AU599196B2 - Pulverulent, water-dispersable carotenoid formulations and their preparation - Google Patents

Abstract

Preparation of pulverulent water-dispersible carotenoid preparations in which the carotenoid is present dissolved in an edible oil and the oil solution is present in the form of small droplets, by rapidly dissolving a carotenoid in a volatile, water-miscible, organic solvent at between 50 and 240 DEG C together with from 1.5 to 20 times the weight, based on the carotenoid, of an edible oil and also an emulsifier, under atmospheric or superatmospheric pressure, immediately mixing the resulting molecularly dispersed solution with an aqueous solution of a protective colloid at between 0 DEG C and 50 DEG C to transfer the hydrophilic solvent component into the aqueous phase, forming the hydrophobic oil phase, which contains the carotenoid in solution, as a microdisperse phase, and stripping the resulting two-phase mixture of solvent and water in a conventional manner.

Description

59 9 1 9 6 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 COMPLETE

SPECIFICATION

(ORIGINAL)

Class Application Number; Lodged: Int. Class Complete Specification Lodged: Accepted: Published: Priority: Ielated Art; a Name of Applicant: BASF AKTIENGESELLSCHAFT Adress of Applicant D-6700 Ludwighshafen, Federal Republic of Germany Actual Inventor: Address for Service DIETER HORN, ERIK LUEDDECKE and PETER SCHAEFER EDWD. WATERS SONS, 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Complote Specification for the invention entitled: PULVERULENT, WATER-DISPERSABLE CAROTENOID

FORMULATIONS

AND THEIR PREPARATION The following statement Is a full description of this Invention, including the best method of performing It kn,;wn to US

I.

I I O.Z. 0050/38936 PuLveruLent, water-dispersable rarotenoid formulations and their preparation The present invention relates to the conversion of carotenoids to a finely divided, pulverulent form, the carotenoid being dissolved in an edible oil and the oil solution being in the form of very small oil drops.

This formulation is used in particular for coLoring food and animal feeds.

The carotenoids constitute a group of colored pigments which have a yellow to red hue, occur widely in nature and impart a typical color to many foods. The most important members of this class of substances are .,o8 B-carotene, B-apo-8 -carotenaL, canthaxanthine and citranaxathine. These substances which can be synthesized 15 are important colorants for both the food and animal feeds industry and pharmaceut cal technology, for example as substitutes for synthetic colorants, and are of interest, for example, because of their provitamin A activity.

S 20 Virtually all carotenoids are insoluble in water and also have only slight solubility in fats and oils.

This limited solubility and the high sensitivity to oxidation prevent the relatively coarse-particled products obtained in the synthesis from being used directly for coloring food or animal feeds, since only a low color yield can be achieved and the substances in coarsely crystalline form are poorly absorbed. These effects which are disadvantageous when the carotenoids are used in practice are particularly evident in an aqueous medium, sirce most of them are completely insoluble therein.

Various methods have been described for improving the color yields and increasing the absorbability, all of which aim at reducing the crystallite size of the active ingredients and bringing it to a particle size range smaller than 10 pm. For example, according to Chimia 21 (1967), 329, B-carotene together with edible oil can be milled to a particle size of from 2 to 5 IJm L_ -2 O.Z. 0050/38936 under a nitrogen atmosphere in a coLLoid miLL. According to Food Technol. 12 (1958), 527, the coating oil simultaneously protects the active ingredient from oxidation. A suspension obtained in this manner and containing up to 20 or 30% of active ingredient can successfully be used for coloring fats and oils since the low solubility is nevertheless sufficient to dissolve the crystals at the low concentration usually employed.

While oily or fatty systems can thus readily be colored with the pure crystalline substances, aqueous systenis are virtually impossible to color with the said oV substances. Furthermore, because most of the carotenoids are completely fnsoluble in water, the pure carotenoids 5 °mixed with the food or with the animal feed are very 15 poorly utilized by the human or animal organism. The .oo carotenoids have very limited solubility even in organic i .solvents, such as alcohols and alkanes.

*The desired coloring and absorption properties can only be achieved via the very finely divided state.

A desirable particle size is smaller than 1 um, which can be achieved by milling only with damage to the active ingredient, if at all.

Processes which represent a cert'in amount of progress in comparison are known processes in which the active ingredient is dissolved in a water-immiscible solvent, preferably a 'chlorohydrocarbon, such as chloroform of iethylene chloride, 'the solution is emulsified by homogenization in a gelatine/sugar solution, and finally ttle solvent is stripped off from the emulsion, the -active ingredient being Liberated in finely crystalline form.

This process is described in Chimia 21 (1967), 329, German Published Application DAS 1,211,911 and German Laid-Open Application DOS 2,534,091. A finely divided powder is then obtained from the resulting suspension by removal of water.

However, the abovementioned process has the disadvantage that chlorohydrocarbons have to be used in -j .i Y *~r 3 O.Z. 0050/38936 order to achieve a sufficiently high concentration of active ingredient in the emulsion phase. Complete removal of the chlorohydrocarbons, which is necessary for toxicological reasons, is technically difficult to achieve.

These disadvantages were overcome by the process of European Patent 65,193, in .hich a carotenoid is dissolved in a volatile, water-miscible organic solvent at from 50 to 200 0 C, if necessary under superatmospheric pressure, in Less than 10 seconds, the carotenoid is immediately precipitated in colloidal form from the resulting molecular disperse solution by rapid mixing with an aqueous solution of a sweleo° Lable colloid at from 0 to 50 0 C, and the resulting dispersion is freed from the solvent and the dispersing medi:m in a conventional manner. The mean size of the solid carotenoid particles produced by this method is lass than 0.3 pm.

In another process (cf. U.S. Patent 2,861,891 and Austrian Patent 202,273), water-dispersable carotenc'd formulation is obtained by preparing, at from 100 to 160 0

C,

a supersaturated solution of the carotenoid in an edible oil which is liquid at about 20-40 C, emulsifying this supersaturated solution in an aqueous, gelatinous material, and converting the emulsion in a conventional manner to small dry particles.

If the dry powder is redispersed in warm water, a cloudy, orange yellow emulsion is formed again. This can be used, for example, for coloring food. Important performance characteristics of these colorant preparations are solubility, hue, color strength, opacity and stability in the medium used Bunnell, W. Driscoll and I.C.

Bauernfeind, Food Technol. XII (1958), 1-81).

However, a spectrophotometric investigation of the finely divided carotenoid formulations produced by the stated prior art shows that, particularly at fairly high concentrations, for example 2% of dry powder, the extinction values at the band maximum of the tinctorially effective absorption bands in the visible spectral range are only 50% of the maximum values achievable in a true .0 I 3 4 oZ. 0050/38936 solution. From the economic point of view, this is a considerable disadvantage since only 50% of the potential color strength of a carotenoid can be utilized, for example for coloring a food, and the dose of the colorant therefore has to be doubled in order to obtain the desired color strength. It is also known that the hue of a food colored with carotenoids is determined to a great extent by the particle size and the physical state (solid, solution). With the prior art products, the r'a of potential differences in the hue of a selected r;arotenoid is far from being exhausted. It is further- "oo more known that the biological absorption of water-insoluble OO° active ingredients, for example after oral administration, is greatly influenced by the particle size and the physi- 15 cal state. The carotenoid preparations produced according to the prior art therefore do not satisfy the precondition for optimum biological absorption.

It is an object of the present invention to provide a process which makes it possible to prepare carotenoid formulations which do not have the stated disadvantages.

We have found that this object is achieved, according to the invention, if the carotenoid is rapidly dissolved in a volatile, water-,mis:sible, organic solvent at from 50 to 240°C, preferably from 150 to 200 0 C, together with from 1.5 to 20 times the weight, based on the carotenoid, of an edible oil, and an emulsifier, under' atmospheric or superatmospheric pressure, the hydrophilic solvent component is transferred to the aqueous phase from the resulting molecular disperse solution by rapid mixing with an aqueous solution of a protective colloid at from 0 to 500C, the hydrophobic oil phase which contains the caroteno id in solution being formed as the microdisperse phase, and the resulting two-phase mixture is freed from the solvent and the water in a conventional manner.

The novel procedure utilizes the fact that the 5 O.Z. 0050/38936 solubility of the carotenoids in a solution of an edible oil in water-miscible solvents, which is very low at low temperatures increases substantially with increasing temperat.ure, but, despite the high temperatures, a short residence time at elevated temperatures substantiaely prevents isomerization which affects the hue, the color strength and the biological activity. However, this was in contradiction to the fact that the isomerization which usually occurs on heating in hot oil is itself used to inhibit recrystallization in the drops of the emulsified oil phase when the temperature is reduced, the said re- 'o crystallization having an adverse effect on the hue and o the color strength of the desired end product. It w s o therefore surprising that, in spite of suppressing the 15 tendency to isomerization at elevated temperatures, and o. after cooling, the product obtained by the novel procedure contains the carotenoid, spectrophotometrically detectable, as a molecular disperse, supersaturated oil 0 solution stabilized to recrystallization, in the form 0 0 S 20 of submicroscopic oil particles, and, compared with prior o oo art products, has up to 100% greater color strength coupled with a shift in the hue to previously unaccessible ranges.

The photochemical stability of the hydrosols prepared by the novel process is superior to that of the products prepared according to the prior art by a factor of more than The carotenoids which can be used for carrying out the invention are the known, obtainable, natural or synthetic members of this class of compounds, which can be used as color-imparting materials, for example carotene, lycopene, bixine, zeaxanthine, cryptoxanthine, citranaxanthine, luteine, canthaxanthine, astaxanthine, Papo-4'-carotenal, O-apo-8'-carotenal, B-apo-12'-carotenal, 5-apo-8'-carotenic acid and esters of hydroxyl-containing and carboxyl-containing members of this group, for example the lower alkyl esters and preferably the methyl and ethyl esters. The compounds which have been readily 6 O.Z. 0050/38936 available industrially to date, such as 8-carotene, canthaxanthine, B-apo-8'-carotenaL and B-apo-8'-carotenates, are particularly preferred.

Water-miscible, heat-stable, volatile solvents containing only carbon, hydrogen and oxygen, eg. alcohols, ethers, esters, ketones and acetals, are particularly suitable for carrying out the novel process. Ethanol, n-propanoL, isopropanol, butane-1,2-diol 1-methyl ether, propane-1,2diol 1-n-propyl ether and acetone are preferably used.

In general, it is advantageous to use solvents which are not Less than 10% water-miscible, have a boiling point of Less than 200 0 C and/or contain less than carbon atoms.

Suitable edible oils are oils which are liquid 15 at from 20 to 400C. Examples are vegetable oils, such as corn oil, coconut oil, sesame oil, peanut oil, soybean oil or cottonseed oil. Peanut oil is particularly preferred. Other suitable oils or fats are shortening, beef dripping and butter fat. The edible oils are generally used in an amount of from 1.5 to 20, preferably from 3 to 8, times the weight of the carotenoid, and the total oil content of the carotenoid formulation should not exceed 60% by weight if it ii intended to prepare a dry powder.

Suitable protective colloids are any conventional protective colloids permitted in food and animal feeds; examples are gelatine, starch, dextrin, dextran, pectin, gus arabic, casein, caseinate, whole milk, skimmed milk, milk powdtr or mixtures of these. However, it is also possible to use polyvinyl af.cohol, polyvinylpyrrolidone, methy\cellulose, carboxymetylcellulose, hydroxypropylcellulose and alginates. For further details, reference may be to R.A. Morton, Fast Soluble Vitamins, Intern.

Encyclopedia of Food and Nutrition, Vol. 9, Pergamon Press, 1970, pages 128-131. To increase the mechanical stability of the end product, it is advantageous to add to the colloid a plastt:izer, such as sugar or sugar r 7 O.Z. 0050/38936 alcohols, eg. sucrose, glucose, Lactose, invert sugar, sorbitol, mannitol or glycerol. Minor amounts of methyl esters or propyl esters of p-hydroxybenzoic acid, sorbic acid and Na benzoate may also be added as preservatives.

The ratio of protective colloid, plasticizer and oil to carotenoid is in general chosen so that the resulting end product contains from 0.5 to 10, preferably from 2 to 5, by weight of carotenoid, from 5 to 50% by weight of an edible oil, from 10 to 50% by weight of a protective colloid and from 20 to 70% by weight of a plasticizer, all percentages being based on the dry weight of the powder, as well as minor amounts of a stabilizer.

The mean particle size of the oil phase present in the .powder and supersaturated molecular disperse carotenoid is less than 0.3 pm, and the half width of the size distribution is less than 50%. The product contains virtually no oil particles having a particle size greater than 1 pm.

To increase the stability of the active ingredient to oxidative degradation, it is advantageous to add stabilizers, such as a-tocopherol, lecithin, tert-butylhydroxytoluene, tert-butylhydroxyanisole, ethoxyquine or ascorbyl palmitate.

They can be added to either the aqueous phase or the solvent phase but are preferably dissolved together with the colorants and the oil, in the solvent phase.

The novel process gives a viscous liquid which has a deep coloration and from which the solvent can be removed in a conventional manner depending on the boiling point, for example by distillation, under atmospheric or reduced pressure, or by extraction with a waterimiscible solvent. Preferably, however, thp solvent is removed together with the water by spray drying or spray granulation.

The dry powder obtained can be redissoLved in water with uniform fine distribution of the active ingredient in the particle size range 0.5 um. 7he L, i., -8 O.Z. 0050/38936 photochemical stability test shows that the resulting hydrosoL of the active ingredient is extremely stable despite being finely divided.

If necessary, the microdisperse oil phase supersaturated with carotenoid can also be brought to a suitable pH and then flocculated together with the protective colloid and thus converted to a form from which the solvent and a major part of the dispersing medium can be removed in a simple manner by filtration or centrifuging. The coi 10 acervate thus obtained is then further dried in a conventional manner and converted to granules.

Specifically, the novel process is carried out as follows, for example using an apparatus as shown schematically in Fig. 1.

The apparatus is divided into parts I, II and III. Part II is the high temperature section, while in parts I and III the temperatures are less than 50 0

C.

In vessel a suspension of the carotenoid together with the oil in the selected solvent in a concentration of from 2 to 20% by weight, based on the mixture, with or without the addition of from 0.1 to 10% by weight of stabilizers, is initially taken. Vessel contains the solvent without admixed carotenoid. The suspensions of active ingredient and the solvent are fed to the mixing chamber via the pumps and respectively; the mixing ratio can be predetermined by choosing the particular delivery of the pumps, and is selected so that, depending on the solvent and the residence time, the resulting carotenoid concentration in the mixing chamber I 30 i from 0,5 to 10% by weight, based on the solution. The J volume of the mixing chamber is such that the residence time in (7 is preferably less than 1 second at the selected delivery of thie pumps and Before entering the mixing chamber, the solvent is brought to the .:sired temperature by means of the heat exchanger while the oil-containing suspension of active ingredient is kept at below 50 0 C by feeding it Y i t -9 O.Z. 0050/38936 via the thermally insulated Line As a result of turbulent mixing :n at from 50 to 240 0 C, preferably from 150 to 200 0 C, the active ingredient goes into solution, and, after a short residence time, preferably less than 1 second, the resulting solution passes via into the second mixing chamber in which, by admixing an aqueous protective colloid/plasticizer solution via pump and feed line the molecular disperse carotenoid solution is divide 'nto a two-phase mixture with formation of a microdisperse oil phase containing the active ingredient in supersaturated solution and a homogeneous, aqueous phase containing the water-miscible solvent. The microdisperse two-phase mixture is then discharged via line (12) and the pressure relief valve and fed to the stock vessel To obtain a very high concentration of active ingredient, the dispersion can be circulated via the suction line If the pressure relief valve (13) is set at above one bar, it is even possible to use solvents at temperatures above their boiling point (under atmospheric pressure) in the novel process.

A pulverulent preparation can be obtained from the dispersion in a conventional manner, for example as described in German Laid-Open Application DOS 2,534,091, by spray drying or by spray cooling or by coating the particles, separation and drying in a fluidized bed.

For spray drying, the dispersion is either first freed from the solvent by distillation, preferably under reduced pressure, or by extraction with a water-immiscible solvent, or the entire mixture 'q spray-dried and water i and solvent are stripped off together in the spray tower in this manner.

The carotenoid powder is obtained in either dry or free-flowing form at the bottom of the spray tower.

In some cases, it may be advantageous additionalLy to carry out complete drying in a fluidized bed. Instead of preparing the powder formulation by spray drying, it _i i 10 O.Z. 0050/38936 is also possible to use any other methods to convert the carotenoids already finely distributed in the water/oil/ solvent dispersion into powder form.

A known and equally suitable method comprises, for example, emulsifying the dispersion freed from the solvent with liquid paraffin, cooling the mixture, separating the liquid paraffin from the coated carotenoid particles, washing the resulting carotenoid preparation with naphtha and drying the preparation in a fluidized bed.

In the novel procedure, it was particularly surprising that the use of the stated water-miscible solvents mixed with an edible oil which may additionally contain emuLsifiers, such as ascorbyl palmitate, monoand diglycerides, esters of monoglycerides with acetic acid, citric acid, Lactic acid or diacetyltrtartaric acid, polyglycerol fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, stearoyl 2- Lactylates or lecithin, permits the preparation of highly supersaturated solutions in which, in spite of suppression of the trans-cis isomerization, no recrystallization of the carotenoid takes place within the submicroscopic oil drops supersaturated with active ingredient in the microdisperse oil phase, after the phase separation induced by turbulent mixing with the aqueous protective colloid solution, even during removal of the volatile solvent, for example by distillation or spray drying, and after cooling.

It is furthermore surprising that admixing of the solvent-cortaining oil solution of the carotenoids with the aqueous protective colloid solution induces phase separation during which the disperse oil phase is obtained in the form of extremely small particles, as cannot be obtained by mechanical homogenization. This finely dispersed state of the oil phase supersaturated with active ingredient is also maintained during removal of the volatile solvent, for example by spray drying. It is ii 11 O.Z. 0050/38936 easily possible to obtain preparations in which the major fraction in the oil phase has a particle size of 0.2 Im, without particles of active ingredient larger than 1 pm simulttaneously being present. The absorption spectrum of suth carotenoid preparations shows the band form and extinction typical of the molecular disperse solution of a carotenoid in an edible oil, even after spray drying and redissolution in an aqueous medium.

The Examples which follow illustrate the novel process.

EXAMPLE 1 g of B-trans-carotene are suspended in 240 g of a solution of 4 g of ascorbyl palmitate, 5 g of So-tocopherol and 20 9 of peanut oil in isopropanol, the pressure relief valve (13) is set at 25 bar and the said suspension is mixed in mixing chamber with 360 g of isopropanol which has been heated to 225 0 C in heat exchanger The suspension is metered at 2 I/h and the solvent at 3 I/h, and the residence time in mixing chamber is 0.35 second. The molecular disperse solution formed at 190 0 C is then fed to mixing chamber in which turbulent mixing with 4,000 g of an aqueous soLu- Sfion of 60 g of gelatine and 90 g of sucrose, brought to PH 9 with 1N NaOH, at a metering rate of 27 l/h results in phase separation with formation of a microdisperse oil phase which contains the 8-carotene in the form of a Ssupersaturated solution. A microdisperse two-phase mixture having a yellow hue and a temperature of 50°C is obtained in collecting vessel Particle size analysis by proton correlation spectroscopy gives a mean particle size of the oil phase of 210 nm and a distribution Swidth of Removal of the solvent under reduced pressure at 0 C in a distillation apparatus gives a viscous Liquid which can be converted to a stable, water-soluble dry powder by spray drying. The 8-carotene content of this dry powder is 2.4% by weight.

'4 I ii 1- ;i i ii Lli 12 O.Z. 0050/38936 RedissoLving the dry powder in cold water gives a yellow solution in Which the oil phase is again present as a microdisperse phase having a particle size of 220 nm Spectrophotometric investigation of this solution shows the B-carotene band form typical of a molecular disperse solution (Fig. 2a). In contrast, the prior art gives a product which, for the same concentration of active ingredient in aqueous solution, gives an absorption spectrum showing the typical curve of a B-carotene solidstate spectrum (Fig. 2b). The ratio of the extinction values at the band maxima is 2.1. Hence, the novel process gives a preparation which has more than twice the color strength of a prior art preparation.

In spite of the extremely finely divided nature and the high color strength, t'l hydrosol exhibits excellent stability in the photostability test. Under standardized irradiation conditions, a loss of active ingredient of 10% is recorded during an irradiation time of 270 minutes. In the case of products having a 8-carotene content of 2.4% and prepared according to the prior art, a loss of active ingredient of 10% is observed under the same irradiation conditions after only minutes.

EXAMPLE 2 A two-phase mixture is obtained as des(eiv t Example 1, but with the use of 10 g $-trans~arotenm 8 g 4f ascorbyl palmitate and 40 g of peanut oil; in the said mixture, the oil phase supersattrated with arotene is in the form of submicroscopic droplets having a mean particle size of 249 nm +52%.

The dry powder obtained by spray drying contains of active ingredient and, after redis -olution in water, gives a hydrosol having a mean particle size of 289 nm Compared with the prior art product, the extinction ratio at the band maximum is 1.8.

.I u F-yYW.iili:-i-_I: ii i L 13 O.Z. 0050/38936 EXAMPLE 3 A dry powder is obtained as described in Example 1, but with the use of 5 g of canthaxanthine; after redissolution in water, the said powder gives a hydrosol having a mean particle size of 191 nin The extinction at the band maximum at X 478 nm is 90% of the theoretical maximum value, whereas prior art products give extinction values which are no more than 50% of the theoretical values.

EXAMPLE 4 A dry powder is obtained as described in Example 1, but with the use of 60 g of gum arabic as a protective colloid; after dissolution in water, the said powder gives Sa hydrosol having a mean particle size of 359 nm +42%.

i t r"

Claims (4)

1. A pulverulent, water-dispersable carotenoid for- mulation in which the carotenoid is dissolved in an edible oil and the oil solution is in the form of small drop ets which-are dispersed as a pulverulent matrixA-e tQ nab by rapidly dissolving a carotenoid in a voLatile, water- miscible, organic solvent at from 50 to 240 0 C, together with from to 20 times the weight, based on the caroten- oid, of an edible oil, and an emulsifier, under atmospheric or superatmospheric pressure, then immediately mixing with an aqueous solution of a protective colloid at from 0 to 50 0 C and thus transferring the hydrophilic solvent component to the aqueous phase, the hydrophobic oil phase which contains the carotenoid in solution being formed as the microdisperse phase, and freeing the resulting two-phase mixture from the solvent and the water in a conventional manner.

2. A process for the preparation of a pulverulent water-dispersable carotenoid formulation in which the carotenoid is dissolved in an edible oil and the oil solution is in the form of small droplets, wherein a carotenoid is rapidly dissolved in a volatile, water- miscible, organic solvent at fror, 50 to 240 0 C, together with from 1.5 to 20 times the weight, based on the carotenoid, of an edible oil, and an emulsifier, under atmospheric or superatmospheric pressure, the hydrophilic solvent component is transferred to the aqueous phase from the resulting molecular disperse solution by immediate mixing with an aqueous solution of a protective colloid at from 0 to 50 0 the hydrophobic oil phase which con- tains the carotenoid in solution being formed as the micro- disperse phase, and the resulting two-phase mixture is freed from the solvent and the water in a conventional manner.

3. A process as claimed in claim 2, wherein the carotenoid is dissolved at from 150 to 200 0 C.

4, A process as claimed in claim 2, wherein the carotenoid is dissolved in less than 1 second, and the F 15 0. Z 0050/38936 resul t ing soLu t ion i s immed iately coo Led by m ix ing wi th the aqueous sol ut ion of the protec tive coL Lo id and con- verted to the microdisperse two-phase mixture. DATED this 21st day of January 1988.- BASF AKTI2ENGESELLSCHAFT 0 0) 0 0 o .0 0 0 0 ~)0 0 00C 00 r 0 0 v 3) 0 COD C 0 C 00 0 o~ C o 0 EDWD. WATERS SONS PATENT ATTORNE~YS 50 QUEEN STREET MELBOURNE. VIC, 3000. L