Flavor encapsulation

A process for incorporating a volatile component into a matrix comprising; (a) forming a melt comprising said volatile component and said matrix, (b) solidifying said melt under a pressure sufficient to prevent substantial volatilization of said volatile component.

TECHNICAL FIELD 
The present invention relates to techniques to encapsulate materials which 
can undergo compositional changes in process and/or storage. Such 
encapsulation improves material shelf-life and usefulness in the 
preparation of products such as foods. 
BACKGROUND 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 flavors. 
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 process 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 turn results in undesirable changes in flavor 
characteristics. 
Freeze-drying solutions of matrix materials containing either dissolved 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 comparatively 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 low 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 isopropyl alcohol. The traces of the isopropyl alcohol 
remaining in the product after quenching can be detrimental. This 
technique limits the materials which can be encapsulated to those which 
are immiscible in the matrix. An additional disadvantage 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 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 
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. Pat. No. 4,610,890 ('890) and 4,707,367 ('367). In these 
patents, a process 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 solvent, 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. Pat. No. 5,009,900. The patents '890 and 
'367 suffer from the same deficiencies noted in prior art techniques, 
i.e., loss of volatile compounds and limitations to immiscible 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 
encapsulant 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. Pat. No. 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 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 
retained, 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 needs to utilize as the 
encapsulant a mixture of materials, one having a melting point 
sufficiently low such that the remainder will melt into it thereby 
becoming extrudable under reasonable process conditions. 
U.S. Pat. No. 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 and mono- or 
disaccharides. 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 restrained by processing 
considerations in the selection of encapsulate material. Similar 
techniques are taught in U.S. Pat. No. 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 
encapsulated therein. The temperatures involved could cause the loss of 
volatile top notes. 
Another example of the technology which is available is U.S. Pat. No. 
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 to the foregoing deficiencies which have been noted in the 
prior art techniques, still other deficiencies 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 encapsulants 
to a very narrow range. 
In producing encapsulated products, it is desirable that the encapsulant 
have a softening temperature significantly above room temperature. If the 
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 resultant matrix is in the glassy state with softening 
temperatures greater than 40.degree. C. 
While solidified melt techniques have, to greater or lesser extent, been 
utilized commercially to encapsulate some flavorants in dense amorphous 
matrices, there are many 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 materials. With flavorants 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. 
DESCRIPTION OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a process 
to encapsulate a wide range of materials, including flavorants, 
fragrances, colors, pharmaceuticals and the like, without the loss of 
volatile materials, oxidative degradation, molecular reactions and other 
adverse interactions with the environment. 
Further, it is 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 still another object of the present invention to provide a process 
which allows the use of encapsulating 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 embodiment involves forming a melt containing an encapsulate 
dissolved in a solvent and an encapsulating matrix which is optionally 
subjected to an elevated pressure, followed by venting to remove at least 
some of the solvent while largely retaining the encapsulate in the 
product. 
In this invention, the dense amorphous, essentially non-crystalline solid 
encapsulant may be described in many cases but not exclusively by those 
knowledgeable in the art as a `glass` as characterized by a glass 
transition temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
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 process 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 sticky and 
agglomerate at lower temperatures yet will melt/dissolve at under normal 
application conditions and 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 provides 
enough plasticity to the matrix ingredients such that they 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. Following, 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 solvent, 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. Pat. No. 
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 vary this 
procedure where 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 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 components 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 chosen 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 described in the prior art for forming a mixture of matrix 
and encapsulant can be used. On a continuous basis, the use of extrusion 
is preferred. When simple sugars are used as the matrix, the heat 
necessary to 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. 
When it is necessary to use a separate solvent to plasticize the matrix 
prior to 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 plasticizer may 
occur either before or after the encapsulate is introduced into the matrix 
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 melt 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 resulting solid product may have undesirable properties, such 
as tackiness, softness at low temperatures and a tendency to agglomerate. 
One technique for avoiding these 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 appropriate 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 
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 physical 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, it is possible to overcoat 
the product with a hard coating which prevents or reduces such migration 
and evaporation. 
FIG. 1 illustrates one method by which the process can be accomplished. In 
FIG. 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 melter 03, the 
injected 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 FIG. 1, a melt 
pump 06 may be employed to feed the extrusion die. In FIG. 1, alternative 
methods are illustrated for cooling the encapsulated material. Discharge 
of the molten matrix/encapsulate mixture to atmospheric pressure 
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 material 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 extruders 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 divided 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 particular embodiment, it would be preferable to employ injection 
molding type apparatus such as is well known in the plastics forming 
industry. In an injection molding apparatus, the molds are normally closed 
and the material injected under pressure and cooled before the mold is 
opened. 
A further alternative is to introduce the melt under pressure 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 
into the liquid body. 
In pressure 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 be readily determined by simple experimentation. 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 require pressure cooling 
since they tend to contain only small quantities of highly 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 FIG. 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 
07, FIG. 2. The remainder of the system is similar to that illustrated in 
FIG. 1. In this embodiment, it is anticipated that the encapsulate in 
vessel 12, will be fed to a pressurized container, 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 embodiment, 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 this technique include fragrances, colors, 
flavors, pharmaceuticals and the like. 
Another embodiment of the invention illustrated in FIG. 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, followed 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 solvents for the 
matrix materials. Thus, 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 determined 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 quantity of solvent thereby 
concentrating 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 desired 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 the advantage of allowing one to effectively concentrate 
vanilla solutions which have generally been difficult to concentrate 
because of the sensitivity of vanilla to degradation. It is believed that 
the matrix serves to stabilize the vanilla during the process. 
These process steps are illustrated in one embodiment in FIG. 3. Matrix 
materials are fed continuously to Melter 1 where they are melted prior to 
flavor injection. The matrix/flavor mixture is 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. Not shown in this illustration is the linkage of 
this process with pressure cooling which would be desirable in some cases. 
Flavorants which can be encapsulated in this technique include: 
______________________________________ 
Wt % orig. flavor 
Flavor Volatile Solvents 
weight matrix 
______________________________________ 
Natural extracts 
Water, ethanol 
10-50% 
Meat hydrolysates 
Water 10-50% 
Aqueous reaction 
Water 10-50% 
flavors 
Compounded flavors 
water, ethanol 
10-50% 
containing solvents 
______________________________________ 
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 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. 
FIG. 4 represents a generalized flow sheet for the 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 materials have required the use of mixtures of 
oligosaccharides plus other materials to achieve successful melting and 
extrusion. 
Many of the mat mix ingredients which are contemplated for use in the 
present process, are excellent film forming materials, such as 
maltodextrin, which tend to foam if extruded. By applying sufficient 
pressure in the pressure confinement to preclude foaming, a glassy matrix 
is achieved. Even matrices which do 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 U.S. Pat. No. 5,009,900 as well 
as those disclosed in U.S. Pat. Nos. 5,124,162, 4,879,130, 4,820,534, 
4,738,724, 4,707,367, 4,690,825, 4,689,235, 4,659,390, 4,610,890, 
4,388,328, 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, 2,919,989, 2,856,291, 2,809,985, 3,041,180. 
The classes of matrix materials include not only those listed in the above 
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. 
The choice of matrix composition is dependent upon the specific application 
and physical properties of the amorphous matrix and encapsulant. Levine 
and Slade (Water Science Reviews volume 3, Chapter 2, "Water as A 
Plasticizer: physico-chemical aspects of low-moisture polymeric systems", 
pp 79-185, F. Franks (ed.), Cambridge University Press, 1988) reviewed the 
interrelationship 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 matrix 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 after flavor agents are incorporated. Therefore, one 
skilled in the art can choose from the variety of components listed in 
Table 1 as well as other ingredients generally available to the food 
technologist. 
TABLE 1 
______________________________________ 
POTENTIAL MATRIX COMPONENTS 
______________________________________ 
1. High Molecular Weight Polymers 
Proteins Hydrocolloids 
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 Molecular Weight Compounds 
Dextrins 
Corn syrup solids 
Cellulans 
Maltose syrup solids 
High fructose corn syrup solids 
3. Low Molecular Weight Compounds 
Plasticizers Surfactants and Lipids 
Water Polyglycerol esters 
Alcohols Distilled monoglycerides 
Glycerol Medium chain triglycerides 
Hydrogenated sugars 
Lecithin 
Sugars Low molecular weight lipids 
Organic acids 
______________________________________ 
Although not illustrated in the drawings, the finished product can be 
coated with an anticaking agent should that be necessary. However, caking 
is generally not a problem when the matrix materials have a sufficiently 
high softening point, typically above about 40.degree. C. When the 
encapsulate 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 quench 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 100.degree. C. and most beneficially below 40.degree. C. 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 successfully 
encapsulated when it has been introduced as a component in oil-based 
flavorants like lemon oil and orange oil. However, the present process 
provides for encapsulating pure acetaldehyde at high loadings above about 
1 gram of acetaldehyde per 100 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 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 of 
the solvent after encapsulate 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 embodiment of the 
present process. Thus, the present process can successfully encapsulate a 
much wider range of materials in dense, amorphous matrices than was 
previously possible. 
The present process when compared with spray 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, 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 for 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. 
EXAMPLE 1 
A carbohydrate based matrix composed of: 
56% Amerfond (Domino Sugar, 95% Sucrose, 5% Invert sugar) 
42% Lodex-10 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 (FIG. 2) with 
water at 2 grams/minute. The mixture was melted in the processor. The 
processor was maintained at 121.degree. C. 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 
138.degree. C. 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 
solidification could take place under either atmospheric or pressurized 
conditions. 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 -18.degree. 
C.) at atmospheric pressure, approximately 130 g sample collected in 2000 
g IP. 
Sample 4: Pressure cooled; approximately 20 minutes under 3275 kPa in a 
cylindrical collection vessel in an ice bath. 
Visually, samples 1-3 were white and puffed with a porous internal 
structure. Sample 4 appeared dense, hard and relatively clear. 
______________________________________ 
Analytical Results 
Sample % Acetaldehyde 
Particle Density (g/cm.sup.3) 
______________________________________ 
1 .84 1.26 
2 .87 -- 
3 .66 1.35 
4 1.67 1.63 
______________________________________ 
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 (FIG. 1) with 
water at 2 grams/minute. The mixture was melted in the processor. The 
processor was maintained at 132.degree. C. 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 atmospheric or 
pressurized conditions. Upon discharge from the melt pump, the product 
temperature was approximately 132.degree. C. 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 -18.degree. 
C.) at atmospheric pressure, approximately 125 g sample collected in 2000 
g IP (final IP temperature was -8.degree. C.). 
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. 
______________________________________ 
Analytical results: 
Sample % Diacetyl 
Particle Density (g/cm.sup.3) 
______________________________________ 
1 2.40 1.33 
2 2.26 -- 
3 2.21 1.33 
4 3.97 1.49 
______________________________________ 
EXAMPLE 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 (FIG. 3). 
The mixture was melted in processor 1. Processor 1 was maintained at 
143.degree. C. 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 (143.degree. C. jacket temperature, 120 RPM). Water and 
ethanol vapor were allowed to escape from the open feedport of processor 
2. The molten mixture was discharged into the melt pump which discharged 
through the nozzle onto trays for cooling and solidification. The product 
temperature exiting processor 1 was 102.degree. C. The product temperature 
at the discharge of the melt pump prior to nozzle forming was 
approximately 115.degree. C. 
After cooling, the product was hard and dense, having the flavor 
characteristics of vanilla extract. 
______________________________________ 
Analytical Results: 
% Water 
% Ethanol 
______________________________________ 
Initial composition 
10.3 6.4 
(by mass balance) 
Actual product composition 
6.4 &lt;.1 
Volatile solvent losses 
3.9 6.4 
______________________________________ 
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 98.degree. C. and the product temperature out of 
processor 2 was 127.degree. C. After cooling, the product was hard and 
dense, having the flavor characteristics of vanilla extract. 
______________________________________ 
Analytical Results: 
% Water 
% Ethanol 
______________________________________ 
Initial composition 
12.4 8.3 
(by mass balance) 
Actual product composition 
7.3 &lt;.1 
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 Maltodextrin (American Maize, 10 DE) 
2% Distilled monoglyceride (Kodak, Myverol 18-07) 
Flavor: 
Natural beef flavor #12001 (Flavor and Food Ingredients, Inc., Middlesex, 
N.J.) having 37.2% total solids and 14.6% salt. Conditions 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 112.degree. C. and the product temperature out of processor 2 was 
129.degree. C. The jacket temperature was maintained at 160.degree. C. 
After cooling, the product was hard and dense, having the flavor 
characteristics of the original flavor. 
______________________________________ 
Analytical Results: 
% Water 
______________________________________ 
Initial composition 15.1 
(by mass balance) 
Actual product composition 
7.0 
Volatile solvent losses 
8.1 
______________________________________