Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
W09~/06308 .; 2 1 2 ~ O 1 0 PCT/US93/07429
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Description ~
Flavor Enca~sulation ~-
Technical Field
The present invention relates to techniques to
encapsulate materials which can undergo compositional
changes in process and/or storage. Such encapsulation
improve~ material shelf-life and usefulness in the
preparation of products such as foods.
Backqround of the Invention
It has long been recognized that it is desirable to
encapsulate materials so as to protect them from
volatilization, the degradation effects of oxygen and heat,
moisture, internal and external molecular interactions and
the like. Flavors are complex substances made up of
multiple chemical components, some comparatively stable,
some extremely volatile, others unstable to oxidation and
reactive interactions and the like. Many flavorants contain
top notes (i.e., dimethyl sulfide, acetaldehyde), which are
quite volatile, vaporizing at or below room temperature.
These top notes are often what give foods their fresh
fla~ors.
Numerous techniques have been suggested and many
commercialized for the encapsulation of flavors. However,
all of these techniques suffer from one or more
deficiencies. One of the most common techniques for
encapsulating flavorants is spray drying. While this
procéss directly produces a finely divided product which can
be readily handled and used in the preparation of finished
foods, spray drying suffers from several serious
deficiencies. ~First, it is difficult to incorporate top
notes into spray dried flavorants in an efficient manner.
Inherent in spray drying is the loss of volatile materials.
Furthermore, materials which are heat and/or oxygen
sensitive are adversely affected by spray drying. The
effect of heat, oxygen and volatilization can make a
substantial change in the materials' composition, which in
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turn results in undesirable changes in flavor
characteristics.
Freeze-drying solutions of matrix materials containing
either dissol~ed or dispersed flavors has also been used to
produce encapsulated flavors These methods generally
result in losses of highly volatile components, and products
having a foamy, porous structure.
Yet another technique which has been employed is that
of melt encapsulation of materials in carbohydrate matrices.
In this application a carbohydrate melt is prepared and the
encapsulate is added. The resulting solution is introduced
into a quenching medium to produce a solid carbohydrate
product containing the flavor. This technique while
successful, is again, limited to comparati~ely high boiling
point flavors because the carbohydrate solution is produced
and delivered to the quenching medium at elevated
temperatures. This technique inherently can result in the
loss of some of~the Iow boiling point constituents in the
flavor. Because of such losses, it is common to enhance the
flavorant by adding extra low-boiling components. The
conventional quenching agent which is commercially employed
is lsopropyl alcohol. The traces of the isopropyl alcohol
remaining in the product after quenching can be detrimental.
The~patent claims for~this technique limit the materials
which can be encapsulated to those which are immiscible in
the matrix. An~additional disadvan~age of the product
resulting from;this process is that although reasonably
dense, the product may contain microporosity when low
boiling point components are present in the flavor. The
~microporosity increases the surface area, and thus, may
increase the evaporation of volatiles and the potential for
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degradation of the product by interaction with atmospheric
oxygen. Furthermore, the effect of the microporosity is
enhanced as the product is sold in a finely divided state,
which increases the surface area of the particles and thus
W094/06308 2 12 ~ O 10 PCT/US93/~7429
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the possibility that degradation of the flavor will occur if
the product is stored over a period of time.
The above encapsulation technology was first developed
using batch type melting and mixing equipment. These
techniques have been improved as described in U.S. Patents
4,610,890 ('890~ and 4,707,367 ('367). In these patents~ a
proce~s is described for preparing a solid, essential-oil
containing composition. This composition is prepared by
forming an aqueous, high-solids solution containing a sugar,
a starch hydrolysate and an emulsifier. The essential oil
is blended with this aqueous solution in a closed vessel
under controlled pressure conditions to form a homogenous
melt which is then extruded into a relatively cold sol~ent,
normally isopropanol, dried and combined with an anti-caking
agent after grinding. A discussion of these and other prior
art techniques for encapsulating materials can be found in
U.S. Patent 5,009,900. The patents '890 and '3Ç7 su~fer
from the same deficiencies noted in prior art techniques,
i.e., loss of volatile compounds and limitations to
mmiscible flavor encapsulates.
While the above described solidified melt encapsulation
technology was first developed using batch type equipment,
more recently similar continuous processes have used
extruders to produce encapsulated products. One problem
encountered in extrusion is the difficulty in obtaining an
encap~ulant which will melt under reasonable extrusion
temperatures. An additional problem with extruded products
under typical melting temperatures is that the product will
expand and foam upon exit from the extruder head due to
expansion of contained volatiles. The objective in
encapsulation is to form a hard, dense, glassy type
encapsulant. One approach is that described in U.S. Patent
4,820,534 ('534). This patent suggests utilizing as the
encapsulant a mixture of two materials, one having a high
molecular weight and the other having a low molecular
weight; as a result, the mixture may be successfully
W094/06308 PCT/US93/074~29
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extruded. During extrusion, according to ~534, the minor
component melts and the major component dissolves into the
minor component. The volatile flavorant becomes dispersed
or solubilized within the molten mass which upon cooling
produces a single phase matrix. In order for volatile
components to be re~ained, and expansion of the matrix
prevented, it is necessary in the process of '534 to
minimize the temperature at the extruder head. If the
material exits the extruder at a higher temperature,
volatiles will be lost from the mixture. The '534 technique
need~ to utilize as the encapsulant a mixture of materials,
one having a melt~ing point sufficiently low such that the
remainder wilI melt into it thereby becoming extrudable
under reasonable process conditions.
U.S. Patent 5,009,900 ('900) is directed to a procedure
very similar to that of '534 only using a more complex
mixture of materials to form the encapsulant material. The
'900 patent requires a water-soluble, chemically-modified
starch, maltodextrin, corn syrup solids ~nd mono- or
di~accharides. The flavorant is mixed into the mixture and
the result is extruded~.
It would not be possible with either of the techniques
of '534 or '900 to encapsulate pure low boiling point
materials such as acetaldehyde in a dense matrix at
commercially significant loads since the resulting product
would foam due to the vaporization of acetaldehyde as it
exits the extruder. Furthermore, in both techniques one is
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restrained by processing considerations in the selection of
encapsulate material. Similar techniques are taught in U.S.
Patent 4,232,047 ('047). The process of '047 proposes to
encapsulate a seasoning or flavoring such as oleoresin,
essential oils and the like in a matrix of starch, protein,
flour and the like. This technique involves the use of
extrusion under high pressure. However, like the other
techniques, it is limited in the materials which can be used
as the encapsulating agent and the materials to be
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encapsulated therein. The temperatures involved could cause
the loss of volatile top notes.
Another example of the technology which is available is
U.S. Patent 4,689,235 ('235) which like '900 and '534 is
directed to specific matrix materials for use in
encapsulation. This patent relies upon the use of an
emulsifier to achieve success.
As evidenced by the foregoing patents, significant
effort has been expended in attempting to develop a
successful method for encapsulating volatile and/or unstable
flavors using solidified melts. These techniques would have
~; the advantage over spray drying in that the product, if a
dense matrix can be formed, would not be porous like the
spray dried product, thus the flavor encapsulate would be
more stable. It would be anticipated that such products
would have a long shelf life. However, these technologies
do not assure a non-porous product when the pressurized melt
exits to ambient pressure and temperature.
In addition ~o the foregoing deficiencies which have
been noted in the prior art techniques, still other
de~ficiencies are that each of these processes is very
specific to the~encapsulating composition. That is, they
significantly~restrict the compositions which can be used as
e~capsulants~to a very narrow range.
In producing encapsulated products~ it is desirable
that the encapsulant have a softeniny temperature
significantly above~room temperature. If th~ softening
temperature is low, the material will become tacky, forming
lumps which are difficult to handle and process. Patents
'534 and '900 suggest utilizing complex mixtures of
materials as the encapsulant, such that the xesultant matrix
is in t~e glassy state with softening temperatures greater
than 40C.
While solidified melt techniques have, to greater or
lesser extent, been utilized commercially to encapsulate
some flavorants in dense amorphous matrices, there are many
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W094/06308 PCT/US93/~7429
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flavorants which simply cannot be encapsulated by existing
technology. For example, flavorants which are normally
commercially produced in the form of a solution simply
cannot be encapsulated at useful levels using existing
techniques if the solvent plasticizes the matrix m-aterials.
With fla~orants such as vanilla extract, it is impossible to
remove the water/alcohol solvent without adversely affecting
the properties of the vanilla. Even in concentrated form,
there still would be appreciable solvent present.
Accordingly, vanilla extract has not been successfully
encapsulated at commercially useful levels using the above
techniques. Therefore, a need exists for a new process to
produce dense, non-porous matrices to encapsulate materials
that exist in high concentrations of solvents.
Disclosure of the_Invention
Accordingly, it is an object of the present invention
to provide a process to encapsulate a wide range of
h materials, including flavorants, fragrances, colors,
pharmaceuticals and the like, without the loss of volatile
materials, oxidative degradation, molecular reactions and
other adverse interact1ons with the environment.
Further, it i~s another object of the present invention
to provide a process for encapsulating both miscible and
.~ ,
` immiscible materials.
:
It is yet another object of the present invention to
provide an encapsulating system for flavorants which are
normally dissolved in water, alcohol or other volatile
solvent systems.
It is still a further object of this invention to
provide a technique for encapsulating flavor components
which have low boiling points in a dense non-porous
encapsulant.
It is stiIl another object of the present invention to
provide a process which allows the use of encapsulating
WO 94/06308 2 1 2 ~ O 1 0 PCT/US93/07429
materials which would normally puff or foam when the melt is
released from pressure.
It is also an object of the invention to prevent
molecular migration by the formation of the dense amorphous
solid, thus reducing molecular interactions and changes.
These and other objects of the invention which will
become apparent from the description hereafter, have been
achieved by a process wherein a melt is made of the
encapsulant and encapsulate; and the molten matrix
containing the encapsulate is cooled by overriding solid,
liquid, or gaseous pressure into a dense amorphous matrix.
A second emhodiment involves forming a melt containing
an encap~ulate dissolved in a sol~ent and an encapsulating
matrix which is optionally subjected to an elevated
pressure, followed by venting to remove at least some o~ the
solvent while largely retaining the encapsulate in the
product.
In this invention, the dense amorphous, essentially
noncrystalline solid encapsulant may be described in many
cases ~ut not exclusively by those knowledgeable in the art
as a 'glass' as characterized by a glass transition
temperature.
Brief Desc_i~tion of the Drawinas
Drawing 1 is an illustration of the present process
where ~he fIavor component to be encapsulated is introduced
into the extruder where a matrix material has been melted.
The drawing shows both atmospheric and pressurized discharge
points. These were used in examples to produce comparative
samples.
Drawing 2 is an illustration of another embodiment
wherein the matrix is first melted in an extruder and the
flavor and melted matrix material are mixed in a static
mixture and then recovered. The drawing shows both
atmospheric and pressurized discharge points. These were
used in examples to produce comparative samples.
WO9~/~6308 PCT/US93/07429
2124010 -8-
Drawing 3 is an illustration of the present process
where the flavor component is diluted in a volatile solvent
and said solvent is removed via venting.
Drawing 4 is a generalized overview of process sequence
steps which can be utilized in the present process.
Best Mode For CarrYing Out The_Invention
In the present process, melting equipment (herein
referred to as "melter") is utilized to convert the matrix
from solid to liquid form. The components of the matrix are
introduced into a melter where they are liquefied. The
melting may be accomplished in a batch containment. The
melter also can be simply a device transporting the matrix
through a heating zone wherein sufficient heat is introduced
to convert the matrix to liquid form, i.e., melted. The
pxocess can utilize a conventional single or twin screw
extruder having mixing zones, homogenizing zones, melting
zones, venting zones and the like as is conventionally known
in the art. The matrix materials may be composed of a
variety of melting compositions so that the resulting dense
matrix will not become s~icky and agglomerate at lower
temperatures yet will melt/dissolve at under normal
application cond1tions an~ temperatures as described in the
prior art. Any meltable matrix ingredient can be utilized.
When utilizing materials having a low melting
temperature, it is often possible to directly melt the
material in a suitable processor. As described in the art,
it may be necessary with high melting temperature materials
to utilize a solvent with the purpose of generating enough
"plasticity" to the matrix materials so they can be
processed successfully. The amount of solvent added
generally is insufficient to dissolve all of the matrix
materials, but is sufficient only to increase plasticity.
The minimum amount of solvent is utilized which pxovides
enough plasticity to the matrix ingredients such that they
W094/06308 2 1 2 ~ O 1 0 PCT/US~3/07429
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can be successfully processed. The optimum amount of
solvent for use varies from matrix to matrix.
The solvents which can function as the plasticizer
include any liquid material in which the matrix is soluble.
Typical solvents include water, water-ethanol, glycerin,
propylene glycol and the like. An optional process step,
venting, can be added where some or all of the solvent can
be removed. FoIlowing, the encapsulate is then mixed into
the matrix. Essentially any encapsulate, insoluble,
slightly soluble or miscible in the matrix may be employed
in this particular embodiment. In cases where the
encapsulate exists as a solution in a volatile solvent ~e.g.
water, alcohol), the melt may be vented to substantially
eliminate the encapsulate solvent.
Cooling of the melt can be accomplished at ambient
conditions, with cooled gas, by direct contact with metal
belts or rolls, or by quenching in a suitable sol~ent, as in
the prior art, or most preferably as introduced by the
invention, under pressure so as to prevent "puffing" or
expansion of the matrix material into a non-dense, porous
form.
When one is concerned with either reducing the
microporosity of the matrix~or with encapsulating volatile
components, this embodiment can be performed using a wide
variety of apparatus to form the melt and to extrude it
through a die into the pressurized zone. The simplest
:~
technique is to form a melt using the procedures described
in U.S. Patents 4,610,890 and 4,707,367. These techniques
utilize a batch reactor to form the melt. In this
technique, the matrix material with suitable solvent is
introduced into the tank and melted. Once the melt has been
established, then the material to be encapsulated is added.
It is possible to ~ary this procedure w~ere the material to
be encapsulated also functions as a solvent for the solid
matrix material. In this instance, the encapsulate and
solid matrix are added together without the use of any
W094/06308 PCT/US93/07429
2124010
separate solvent and the melt established. The tank or
vessel in which this is accomplished, can either be opened
to the atmosphere or closed. It is particularly preferred
that the vessel be a pressure vessel and closed during the
process so as to reduce the losses of any volatile
components in the material to be encapsulated. If the
volatile component~ comprise a significant portion of the
encapsulant, then pressure should be established in the
vessel so as to reduce the vaporization of the low boiling
components in the vessel and thereby increase their yield.
Once the melt has been established, the vessel can then be
- pressurized further, if necessary, and the pressure in the
vessel used to force the melt through the die into a
solidification zone. Prior art as described above used an
ambient pressure solidification step. The present invention
introduces the use of a pressurized solidification zone
having a pressure sufficient to preclude the vaporization of
the significant portion of the volatile components in the
melt during solidification. The pressure in the
solidification zone is ~hosen to be sufficient so as to
prevent puffing or microporosity. The melt can be delivered
by either the pressure of the containment or by a pump to
the die. Other~techniques for forming a melt containing the
matrix and encapsulant can also be used. Essentially any of
the techniques de~scribed in the prior art for forming a
mixture of matrix and encapsulant can be used. On a
continuous basi~s, the~use of extrusion is preferred. When
simple suyars are used as the matrix, the heat necessary to
~i~ - form the melt can be provided by the mechanical working of
the screw alone or in cooperation with external sources of
heat. Heated extruders for use in the food industry are
well known and can be used for this purpose so that heat
from both the external sources, such as the steam jacket
around the extruder, as well as from the mechanical working
of~the extruder can be used.
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When it is necessary to use a separate solvent to
plasticize the matrix prior ~o introducing the encapsulant,
the plasticizer/matrix melt may have its pressure reduced so
as to vaporize a portion of the plasticizer. This reducing
of pressure or venting to vaporize a portion of pIasticizer
may occur either before or after the encapsulate is
introduced into the ma~rix into the melt when the
encapsulate is of low volatility. If it is a highly
volatile encapsulate then, the venting should occur prior to
introduction of the high volatile component. After the
highly volatile component is added, the mel~ is then
extruded through a die and pressure cooled. Venting is
particularly advantageous for use with encapsulates which
are dissolved in a solvent which also function as
plasticizers for the melts. Where both plasticizer and
encapsulate are used and the matrix is soluble in both, the
reæulting solid product may have undesirable properties,
such as tackiness, softness at low temperatures and a
tendency to agglomerate. One techni~ue for a~oiding ~hese
problems is to simply use a total quantity of plasticizer
and encapsulate which results in the desired properties.
This procedure would restrict the loading of encapsulate
which can be used. By venting the plasticizer, it is
possible to incorporate higher quantities of encapsulate
into the matrix without adversely affecting the properties
of the final product.
~; When venting is used, it is necessary to repressurize
the melt after the venting so as to eliminate from the melt
any bubbles which might have been caused by venting of the
solvent. In an extruder, this is easily accomplished using
appropria~e screw configurations. In other techniques,
introduction of the melt into a melt pump after venting can
accomplish the same purpose. The degree of repressurization
depends upon the degree of pressure necessary to remove the
voids which were formed in the matrix by the venting and be
sufficient to allow extrusion through the die into the
W094/06308 PCT/US93/074~
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pressurized zone where cooling or solidification of the melt
occurs.
While the foregoing discussion has presupposed that it
is necessary to utilize a plasticizer and/or encapsulant to
form the matrix melt, some matrices can be melted directly
without the use of plasticizer and the encapsulate directly
introduced into this melt. With such matrices, venting is
not necessary. Further, when.one is encapsulating an
immiscible encapsulate, venting does not increase the total
amount of encapsulate which can be incorporated into the
matrix since the immiscible encapsulates have only a small
effect upon the phys~ical properties of the final product.
In such instances, the removal of plasticizer is used
primarily to control the properties of the final product.
The use of large~ quantities of plasticizer tends to produce
a softer and tackier product than reduced quantities of
plasticizer in general. ~When the finished product is tacky,
it may be overcoated with a material to reduce tackiness.
Furthermore, in~the case of a soft product, there is more of
a tendency for the~encapsulate to migrate to the surface and
possibly to evaporate from the product. In such instances,
t~is~possible to~overcoat the product with a hard coating
which prevents~or reduces such migration and evaporation.
Figure 1 illu~strates one method by which the process
can~be accomplished.~; ~In Figure 1, the matrix material is
introduced into~a continuous melter where it is melted. If
necessary, ~the~solvents~described;above will also be used to
assist in the~melting process. In the mixing zone of the
meltér 03, the inj~ected encapsulate is mixed into the
matrix. The matrix~is then extruded and cooled to form the
encapsulated product. The extrusion may be directly from
the melting equipment under pressure or, as shown in Figure
1, a melt pump 06 may b:e employed to feed the extrusion die.
In Figure 1, alternative methods are illustrated for cooling
the encapsuiated material. Discharge of the molten
matrix/encapsulate;mixture to atmospheric pressure
212~01~
WOg4/~6308 PCT/US93/07~29
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-13-
illustrates the state of the art technique. For the
embodiment of the current invention, the mixture of matrix
and encapsulate is introduced into a pressure vessel, 08,
where it is formed through a nozzle 09 into a
continuous/batch pressure confinement. In this particular
embodiment the pressure is provided by any gas, if
necessary, food grade and/or inert, such as nitrogen,
helium, or the like in pressure holding vessel 13. Pressure
cooling is utilized wherein either the encapsulate contains
a substantial quantity of volatile components, that is,
components having boiling points substantially below the
temperature of the melt.
After cooling under pressure, the product generally
needs size reduction by grinding or the like to provide a
free flowing matérial which is readily mixed with other
components. If extruded, the nozzle utilized to extrude can
:
be any type of nozzle and the size of the strands to be
extruded is not critical. Typically, a "spaghetti" type
nozzle will be employed so as to minimize the amount of
particle size reduction which must be accomplished
mechanically.
Numerous techniques exist in the plastics industry to
chop or otherwise reduce in size long plastic strands for
subsequent sale~and use. Similar types of size reduction
apparatus can be utilized in the~present process. Some
extrude~s have been sold where the face of the die is wiped
continuously by knives to immediately reduce the exiting
material to the desired size while plastic, and the thus
di~ided material quenched in a suitable coolant. Such
techniques can be applied in the present process as well.
An alternative method of recovering the product is to
extrude the material into a pressurized mold and then
allowing the material to solidify into a dense, nonporous
mass. The mold can be cooled to assist in this process. In
this partlcular embodiment, it would be preferable to employ
injection molding type apparatus such as is well known in
W094/06308 PCT/US93/0~429
212~010 -14-
the plastics forming industry. In an injection molding
apparatus, the molds are normally closed and the material
injected under pressuxe and cooled before the mold is
opened.
A further alternative is to introduce the melt under
presqure into a body of liquid having a sufficient liquid
head so as to establish a pressure at the point of melt
introduction sufficient to preclude substantial
volatilization of the volatile component. Essentially any
liquid can be used for this purpose, however, food grade
liquids are preferred. Alternatively, overriding gas
pressure can be used over the body of liquid to assist in
establishing the pressure at the point of melt introduction
inbo the liquid body.
In pressiure~cooling, the pressure is chosen to be
sufficiently high so as to prevent foaming of the matrix if
the matrix expands due to the vapor pressure of the
plasticizer, solvent, or encapsulate. The amount of
pressure necessary can ~e readily determined by simple
experiment~tion. In the case of volatile components, the
pressure should be;greater than the vapor pressure exerted
by the volatile components at the molten product exit
temperature. Many materials, e.g., the essential oils like
orange oil, lemon oil and the like do not necessarily
re~ulre pressure~cooling since they tend to contain only
small quantities of~hlghly volatile materials. However,
when these materials~are enhanced with low boiling point top
notes such as acetaldehyde, pressure cooling may offer
advantages in reducing the microporosity of the finished
product. The use of pressure cooling or atmospheric cooling
with these materials is a matter of choice.
In an alternative embodiment, illustrated in Figure 2,
the encapsulate is not introduced into the melter directly
but rather is introduced either immediately prior to or into
a static mixer into which the melted matrix ingredients are ~
also introduced. The static mixer is illustrated as item
~r~ r~ ,,.r~;;S)~ r,~,~"(,r,~ ,,,s;~ ,~r.,~ , r~ ~?V~ ,tr~p,fi
W094/06308 2 1 2 ~ 0 1 0 PCT/US93~07429
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07, Figure 2. The remainder of the system is similar to
that illustrated in Fisure 1. In this embodiment, it is
anticipated that the encapsulate in vessel 12, will be fed
to a pressurized con~ainer, 04, and then pumped to the
static mixer. However, the use of a pressurized container
is dependent on the volatility of the encapsulate. In this
embodiment, as in the previous embodîment, the plasticizer
solvent can be vented from the system before the matrix and
flavor components are admixed. Further, the melt pump, 06,
can be omitted if the molten matrix is introduced directly
from the continuous processor into the static mixer. In
this embodiment, the encapsulates which are employed are
typically those which have high solubility in the molten
matrix, or disperse easily at the desired concentration
level. In addition, this system also finds particular use
when highly volatile components are to be encapsulated. The
use of pump 05 and melt pump 06 facilitate the injection of
low boiling point components into the molten matrix. The
remainder of the process after the static mixer is the same
as for the previous embodiment. Examples of products which
can be encapsulated~by thls technique include fragrances,
colors, flavors, pharmaceuticals and the like.
Another embodiment of the invention illustrated in
Figure 3 is involved when encapsulating materials that are
diluted in large~amounts of volatile solvents that
plasticize the matrix. When this is the case, the process
would consist of an initial melting zone, a flavor mixing
.
zone, a venting zone~from which the solvent(s) are allowed
to escape, fol~lowed by a re-pressurization zone and
~; subsequent forming and cooling. Cooling could take place at
either ambient or pressurized conditions, depending on
matrix composition, process parameters, and encapsulate.
The equipment which can be used for this process can be
:
; essentially the same as that described above. In general,
the solvents in which the materials to be encapsulated are
dissolved are also sol~ents for the matrix materials. Thus,
W094/06308 PCT/US93/07429
~ 12kO10 -16-
the use of a separate solvent in the formation of the melt
is optional. However, the use of a separate solvent may be
useful to eliminate losses of the desired components during
the phase in which the solid matrix is being converted into
a melt. The melt may be formed either in a batch process
using a tank or large vat as discussed previously or through
the use of extruder technology also as discussed previously.
The melt is then vented at atmospheric pressure or under
vacuum depending on the desired level of solvent removal,
vapor pressure of the solvent itself, vapor pressure of the
encapsulate, and molten matrix characteristics. The
temperature is determlned primarily by the conditions under
which the venting of the melt is to occur and by the
inherent vapor~pressure of the solvent or solvents to be
removed. If venting is accomplished to atmospheric
pressure, higher temperatures are required than if vacuum
conditions are used to vent. Once the melt has been vented
to remove the desired q~antity of solvent thereby
concen~rating the encapsulate, the matrix is repressurized
so as to remove any voids which are formed during the
venting and then formed through a die. The amount of
solvent to be removed differs depending upon the matrix, the
final properties deslred in the solidified product, and
loading. For hard, dense products more solvent must be
removed than if the final product is to be soft. The
product at this point~may be either cooled under ambient
pressure or under elevated pressure as described previously.
Furthermore, once the matrix has been repressurized after
venting, additional encapsulates may be introduced if
desired. If these additional encapsulates are volatile,
then it is preferred that the melt be extruded into a
pressurized zone having sufficient pressure so as to
preclude vaporization of significant quantities of the
volatile components during solidification.
This technique has ~he advantage of allowing one to
effectively concentrate vanilla solutions which have
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W094t063~ 2 1 2 ~ O 1 0 PCT/USg3/07429
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generally been difficult to concentrate because of the
sensitivity of vanilla to degradation. It is believed that
the matrix serves to stabilize the ~anilla during the
process.
These process steps are illustrated in one embodiment
in Figure 3. Matrix materials are fed continuously to
Melter 1 where they are melted prior to flavor injection.
The matrix/flavor mixture i5 discharged to the feed port of
Melter 2. Volatile solvents are vented out of the feed port
of Melter 2, while the flavor containing melt is conveyed
forward and discharged. In this embodiment, the material is
fed to a melt pump which conveys the matrix/flavor mixture
to forming and cooling operations. Of course, the melt pump
is optional. ~ot shown in this illustration is the linkage
of this process with presæure cooling which would be
desirable in some cases. Flavorants which can be
encapsulated in ~his technique include:
lavor Volatile Solvents Wt ~ oriq. flavor
weight matrix
Natural Water, ethanol 10 - 50
extracts
Meat hydroly-
sates Water 10 - 50
Aqueous
reaction
flavors Water 10 - 50
Compounded
flavors
containing
solvents Water, ethanol 10 - 50%
Additionally, the invention provides for a further
enhancement of the above technique by a secondary injection
of volatile encapsulates after venting of the solvent from
the primary encapsulate and re-pressurization. This,
especially when combined with the previously described
WOg4/063n~ PCT/US93/0742c9
.....
~2~l 0 -18-
pressure cooling, allows the encapsulation of a massive
variety of encapsulate compositions.
A further variation on the above processes just
described involves venting the melting equipment to remove
the solvent which has been added to serve as the plasticizer
before injection of the flavor component. Thus, if the
solvent utilized is water, in case of continuous melting
equipment, it would be arranged to have a first mixing zone
where the matrix and water are intimately mixed, a second
where heat and/or pressure are applied by any means to cause
the matrix materials to melt/fluidize and then a pressure
reduction section from which the water is allowed to
vaporize and thus be removed. Re-pressurization of the
matrix would follow, with subsequent flavor injection,
mixing, forming, and-finally cooling.
Figure 4 represents a generalized flow sheet for ~he
foregoing embodiments. In its broadest aspect, the process
involves converting the matrix materials into a melt, and
mixing in the encapsulate and then cooling to produce a
dense, amorphous product. When the encapsulate is not
soluble in the matrix or is only slightly soluble, the
result is an encapsulated product while if the encapsulate
is soluble in the matrix material there results essentially
a solid solution. In the preferred embodiments, a
plasticizer solvent is introduced with the matrix to assist
in melting. This~plasticizer solvent may be vented if
desired or may be retained in the mixture. The mixing of
the encapsulate and matrix can occur either in a continuous
process such as in a tubular reactor containing a helix
screw to provide positive movement of the matrix from one
end to the other or in a separate static mixture which is in
fluid communication with the continuous melter which
converts the matrix into a melt.
The foregoing process has the advantages of the prior
art in that it is not limited to the use of a specific
material. Prior art attempts to use maltodextrins as matrix
212~010
WOg4/06308 PCT/~S93/U7429
-19-
materials have required the use of mixtures o~
oligosaccharides plus other materials to achieve successful
melting and extrusion.
Many of the matrix ingredients which are contemplated
for use in the present process, are excellent film forming
materials, such as maltodextrins, which tend to foam if
extruded. By applying sufficient pressure in the pressure
confinement to preclude foaming, a dense glassy matrix is
achieved. Even matrices which do not naturally foam, will
foam if the encapsulate contains substantial quantities of
low boiling components such as acetaldehyde.
The materials which can be encapsulated will depend
upon the matrix material chosen. By selecting the
appropriate matrix, it is possible to encapsulate virtually
any material with this particular technique. This includes
insoluble, and slightly soluble encapsulates and also
encapsulates which are soluble when the encapsulate does not
detrimentally affect the plasticity and melting point of the
matrix. Many matrix materials can be used in this
embodiment. Indeed, prior art matrix materials such as
those described in the United States Patent 5,009,900 as
well as those disclosed in United States Patents 5,124,162,
4,:879,130, 4,820,534, 4,738,724, 4,707,367, 4,690,825,
4:,689,~35, 4,659,390, 4,610,890, ~,388,328, 4,230,687,
3,922,354, 4,547,377, 4,398,422, 3,989,852, 3,970,766,
3,970,765, 3,857,964, 3,704,137., 3,625,709, 3,532,515,
3:,041,180, 2,919, g89, ~2,856,291, 2,809,985, 3,041,180.
The classes of matrix materials include not only those
listed in the abo~e citations, but also materials such as
mono- and disaccharides, oligomeric carbohydrates such as
dextrins, and polymeric carbohydrates such as starches;
soluble proteins and especially partially hydrolyzed
proteins such as gelatin; other biopolymers; for example,
hydrocolloids, gums, natural and modified celluloses;
lipids, derivatives and/or any suitable mixtures of the
above.
:
WOg4/06308 PCT/US93/07429
2124010
The choice of matrix composition is dependent upon the
specific application and physical properties of the
amorphous matrix and encapsulant. ~evine and Slade (Water
Science Reviews, Volume 3, Chapter 2,"Water as A
Plasticizer: physics-chemical aspects of low-moisture
polymeric systems"~, pp 7g-185, F. Franks (ed.), Cambridge
Uni~ersity Press, 1988) reviewed the interrela~ionship
between polymer molecular weight, process, and the role of
water as a plasticizer~in various food matrices. The
physical attributes of glass matrices are key attributes in
flavor encapsulation applications. A key requirement in
matrlx formulation~is to control the plasticizer component
of the matrix. While water is the most efficient agent for
melt processing, the resultant matrix must remain in the
non-rubbery state a~fter flavor agents are incorporated.
Therefore, one 3killed in the art can choose from the
variety of components~listed in Table 1 as well as other
ingredlents generally available to the food technologist.
;
W094/063~8 2 1 2 ~ O 1 0 PCT/US93~07429
.~ .
-21-
TABLE 1
POTENTIAL MATRIX ~OMæONENTS
1. Hiqh Molecular Weiaht PolYmers
Proteins Hvdrocolloids
Gelatin Locust bean gum
Casein Glucans
Lactalbumins Guar gum
Glutein/glutenin Pectins
Soy protein Tragacanth
Myosin Gum Arabic
Actinomyosin Carageenans
Other soluble or meltable Alginates
proteins Inulins
Modified starches
Pre-gelled starch
Xanthan
Gellan
: Modified Celluloses
Methyl cellulose
Hydroxypropyl cellulose
` Hydroxypropyl methyl
cellulose
. Sodium carboxymethyl
: cellulose (CMC)
: : :
2~. :Intermediate Mo1ec~ular Weiq~t__ompounds
Dextrins : :~
`Corn syrup solids
: : Cellulans : ~ ~
: Mal~ose syrup:solids:
Hi:gh:~fructose corn~syrup solids
; 3~ Low Molecular Weiaht ComPounds
;:: Plasticizers : Surfactants and LlPids
Water Polyglycerol esters
. Alcohols Distilled monoglycerides
~: Glycerol Medium chain triglycerides
Hydrogenated sugars Lecithin
:: ~ Sugars Lcw molecular weight lipids
~: : Organic acids
W094/063~X PCT/US93~07429
Z I Z-l a1 0 -22-
Although not illustrated in the drawings, the finished
product can be coated with an anticaking agent should that be
necessary. ~owever, caking is generally not a problem when
the matrix materials have a sufficiently high softening point,
typically above about 40~C. When the encap~ulate is not
soluble in the matrix, any encapsulate which remains on the
surface of the finished product can be removed by utilization
of suitable solvent in which the encapsulate is soluble but
the matrix is either insoluble or only slightly soluble.
While essentially any solvent having such characteristics can
be utilized, food grade solvents having those characteristics
are preferred. When the encapsulate is a lipophilic flavorant
such as lemon oil, orange oil and the like, isopropanol has
proven a successful solvent. Such washing may not be
necessary where cooling has been accomplished by quenching in
a ~uench medium selected to both cool and remove any surface
flavorant from the product.
The present process allows for the successful
encapsulation not ;only of high boiling point materials but
also those having boiling points below about 100C and most
beneficially below 40C in molten amorphous matrices. In the
; prior molten~matrix encapsulation art, materials having
boiling~points below these limits~ have not been successfully~
encapsulated in concentrated form but only when diluted with
other~flavorants~. ~For~example, acetaldehyde may be somewhat
sùccessfully encapsulated when it has been introduced as a
component in oil-based~flavorants like lemon oil and orange
oil. However, t:he present process provides for encapsulating
pure acetaldehyde at high loadings above about 1 gram of
acetaldehyde per lOO grams of matrix. Similar concentrations
are~possible with other low boiling point materials. With the
low boiling point materials, the use of pressure cooling
allows for the formation of a dense amorphous matrix, which
may be known in the art as a glass; this material being
substantially free of porosity, both gross~porosity and
microporosity. This substantial freedom from porosity will
~ W094/0630~ 2 1 2 ~ O 1 0 PCT/US93/07429
- -23-
extend the shelf life of the product by reducing the amount of
surface area exposed to the atmosphere. Thus, with low
boiling point materials, the present process offers the
advantage of increased loadings of materials in the matrix and
a longer shelf life. The absence of porosity also ensures a
dense material that will penetrate through the surface tension
of liquids, expediting dissolution, and reducing the
opportunity for lumping.
Further, the present process allows for the successful
dense matrix encapsulation of materials diluted in volatile
solvents. In the prior art, encapsulates diluted in volatile
solvent systems could not be successfully encapsulated at
commercially significant loads due to the plasticizing effect
of the solvent on the matrix. This is overcome by the removal
o~ the solvent after ~ncapsulate injection via atmospheric or
vacuum venting. Since the solvent removal takes place from
the molten process stream, the resulting product is dense,
thus the porosity formation caused by other solvent removal
techniques such as spray or freeze drying is avoided.
Additionally, secondary encapsulates may be injected into the
process stream after removal of the primary encapsulate
solvent. This is especially applicable to highly volatile
secondary encapsulates, particularly when combined with the
pressure cooling e~bodiment of the present process. Thus, the
present process can successfully encapsulate a much wider
ra~ge of materials in dense, amorphous matrices than was
previously possibIe.
The present process when compared with spxay drying and
other state of the art processes, offers greater efficiency in
encapsulating materials containing volatile components or
those diluted in volatile solvents, often at a processing cost
advantage; Furthermore, because essentially any material can
be encapsulated by proper selection of processing conditions
and matrix materials, a wide variety of products can be
produced all having essentially about the same density and
flow characteristics, an advantage in blending. Furthermore,
W094/06308 PCT/US93/07429
212 ~0 l 0 -24-
products which have been encapsulated or otherwise
incorporated into matrix materials can be blended together to
produce unique flavor combinations with reduced concern for
settling or stratification upon standing since the relative
densities and particle sizes of the materials can be chosen to
be approximately the same. Thus the present process will
offer a full range of encapsulants all having approximately
the same density and flow characteristics making handling,
metering, measuring and the like much easier for the
processor.
In the present description, the term "encapsulated
product" includes not~only those products truly encapsulated,
where the encapsulate is insoluble in the matrix but also
those products wherein the encapsulate is soluble in the
matrix. ~
As can be appreciated from the foregoing description, the
encapsulates in the~present process do not need to be
subjected to elevated temperatures in the presence of oxygen.
This is a significant improvement over spray drying where the
use of antioxidants is~essential to be able to encapsulate
products~sensitive to oxidation. Such materials include but
are not limited to citrus oils, highly unsaturated lipids,
oxidation sensitive colorants and the like. The present
process allows the~encapsulation of such products reducing the
need f~or~the~use~of~antioxidants.
The foregoing process and its variations are illustrated
in the ~examples~which~follow. These examples are for
illustration only and are not intended to limit the scope or
application of the present process.
Exam~le 1 ~
A carbohydrate based matrix composed of:
56% Amerfond (Domino Sugar, 95~ Sucrose, 5~ Invert sugar)
42~ Lodex-lO~Maltodextrin (American Maize, 10 DE)
2~ Distilled monoglyceride (Kodak, Myverol 18-07)
was fed at a rate of approximately 114 grams/minute into the
continuous processor (Figure 2) with water at 2 grams/minute.
21~0'10
W094/06308 PCT/US93/07429
-25-
The mixture was melted in the processor. The processor was
maintained at 121C. The processor screws were operating at
120 RPM. The molten mixture was discharged directly to the
melt pump. Acetaldehyde was injected into the molten matrix
on the discharge side of the melt pump using a piston metering
pump. A static mixer was used to blend the matrix and flavor
together. Immediately prior to flavor injection the
temperature of the molten matrix was approximately 138C. The
matrix and acetaldehyde mixture was then delivered under
pressure to one of the nozzle discharges for forming and
subsequent collection. The flow system was arranged so that
forming and solidiflcat~ion could take place under either
atmospheric or pressurized conditions. Four samples were
taken: ~
; Sample 1: Am~ient air cooled on trays.
; Sample 2: Atmospheric pressure cylindrical collection
ves~sel in ice bath-
Sample 3: Cooled in cold 99~ isopropanol (initial
temperature -18C) at atmospheric pressure,
approximately 130 g sample collected in
2000~g~IP~ ~
Sample 4: Pre~ssure~cooled; approximately 20 minutes under
3275 kPa in a cylindrical collection vessel in
an~lce bath.
Visually, samples 1-~3~were white and puffed with a porous
internal structure~ Sample~4 appeared dense, hard and
relatively clear~
Analytical ~esults
Acetaldehyde~Particle Density (q/cm3)
1 .84 ~ 1.26
~ ,~
2 .87~
3 .66 1.35
~ .
~ 4 1.67 1.63
: ~ :
:~ -
' ~
WO 94fO63Q8 ` ~ PCI'/US93/07~f2~9
2124010
-26-
Example 2
A carbohydrate based matrix composed of:
56% Sucrose Confectioner/s sugar 6X (Domino Sugar)
42~ Lodex Maltodextrin (American Maize, 10 DE)
2~ Distilled monoglyceride (Kodak, Myverol 18-07)
was fed at a rate of approximately 114 grams/minute into the
continuous processor (Figure 1) with water at 2 grams/minute.
The mixture was melted in the processor. The processor was
maintained at 132C. The processor screws were operating at
70 RPM. Diacetyl was injected into the molten mixture through
a port in the continuous processor using a piston metering
pump at a rate of approximately 10 grams /minute. After
mixing the mixture was discharged directly into the Zenith
melt pump. The matrix and diacetyl mixture was then delivered
under pressure to one of the nozzle discharges for forming and
subsequent collection. The flow system was arranged so that
forming and solidification could take place under either
tmospheric or pressurized conditions. Upon discharge from
the~melt pump, the product temperature was approximately
132C. Four samples were taken.
Sample 1: Ambient air cooled on trays
Sample 2: Atmospheric pressure cylindrical collection
vessel in ice bath
Sample 3: Cooled in cold 99~ isopropanol (initial
temperature -18C) at atmospheric pressure,
approximately 125 g sample collected in 2000 g
` IP ~final IP temperature was -8C).
Sample 4: Pressure cooled; approximately 20 minutes under
2068 kPa in a cylindrical collection vessel in
an ice bath. -
Visually, samples 1-3 were pale yellow, relative opaque, and
puffed with a porous internal structure. Sample 4 appeared
dark yellow, dense, hard and relatively translucent.
~ "~-7"~-r~-""~~ ,r~ ;t,~ . ",
~WO 94~6308 2 1 2 ~ O 1 0 PCI/US9~/074~9
--27--
Analytical results:
Sample ~ Diacetvl _article Density (q~cm3)
1 2.40 1.33
2 2.26 ----
3 2.~1 1.33
4 3.97 1.49
Exam~le 3
A carbohydrate based matrix composed of:
56% Amerfond (Domino Sugar, 95~ Sucrose, 5~ Invert sugar)
42~ Lodex Maltodextrin (American Maize, 10 DE)
2~ Distilled monoglyceride (Kodak, Myverol 18-07)
Flavor:
Vanilla extract (3 1/3 fold, 11.9~ solids, 39 . 8~ alcohol)
was fed at a rate of approximately 114 grams/minute into
continuous processor 1 (Figure 3). The mixture was melted in
processor 1. Processor 1 was maintained at 143C. Processor
1 screws were operating at 70 RPM. The vanilla extract was
injected into processor 1 through a port at a flow rate of
approximately 22 grams/minute. The molten mixture was
discharged directly into processor 2 (143C jacket
temperature, 120 RPMj.~ Water and ethanol vapor were allowed
to escape from the open feedport of processor 2. The molten
mix~ure was dischaxged into the melt pump which discharged
throuyh the nozzle onto trays for cooling and solidification.
The product tempera~ure exiting proce~sor 1 was 102C. The
product temperature at the discharge of the melt pump prior to
:: :
nozzle forming was approximately 115C.
After cooling, the product was hard and dense, having the
fla~or characteristics of vanilla extract.
Analvtical Results:
Water ~Ethanol
Initial composition
(by mass balance) 10.3 6.4
Actual product c~mposition 6.4 ~.1
Volatile solvent losses 3.9 6.4
W094/0630~ PCT/US93/07 ~
212~010 -28~
Example 4
Conditions were as described in Example 3 except the feed
rate for the vanilla was 30 grams/minute and no melt pump was
used. The temperature out of processor 1 was 98C and the
product temperature out of processor 2 was 127C.
After cooling, the product was hard and dense, having the
flavor characteristics of vanilla extract.
Analytical Results:
; ~ Water ~Ethanol
Initial composition
(by mass balance) 12.4 8.3
Actual product composition 7.3 <.l
Volatile solvent losses 5.1 8.2
Example 5
A carbohydrate based matrix composed of:
:
56~ Amerfond ~Domino Sugar, 95~ Sucrose, 5~ Invert sugar)
42% Lodex Malt~dextrin (American Maize, 10 DE)
2~ Distilled~monoglyceride (Kodak, Myverol 18-07)
Flavor: ~
Natural beef ~lavor #12001 (Flavor and Food Ingredients,
Inc.,~ Middlesex, N3) having 37.2~ total solids and 14.6% salt~
; Condit~ions were as described in Example 3 except the feed
rate for the beef flavor was 29 grams/minute and no melt pump
was used. The temperature out of processor 1 was 112C and
the product temperature out of processor 2 was 129C. The
jacket temperature was maintained at 160C.
, After cooling, the product was hard and dense, having the
flavor characteristics of the original flavor.
Analvtical Results:
Water
Initial~composition
(by mass balance) 15.1
Actual product composition 7.0
Volatile solvent losses 8.1
