EP2136656A1 - Encapsulating with the aid of a double suspension - Google Patents

Encapsulating with the aid of a double suspension

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Publication number
EP2136656A1
EP2136656A1 EP08723867A EP08723867A EP2136656A1 EP 2136656 A1 EP2136656 A1 EP 2136656A1 EP 08723867 A EP08723867 A EP 08723867A EP 08723867 A EP08723867 A EP 08723867A EP 2136656 A1 EP2136656 A1 EP 2136656A1
Authority
EP
European Patent Office
Prior art keywords
phase
polymer
particles
edible
suspension
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08723867A
Other languages
German (de)
French (fr)
Inventor
Albert Thijs Poortinga
Ramona Maria Henricus Prickaerts
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FrieslandCampina Nederland BV
Original Assignee
Friesland Brands BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Friesland Brands BV filed Critical Friesland Brands BV
Publication of EP2136656A1 publication Critical patent/EP2136656A1/en
Withdrawn legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5089—Processes
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L27/00—Spices; Flavouring agents or condiments; Artificial sweetening agents; Table salts; Dietetic salt substitutes; Preparation or treatment thereof
    • A23L27/70—Fixation, conservation, or encapsulation of flavouring agents
    • A23L27/72—Encapsulation
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L33/00—Modifying nutritive qualities of foods; Dietetic products; Preparation or treatment thereof
    • A23L33/10—Modifying nutritive qualities of foods; Dietetic products; Preparation or treatment thereof using additives
    • A23L33/115—Fatty acids or derivatives thereof; Fats or oils
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L33/00—Modifying nutritive qualities of foods; Dietetic products; Preparation or treatment thereof
    • A23L33/10—Modifying nutritive qualities of foods; Dietetic products; Preparation or treatment thereof using additives
    • A23L33/135—Bacteria or derivatives thereof, e.g. probiotics
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
    • A23L33/00—Modifying nutritive qualities of foods; Dietetic products; Preparation or treatment thereof
    • A23L33/10—Modifying nutritive qualities of foods; Dietetic products; Preparation or treatment thereof using additives
    • A23L33/15—Vitamins
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23P—SHAPING OR WORKING OF FOODSTUFFS, NOT FULLY COVERED BY A SINGLE OTHER SUBCLASS
    • A23P10/00—Shaping or working of foodstuffs characterised by the products
    • A23P10/30—Encapsulation of particles, e.g. foodstuff additives
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23P—SHAPING OR WORKING OF FOODSTUFFS, NOT FULLY COVERED BY A SINGLE OTHER SUBCLASS
    • A23P30/00—Shaping or working of foodstuffs characterised by the process or apparatus
    • A23P30/40—Foaming or whipping
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K9/00—Medicinal preparations characterised by special physical form
    • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
    • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
    • A61K9/5005—Wall or coating material
    • A61K9/5021—Organic macromolecular compounds
    • A61K9/5052—Proteins, e.g. albumin
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
    • A23V—INDEXING SCHEME RELATING TO FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES AND LACTIC OR PROPIONIC ACID BACTERIA USED IN FOODSTUFFS OR FOOD PREPARATION
    • A23V2002/00—Food compositions, function of food ingredients or processes for food or foodstuffs

Definitions

  • the invention relates to a method of preparing edible particles, to a double suspension comprising edible particles, to edible particles, and to a food comprising edible particles.
  • particles with a hierarchical structure are particles composed of different substances, in particular particles having therein one or more compartments of a first substance which are surrounded by a second substance.
  • Particles with a hierarchical structure have various uses. For instance, particles of an active substance, such as a medicinal product or a nutrient, can be surrounded by a protective layer (as by means of encapsulation) to protect the active substance from undesired effects from the environment and/or to protect the environment from the active substance.
  • a protective layer as by means of encapsulation
  • WO 01/60339 describes a method for the preparation of microencapsulated colloidal systems, for pharmaceutical uses in which an emulsion is formed of a first phase comprising a cross-linkable polymer in a second phase comprising a second polymer. Further, a colloidal system is suspended in the first phase. The preparation of edible particles for foods, utilizing an edible cross-linkable polymer and an edible second polymer is not described.
  • EP-A 0 797 925 describes the encapsulation of particles in a non- cross-linked protein layer, utilizing a separating protein polysaccharide two-phase system.
  • the particles are separated from the phase-separated protein phase by means of depositing or centrifuging. It is not mentioned to cross-link the protein first. (Partly) as a result thereof, the protein layer around the particles will be relatively thin. It is an object of the invention to provide a new method of preparing edible particles, in particular particles with a hierarchical structure, for instance particles with a core -shell morphology.
  • the invention relates to a method of preparing edible particles comprising at least a first phase, which first phase at least substantially comprises a second phase, which second phase is solid, liquid or gaseous and/or comprises a microorganism, the method comprising a) suspending an edible solid material, liquid, gas and/or microorganism (for the above-mentioned second phase) in a first solution comprising a first edible polymer; and b) suspending the suspension prepared under a) in a second solution comprising a second edible polymer, thereby forming a double suspension, where at least one polymer (polymer A) of above-mentioned second and first polymer is at least substantially present in the suspended phase of the double emulsion and at least one other polymer (polymer B) of above-mentioned first and second polymer is at least substantially present in the continuous phase.
  • c) polymer A is cross-linked or otherwise fixed.
  • a double suspension in which a suspension is present comprising the first and the second phase, which is in turn surrounded by a third phase (the continuous phase).
  • the preparation of the double suspension is based on the principle that solutions of two or more types of polymers (A and B, respectively) can separate if they are present in a particular concentration. Then at least two phases are created, with polymer A mainly ending up in one phase and polymer B in the other. In this manner, a suspension can be created in which one phase is dispersed as small drops in the other phase. The continuous and the dispersed phase then contain at least substantially the same liquid, the driving force behind maintaining the emulsion are the polymers. In the case that water is the solvent, this is also referred to as a water-in -water emulsion.
  • the polymer in the suspended phase (polymer A) is typically cross-linked or otherwise fixed, thereby forming the first (solid) phase which at least substantially surrounds the second phase.
  • the fixing at least substantially takes place after the second phase has (at least substantially) been surrounded by the first phase. This may be advantageous for one or more properties of the particles, in particular of the first phase (the surrounding phase).
  • fixing examples are, in addition to cross-linking: precipitating, denaturing and gelling.
  • the fixing preferably comprises a cross-linking step.
  • cross-linking generally essentially covalent bonds are formed between two or more molecules of the polymer A in at least a part of the second phase.
  • the particles are isolated, in particular by filtration, and optionally dried and/or added to another phase, preferably a foodstuff, in particular an article of food, including drinks.
  • “edible” is in particular understood to mean “suitable for human consumption”, more in particular suitable for use in a food, such as for instance a dairy product or a fruit drink.
  • solid is in particular understood to mean that a substance is essentially form-stable at room temperature (20°C) under atmospheric pressure, such as a substance in solid aggregation condition (a substance with a melting temperature above room temperature), a gel, an edible material, such as an herb, spice or dietary fiber and the like.
  • liquid is in particular understood to mean that a substance behaves like a liquid at room temperature (20 °C) under atmospheric pressure, such as a substance in liquid aggregation condition (a substance with a melting temperature below room temperature and a boiling temperature above room temperature), such as a vegetable or animal oil, for instance fish oil, olive oil, Unseed oil, and the like.
  • gaseous is in particular understood to mean that a substance behave like a gas at room temperature (20°C) under atmospheric pressure, such as a substance with a boiling temperature below room temperature, such as air, oxygen, CO2, nitrogen, and the like.
  • At least substantially is generally understood to mean for more than 50% up to maximally 100%, in particular for at least 75%, more in particular for at least 90%.
  • At least substantially surrounded is in particular understood to mean: surrounded for 90%-100% of the surface, more in particular for at least 95%, such as at least 99% of the surface.
  • Fig. 1 schematically shows a particle (prepared) according to the invention with a core -shell morphology.
  • Fig. 2 schematically shows a particle in which the first phase surrounds more than one compartment formed by the second phase per particle.
  • Fig. 3 shows a photograph of a double emulsion of an oil-in-protein solution in a polysaccharide solution.
  • Fig. 4 shows a number of photographs taken with confocal scanning laser micrography (CSLM) of a particle according to the invention in an aqueous continuous phase (i.e. a continuous phase at least substantially consisting of water).
  • Fig. 5 illustrates the degree of oxidation of a second phase (oil) which is surrounded by a first phase (cross-linked protein) in particles according to the invention, compared with conventionally obtained particles.
  • CSLM confocal scanning laser micrography
  • Fig. 6 illustrates an embodiment of the invention in which the particles have a delayed digestion profile in (simulated) gastrointestinal conditions.
  • Fig. 7 shows hollow particles according to the invention, filled with air.
  • Fig. 8 shows particles according to the invention in which probiotics are surrounded by a protein.
  • a first phase in particular a solid first phase
  • one or more effects can be brought about.
  • the first phase can serve to mask a smell or taste possibly experienced as unpleasant (such as for instance if the second phase comprises fish oil), to prevent the second phase from being prematurely absorbed, inactivated or degraded by the gastrointestinal tract (for instance in the case of prebiotics, probiotics or microorganisms intended to bring about an effect in the large intestine), for chemical and/or mechanical stabilization of the second phase against an influence from the environment (for instance in the case of oxidizable substances such as vitamins or (unsaturated) oils, certain aromatic substances or flavorings, gas bubbles, microorganisms).
  • a delayed digestion is, for instance, desired to delay a feeling of hunger, which can be desired for diet purposes to prevent overweight or for a more gradual release of a food (ingredient), so that an improved (prolonged) action can be obtained.
  • a method according to the invention is excellently suitable for, if desired, preparing particles with a core -shell morphology in a simple manner, such as capsules with a core (comprising the second phase) and a solid shell (comprising the first phase, which comprises polymer A).
  • a particle is schematically shown in Fig. 1, in which the surrounding phase 1 envelopes one second phase 2.
  • Particles with such a morphology can have one or more advantages compared to particles in which the contents of the particles are distributed over a large number of compartments.
  • a particle with such a morphology may consist of internal phase for a larger part.
  • the release of the inner material can be controlled better or at least be brought about differently.
  • a (micro)capsule with a core-shell morphology will, for instance, be able to burst open under the influence of shearing forces and thereby release its contents completely or at least substantially instantaneously. This may, for instance, bring about a special organoleptic effect, if the second phase comprises an aromatic substance and/or flavoring.
  • the average thickness of the shell (the first phase) may be chosen within a broad range, by choosing the nature and concentration of the polymers, the solvents and process conditions such as the degree of agitation (e.g. the stirring rate).
  • the invention is very suitable for preparing particles with a shell of at least 0.1 ⁇ m, as determined by means of microscopy.
  • the thickness of the shell is at least 0.12 ⁇ m, at least 0.15 ⁇ m or at least 0.25 ⁇ m.
  • the thickness of the shell is up to 10 ⁇ m.
  • the stirring rate may be set at which generally a thinner shell is obtained as agitation (such as stirring) takes place more quickly.
  • the particle may comprise one or more cores (of second phase) and/or more than one shell.
  • a next shell may be provided in a conventional manner, or optionally by using the particles (prepared) according to the invention as a second phase in a follow-up method according to the invention, utilizing for instance a different polymer A.
  • particles where the particles comprise more than one compartment with a second phase which are surrounded by a substantially continuous phase, for instance as schematically shown in Fig. 2.
  • the second phases in the compartment may then be the same. It is also possible to prepare particles with different second phases.
  • the polymer A is preferably at least used in step a) and the polymer B is preferably at least used in the second solution for forming the continuous phase of the double suspension.
  • polymer A and polymer B are chosen such that the second phase prefers to be in contact with the solution of polymer rather than with the solution of polymer B. This can be empirically determined on the basis of general expert knowledge and what is described herein.
  • Polymer A and polymer B are different from each other.
  • polymer A and/or B can be chosen from edible biopolymers, in particular from the group of edible polypeptides, including edible proteins, and edible polysaccharides, more in particular from the group of whey proteins (such as beta-lactoglobulins, alpha -lactalbumin, immunoglobulins), casein, ovalbumin, soy protein, dextran (in particular underived dextran), caseinate, alginate, starch, pectin, cellulose, including derivates thereof acceptable for use in a food, such as for instance an alkyl cellulose, in particular methyl cellulose, or an alkoxy pectin, for instance methoxy pectin, lupin bean protein, coconut milk protein, gum arabic, carob flour, carrageenan, fenugreek gum, guar gum, tara gum and cassia gum.
  • edible biopolymers in particular from the group of edible polypeptides, including edible
  • polymers A and B are of different classes.
  • classes are in particular the class of polypeptides, including proteins, and the class of polysaccharides.
  • Good results have been obtained with a polypeptide, in particular a protein, as polymer A and a polysaccharide, in particular a dextran or a cellulose, which dextran or cellulose may be derived, as polymer B.
  • Particular polymers such as sulfurous proteins, can be cross-linked by means of heating (with disulfide bonds providing the cross-linking), such as for instance whey proteins such as beta lactoglobulin and alpha lactalbumin, soy protein and ovalbumin.
  • Particular carbohydrates such as alginates, pectin, and the like can be cross-linked by addition of cations such as calcium.
  • a number of polymers can be cross-linked by acidification or under the influence of an enzyme.
  • An enzyme such as trans glutaminase is, for instance, very suitable to cross-link a protein in mild conditions.
  • Chemical cross-linking reactions (by reaction with a cross-linking agent) are also possible.
  • the polymer which is at least substantially intended for the continuous phase of the double suspension is preferably chosen such that, at least in the conditions in which the polymer for the first phase (polymer A) is optionally fixed, it is substantially not fixed.
  • Very suitable is, for instance, a protein cross-linkable by heating for the first phase and a polysaccharide, such as a dextran, as a non-cross-linking polymer.
  • Suitable concentrations for polymer A and polymer B can be determined empirically depending on the chosen polymers.
  • the concentrations of polymers A and B are preferably chosen such that, with suspending in step b), the solvents remain separated, while, in the suspended phase (the suspension formed in step a), the weight concentration of the polymer A (CA) is higher and the weight concentration of the polymer B (CB) is lower than the respective concentrations in the continuous phase of the double suspension.
  • a concentration is suitable, based on weight, which is such that CA in the first phase is 2-50 times higher than in the continuous phase and/or CB in the first phase is 2-50 times lower than in the continuous phase.
  • polymers A and B are preferably chosen such that the phase to be encapsulated has more affinity for the suspended phase than for the continuous phase.
  • any solvent can be used for the liquid phases (particularly provided that they are soluble in one another or at least are completely miscible with one another, at least at the temperature at which the method is carried out).
  • the solvent may be polar or non-polar.
  • the solvent for each of the liquid phases is polar, i.e. water or water -miscible or water- soluble.
  • Particularly suitable are liquids chosen from the group consisting of water, aqueous solvents and water-miscible solvents, such as water-miscible alcohols, in particular methanol, ethanol, propanol, glycerol; water-miscible ketones, such as acetone; and mixtures thereof.
  • the solvents are preferably chosen from the group of water, aqueous solvents and water-miscible solvents, such as a water-miscible alcohol or ketone.
  • the solvent is preferably water or a liquid consisting at least substantially of water, i.e. for more than 50 to 100 wt.%, in particular for at least 75 wt.%, more in particular for at least 95 wt.%, such as for at least 99 wt%.
  • the solvents in above-mentioned solutions are preferably the same or at least, in the absence of the polymers, soluble in one another or completely miscible at the temperature at which the double suspension is prepared.
  • the value of the pH can be set to facilitate the phase separation. It may be particularly advantageous if a polypeptide or another amphoteric polymer is used, to set the pH at a value around the isoelectric point of the amphoteric polymer.
  • the second phase comprises, at least at room temperature, solid material, a liquid, a gas and/or a microorganism which at least substantially does not dissolve on a molecular scale in the polymer solutions.
  • at least substantially not dissolving is understood to mean that more than 50 wt.%, preferably more than 90 wt.%, in particular more than 99% of the solid material, the liquid, the gas or the microorganism for the second phase, respectively, does not dissolve in the preparation conditions.
  • the second phase may assume the form of solid particles, liquid particles (drops), bubbles or particles of one or more microorganisms. Combinations thereof are also possible, for instance microorganisms in a liquid or a mixture of microorganisms and a carrier, for instance a dietary fiber.
  • the dimensions of the particles or bubbles can be chosen within a broad range.
  • the invention relates to essentially spherical particles.
  • the number-average particle size (diameter) of the particles or bubbles is at least 1 ⁇ m, preferably at least 5 ⁇ m.
  • the number-average particle size is preferably maximally 100 ⁇ m, in particular maximally 50 ⁇ m.
  • the solid material, the liquid, the gas and/or the microorganism for the above-mentioned second phase can be chosen from the group of flavorings: herbs; spices; oils; fats; probiotics (i.e. bacteria desired in the intestinal flora); prebiotics; air, nitrogen, carbon dioxide, dinitrogen oxide (laughing gas), oxygen, and mixtures thereof; salts; minerals; crystals, in particular of a carbohydrate such as sugar or of a (mineral) salt; at least substantially water -insoluble substances, such as beta carotene and sterols, at least substantially water -insoluble enzymes such as coenzyme QlO, and at least substantially water-insoluble vitamins, such as vitamin A and other fat-soluble vitamins.
  • flavorings herbs; spices; oils; fats; probiotics (i.e. bacteria desired in the intestinal flora); prebiotics; air, nitrogen, carbon dioxide, dinitrogen oxide (laughing gas), oxygen, and mixtures thereof; salts; minerals; crystal
  • oils and fats may in particular be chosen from vegetable and animal oils and fats, including saturated, mono-unsaturated and poly- unsaturated oils and fats, including mixtures of fats and/or oils, such as fish oil.
  • Examples of good bacteria are in particular Lactobacilli and Bifidobacteria.
  • prebiotic carbohydrates such as fructo-oligosaccharides, galacto-oligosaccharides, inulin, and the like.
  • the invention further relates to a double suspension, such as a double suspension obtainable by means of a method comprising steps a) and b) as defined in a method according to the invention, which suspension comprises edible particles, which particles contain at least a first phase (which is solid at least at room temperature) comprising a first polymer, which first phase at least substantially surrounds a second phase, which second phase is (at least at room temperature) solid, liquid or gaseous, and/or comprises a microorganism, while the particles are suspended in a third phase comprising a solution of a second polymer.
  • the concentration of the first polymer in the first phase is preferably 2-50 times higher than in the third phase and/or the concentration of the second polymer in the first phase is preferably at least 2 times lower than in the third phase.
  • the invention relates to a method of preparing encapsulated gas bubbles.
  • a method is very suitable for stabilizing gas bubbles.
  • the foaming can be carried out with the aid of a conventional beating method such as a rotor-stator mixer.
  • any method of foaming can be used.
  • stabilized foam By cross-linking or otherwise fixing the first polymer, a stabilized foam is created.
  • stabilized refers to the possibility to store the encapsulated gas bubbles for a prolonged period without previous changes in the size of the gas bubbles present resulting in undesired coarsening and/or other undesired structural changes.
  • the fixing may take place in a manner as described hereinabove, particularly by cross-linking.
  • a protein to form the first phase in particular a whey protein.
  • (whey) protein as a polymer in the enveloping phase (second phase) yields good results.
  • Whey protein is also advantageous to provide particles with a low digestion rate. Particularly of particles comprising cross-linked whey protein, a low digestion rate has been found.
  • the protein molecules present, or at least a part thereof, can be mutually cross-linked with the aid of a heating step where the food is heated up to above the denaturation temperature of the proteins, for a sufficiently long time.
  • a heating which is such that at least a part of the proteins unfolds and mutually crosslinks.
  • such a heating comprises, for instance, 4 minutes and 45 seconds at 90 0 C, but other temperature/time combinations are also possible.
  • the average bubble size of the encapsulated gas bubbles according to the invention can be determined with microscopic techniques.
  • the bubbles will have a largest diameter in the range between 1 and 500 ⁇ m. In a preferred embodiment, this is at least 5 and/or maximally 100 ⁇ m.
  • the layer thickness of the surrounding phase is at least
  • 0.1 ⁇ m in particular at least 0.15 ⁇ m, preferably at least 1 ⁇ m.
  • the layer thickness of the surrounding phase is maximally 10 ⁇ m, preferably maximally 5 ⁇ m.
  • the product according to the invention can be used as an ingredient or component of foods such as dairy products and fruit juices.
  • This use provides the food enriched with the product according to the invention with a number of advantageous properties.
  • it can serve as a fat substitute; it makes the food taste creamier and/or causes a softer mouthfeel.
  • the foam is, for instance, suitable for addition to a mousse, whipped cream, ice cream, cappuccino cream, a topping, a cream base or meringue.
  • the invention further relates to edible particles obtainable by means of a method according to the invention.
  • such particles comprise at least substantially polymer A in the first phase.
  • polymer A is a protein, in particular a cross-linked or gelled protein.
  • concentration of polymer A as a weight percentage of the sum of polymers A and B is at least 50%, in particular at least 90%. If present, the concentration of polymer B in the first phase of the particles is typically 5 to 50 wt.%, in particular maximally 10 wt.%.
  • a particle according to the invention is characterized by a high degree of smoothness, for instance compared with particles prepared by means of complex coacervation, where for instance a protein and a polysaccharide are present in the surrounding phase of the particle in a ratio of about 1:1.
  • a protein and a polysaccharide are present in the surrounding phase of the particle in a ratio of about 1:1.
  • the second phase it is possible to protect the second phase from an influence from the environment, in particular in an embodiment according to the invention in which the first phase, such as a protein, is cross-linked.
  • the first phase such as a protein
  • the protective action may, for instance, comprise a reduced degradation rate of the second phase, for instance a reduced digestion rate of a food or ingredient for this, in gastrointestinal conditions, compared with particles encapsulated in a conventional manner.
  • the second phase can be protected against oxidation by the first phase.
  • the first phase can provide some protection against damage of the second phase under the influence of shearing forces, in particular if the second phase is a fairly soft material, such as a fat globule or if the second phase is liquid, for instance an oil. More specifically, the first phase can provide some protection against damage of an emulsion, such as oil drops filled with water drops, surrounded by the first phase.
  • the invention further relates to a food comprising a double suspension or edible particles (prepared) according to the invention, preferably a dairy product, most preferably a food chosen from the group of cheese, yoghurt, whipped cream, mousses, desserts, dairy beverages, ice cream, cappuccino foam, toppings, cream bases and meringue.
  • a dairy product most preferably a food chosen from the group of cheese, yoghurt, whipped cream, mousses, desserts, dairy beverages, ice cream, cappuccino foam, toppings, cream bases and meringue.
  • the enveloping whey protein phase was then cross-linked in the emulsion by heating for 60 minutes at 85°C, after which the particles were centrifuged off and again dispersed in demineralized water.
  • the CSLM images in Fig. 4 show that a protein layer 1 (in white/light gray) surrounds the oil drops 2 well (the back/dark gray surrounded by the white/light gray).
  • the continuous phase 3 black contains substantially water.
  • the protein In the original of the photograph (in color), in the focused part, the protein is shown in green, the oil drops in black, and the continuous phase in blue.
  • Oxidation test The encapsulated oil drops were produced as described hereinabove. As oil, a 1 to 1 mixture of soy and linseed oil was used. After preparation, a part of the capsule solution was dried for an hour in an oven at 50°C. A part of the emulsion of oil in whey protein solution was kept separate as a blank. A part of this was also dried for an hour at 50°C. Then, of both wet variants (blank and encapsulated), 14 ml was put into glass jars of 30 ml. Of both dry variants, 3 g of powder was put in the glass jars. To the wall of the jars, an OxyDot was fixed. The jars were sealed hermetically. With the aid of the OxyDot, the oxygen content in the jars in the course of time was monitored.
  • Fig. 5 shows that, in the particles according to the invention (curves 1 and 3), the oil is better protected than in the corresponding comparative examples.
  • fatty acid content found is shown as a function of time in Fig. 6. It can clearly be seen that particles according to the invention are digested more slowly than the particles encapsulated in a conventional manner.
  • the method of preparation took place in a manner analogous to the preparation of encapsulated oil drops, provided that air instead of oil was dispersed in the protein solution, up to a storage of about 100%, and that cross-linking was carried out by adding 1% glutaraldehyde. After cross-linking, the bubbles formed were separated and centrifuged. Fig. 7 shows a photograph of the bubbles. It was found that the bubbles had an essentially unchanged diameter after a week.
  • whey protein concentrate Hiprotal 580, DOMO
  • This suspension was added to a 4 wt.% methyl cellulose solution in a ratio of 1:4 and stirred with a stir bar.
  • drops of whey protein solution with bacteria therein were created, as shown in Fig. 4.
  • the whey proteins may then be cross-linked enzymatically, for instance with the aid of trans glutaminase.

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Abstract

The invention relates to a method of preparing edible particles, comprising at least a first phase, which first phase at least substantially surrounds a second phase, which second phase is solid, liquid or gaseous and/or comprises a microorganism, the method comprising a) suspending an edible solid material, liquid, gas and/or microorganism (for the said second phase) in a first solution comprising a first edible polymer; b) suspending the suspension prepared in a) in a second solution comprising a second edible polymer, thereby forming a double suspension, wherein at least one polymer (polymer A) of said first and second polymer is at least substantially present in the suspended phase of the double emulsion and at least another polymer (polymer B) of said first and second polymer is at least substantially present in the continuous phase; and c) cross-linking or otherwise fixing polymer A.

Description

Title: Encapsulating with the aid of a double suspension
The invention relates to a method of preparing edible particles, to a double suspension comprising edible particles, to edible particles, and to a food comprising edible particles.
In this specification, particles with a hierarchical structure are particles composed of different substances, in particular particles having therein one or more compartments of a first substance which are surrounded by a second substance.
Particles with a hierarchical structure have various uses. For instance, particles of an active substance, such as a medicinal product or a nutrient, can be surrounded by a protective layer (as by means of encapsulation) to protect the active substance from undesired effects from the environment and/or to protect the environment from the active substance.
WO 01/60339 describes a method for the preparation of microencapsulated colloidal systems, for pharmaceutical uses in which an emulsion is formed of a first phase comprising a cross-linkable polymer in a second phase comprising a second polymer. Further, a colloidal system is suspended in the first phase. The preparation of edible particles for foods, utilizing an edible cross-linkable polymer and an edible second polymer is not described.
EP-A 0 797 925 describes the encapsulation of particles in a non- cross-linked protein layer, utilizing a separating protein polysaccharide two-phase system. The particles are separated from the phase-separated protein phase by means of depositing or centrifuging. It is not mentioned to cross-link the protein first. (Partly) as a result thereof, the protein layer around the particles will be relatively thin. It is an object of the invention to provide a new method of preparing edible particles, in particular particles with a hierarchical structure, for instance particles with a core -shell morphology.
It is further an object of the invention to provide a new method of preparing particles with a hierarchical structure where the particles are composed of two or more solid substances, from particles which are composed of at least a solid substance and a liquid, in particular an at least not completely water-soluble substance, and/or where the particles comprise a gaseous phase which is surrounded by a solid phase. It is further an object of the invention to provide edible particles with a stabilized particle size, in particular such particles comprising a gas phase and a solid phase, such as foam particles.
One or more other objects which can be achieved by means of the invention follow from the rest of the specification and/or claims. It has now been found that it is possible to prepare particles with a hierarchical structure from a particular type of double suspension.
Therefore the invention relates to a method of preparing edible particles comprising at least a first phase, which first phase at least substantially comprises a second phase, which second phase is solid, liquid or gaseous and/or comprises a microorganism, the method comprising a) suspending an edible solid material, liquid, gas and/or microorganism (for the above-mentioned second phase) in a first solution comprising a first edible polymer; and b) suspending the suspension prepared under a) in a second solution comprising a second edible polymer, thereby forming a double suspension, where at least one polymer (polymer A) of above-mentioned second and first polymer is at least substantially present in the suspended phase of the double emulsion and at least one other polymer (polymer B) of above-mentioned first and second polymer is at least substantially present in the continuous phase. Typically, then c) polymer A is cross-linked or otherwise fixed. Surprisingly, it has been found possible to obtain, by means of the invention, a double suspension in which a suspension is present comprising the first and the second phase, which is in turn surrounded by a third phase (the continuous phase).
The preparation of the double suspension is based on the principle that solutions of two or more types of polymers (A and B, respectively) can separate if they are present in a particular concentration. Then at least two phases are created, with polymer A mainly ending up in one phase and polymer B in the other. In this manner, a suspension can be created in which one phase is dispersed as small drops in the other phase. The continuous and the dispersed phase then contain at least substantially the same liquid, the driving force behind maintaining the emulsion are the polymers. In the case that water is the solvent, this is also referred to as a water-in -water emulsion.
For obtaining particles with at least a solid first phase, the polymer in the suspended phase (polymer A) is typically cross-linked or otherwise fixed, thereby forming the first (solid) phase which at least substantially surrounds the second phase. Preferably, the fixing at least substantially takes place after the second phase has (at least substantially) been surrounded by the first phase. This may be advantageous for one or more properties of the particles, in particular of the first phase (the surrounding phase).
Examples of fixing are, in addition to cross-linking: precipitating, denaturing and gelling. The fixing preferably comprises a cross-linking step. With cross-linking, generally essentially covalent bonds are formed between two or more molecules of the polymer A in at least a part of the second phase. Typically, the particles are isolated, in particular by filtration, and optionally dried and/or added to another phase, preferably a foodstuff, in particular an article of food, including drinks.
Herein, "edible" is in particular understood to mean "suitable for human consumption", more in particular suitable for use in a food, such as for instance a dairy product or a fruit drink.
Herein, "solid" is in particular understood to mean that a substance is essentially form-stable at room temperature (20°C) under atmospheric pressure, such as a substance in solid aggregation condition (a substance with a melting temperature above room temperature), a gel, an edible material, such as an herb, spice or dietary fiber and the like. Herein, "liquid" is in particular understood to mean that a substance behaves like a liquid at room temperature (20 °C) under atmospheric pressure, such as a substance in liquid aggregation condition (a substance with a melting temperature below room temperature and a boiling temperature above room temperature), such as a vegetable or animal oil, for instance fish oil, olive oil, Unseed oil, and the like.
Herein, "gaseous" is in particular understood to mean that a substance behave like a gas at room temperature (20°C) under atmospheric pressure, such as a substance with a boiling temperature below room temperature, such as air, oxygen, CO2, nitrogen, and the like.
"At least substantially" is generally understood to mean for more than 50% up to maximally 100%, in particular for at least 75%, more in particular for at least 90%. "At least substantially surrounded" is in particular understood to mean: surrounded for 90%-100% of the surface, more in particular for at least 95%, such as at least 99% of the surface.
Fig. 1 schematically shows a particle (prepared) according to the invention with a core -shell morphology. Fig. 2 schematically shows a particle in which the first phase surrounds more than one compartment formed by the second phase per particle.
Fig. 3 shows a photograph of a double emulsion of an oil-in-protein solution in a polysaccharide solution.
Fig. 4 shows a number of photographs taken with confocal scanning laser micrography (CSLM) of a particle according to the invention in an aqueous continuous phase (i.e. a continuous phase at least substantially consisting of water). Fig. 5 illustrates the degree of oxidation of a second phase (oil) which is surrounded by a first phase (cross-linked protein) in particles according to the invention, compared with conventionally obtained particles.
Fig. 6 illustrates an embodiment of the invention in which the particles have a delayed digestion profile in (simulated) gastrointestinal conditions.
Fig. 7 shows hollow particles according to the invention, filled with air.
Fig. 8 shows particles according to the invention in which probiotics are surrounded by a protein. By surrounding the second phase with a first phase, in particular a solid first phase, one or more effects can be brought about. Thus, the first phase can serve to mask a smell or taste possibly experienced as unpleasant (such as for instance if the second phase comprises fish oil), to prevent the second phase from being prematurely absorbed, inactivated or degraded by the gastrointestinal tract (for instance in the case of prebiotics, probiotics or microorganisms intended to bring about an effect in the large intestine), for chemical and/or mechanical stabilization of the second phase against an influence from the environment (for instance in the case of oxidizable substances such as vitamins or (unsaturated) oils, certain aromatic substances or flavorings, gas bubbles, microorganisms). It is also possible to realize a delayed digestion in the gastrointestinal tract, for instance of an oil or fat encapsulated in a protein. A delayed digestion is, for instance, desired to delay a feeling of hunger, which can be desired for diet purposes to prevent overweight or for a more gradual release of a food (ingredient), so that an improved (prolonged) action can be obtained.
A method according to the invention is excellently suitable for, if desired, preparing particles with a core -shell morphology in a simple manner, such as capsules with a core (comprising the second phase) and a solid shell (comprising the first phase, which comprises polymer A). Such a particle is schematically shown in Fig. 1, in which the surrounding phase 1 envelopes one second phase 2.
Particles with such a morphology can have one or more advantages compared to particles in which the contents of the particles are distributed over a large number of compartments. Thus, there is a clearly distinctive core with well controllable properties which may differ from those of the capsule. Also, a particle with such a morphology may consist of internal phase for a larger part. Further, the release of the inner material can be controlled better or at least be brought about differently. A (micro)capsule with a core-shell morphology will, for instance, be able to burst open under the influence of shearing forces and thereby release its contents completely or at least substantially instantaneously. This may, for instance, bring about a special organoleptic effect, if the second phase comprises an aromatic substance and/or flavoring.
The average thickness of the shell (the first phase) may be chosen within a broad range, by choosing the nature and concentration of the polymers, the solvents and process conditions such as the degree of agitation (e.g. the stirring rate). The invention is very suitable for preparing particles with a shell of at least 0.1 μm, as determined by means of microscopy. Preferably, the thickness of the shell is at least 0.12 μm, at least 0.15 μm or at least 0.25 μm. In particular, the thickness of the shell is up to 10 μm. Particularly for setting the shell thickness, the stirring rate may be set at which generally a thinner shell is obtained as agitation (such as stirring) takes place more quickly.
If desired, the particle may comprise one or more cores (of second phase) and/or more than one shell. A next shell may be provided in a conventional manner, or optionally by using the particles (prepared) according to the invention as a second phase in a follow-up method according to the invention, utilizing for instance a different polymer A.
It is also possible to prepare particles where the particles comprise more than one compartment with a second phase which are surrounded by a substantially continuous phase, for instance as schematically shown in Fig. 2. The second phases in the compartment may then be the same. It is also possible to prepare particles with different second phases.
By means of the invention, it has surprisingly been found possible to choose conditions such that a substance at least substantially not soluble in the solvent is or remains preferably dispersed in the dispersed phase.
For reasons of effectiveness, the polymer A is preferably at least used in step a) and the polymer B is preferably at least used in the second solution for forming the continuous phase of the double suspension. To this end, polymer A and polymer B are chosen such that the second phase prefers to be in contact with the solution of polymer rather than with the solution of polymer B. This can be empirically determined on the basis of general expert knowledge and what is described herein.
Polymer A and polymer B are different from each other. In particular, polymer A and/or B can be chosen from edible biopolymers, in particular from the group of edible polypeptides, including edible proteins, and edible polysaccharides, more in particular from the group of whey proteins (such as beta-lactoglobulins, alpha -lactalbumin, immunoglobulins), casein, ovalbumin, soy protein, dextran (in particular underived dextran), caseinate, alginate, starch, pectin, cellulose, including derivates thereof acceptable for use in a food, such as for instance an alkyl cellulose, in particular methyl cellulose, or an alkoxy pectin, for instance methoxy pectin, lupin bean protein, coconut milk protein, gum arabic, carob flour, carrageenan, fenugreek gum, guar gum, tara gum and cassia gum. Preferably, polymers A and B are of different classes. Examples of different classes are in particular the class of polypeptides, including proteins, and the class of polysaccharides. Good results have been obtained with a polypeptide, in particular a protein, as polymer A and a polysaccharide, in particular a dextran or a cellulose, which dextran or cellulose may be derived, as polymer B.
At least if it is desired to fix the polymer for the first phase, at least the polymer for the first phase (polymer A) is preferably cross-linkable. Particular polymers, such as sulfurous proteins, can be cross-linked by means of heating (with disulfide bonds providing the cross-linking), such as for instance whey proteins such as beta lactoglobulin and alpha lactalbumin, soy protein and ovalbumin.
Particular carbohydrates, such as alginates, pectin, and the like can be cross-linked by addition of cations such as calcium. A number of polymers can be cross-linked by acidification or under the influence of an enzyme. An enzyme such as trans glutaminase is, for instance, very suitable to cross-link a protein in mild conditions. Chemical cross-linking reactions (by reaction with a cross-linking agent) are also possible.
The polymer which is at least substantially intended for the continuous phase of the double suspension (polymer B) is preferably chosen such that, at least in the conditions in which the polymer for the first phase (polymer A) is optionally fixed, it is substantially not fixed. Very suitable is, for instance, a protein cross-linkable by heating for the first phase and a polysaccharide, such as a dextran, as a non-cross-linking polymer.
Suitable concentrations for polymer A and polymer B can be determined empirically depending on the chosen polymers. The concentrations of polymers A and B are preferably chosen such that, with suspending in step b), the solvents remain separated, while, in the suspended phase (the suspension formed in step a), the weight concentration of the polymer A (CA) is higher and the weight concentration of the polymer B (CB) is lower than the respective concentrations in the continuous phase of the double suspension.
As a rule, a concentration is suitable, based on weight, which is such that CA in the first phase is 2-50 times higher than in the continuous phase and/or CB in the first phase is 2-50 times lower than in the continuous phase. Thus, it is possible to prepare a suspension where there is no or hardly any exchange of polymers between the different phases.
Particularly for obtaining at least virtually completely encapsulated particles, polymers A and B are preferably chosen such that the phase to be encapsulated has more affinity for the suspended phase than for the continuous phase.
In principle, any solvent can be used for the liquid phases (particularly provided that they are soluble in one another or at least are completely miscible with one another, at least at the temperature at which the method is carried out). So, the solvent may be polar or non-polar. Preferably, the solvent for each of the liquid phases is polar, i.e. water or water -miscible or water- soluble. Particularly suitable are liquids chosen from the group consisting of water, aqueous solvents and water-miscible solvents, such as water-miscible alcohols, in particular methanol, ethanol, propanol, glycerol; water-miscible ketones, such as acetone; and mixtures thereof.
The solvents are preferably chosen from the group of water, aqueous solvents and water-miscible solvents, such as a water-miscible alcohol or ketone. Here, the solvent is preferably water or a liquid consisting at least substantially of water, i.e. for more than 50 to 100 wt.%, in particular for at least 75 wt.%, more in particular for at least 95 wt.%, such as for at least 99 wt%.
The solvents in above-mentioned solutions are preferably the same or at least, in the absence of the polymers, soluble in one another or completely miscible at the temperature at which the double suspension is prepared.
Optionally, the value of the pH can be set to facilitate the phase separation. It may be particularly advantageous if a polypeptide or another amphoteric polymer is used, to set the pH at a value around the isoelectric point of the amphoteric polymer.
The second phase comprises, at least at room temperature, solid material, a liquid, a gas and/or a microorganism which at least substantially does not dissolve on a molecular scale in the polymer solutions. In particular, at least substantially not dissolving is understood to mean that more than 50 wt.%, preferably more than 90 wt.%, in particular more than 99% of the solid material, the liquid, the gas or the microorganism for the second phase, respectively, does not dissolve in the preparation conditions.
In the suspension, the second phase may assume the form of solid particles, liquid particles (drops), bubbles or particles of one or more microorganisms. Combinations thereof are also possible, for instance microorganisms in a liquid or a mixture of microorganisms and a carrier, for instance a dietary fiber.
The dimensions of the particles or bubbles can be chosen within a broad range. In particular, the invention relates to essentially spherical particles.
Typically, the number-average particle size (diameter) of the particles or bubbles, as determinable by means of microscopy, preferably in two or three dimensions, is at least 1 μm, preferably at least 5 μm. The number-average particle size is preferably maximally 100 μm, in particular maximally 50 μm.
In particular, the solid material, the liquid, the gas and/or the microorganism for the above-mentioned second phase can be chosen from the group of flavorings: herbs; spices; oils; fats; probiotics (i.e. bacteria desired in the intestinal flora); prebiotics; air, nitrogen, carbon dioxide, dinitrogen oxide (laughing gas), oxygen, and mixtures thereof; salts; minerals; crystals, in particular of a carbohydrate such as sugar or of a (mineral) salt; at least substantially water -insoluble substances, such as beta carotene and sterols, at least substantially water -insoluble enzymes such as coenzyme QlO, and at least substantially water-insoluble vitamins, such as vitamin A and other fat-soluble vitamins.
The oils and fats may in particular be chosen from vegetable and animal oils and fats, including saturated, mono-unsaturated and poly- unsaturated oils and fats, including mixtures of fats and/or oils, such as fish oil.
Examples of good bacteria are in particular Lactobacilli and Bifidobacteria.
Particularly suitable prebiotics are prebiotic carbohydrates, such as fructo-oligosaccharides, galacto-oligosaccharides, inulin, and the like.
The invention further relates to a double suspension, such as a double suspension obtainable by means of a method comprising steps a) and b) as defined in a method according to the invention, which suspension comprises edible particles, which particles contain at least a first phase (which is solid at least at room temperature) comprising a first polymer, which first phase at least substantially surrounds a second phase, which second phase is (at least at room temperature) solid, liquid or gaseous, and/or comprises a microorganism, while the particles are suspended in a third phase comprising a solution of a second polymer. The concentration of the first polymer in the first phase is preferably 2-50 times higher than in the third phase and/or the concentration of the second polymer in the first phase is preferably at least 2 times lower than in the third phase.
In one embodiment, the invention relates to a method of preparing encapsulated gas bubbles. Such a method is very suitable for stabilizing gas bubbles. In such a method a) the first solution, comprising the first edible polymer (typically polymer A), is foamed with the gas; and b) the foam is then stirred through the second solution, comprising the second edible polymer (typically polymer B). The foaming can be carried out with the aid of a conventional beating method such as a rotor-stator mixer. Incidentally, any method of foaming can be used.
By cross-linking or otherwise fixing the first polymer, a stabilized foam is created. In this context, the term "stabilized" refers to the possibility to store the encapsulated gas bubbles for a prolonged period without previous changes in the size of the gas bubbles present resulting in undesired coarsening and/or other undesired structural changes.
It has been found that it is possible by means of the invention to obtain a foam where the bubbles do not become essentially larger within a desired period, in particular a period of at least a week, in particular when a protein, in particular a milk protein, is chosen as polymer A and, if desired, a polysaccharide as polymer B.
It is in particular possible to stabilize a foam for at least a particular time against disproportioning of the gas bubbles by creating a rigid surface (the fixed polymer) on the bubbles. In other words, the stability is not primarily caused by the bulk of the product.
The fixing may take place in a manner as described hereinabove, particularly by cross-linking. In a preferred embodiment, use is made of a protein to form the first phase, in particular a whey protein. It has particularly been found that, for a material to be encapsulated, such as oil drops, air bubbles or bacteria, use of (whey) protein as a polymer in the enveloping phase (second phase) yields good results. Whey protein is also advantageous to provide particles with a low digestion rate. Particularly of particles comprising cross-linked whey protein, a low digestion rate has been found.
The protein molecules present, or at least a part thereof, can be mutually cross-linked with the aid of a heating step where the food is heated up to above the denaturation temperature of the proteins, for a sufficiently long time. Thus, the foamed product is subjected to a heating which is such that at least a part of the proteins unfolds and mutually crosslinks. For milk protein, such a heating comprises, for instance, 4 minutes and 45 seconds at 900C, but other temperature/time combinations are also possible.
Incidentally, preferred methods and apparatuses applicable in the method of preparing encapsulated gas bubbles (for step a and/or the optional cross-linking) are described in detail in the patents with number NLl 024 433, NLl 024 43, NL 1 024 435 and NL 1 024 438. The method and apparatuses described therein are incorporated in this specification by reference as preferred embodiments of the present method. Another suitable manner of cross-linking comprises the use of an enzyme, such as for instance trans glutaminase.
The average bubble size of the encapsulated gas bubbles according to the invention can be determined with microscopic techniques. As a rule, the bubbles will have a largest diameter in the range between 1 and 500 μm. In a preferred embodiment, this is at least 5 and/or maximally 100 μm.
By means of the invention, it has been found that, compared with a known method of stabilizing foam, such as for instance a method described in NL 1 024 435, it is possible to realize a higher stability with a same bubble size, and/or a similar stability with a larger bubble size. It is suspected that, here, the possibility to make encapsulated bubbles with a relatively thick surrounding phase contributes to this. Typically, the layer thickness of the surrounding phase is at least
0.1 μm, in particular at least 0.15 μm, preferably at least 1 μm.
Typically, the layer thickness of the surrounding phase is maximally 10 μm, preferably maximally 5 μm.
By means of the invention, it is possible to make a foam with a high degree of dimensional stability, with a particular thickness of the layer. Thus, it is possible to obtain a foam where the average diameter of the bubbles is at least substantially maintained for a period of 7 days or more.
The product according to the invention can be used as an ingredient or component of foods such as dairy products and fruit juices. This use provides the food enriched with the product according to the invention with a number of advantageous properties. Thus, it can serve as a fat substitute; it makes the food taste creamier and/or causes a softer mouthfeel. The foam is, for instance, suitable for addition to a mousse, whipped cream, ice cream, cappuccino cream, a topping, a cream base or meringue.
The invention further relates to edible particles obtainable by means of a method according to the invention. In particular, such particles comprise at least substantially polymer A in the first phase. More preferably, polymer A is a protein, in particular a cross-linked or gelled protein. Preferably, the concentration of polymer A as a weight percentage of the sum of polymers A and B is at least 50%, in particular at least 90%. If present, the concentration of polymer B in the first phase of the particles is typically 5 to 50 wt.%, in particular maximally 10 wt.%. In one embodiment, a particle according to the invention is characterized by a high degree of smoothness, for instance compared with particles prepared by means of complex coacervation, where for instance a protein and a polysaccharide are present in the surrounding phase of the particle in a ratio of about 1:1. Without wishing to be bound to any theory, it is suspected that this could be connected with a possibly high degree of homogeneity of the first phase in particles according to the invention.
It has further been found that, by means of the invention, it is possible to protect the second phase from an influence from the environment, in particular in an embodiment according to the invention in which the first phase, such as a protein, is cross-linked. Without wishing to be bound to any theory, it is suspected that, by means of the invention, it is possible to provide a layer protecting better in one or more respects or an improved barrier layer around the second layer compared with a conventional method such as for instance complex coacervation, by providing the first phase around the second phase and only then fixing the first phase, in particular then cross-linking it.
The protective action may, for instance, comprise a reduced degradation rate of the second phase, for instance a reduced digestion rate of a food or ingredient for this, in gastrointestinal conditions, compared with particles encapsulated in a conventional manner.
It has also been found that, in particles according to the invention, the second phase can be protected against oxidation by the first phase. Further, in one embodiment, the first phase can provide some protection against damage of the second phase under the influence of shearing forces, in particular if the second phase is a fairly soft material, such as a fat globule or if the second phase is liquid, for instance an oil. More specifically, the first phase can provide some protection against damage of an emulsion, such as oil drops filled with water drops, surrounded by the first phase. The invention further relates to a food comprising a double suspension or edible particles (prepared) according to the invention, preferably a dairy product, most preferably a food chosen from the group of cheese, yoghurt, whipped cream, mousses, desserts, dairy beverages, ice cream, cappuccino foam, toppings, cream bases and meringue.
The invention is now illustrated on the basis of a number of examples.
Example 1
Encapsulation of oil drops in whey protein
20 wt.% oil was emulsified in a 40 wt.% whey protein concentrate (Hiprotal 580, DOMO) solution with pH 5.2 with the aid of a Turrax. The emulsion thus obtained was stirred through a 20 wt.% dextran (sigma D5376) solution (pH 5.2) in ratio of 1 to 9. Thus, a double emulsion was created of an emulsified oil-in-protein solution, which was emulsified in dextran solution. A photograph thereof is shown in Fig. 3.
The enveloping whey protein phase was then cross-linked in the emulsion by heating for 60 minutes at 85°C, after which the particles were centrifuged off and again dispersed in demineralized water. The CSLM images in Fig. 4 show that a protein layer 1 (in white/light gray) surrounds the oil drops 2 well (the back/dark gray surrounded by the white/light gray). The continuous phase 3 (black) contains substantially water. In the original of the photograph (in color), in the focused part, the protein is shown in green, the oil drops in black, and the continuous phase in blue.
With these particles, a number of application tests were carried out.
Oxidation test The encapsulated oil drops were produced as described hereinabove. As oil, a 1 to 1 mixture of soy and linseed oil was used. After preparation, a part of the capsule solution was dried for an hour in an oven at 50°C. A part of the emulsion of oil in whey protein solution was kept separate as a blank. A part of this was also dried for an hour at 50°C. Then, of both wet variants (blank and encapsulated), 14 ml was put into glass jars of 30 ml. Of both dry variants, 3 g of powder was put in the glass jars. To the wall of the jars, an OxyDot was fixed. The jars were sealed hermetically. With the aid of the OxyDot, the oxygen content in the jars in the course of time was monitored.
The results are shown in Fig. 5. The decrease of the oxygen content is an indication of the oxidation of the oil. Fig. 5 shows that, in the particles according to the invention (curves 1 and 3), the oil is better protected than in the corresponding comparative examples.
Digestion test
Of a suspension of encapsulated sunflower oil, prepared as described hereinabove, with an oil content of 5%, the digestion rate was measured by means of an in vivo test. As references, the original emulsion, diluted to an oil content of 5%, was taken, as well as a commercially available preparation, Fabuless (consisting of oil drops covered with a special type of emulsifier), also with an oil content of 5% and an emulsion (5% oil, 2.5% whey protein) which has been subjected to a same heating as the encapsulated variant. The in vitro test used is described in WO 2004/105520A1, in which the samples are in the simulated stomach for up to 60 minutes, and then in the simulated intestine.
The fatty acid content found is shown as a function of time in Fig. 6. It can clearly be seen that particles according to the invention are digested more slowly than the particles encapsulated in a conventional manner.
Example 2
Encapsulated air bubbles
The method of preparation took place in a manner analogous to the preparation of encapsulated oil drops, provided that air instead of oil was dispersed in the protein solution, up to a storage of about 100%, and that cross-linking was carried out by adding 1% glutaraldehyde. After cross-linking, the bubbles formed were separated and centrifuged. Fig. 7 shows a photograph of the bubbles. It was found that the bubbles had an essentially unchanged diameter after a week.
Example 3
Encapsulation of probiotics
5 wt.% bacteria (Lactobacillus casei CRL431) were added to
30 wt.% whey protein concentrate (Hiprotal 580, DOMO) in water. This suspension was added to a 4 wt.% methyl cellulose solution in a ratio of 1:4 and stirred with a stir bar. Here, drops of whey protein solution with bacteria therein were created, as shown in Fig. 4. The whey proteins may then be cross-linked enzymatically, for instance with the aid of trans glutaminase.

Claims

1. A method of preparing edible particles, comprising at least a first phase, which first phase at least substantially surrounds a second phase, which second phase is solid, liquid or gaseous and/or comprises a microorganism, the method comprising
5 a) suspending an edible solid material, liquid, gas and/or microorganism (for the said second phase) in a first solution comprising a first edible polymer; b) suspending the suspension prepared in a) in a second solution comprising a second edible polymer, thereby forming a double suspension, wherein at least one polymer (polymer A) of said first and second polymer is at least0 substantially present in the suspended phase of the double emulsion and at least another polymer (polymer B) of said first and second polymer is at least substantially present in the continuous phase; and c) cross-linking or otherwise fixing polymer A.
2. A method according to claim 1, comprising d) isolating the particles5 formed.
3. A method according to claim 1 or 2, wherein the solvents in said solutions are the same or, at least in the absence of the polymers A and B, soluble in one another or completely miscible at the temperature at which the double suspension is prepared, wherein the concentrations of the o polymers A and B are chosen such that, during mixing in step b), the solvents remain separated, wherein, in the suspended phase (the suspension formed in step a)), the weight concentration of the polymer A (CA) is higher and the weight concentration of the polymer B (CB) is lower than the respective concentrations in the continuous phase. 5
4. A method according to any one of the preceding claims, wherein, in both the suspension prepared in a) and the solution of polymer B, at least one solvent for the polymers A and B, respectively, is present, chosen from the group of water, aqueous solvents and water-miscible solvents, such as a water-miscible alcohol or ketone, and wherein the solvent is preferably water or a liquid which consists at least substantially of water.
5. A method according to any one of the preceding claims, wherein the polymer A and/or B is chosen from the group of biopolymers, in particular from the group of proteins and polysaccharides, more in particular from the group of whey proteins (such as beta lactoglobulins, alpha lactalbumin, immunoglobulins), caseins, dextran, caseinate, alginate, starch, pectin, cellulose, including derivates thereof.
6. A method according to any one of the preceding claims, wherein the edible solid material, liquid, gas and/or microorganism (for the said second phase) is chosen from the group of flavorings; aromatic substances; herbs; spices; oils; fats; probiotics; "good" bacteria; prebiotics; carbon dioxide , nitrogen, dinitrogen oxide, oxygen and mixtures thereof, such as air; salts; minerals; crystals, in particular of a carbohydrate such as sugar; poorly water-soluble substances, such as beta carotene or poorly soluble enzymes, such as coenzyme QlO and vitamins, such as vitamin A and other vitamins, particularly other fat-soluble vitamins.
7. A method according to any one of the preceding claims, wherein the first phase comprises a gas, wherein a) the first solution, comprising the first edible polymer (A), is foamed with the gas; and b) the foam is then stirred through the second solution, comprising the second edible polymer (B).
8. A double suspension, such as a double suspension obtainable by means of a method comprising steps a) and b) as defined in one of the preceding claims, which suspension comprises edible particles, which particles contain at least a first phase (which is, at least at room temperature, solid) comprising a first polymer (A), which first phase at least substantially surrounds a second phase, which second phase is (at least at room temperature) solid, liquid or gaseous and/or comprises a microorganism, wherein the particles are suspended in a third phase comprising a solution of a second polymer (B).
9. A double suspension according to claim 8, wherein the solvents are chosen from the solvents mentioned in claim 4, the polymer A from the polymers mentioned in claim 5, the polymer B from the polymers mentioned in claim 5, and/or the second phase comprises at least one solid material, liquid, gas and/or microorganism mentioned in claim 6.
10. A double suspension according to claim 8 or 9, wherein CA in the first phase is 2-50 times higher than in the third phase and/or CB in the first phase is at least 2 times lower than in the third phase.
11. Edible particles obtainable by means of a method according to any one of claims 1-7.
12. Edible particles, such as particles obtainable by means of a method according to any one of claims 1-7, which particles contain at least a first phase, which is, at least at room temperature, solid, comprising a first cross- linked polymer A, which first phase at least substantially surrounds a second phase, which second phase is gaseous and wherein the average thickness of the first phase is 0.1-10 μm.
13. Edible particles according to claim 12 or 13, wherein polymer A comprises a cross-linked protein, preferably a cross-linked whey protein.
14. A food comprising a double suspension according to any one of claims 8-10 or edible particles according to any one of claims 11-13, preferably a dairy product, most preferably chosen from the group formed by cheese, yoghurt, whipped cream, mousses, desserts, dairy beverages, ice cream, cappuccino foam, toppings, cream bases and meringue.
EP08723867A 2007-03-30 2008-03-31 Encapsulating with the aid of a double suspension Withdrawn EP2136656A1 (en)

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NL1033621A NL1033621C2 (en) 2007-03-30 2007-03-30 Encapsulate using a double suspension.
PCT/NL2008/000095 WO2008120975A1 (en) 2007-03-30 2008-03-31 Encapsulating with the aid of a double suspension

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WO2009070012A1 (en) * 2007-11-29 2009-06-04 Nizo Food Research B.V. Protein-based probiotic encapsulates
NL2002049C (en) * 2008-10-01 2010-04-02 Friesland Brands Bv ENCAPSULATE USING A DOUBLE SUSPENSION.
ES2392150T3 (en) 2010-01-22 2012-12-05 Unilever N.V. Frozen Particle Manufacturing Procedure
WO2014082131A1 (en) * 2012-11-29 2014-06-05 Progel Pty Ltd A microparticle composition comprising a probiotic, cross-linkable reagent and an emulsion containing a hydrophobic active
AU2013351920B2 (en) 2012-11-29 2018-08-23 Progel Pty Ltd Microparticles comprising a probiotic, cross-linkable reagent, a denatured protein, polyol plasticiser and trehalose

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SE459005B (en) * 1985-07-12 1989-05-29 Aake Rikard Lindahl SET TO MANUFACTURE SPHERICAL POLYMER PARTICLES
DE69616978T2 (en) * 1996-03-27 2002-05-29 Nestle Sa Protein-encapsulated particles from a polysaccharide-containing dispersion
US6395302B1 (en) * 1996-11-19 2002-05-28 Octoplus B.V. Method for the preparation of microspheres which contain colloidal systems

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