Process for the preparation of an edible dispersion comprising oil and structuring agent

Abstract

The invention relates to a process for the preparation of an edible dispersion comprising oil and structuring agent and one or more of an aqueous phase and/or a solid phase, in which the dispersion is formed by mixing oil, solid structuring agent particles and the aqueous phase and/or the solid phase, wherein the solid structuring agent particles have a microporous structure of submicron size particles.

Claims

1. A process for the preparation of an edible dispersion comprising a) oil and structuring agent and b) an aqueous phase, comprising: a) preparing solid structuring agent particles comprising edible fat, and having a microporous structure of submicron size particles, by preparing a homogeneous mixture of A) structuring agent and B) liquefied gas or supercritical gas, at a pressure of 5-40 MPa, and expanding the mixture through an orifice, in which the structuring agent is solidified; and b) forming the edible dispersion by mixing i) the oil, ii) the solid structuring agent particles, and iii) the aqueous phase, wherein said edible dispersion comprises a water-in-oil emulsion.

2. The process of claim 1, wherein the solid structuring agent particles are at least 50% alpha-polymorph.

3. The process of claim 1, wherein the solid structuring agent particles have an average diameter D.sub.3,2 of 60 μm or lower.

4. The process of claim 1, wherein the homogenized mixture comprises oil.

5. The process of claim 1, wherein the temperature of the mixture of structuring agent and liquefied gas or supercritical gas is below the slip melting point of the structuring agent at atmospheric pressure and above the temperature at which phase separation of the mixture occurs.

6. The process of claim 1, wherein the mixture is expanded through the orifice under conditions that a spay jet is applied and wherein a gas jet is applied in addition to the spray jet.

7. The process of claim 1, wherein the gas comprises carbon dioxide.

8. The process of claim 1, wherein the pressure is within the range of 15-40 MPa.

9. The process of claim 1, wherein in the course of preparation of the dispersion the microporous structure is broken into submicron particles.

10. A process for the preparation of an edible dispersion comprising (a) oil and structuring agent and (b) one or more of an aqueous phase and/or a solid phase, comprising: a) preparing solid structuring agent particles having a microporous structure of submicron size particles by preparing a homogeneous mixture of (A) structuring agent and (B) liquefied gas or supercritical gas at a pressure of 5-40 MPa, expanding the mixture through an orifice, in which the structuring agent is solidified; and b) forming the edible dispersion by mixing (i) the oil, (ii) the solid structuring agent particles, and (iii) the aqueous phase and/or the solid phase, wherein the edible dispersion is an emulsion and wherein in the course of preparing the edible dispersion the microporous structure of the solid structuring agent particles is broken into submicron particles.

11. The process of claim 10, wherein the gas comprises carbon dioxide.

12. The process of claim 1, wherein the solid structuring agent particles are at least 90% alpha-polymorph.

13. The process of claim 1, wherein the solid structuring agent particles are 100% alpha-polymorph.

14. The process of claim 1, wherein the solid structuring agent particles are not heated above the melting point of the solid structuring agent during steps a) or b).

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1: Schematic view of the micronisation apparatus used in the examples

(2) FIG. 2: Schematic view of the nozzle configuration with gas inlet for tangential gas-flow.

(3) FIG. 3: SEM Photograph of micronised fat powder prepared in example 1 (magnification 250×)

(4) FIG. 4: SEM Photograph of micronised fat powder prepared in comparative experiment A (magnification 250×)

(5) FIG. 5: SEM Photograph of micronised fat powder prepared in comparative experiment B (magnification 250×)

(6) FIG. 6: SEM Photograph of micronised fat powder prepared in example 1 (magnification 1000×)

(7) FIG. 7: Enlarged SEM photograph of the micronised fat powder of example 1

(8) FIG. 8: Enlarged SEM photograph of the micronised fat powder of example 8

(9) FIG. 9: Enlarged SEM photograph of the micronised fat powder of example 9

(10) FIG. 10 Enlarged SEM photograph of the micronised fat powder of example 10

EXAMPLES

General

(11) Method to Determine Slip Melting Point

(12) The slip melting point of structuring agent is determined in accordance with F. Gunstone et al, The Lipid Handbook, second edition, Chapman and Hall, 1995, page 321, Point 6.2.3, Slip point.

(13) Method to Determine D.sub.3,2 of the Particle Size Distribution of Micronised Fat Particles

(14) Low-angle laser light scattering (LALLS, Helos Sympatic) was used to measure the average particle size (D.sub.3,2). The fat particles were suspended in water in a quixel flow cuvette with an obscuration factor of 10-20%. The diffraction pattern was measured at 632.8 nm with a lens focus of 100 mm and a measurement range of 0.5-175 μm. Calculations were bases on the Fraunhofer theory.

(15) A full description of the principle of LALLS is given in ISO 13320-1.

(16) Method to Determine D.sub.3,3 of Water Droplet Size Distribution in an Emulsion

(17) The water droplet size was measured using a well-known low resolution NMR measurement method. Reference is made to Van den Enden, J. C., Waddington, D., Van Aalst, H., Van Kralingen, C. G., and Packer, K. J., Journal of Colloid and Interface Science 140 (1990) p. 105.

(18) Method to Determine Oil Exudation

(19) Oil exudation is determined by measuring the height of the free oil layer that appears on top of the product. This free oil layer is considered a product defect. In order to measure oil exudation, the product is filled into a scaled glass cylinder of 50 ml. The filling height is 185 mm. The filled cylinder is stored in a cabinet at constant temperature (15° C.). Height measurements are executed every week, by measuring the height of the exuded oil layer in mm with a ruler. Oil exudation is expressed as the height of the exuded oil layer divided by the original filling height and expressed in %. Shaking of the cylinders should be avoided.

(20) Method to Determine Pourability

(21) Pourability for pourable compositions according to the invention is measured according to the standard Bostwick protocol. The Bostwick equipment consists of a 125 ml reservoir provided with a outlet near the bottom of a horizontally placed rectangular tub and closed with a vertical barrier. The tub's bottom is provided with a 25 cm measuring scale, extending from the outlet of the reservoir. When equipment and sample both have a temperature of 15° C., the reservoir is filled halfway with 62.5 ml of the sample after it has been shaken by hand ten times up and down. When the closure of the reservoir is removed the sample flows from the reservoir and spreads over the tub bottom. The path length of the flow is measured after 15 seconds. The value, expressed as cm per 15 seconds is the Bostwick rating, which is used as yardstick for pourability.

Example 1

Fat Micronisation

(22) A set-up was constructed to dissolve carbon dioxide in the melt and expand the mixture over a nozzle to atmospheric pressure. The micronised product was collected in a drum (6) of 250 liters. The set-up is illustrated in FIG. 1. Autoclave The equipment consists of a 1-liter autoclave (2) equipped with a mechanical stirrer (6-blade turbine impeller), a water jacket for heating and a Pt-100 resistance thermometer. The inner diameter of the autoclave is 76 mm. The autoclave has connections at the top and at the bottom. Tubing The bottom connection of the vessel was used to pressurise the system with carbon dioxide or to lead the mixture to the nozzle. A 3-way valve (12) is used to switch between CO.sub.2 supply (1) and nozzle (3). To expel the mixture from the vessel the CO.sub.2 is supplied to the top of the autoclave via valve (11). The length of tube between the bottom connection and the nozzle (3) is approximately 30 cm. All tubing has an outer diameter of ¼″ (inner diameter approximately ⅛″) and is equipped with electrical tracing. Additional gas, N2 or He, can be supplied through (10) to maintain a constant pressure inside the autoclave during the expansion over the nozzle Nozzle The nozzle (3) can be designed with different orifice diameters (opening outlet) and cores (construction of the supply to the orifice). For this work nozzles were used with an orifice of 0.34 mm and standard core. The nozzle was heated by electrical tracing and its temperature was registered by a thermocouple Pt-100. Collection The nozzle was mounted to a Perspex tube (7) of 30 cm diameter and 20 cm length to allow observation of the jet during expansion. This transparent Perspex tube (7) with the nozzle (3) was mounted on top of an oil-drum (6) (250 liters) with a removable lid, which served as the collection chamber. The lid of the drum has an outlet (8) to allow the expanded CO.sub.2 to escape. A separator (9) retains the solid particles in the collection chamber. An additional gas jet (CO.sub.2) may be supplied though nozzle (4) connected to a gas supply (CO.sub.2 bottle) (5). Loading The equipment was heated to the required temperature. Approximately 300 grams of fat (RP70, rapeseed oil hardened to a slip melting point of 70° C.) was completely melted and heated to 20 degrees above its melting point and charged into the autoclave. Equilibrium The autoclave was pressurised in about 10 minutes through the bottom connection. During pressurisation the CO.sub.2 supply to the top was closed. After reaching the final pressure the top valve was opened and the 3-way valve was closed. The melt was allowed to absorb CO.sub.2 and equilibrate for 30 minutes, while stirring the mixture and supplying additional CO.sub.2. The equilibrium pressure in the autoclave was 15 MPa and the temperature in the autoclave was 60° C. Expansion To expand the melt the stirrer was stopped and the supply of additional gas to the collection chamber was turned on. Next the 3-way valve was switched to supply the mixture to the nozzle. During expansion of the mixture in example 1 the pressure in the autoclave was maintained by the CO2 supply. In examples 2 and 3 the pressure in the autoclave was increased to and maintained at MPa by supplying He to the top of the vessel, after first equilibrating with CO2. A micronised fat powder that was obtained which was a very fine and dry solid powder. The powder was 100% alpha-polymorph. In the X-ray diffractogramme, peaks for the β′ and β-polymorph were totally absent. The micronised fat powder was stored at 5° C. When stored at 5° C. the micronised fat powder stayed 100% alpha-polymorph during more than one month.

(23) The micronisation parameters are given in table 2.

(24) Preparation of an Edible Water-in-Oil Emulsion

(25) A pourable margarine was prepared with the composition shown in table 1:

(26) TABLE-US-00001 TABLE 1 Composition of pourable margarine Amount Ingredient (wt. %) Oil phase Sunflower oil 79.62 Micronised Rp 70 powder 1.95 Lecithin Bolec MT.sup.1 0.18 Fractionated lecithin 0.10 Cetinol.sup.2 Beta-carotene (0.4 wt. % 0.15 solution in sunflower oil) Water phase Water 16.5 Sodium chloride 1.5

(27) Explanation of table 1:

(28) The balance of all composition to 100% is water

(29) RP 70: Rapeseed oil hardened to a slip melting point of 70° C.

(30) 1: Lecithin was hydrolysed soybean lecithin (Bolec MT) obtained from UMZ (Unimills Zwijndrecht, Netherlands)

(31) 2: Alcohol-soluble fraction from fractionation of native soybean lecithin with alcohol; Cetinol from UMZ.

(32) The water phase was prepared by adding salt to distilled water and adjusting the pH of distilled water from 7.7 to 4.0 using 5 wt. % citric acid, and heated for 5 minutes in a bath of 60° C. to dissolve the solids. The oil phase was prepared by dissolving the emulsifier ingredients and β-carotene in the total amount of sunflower oil at 15° C. Subsequently the micronised fat powder was added to the oil phase carefully using a spatula and the oil phase was mixed with a Turrax at 22000 rotations per minute (rpm) for 6 minutes. Then the water phase was added to the oil phase and the resulting mixture was mixed with a Turrax for 5 minutes at 23500 rpm in a water bath at having a temperature of 15° C.

(33) The temperature of the mixture in the Turrax increased due to the viscous dissipation. However during the whole experiment the temperature was kept below 20° C. The Turrax (type T50) was delivered by Janke & Kunkel IKA Labortechnik. This type of Turrax is designed to minimise air entrainment.

(34) The emulsion was partly poured into a glass cylinder and partly into a twist off pot of 100 ml and both were containers were stored in a cabinet at 15° C.

(35) Results

(36) The prepared emulsions were tested in accordance with the test methods described herein and the results of the tests are given in table 3. A SEM photograph of the micronised fat powder of example 1 (magnification 250 times) is given in FIG. 3, with magnification of 1000 times in FIG. 6, and with magnification of 2000 times in FIG. 7.

(37) Comparative Experiment A

(38) Comparative experiment A was conducted as example 1, however the fat micronisation step was modified in that the equilibrium pressure in the autoclave was 5 MPa instead of 15 MPa. Before and during depressurisation over the nozzle the mixture in the autoclave was pressurised with Helium to 15 MPa.

(39) The results are shown in table 3. A SEM-photograph of the micronised fat powder is given in FIG. 4.

(40) Comparative Experiment B

(41) Comparative experiment B was conducted as example 1, however the fat micronisation step was modified in that the equilibrium pressure in the autoclave was 10 MPa instead of 15 MPa. Before and during depressurisation over the nozzle the mixture in the autoclave was pressurised with Helium to 15 MPa.

(42) The results are shown in table 2. A SEM-photograph of the micronised fat powder is given in FIG. 5.

(43) All powders of example 1 and comparative experiments A and B showed the presence of 100% alpha-polymorph material. The micronised powder according to example 1 has a low particle size (see table 2) and has a macroporous structure of submicron size particles, as is shown in FIG. 6. In contrast the powders of comparative experiments A and B have a higher particle size and a structure in which submicron size particles are not apparent.

(44) TABLE-US-00002 TABLE 2 Micronisation parameters of example 1 and comparative experiments A and B Amount of Equilibrium CO.sub.2 Pressure Temperature dissolved D.sub.3,2 Example (MPa) (° C.) (wt. %) (μm) 1 150 60 19 39 A 50 70 7 72 B 100 60 16 75

(45) TABLE-US-00003 TABLE 3 Oil exudation (%) of the emulsions of example 1 and comparative experiments A and B as function of the storage time at 15° C. Storage time Example 1 Comp. Ex. A Comp. Ex. B  1 day 35.1  2 days 40.5  3 days 0 48.6  1 week 0 1.1 59.5  2 weeks 0 16.2 59.5  3 weeks 0 18.9 62.2  4 weeks 62.2  5 weeks  6 weeks  7 weeks 0.5 18.9  8 weeks  9 weeks 64.9 10 weeks 11 weeks 0.5 18.9 12 weeks 14 weeks 64.9 15 weeks 0.5 16 weeks 21.6

(46) The results show that the emulsion according to example 1 shows a very low oil exudation, which whereas those of comparative experiments A and B have a high oil exudation and therefore the emulsions are not stable.

Examples 2-4

(47) Example 1 was repeated, but now instead of fat a mixture of fat and sunflower oil was micronised. The composition of the mixture of fat and oil is shown in table 3. In the preparation of the emulsion a Turrax speed of 8000 rpm was used and the Turrax time was 4 minutes.

(48) TABLE-US-00004 TABLE 4 Micronisation parameters and emulsion properties of examples 2-4 Fraction Texture of sunflower micronised Bostwick D.sub.(3,3) Example oil (wt. %) product (cm) (μm) 2 22 Fine dry 14 4.36 powder 3 50 Slightly 14.6 3.06 granular somewhat sticky powder 4 75 Ointment 10 — like structure

(49) All micronised products of examples 2-4 showed the presence of alpha-polymorph material in an amount of 100% and comprised submicron size particles. ‘-’ means not determined. Table 5: Oil exudation (%) of the emulsions of examples 2 to 4 as function of the storage time at 15° C.

(50) TABLE-US-00005 Storage time Example 2 Example 3 Example 4  1 day 5 0 0  4 days 18 0 0  5 days 40 0 0  1 week 45 0 0  2 weeks 52 0.5 0  3 weeks 52 0.5 0  4 weeks 52 1 0  6 weeks 52 1.5 0  8 weeks 55 2 0 10 weeks 55 2 0 12 weeks 55 2 0 14 weeks 55 2 0.5 16 weeks 55 2 0.5

(51) Examples 2-4 show that the addition of oil to the structuring agent prior to micronisation leads to a reduction in oil exudation of the emulsion prepared using the micronised structuring agent. The micronised mixtures have a different appearance depending on the amount of oil added.

Example 5

(52) Micronised fat was prepared according to example 1, fat micronisation using instead as fat rapeseed oil hardened to a slip melting point of 68° C.

(53) A dispersion of solid matter in a fat phase was prepared by first preparing a mixture of 4.6 parts (all parts are weight parts) micronised fat in 4.6 parts sunflower oil and stirring the mixture for 3 minutes at about 18° C. under vacuum. The obtained mixture was added to 49 parts sunflower oil and mixed under vacuum at about 18° C. for 1 minute.

(54) To this mixture was added 41.2 parts flour and 0.6 parts parsley flakes (dried) and the resulting mixture was stirred under vacuum at about 18° C. for 1 minute, 30 seconds. The resulting dispersion was stable for more than one month at room temperature without substantial oil exudation.

Example 6

(55) A dispersion was prepared with the following composition (wt. % on final product):

(56) TABLE-US-00006 Flour 49% Dried herb pieces 1% Sunflower oil 45% Micronised fat powder (see example 5) 5%

(57) The product was prepared by mixing all ingredients at room temperature using an ultraturrax mixing equipment. The product showed no oil exudation for one month.

Example 7

(58) A dispersion was prepared similar to that of example 6, however using 47.5 wt. % sunflower oil and 2.5 wt. % micronised fat prepared in example 1. The processing was the same. When stored at 5° C. for one month, the product showed minimal oil exudation.

Examples 8 to 10

(59) Example 1 was repeated, however instead of Rp70, SF69 (sunflower oil hardened to a slip melting point of 69° C.) was micronised and used as hardstock in the preparation of the emulsion.

(60) To investigate how Ta (Equilibrium autoclave temperature) influences the morphology of the powders after micronisation, three different experiments were performed at Ta=Tm−10° C. (Example 8), Ta=Tm−5° C. (Example 9) and Ta=Tm (Example 10) respectively, with P=180 bar, in which Tm is the melting point of the hardstock, for Rp69 in these example 69° C.

(61) Xray diffraction showed that all micronised powders are in the α polymorph. SEM analysis shows no real differences in morphology within the chosen range of temperatures, although for Tm−10° C. (59° C.) and Tm−5° C. (64° C.) the morphology seems to be a little more brittle than for Tm (69° C.).

(62) Model Emulsions

(63) Model emulsions were prepared using standard conditions and stored at 15° C. and 25° C. In table 6, a summary of the measured oil exudation (O.E.) and Bostwick values (BW) as function of storage time is given.

(64) TABLE-US-00007 TABLE 6 Results of Examples 8-10, Oil exudation (O.E. [%]) and Bostwick values (BW [cm]) as function of storage time and temperature Tm P Bostwick value [cm] Example [° C.] [MPa] Start 2 wks 5 wks 9 wks 8 59 18 10 10 10 9 9 64 18 12 11 11 10 10 69 18 10 9 10 10 O.E. at 15° C. O.E. at 25° C. 2 wks 5 wks 9 wks 2 wks 5 wks 9 wks 8 0 0 0 0.8 1.1 1.5 9 0 0 0 0 1.1 1.5 10 0 0 0 1.5 3.8 5.3

(65) Results show that at Tm of 59° C. and 64° C., good O.E. and BW values after 9 weeks were achieved. At Tm=69° C. the oil exudation at 25° C. is less favourable.

(66) Enlarged SEM photographs (5000× magnification) of the micronised powders of examples 8, 9 and 10 are shown in FIGS. 8, 9 and 10 respectively.