneity during
shipping and storage. Density is critical to deli~er-
ing the proper recipe level of the material in a
given serving preparation. Flowability is essential
in ensuring smooth handling of the material during
processing.
The physical attributes of a spray-dried material
are generally controlled by the conditions attendant
to the drying step. A need has developed to produce
materials having a density considerably lower than
previously practiced in the art, while at the same
time having good flowability and a particle size
distribution which ensures homogeneity in a dry-blended
product. This need is particularly pronounced for
product formulations wherein it is desired to replace
sugar with a non-caloric sweetener such as aspartame,
since a dramatically lower level of aspartame is
necessary to achieve the same level of sweetness
perception.
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Thus, it is an object of the invention to
produce spray-dried materials having a low density,
while exhibiting good flowability, an acceptable
particle size distribution, and acceptable organo-
05 leptic characteristics.
It is another object that a method for producinga low density material be efficient and controllable.
These and other objects will become apparent as
the invention is described below.
SUMMARY OF_THE INVENTION
It has been found that the objects of the
invention are met by a novel method of spray-drying.
According to the invention, a uniquely designed
spray-drying nozzle is employed which enables injec-
tion of a gas into an aqueous stream prior to its
introduction to the spray-drying chamber. The
nozzle is of a multi-fluid design and it acts to
atomize an aqueous stream into fine droplets and
then enable injection of a gas into the atomized
droplets, before spraying the droplets into the
drying chamber.
Accordingly, a low density material is produced
having a desirable particle size distribution and
excellent flowability. The drying conditions are
controlled to produce a dried material possessing
good organoleptic quality. Materials produced
according to the invention are suitable for many
applications, but particularly for dry blending in
product formulations where sugar is being replaced
by a non-caloric sweetener such as *aspartame.
*Trade Mark
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BRIEE DESC~IPTION OF 1~ DRAWING
The foregoing and other features and advantages
of the novel method and apparatus for atomizing and
gas injecting a material in accordance with the
05 teachings of the present invention may be more
readily understood by one skilled in the art, refer-
ence being made to the following detailed description
of several preferred embodiments thereof, taken in
conjunction with the accompanying drawing.
Figure 1 is an elevational sectional view
illustrating an embodiment of a two-fluid nozzle
constructed in accordance with the teachings of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
The mutli-fluid nozzle of the present invention
provides a means for atomizing an aqueous stream
into fine droplets, a means for injecting a gas
stream such that gas is entrained in the atomized
droplets, and a means for spraying the atomized, gas-
entrained droplets into a chamber, typically a
drying chamber. The multi-fluid nozzle permits
controlled gas injection at a point immediately
before the atomized droplets are introduced to the
drying chamber, thus eliminating any need for pumping
of a gas-entrained agueous stream. Because the
multi-fluid nozzle allows such excellent control of
the rate and degree of gas entrainment, an end-product
may be produced having a desirable density, flow-
ability and pa~ticle size distribution.
The multi-fluid nozzle of the invention is
suitable for use with any agueous stream. The
solids concentration of the stream effects the
degree to which gas is entrained in the atomized
droplets and the evaporative load placed on the
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drye~. A more dilute aqueous stream places a higher
evaporative load on the dryer and will tend to entrain
more of the injected gas per pounds solids than a
more concentrated aqueous stream, as would be apparent
05 to one with ordinary skill in the art. Additionally,
the concentration of the aqueous stream will impact
on the operating parameters selected within the
drying chambe~ and thereby will have an effect on
the flavor and other organoleptic characteristics of
the finished product. Thus, the concentration of
the aqueous stream entering the multi-fluid nozzle
is selected based on many criteria well within the
ordinary skill of one in the art for a given appli-
cation of the invention.
The invention may be applied to aqueous streams
such as coffee extracts, aqueous mixtures of flavor-
ants, acids, emulsifiers, etc., and has been found
to be particularly suitable for use with an aqueous
non-dairy creamer stream. Non-dairy creamer formu-
lations typically contain a fat, a protein, and a
carbohydrate. Such formulations may also contain a
buffer, flow agent, and emulsifying agent, as is
well known in the art. For the purposes of illustra-
tion, the discussion below will be directed to
producing a low density non-dairy creamer, but such
discussion is limited thereto merely for the purposes
of illustration. The scope of the invention, however,
is not limited thereto, but encompasses the production
of low density products from any aqueous stream.
The invention may be more fully understood by
reference to Figure 1, which is an elevational
sectional view of a two-fluid nozzle lO constructed
pursuant to the teachings of the invention. In this
embodiment of the invention, the aqueous stream
enters the nozzle through a conduit 12 provided in
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its ~ight-hand portion (as viewed in Figure 1) and
is first directed radially inwardly and then axially
downwardly through an aperture 14 formed in the
central portion of the nozzle. An insert 16 is
oS located in the lower portion of the aperture 14
serving to atomize the aqueous stream into fine
droplets. A second conduit 18 is located in the
left-hand portion of the nozzle (as viewed in
Figure 1) for the introduction of a gas. The gas
flows ~hrough the conduit 18 to an annular manifold
20 positioned about the downwardly-extending aperture
14, and downwardly through a gas injection aperture
22 to a gas injection chamber or gas cap 24, in
which gas is entrained in the finely atomized drop-
lets.
The gas cap 24 is fully sealed except for theaperture 14 with insert 16, the gas injection aperture
22, and spray aperture 26 through which the gas-
entrained finely atomized droplets exit. As such,
the gas cap is generally at a positive pressure,
typically at or near the pressure of the gas as it
enters the second conduit 18. The gas-entrained
droplets typically enter a drying chamber ~not
pictured) after exiting the spray aperture 26, in
which the droplets are dried to a powder.
While Figure 1 illustrates a preferred embodi-
ment of the multi-fluid nozzle of the invention,
other nozzie configurations providing for the atomi-
zation of an aqueous stream into fine droplets and
the entrainment of a gas in said droplets, fall
within the scope of the invention. The nozzle
components are typically constructed of a metal or a
plastic material of sufficient hardness. Stainless
steel is a preferred metal of construction and is
suitable for food processing. The insert 16 shown
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in Fi~ur~ 1 is typically of a harder material of
construction, as for example tungsten carbide.
Any gas may be employed according to the inven-
tion. Gases such as air, carbon dioxide and nitrogen
05 are particularly suitable because they are relative-
ly inexpensive and inert. The pressure at which the
gas is injected is a critical control parameter in
determining the physical properties of the end-
product, particularly the end-product density. For
example, when operating with a non-dairy creamer
stream, a gas pressure of about 60-80 psi yields
about a 20-40% density reduction versus a control.
Having thus described the invention, the inven-
tion is further illustrated by reference to the
following examples.
EXAMPLE I
A non-dairy creamer stream was prepared by
blending the ingredients from Table I with water
such that a solids concentration of 60% by weight
was achieved. The aqueous stream was agitated for
30 minute~ to ensure homogeneity.
TABLE I
Ingredient Weight Percent
Hydrogenated Coconut Oil 47.0
Corn Syrup Solids 40.8
Sodium Caseinate Solids 5.8
Dipotassium Phosphate (Buffer) 2.6
Glycerides 1.7
Sugar 1.7
Silicon Dioxide (Flow Agent) 0.3
Lecithin (Emulsifying Agent) 0.1
100.O
The aqueous stream was fed to a two-fluid
nozzle of the design illustrated in Figure 1. The
stream was thus atomized into fine droplets. Air
was fed to the nozzle as the second fluid at a
05 pressure of about 60 psi. The finely atomized
droplets exited the nozzle entrained with air into a
drying chamber and were dried to a powder.
The physical attributes exhibited by the non-
dairy creamer produced are summarized in Table II.
TABLE II
Density 0.26 gm/cc
Flowability 43 cc
Particle Size Distribution
(U.S. Sieve)
+ 30 Mesh %
+ 60 Mesh 10%
+ 140 Mesh 70%
Pan 20%
Moisture Content 1.2%
pH
A control run was made using an aqueous stream
identical to that described above. The control
stream was dried using a typical high pressure
nozzle as is known in the art, i.e., absent gas
injection.
The control non-dairy creamer exhibited the
physical attributes summarized in Table III.
TABLE III
Density 0.45 gm/cc
Flowability 43 cc
Particle Size Distribution
+ 30 Mesh 0%
+ 60 Mesh 10%
+ 140 Mesh 70%
Pan 20%
Moisture Content 1.2%
pH 7.5
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As is apparent, a 42% reduction in density was
achieved by practicing the present invention, but
other physical attributes were uneffected. An expert
panel judged both the control and low density non-
oS dairy creamer to be of good quality, with no discern-
ible flavor difference be~ween the two samples.
EXAMPLE II
An aqueous stream containing tea solids at a
concentration of 20% by weight was fed to a two-fluid
nozzle of the design illustrated in Figure 1. Air
was fed to the nozzle as the second fluid at a
pressure of about 60 psi. The aqueous stream was
atomized into fine droplets and air was entrained in
the fine droplets within the nozzle. The air-
entrained fine droplets were then sprayed from the
nozzle and dried in a drying chamber. The density
of the spray-dried tea was found to be 0.21 gm/cc.
A control run was made by spray-drying the same
aqueous tea stream using a standard high pressure
nozzle with a final density of 0.46 gm/cc being
obtained. The products were very similar in all
other physical and organoleptic attributes.
