WO2012021936A1

WO2012021936A1 - Encapsulation processes

Info

Publication number: WO2012021936A1
Application number: PCT/AU2011/001060
Authority: WO
Inventors: Andrew Thomas Fotheringham
Original assignee: Taste Master Pty Ltd
Priority date: 2010-08-19
Filing date: 2011-08-18
Publication date: 2012-02-23

Abstract

Disclosed is a process for producing amorphous carbohydrate granules containing a functional ingredient encapsulated therein. The process comprises: providing a carbohydrate mixture comprising 35 - 75% by weight of a water-soluble polymeric carbohydrate and 25 - 65% by weight sucrose; feeding the carbohydrate mixture to a twin screw extruder; feeding 0.1-5% by weight water to the extruder; feeding the functional ingredient to the extruder; mixing in the extruder to provide a substantially even distribution of water and the functional ingredient in the carbohydrate mixture; heating the substantially uniform mixture in the extruder to a temperature of from about 140°C to about 190°C, wherein said temperature is sufficient to melt all crystals of carbohydrate present in the mixture and is, at least in part controlled, by the amount of water added; applying dispersive shear forces to the melt to gain a desired particle size of the functional ingredient within the carbohydrate matrix; cooling the heated mixture both in the extruder and post the extruder to yield an amorphous solid material containing the functional ingredient encapsulated therein; and cutting or grinding the solid material thus obtained to form said amorphous carbohydrate granules.

Description

ENCAPSULATION PROCESSES

FIELD

The present invention relates to processes for producing granules containing a functional ingredient, such as a flavour, fragrance, pharmaceutical or nutraceutical. The granules may be a foodstuff or

pharmaceutical product suitable for human or animal consumption or they may be used to deliver fragrances in personal care or household applications such as cleaning compositions.

INCORPORATION BY REFERENCE

This patent application claims priority from Australian Provisional Patent Application No. 2010903722 titled "Encapsulation Processes" and filed 19 August 2010, the entire contents of which are hereby incorporated by reference

BACKGROUND

Many functional ingredients, such as flavour and fragrance ingredients, are easily oxidised or are volatile and these properties can make such ingredients difficult to handle or can provide problems with long term storage stability. As a result, much work has been carried out on encapsulating functional ingredients in some form of protective matrix. In such a case, encapsulation makes it possible to minimise or prevent oxidation and volatilization of the functional ingredient, thereby leading to improved delivery of functional outcome, shelf life, and handling characteristics.

A variety of methods have been suggested in the prior art to encapsulate flavour components in edible carrier matrices, including spray drying with a suitable carrier material (e.g. gum arabic, maltodextrin, etc); absorption onto a suitable carrier; or extrusion into a carbohydrate matrix.

For example, U.S. Patent No. 3,041,180 discloses a process for forming particles comprising a flavour component encapsulated in a carbohydrate that is otherwise known as a "glassy matrix". In this process, an emulsified composition of a flavour component and water, sucrose and hydrolyzed cereal solids with DE below 20 is emulsified and extruded in the form of rods into a cold organic solvent. Likewise, U.S. Patent Nos. 4,610,890 and 4,707,367 each disclose a process comprising forming an aqueous solution containing sugar, a starch hydrolysate, and an emulsifier. A flavour component is blended with the aqueous solution to form a homogeneous melt which is extruded into a cold organic solvent, dried and then sieved. Isopropanol (IP A) is the organic solvent most commonly used. However, there are safety and environmental concerns associated with the use of IP A in these processes. In contrast, International patent application WO 2006/038067 discloses a process in which the extruded melt is cooled in liquid nitrogen. Each of the aforementioned processes has some drawbacks in that it is a batch wise process that also requires a separate drying step, thus leading to processing inefficiencies. U.S. Patent No. 4,820,534 discloses a process in which maltodextrin and, optionally, a minor amount of glucose is mixed with flavour components without any added moisture. The obtained mixture is heated above the glass transition temperature of the substrate (e.g. above about 180°C) in a single screw extruder. Then it is extruded, cooled and moulded to thereby give glassy particles. This process does not use water in the mixture and, therefore, avoids the need for a separate drying step. However, the high temperatures required to exceed the glass transition temperature can be detrimental to the stability of the flavour component.

There is a need for functional ingredient encapsulation processes that overcome at least one of the problems or drawbacks associated with prior art processes, or at least provide an alternative to prior art processes.

SUMMARY

The present invention arises from our discovery that a sucrose/polymeric carbohydrate-based amorphous glassy matrix into which is homogenised a functional ingredient can be formed in a single continuous process using a twin screw extruder without the need for a solvent cooling process and provides a product in a stable, crystal-free amorphous glassy state.

We have found that the addition of a small amount of water to a mixture of sucrose and a polymeric carbohydrate has the effect of lowering the temperature required to melt all crystals present. This not only minimises the risk of thermal degradation and/or volatilization of the functional ingredient but also leads to the formation of a glassy matrix that is stable at ambient temperature and, therefore, has a good shelf life.

In a first aspect, the present invention provides a process for producing amorphous carbohydrate granules containing a functional ingredient encapsulated therein, the process comprising:

(a) providing a carbohydrate mixture comprising 35 - 75% by weight of a water-soluble polymeric carbohydrate and 25 - 65% by weight sucrose;

(b) feeding the carbohydrate mixture to a twin screw extruder;

(c) feeding 0.1 -5% by weight water to the extruder;

(d) feeding the functional ingredient to the extruder;

(e) mixing in the extruder to provide a substantially even distribution of water and the

functional ingredient in the carbohydrate mixture; (f) heating the substantially uniform mixture in the extruder to a temperature of from about 140°C to about 190°C, wherein said temperature is sufficient to melt all crystals of carbohydrate present in the mixture and is, at least in part controlled, by the amount of water added in step (c);

(g) applying dispersive shear forces to the melt to gain a desired particle size of the

functional ingredient within the carbohydrate matrix;

00 cooling the heated mixture both in the extruder and post the extruder to yield an

amorphous solid material containing the functional ingredient encapsulated therein; and

(i) cutting or grinding the solid material thus obtained to form said amorphous carbohydrate granules.

In some embodiments, the water-soluble polymeric carbohydrate is maltodextrin. In some embodiments, the maltodextrin has 10 to 30 dextrose equivalents (D.E.). In some specific aspects, the maltodextrin has 10 to 25 dextrose equivalents (D.E.). In more specific embodiments, the maltodextrin has 20 to 25 dextrose equivalents (D.E.). In further specific embodiments, the maltodextrin has 20 dextrose equivalents (D.E.).

In some embodiments, the content of the functional ingredient to the carbohydrate mixture is from about 0.2 to about 20% by weight.

In a second aspect, the present invention provides a functional ingredient-containing granule formed by a process of the first aspect of the invention. DETAILED DESCRIPTION

As previously described, the present invention provides a process for producing amorphous carbohydrate granules containing a functional ingredient encapsulated therein. The process comprises:

(b) feeding the carbohydrate mixture to a twin screw extruder;

(c) feeding 0.1 -5% by weight water to the extruder;

(d) feeding the functional ingredient to the extruder;

functional ingredient in the carbohydrate mixture; (0 heating the substantially uniform mixture in the extruder to a temperature of from about 140°C to about 190°C, wherein said temperature is sufficient to melt all crystals of carbohydrate present in the mixture and is, at least in part controlled, by the amount of water added in step (c);

functional ingredient within the carbohydrate matrix;

(h) cooling the heated mixture both in the extruder and post the extruder to yield an

amorphous solid material containing the functional ingredient encapsulated therein; and cutting or grinding the solid material thus obtained to form said amorphous carbohydrate granules.

The water-soluble polymeric carbohydrate may be maltodextrin. In some embodiments, the maltodextrin has 10 to 30 dextrose equivalents (D.E.). Generally, a commercial maltodextrin with a D.E. of 10-25 will be used. In some specific embodiments, a maltodextrin with a D.E. of 20-25 is used. In further specific embodiments, a maltodextrin with a D.E. of 20 is used. The preferred D.E. of the maltodextrin will depend on a number of material and processing factors and variables and may be determined by routine experimentation. As will be appreciated by the person skilled in the art, the term dextrose equivalent (D.E) refers to the percentage of reducing sugars (dry basis) in a product calculated as dextrose.

Other polymeric carbohydrates that may be used as an alternative to maltodextrin and/or in addition to maltodextrin include hydrogenated starch hydrolysates, oligofructans, trehalose, agar, carrageenan, inulin, other gums, polydextrose, and derivatives of any of the aforementioned.

The carbohydrate mixture comprises 35-75% water-soluble polymeric carbohydrate and 25-65% sucrose. We have found that the inclusion of sucrose in the carbohydrate mixture leads to an amorphous (i.e. noncrystalline) glassy matrix product which provides enhanced encapsulation of the functional ingredient compared to when other materials such as glucose are used. This enhanced encapsulation ultimately gives rise to improved protection of the functional ingredient and, therefore, improved shelf life.

0.1 to 5% by weight of water is added to the carbohydrate mixture. The skilled person will appreciate that some of the other ingredients used in the composition may inherently contain moisture. However, the water that is added is in addition to any water inherently contained in any of the other components of the mixture. The water that is added may be pure water or an aqueous solution or suspension of one of the components or other suitable ingredients.

The person skilled in the art will appreciate that the glass transition temperature (Tg) of the carbohydrate mixture decreases with increasing moisture content or decreasing molecular weight of the maltodextrin. If too much water is present in the mixture the Tg will be too low and it will not be possible to form a glassy matrix that is stable at room temperature. As described previously, when water is used in the encapsulation process it is generally necessary to extrude the molten material into a cooling solvent in order to form a glassy matrix. Conversely, if too little (or no moisture) is present it will generally be necessary to heat the mixture to higher temperatures which may be detrimental to the functional ingredient. We have found that using a combination of 35-75% maltodextrin having a D.E. of 10-25, 25- 65% sucrose and 0.1-5% water in a twin screw extruder it is possible to form products having a glassy matrix at room temperature and without the need for a solvent cooling step and/or subsequent drying step.

The term "functional ingredient", and variations, as used herein means any compound or mixture of compounds having at least one functional characteristic. Examples of functional ingredients include flavours, fragrances, pharmaceuticals, nutraceuticals, etc.

In some embodiments, the functional ingredient is a flavour ingredient or composition. The flavour ingredient or composition may be a natural or synthetic compound or mixture of compounds. The flavour ingredient or composition may be any of the wide range of ingredients known to the person skilled in the art. Examples of flavour ingredients or compositions include (but are not limited to): spice oleoresins derived from allspice, basil, capsicum, cinnamon, cloves, cumin, dill, garlic, marjoram, nutmeg, paprika, black pepper, rosemary and tumeric; essential oils: anise oil, caraway oil, clove oil, eucalyptus oil, fennel oil, garlic oil, ginger oil, peppermint oil, onion oil, pepper oil, rosemary oil, spearmint oil; citrus oils: orange oil, lemon oil, bitter orange oil and tangerine oil; alliaceous flavours: garlic, leek, chive, and onion; botanical extracts: arnica flower extract, chamomile flower extract, hops extract, and marigold extract; botanical flavour extracts: blackberry, chicory root, cocoa, coffee, kola, licorice root, rose hips, sarsaparilla root, sassafras bark, tamarind and vanilla extracts; protein hydrolysates: hydrolyzed vegetable protein, meat protein hydrolysates, milk protein hydrolysates; and compounded flavours both natural and artificial including those disclosed in S. Heath, Source Book of Flavors. Avi Publishing Co., Westport, Conn., 1981, pp. 149-277. The flavour ingredient or composition may be in the form of a solid, oil, liquid, aqueous solution, non-aqueous solution or an emulsion. The flavour component may be a single pure compound or a mixture of compounds (both flavour and non-flavour compounds).

Whilst the process described herein is particularly suitable for preparing granules having a flavour ingredient or composition encapsulated therein, it is not necessarily limited to that application and, for example, could be used to encapsulate other functional ingredients as described earlier. For example, the functional ingredient may be a fragrance ingredient. In this application, the granules having the fragrance ingredient encapsulated therein may be used as a foodstuff or may be used in other personal care or household applications, such as cosmetics, laundry care, and personal care items. A range of fragrance ingredients are available commercially and/or known to the person skilled in the art and can be used herein. Examples of fragrance ingredients include: aromatic, terpenic and or sesquiterpenic

hydrocarbons, and more particularly essential oils containing these molecules, even more particularly essential oils of citrus (lemon, orange, grapefruit or bergamot) or of nutmeg, aromatic alcohols, and more particularly benzyl alcohol, phenylethyl alcohol and phenylpropyl alcohol, primary, secondary or tertiary, saturated or unsaturated, cyclic or acyclic nonaromatic alcohols, and more particularly linalol, citronellol, geraniol, nerol, 2,6-dimethyl-7-octen-2-ol, terpineol, and fatty alicyclic alcohols whose chain contains from 4 to 10 carbon atoms, aldehydes, and more particularly saturated or unsaturated alicyclic fatty aldehydes whose carbon chain contains from 4 to 12 carbon atoms, aromatic aldehydes such as cinnamaldehyde, (o amylcinnamaldehyde, O!-hexylcinnamaldehyde, butyl-phenylmethylpropional, and phenolic aromatic aldehydes such as vanillin and ethylvanillin, phenols and more particularly aromatic phenols such as eugenol, isoeugenol and also the methyl ethers thereof, carboxylic acids, mainly in their following form: esters, and more particularly acetic esters of benzyl alcohol, of geraniol, of citronellol, of nerol, of terpineol, of borneol or of linalol, esters of aromatic acids such as benzoates and salicylates and also cinnamates esterified with alcohols of the aliphatic series containing a carbon-based chain of 1 to 6 carbon atoms, aromatic phenol-acids, mainly in their lactone/aromatic form, such as coumarin and dihydrocoumarin, carboxylic alcohol acids in their lactone form, and more particularly gamma-octa, gamma-nona, gamma-undeca, gamma-dodeca, delta-deca, delta-undeca and delta-dodeca lactones in their saturated or unsaturated form, and also macrocyclic lactones whose carbon-based chain contains from 12 to 16 carbon atoms, aromatic and/or nonaromatic ethers and acetals in their acyclic or cyclic form, and more particularly acetals of aldehydes with a carbon-based chain containing from 4 to 10 carbon atoms and also substituted or unsubstituted furanyl or pyranyl cyclic ethers, heterocycles containing a nitrogen atom, and more particularly indole derivatives, and also heterocycles containing two nitrogen atoms, and more particularly derivatives of the pyrazine series, ketones, in particular aromatic ketones such as 4-(p- hydroxyphenyl)-2-butanone, and saturated or unsaturated, cyclic or noncyclic nonaromatic ketones, aromatic or nonaromatic sulfides, disulfides, and mercaptans.

The amount of functional ingredient encapsulated in the granules will depend on a number of factors, including the nature of the matrix, the specific functional ingredient used, and the anticipated end use of the final composition. The granules will typically comprise 0.2-20% (by weight) of the functional ingredient, based on the total weight of the final composition.

Other ingredients that are conventionally used in the art may also be incorporated into the granules. For example, colorings, sweeteners, fragrances, diluents, fillers, preservatives, antioxidants, stabilisers, lubricants, and the like may be incorporated into the granules if desired.

The process is carried out in a co-rotating twin screw extruder. Twin screw extruders are available commercially and can be used or adapted for use in the process described herein. Twin screw extruders can be configured with a variety of zones, including mixing zones, high shear zones, back pressure zones, heating zones, etc. The process described herein is preferably performed using a twin screw extruder utilising mixing zones in combination with back pressure to achieve the crystal melt and subsequent homogenisation of the functional ingredient with the carbohydrate matrix. The process is initiated by addition of the carbohydrate mixture to the extruder. The carbohydrate mixture may be formed outside of the extruder and then the mixture added to the extruder via a first feed port. Alternatively, the individual components of the carbohydrate mixture may be added to the extruder individually via the same or different feed ports. The water is then added to the extruder via a second feed port which is downstream from the first feed port. The functional ingredient is then added to the extruder. The resultant mixture is mixed within the extruder and is transferred downstream to a heating zone where it is heated to a temperature at which all of the crystalline carbohydrate melts. The temperature in the heating zone will be determined, at least in part, by the amount of water added.

However, the temperature will typically be in the range of 140°C to 190°C. The molten mixture is then exposed to a high shear mixing zone of the extruder in which dispersive shear forces are applied to the melt to gain a desired particle size of the functional ingredient within the carbohydrate matrix. The size range may vary with different functional ingredients and different applications but will generally fall in the size range of about 0.1 to about 10 microns.

The molten mixture having the functional ingredient evenly dispersed therein is then transported in the extruder to an exit containing a die comprising one or more extrusion orifices. The temperature of the mixture as it passes through the die will have dropped to about 115°C and, on exiting the extruder the mixture cools rapidly in air to form a glassy matrix encapsulating the functional ingredient. Typically, the components have an extruder residence time in the order of about 10 to 30 seconds.

The final extruded product may be used as extruded, that is, in the form of an extruded rod or filament. Alternatively, the extruded product can be formed into smaller particles by any suitable means. For instance, it can be chopped whilst it is exiting the extruder. For example, the die orifice itself can be equipped with a knife or any other cutting device. Alternatively, a cutting device can be provided separately downstream from the die orifice.

The term "granules", and related terms, as used herein means particles that have been formed by extrusion as described herein. The granules may be any shape or size and, for example, may be in the form of pellets, powders, etc.

The person skilled in the art will appreciate that the temperature and pressure conditions under which the extrusion step is carried out can be adjusted without particular effort and as a function of the nature of the ingredients and of the quality of the product which is desired to obtain, i.e. its granulometry and shape.

The resulting products are in the form of granules, which have amorphous carbohydrate as a continuous domain, in which discontinuous domains of flavour component is entrapped.

The present invention is hereinafter further described by way of the following, non-limiting example(s). EXAMPLE(S)

Example 1 - Orange flavour containing granules

A carbohydrate mixture was prepared by blending 55% by weight maltodextrin (20 D.E.), 45% by weight sucrose. This powder was fed into a Clextral EV32 twin screw extruder. 1.9% by weight water and 10% by weight of TASTE MASTER™ orange flavour were added to a second port of the extruder. The extruder was configured with a high pressure, high shear mixing zone which is heated to achieve a crystal free melt. The product was heated to 174°C. The mixture was then cooled in the remaining sections of the extruder and extruded through a die with 1mm diameter holes. The extruded product was cut into chips at the die face and pneumatically conveyed and cooled prior to packing. Example 2 - Bergamot flavour containing granules

A carbohydrate mixture was prepared by blending 60% by weight maltodextrin (20 D.E.) and 40% by weight sucrose. The powder was fed into a Clextral EV32 twin screw extruder. 1% by weight water and 5% by weight of bergamot flavour were added to a second port of the extruder. The extruder was configured with a high pressure, high shear mixing zone which is heated to achieve a crystal free melt. The product was heated to 174°C. The mixture was then cooled in the remaining sections of the extruder and extruded through a die with 1mm diameter holes. The extruded product was cut into chips at the die face and pneumatically conveyed and cooled prior to packing.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

All publications mentioned in this specification are herein incorporated by reference. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of each claim of this application.

Claims

1. A process for producing amorphous carbohydrate granules containing a functional ingredient encapsulated therein, the process comprising:

(b) feeding the carbohydrate mixture to a twin screw extruder;

(c) feeding 0.1 -5% by weight water to the extruder;

(d) feeding the functional ingredient to the extruder;

(e) mixing in the extruder to provide a substantially even distribution of water and the functional ingredient in the carbohydrate mixture;

(f) heating the substantially uniform mixture in the extruder to a temperature of from about 140°C to about 190°C, wherein said temperature is sufficient to melt all crystals of carbohydrate present in the mixture and is, at least in part controlled, by the amount of water added in step (c);

functional ingredient within the carbohydrate matrix;

2. The process according to claim 1 , wherein the water-soluble polymeric carbohydrate is maltodextrin.

3. The process according to claim 2, wherein the maltodextrin has 10 to 25 dextrose equivalents (D.E.).

4. The process according to claim 3, wherein the maltodextrin has 20 to 25 dextrose equivalents (D.E.).

5. The process according to claim 4, wherein the maltodextrin has 20 dextrose equivalents (D.E.).

6. The process according to any one of the preceding claims, wherein the functional ingredient is a flavour ingredient or composition.

7. The process according to any one of the preceding claims, wherein the content of the functional ingredient to the carbohydrate mixture is from about 0.2 to about 20% by weight.

8. The process according to any one of the preceding claims, wherein the extruder includes at least one mixing zone.

9. A functional ingredient-containing granule formed by a process of any one of the preceding claims.