Spice Extract

This invention relates to a process for the production of an aromatic spice extract.

There are so many different processes for producing aromatic extracts that a particular terminology has been created for designating these extracts according to the nature of the processes by which they are obtained. For example, an extract produced by stripping the starting material with steam is known as an "essential oil"; an extract produced by a simple squeezing operatin, i.e. an operation in which the material is squeezed to extract its goodness or juice is known as "essence"; extracts obtained by treating fresh vegetable materials with organic solvents are known as "concrete essences" or "absolute essences" after extraction with ethanol. Finally, the terms "resinoids" or "oleoresins" are reserved for the extracts obtained by treating dried vegetable materials or spices with organic solvents.

Although some of these techniques are ill-suited to spices, others are commonly used, especially the solvent techniques. For example, French Patent Application No. 2,192,852 describes a process for extracting flavours and fragrances from a vegetable material by treatment with one or more organic solvents.

In addition, there are processes for capturing the highly volatile fractions of the spice, such as those which are given off during grinding. One such process is described for example in U.S. Pat. No. 3,314,802.

Although it is indisputable that most of the aromatic extracts obtained by one or other of these processes are of good quality, the fact remains that they do not entirely reproduce the natural aroma of the spice in all its richness and completeness.

By contrast, aromatic extracts of an exceptional quality which is superior to that of the spice extracts normally found on the market are obtained by the present invention. The present invention provides a process for the production of an aromatic spice extract, which comprises

(a) grinding a spice and collecting an aromatic fraction A consisting of the gases given off during grinding,

(b) treating the spice with an apolar organic solvent so as to obtain an aromatic fraction B contained in this apolar solvent, and

(c) treating the spice with at least one polar solvent so as to obtain an aromatic fraction C contained in this polar solvent,

the combination of the aromatic fractions A, B and C constituting the aromatic spice extract.

It has been found that the combination of the gases given off during grinding with an aromatic fraction obtained by treatment with an apolar solvent and an aromatic fraction obtained by treatment with a polar solvent produces a very considerable improvement in regard to aromatic quality.

The above distinction between fractions A, B and C is made solely in the interest of convenience of the description and is not meant in any way to imply that these fractions have to be separately produced. For example, in one embodiment of the process, the spice obtained after grinding is directly treated with a mixture of an apolar solvent and at least one polar solvent, one advantageous variant of this embodiment consisting in the use of an azeotropic mixture.

In addition, it is pointed out that the expression "the combination of the aromatic fractions A, B and C constituting the aromatic spice extracts" should not necessarily be interpreted as implying a complete combination. On the contrary, the fractions in question, where they have obviously been separately produced, may if desired only be partly recombined so as to act on the organoleptic equilibrium of the aromatic spice extract obtained.

In the context of the invention, apolar organic solvents are the organic liquids commonly designated as such by the chemist. This category includes in particular hydrocarbons or mixtures of hydrocarbons, such as pentane, hexane, cyclohexane, cyclohexene and petroleum ethers.

So far as the expression "polar organic solvents" is concerned, it is advisable to interpret it in relative terms and to consider that the solvents covered by this definition are those of which the polarity is distinctly higher than that of the solvents belonging to the category mentioned in the preceding paragraph. In the context of the invention, polar organic solvents are, for example, the Freons (chlorofluoroalkanes), methylene chloride, trichloroethylene, acetone, ethylacetate, methanol, ethanol, isopropanol, n-propanol. These solvents may be used individually, in admixture with one another or even in admixture with other liquids, such as water for example. In the latter case, the azeotropic mixture may be a ternary mixture for example. Numerous binary and ternary azeotropic mixtures are set out by way of example in the following Table:

In general, the apolar and polar solvents are selected from the solvents having a boiling point which enables them to be readily eliminated without any excessive increase in temperature, or even from the solvents capable of forming azeotropic mixtures having a boiling point of this order.

In a first embodiment of the process according to the invention, a spice or a mixture of spices selected, for example, from cardamom, caraway, coriander, cumin, curcuma, cloves, laurel, nutmeg, paprika, pimentoes, chillies and pepper, is finely ground at a low temperature of the order of -40.degree. C. (a dry grinding). The grinding gases are liberated by heating the powder to around 20.degree. C. and are entrained by passing a gentle stream of inert gas, preferably under reduced pressure, over the powder for a period ranging, for example, from 2 to 12 hours. They are condensed in cold traps kept at a temperature of -80.degree. C. The condensate obtained, which represents from 1 to 6% by weight of the ground spice, constitutes the aromatic fraction A. The powder is then treated by conventional solid-liquid extraction at 15.degree. to 35.degree. C. with an apolar solvent, for example petroleum ether or hexane, in a quantity of from 2 to 6 liters of liquid per kg of powder either once or several times. After separation of the undissolved fractions, the liquid phase containing the aromatic fraction B, which represents from 2 to 20% by weight of the ground spice, is collected. The extraction treatment is then repeated on the drained powder with a polar solvent, preferably ethanol for reasons of food legislation. After separation of the undissolved fractions, the liquid phase containing fraction C, which represents from 1 to 15% of the ground spice, is collected. The required aromatic extract is obtained by combining the three aromatic fractions A, B and C and may be concentrated under reduced pressure. Fractions B and C are preferably concentrated before mixing. In this way, it is possible to obtain concentrated extracts of which the residual solvent contents are below the detection limit.

In a second embodiment, the spice which has been ground and freed from its grinding gases in the same way as described above (dry grinding), is treated with a mixture of an apolar solvent and at least one polar solvent, preferably with an azeotropic mixture, for example hexane/ethanol or hexane/ethanol/water. The liquid phase obtained after separation of the undissolved fractions and, optionally, concentration is enriched with fraction A to form the aromatic extract.

In a third embodiment, the crude spice is ground in the presence of an organic solvent (wet grinding). For example, the spice is immersed in hexane in a quantity of from 15 to 30% by weight and then ground therein. After separation of the undissolved fractions, a liquid phase containing the grinding gases is collected. The ground powder is then treated with an apolar solvent, preferably the same as that used for grinding, and then with a polar solvent in the same way as described above. The combination of the three liquid phases obtained, optionally after concentration, constitutes the required aromatic extract.

In a fourth embodiment, the crude spice is again ground in the presence of an organic solvent (wet grinding) so as to obtain a liquid phase containing the grinding gases. The ground powder is then treated with a mixture of solvents of which one is preferably the solvent which was used for grinding, this mixture advantageously being an azeotropic mixture. The combination of the two liquid phases obtained, optionally after concentration, constitutes the required aromatic extract.

As can be seen by consulting the results of the tasting tests reported in the Examples, the aromatic spice extracts produced by the process according to the invention which, after concentration, may be grouped under the category of oleoresins, are of high quality and may be considered as luxury products by comparision with standard commercial-grade extracts. In dilute conditions, they are normally in the form of a homogeneous liquid. By contrast, after concentration, the oleoresins are more in the form of clouded, more or less viscous liquids, mixtures with two liquid phases or mixtures with a liquid phase and a solid phase, depending on the circumstances, the percentage of solids being determined both by the nature of the spice treated and by the quantity of residual solvent present. Moreover, the residual solvent content may be reduced below the limits of detection.

These oleoresins may be used with advantage for flavouring or for strengthening the flavour of an edible material either directly or indirectly after fixing to a flavour carrier, such as sugar or salt, as it is well know. In such a case, fixing may be carried out either globally from the extract itself or fractionally, i.e. from the fractions which make up this extract where they have been separately obtained.

Since cooking is a matter of taste, customs and civilisation, it would be futile to attempt to dictate what particular aromatic extract is best suited to a particular food, or even to seek to specify the quantities in which this extract should be used.

The process according to the invention is illustrated by the following Examples. Unless otherwise indicated, the values quoted in these Examples represent values by weight.

350 kg of nutmeg are finely ground (average grain size approximately 0.8 mm) in an Urschel mill kept at -40.degree. C. The powder obtained is transferred to a tank where it is heated to 20.degree. C. During heating, the tank is evacuated, after which a gentle stream of nitrogen under a pressure of 12 mm Hg is passed through it for 12 hours. The grinding gases are condensed in three cold traps which are kept at -80.degree. C. and which are situated downstream of the tank. 6.2 kg of fraction A are thus obtained.

The powder is then treated with 500 liters of rectified petroleum ether 40-60 (i.e. a fraction having a b.p. of 40.degree. to 60.degree. C.) which is circulated in a closed loop by pumping the solvent to the bottom of the tank and reintroducing it at the top. The solvent is renewed after 2 hours and is then renewed once again after another 2 hours. The three volumes of solvents are then combined and concentrated in vacuo at approximately 30.degree. C. so as to obtain a fraction B of 63.7 kg which contains approximately 22% of solids. The concentration time is of the order of 2 hours for 10 liters to be concentrated.

The same operation are then repeated for the treatment with ethanol, giving a fraction C of 28.0 kg with a solids content of 50%.

The required aromatic extract is obtained by combining fractions A, B and C (97.9 kg). 280 kg of grounds are also obtained and approximately 1500 liters of petroleum ether and 1500 liters of ethanol are recovered, being recycled after rectification.

The solvent is removed as far as possible from fraction C by evaporation in vacuo at 30.degree. C. Fraction B is added to the concentrate obtained, after which the solvents contained in the mixture are eliminated as far as possible by evaporation in vacuo at 30.degree. C. Fraction A is then added to the new concentrate obtained, giving 69.9 kg of an oleoresin of nutmeg containing less than 10 ppm of residual solvents.

The operations described in the preceding Example are repeated mutatis mutandis on other spices. The results obtained are set out in the following Tables:

The aromatic extracts are submitted to the appreciation of a panel of six trained tasters either on a neutral base (consisting of an 80 g/l solution of sodium glutamate 7.1%, cooking salt 7.1%, potato starch 7.1%, powdered milk 24.2%, flour 34.3% and Biscuitine C 20.2%) in a quantity of 0.05 g/100 ml, or in an edible material.

The extract of Example 1 (nutmeg) on the neutral base was found to be powerful and full-bodies. Four tasters preferred it to a comparable extract, but freed from the grinding gases. It was recommended as a flavouring agent for a mashed potato in a quantity of 0.07 to 1.5 g/kg of puree.

The extract of Example 2 (paprika) on the neutral base was qualified as having a "good taste of paprika".

The extract of Example 3 (cardamom) was recommended as a flavouring agent for a mayonnaise in a quantity of 1 to 20 g/kg of mayonnaise.

The extract of Example 6 (black pepper) on the neutral base was found to be very intense and highly aromatic. Five tasters preferred it to a comparable extract, but freed from the grinding gases (extract qualified as weak).

The extract of Example 7 (cumin) on the neutral base was judged to be round, fruity and agreeable. Five tasters preferred it to a comparable extract, but freed from the grinding gases. It may be used as a flavouring agent for butter in a quantity of 13 to 20 g/kg of butter.

The aromatic extracts of Examples 1, 6 and 7 were then compared with corresponding reference extracts obtained by the process described in French Patent Application No. 2,192,852 mentioned at the beginning of the description using the following solvents: Freon, then petroleum ether/acetone.

Four tasters preferred the extract of Example 1 (nutmeg) to the corresponding reference. Five tasters preferred the extract of Example 6 (black pepper) to the corresponding reference. Finally, the six tasters preferred the extract of Example 7 (cumin) to the corresponding reference.

The procedure described in Example 1 is repeated to obtain the grinding gases. By contrast, the powder obtained is only treated with one solvent, an azeotropic mixture. The desired aromatic extract is obtained by combining the grinding gases and the product obtained by extraction of the ground spice with the azeotropic mixture after partial concentration, as described in Example 1. The oleoresins are obtained in accordance with the variant of that Example. The results obtained are as follows:

The extract of Example 8 (cumin) on the neutral base was found to be fresh and good. It was preferred by five tasters to a similar extract, but without the grinding gases.

The extract of Example 11 (black pepper) on the neutral base was found to be green and fresh, intense. It was preferred by five tasters to a similar extract, but without the grinding gases.

A trigonal mill (Siefer type SM 180) is filled with freshly rectified hexane to remove the air from the grinding chamber, after which the mill is switched on and is fed with black pepper so as to obtain a suspension containing around 200 g of pepper per liter of hexane.

After 10 minutes' operation, the mill is stopped, after which the grounds are separated and the liquid fraction recovered for concentration under reduced pressure. The grounds are then introduced into an extraction tank and are treated with fresh hexane under the same conditions as in Example 1. The same operations are then repeated for the treatment with ethanol of the grounds obtained.

The combination of the various liquid phases obtained consititutes the required aromatic extract. From 90 to 110 g of this extract are obtained for 1 kg of black pepper. This extract is judged by the tasters to be green, fresh and intense.

Black peper is wet ground in the same way as described in Example 12. Hexane is again used as solvent.

In contrast to Example 12, the grounds obtained are not successively treated with fresh hexane and ethanol, but are directly treated with an azeotropic mixture of hexane (21%) and ethanol (79%).

The various liquid phases obtained are then combined to give the required aromatic extract. Once again, from 90 to 110 g of extract are obtained for 1 kg of black pepper.

An aromatic extract of nutmeg is prepared in accordance with the general directions of Example 1. 1.25 kg of nutmeg gives 34 g of fraction A, 540 g of fraction B with a dry matter content of 40% and 302 g of fraction C with a dry matter content of 44%. Fraction C is then added to 4.65 kg of cooking salt and the mixture is treated in a Buchi rotary evaporator for 30 minutes at 30.degree. C. under 50 to 100 mm Hg. Fraction B is added to the product obtained and the evaporator is started up again for 30 minutes under 50 to 200 mm Hg at a temperature below 30.degree. C. Finally, fraction A is added to the product obtained and the mixture is homogenised simply by switching on the evaporator for 10 minutes at normal temperature and pressure.

Approximately 5 kg of oleoresin of nutmeg fixed to a salt support are thus obtained, this extract being in the form of a very pale yellow-orange, highly odoriferous crystalline powder.

An excellent instant mashed potato is prepared by using 1 kg of standard commercial-grade potato flakes, 0.2 liter of milk, 50 g of butter, 20 g of salt and 1.4 g of the oleoresin on a salt support described above.

The procedure described in Example 14 is adopted to obtain 5 kg of oleoresin of black pepper on malto-dextrin. The ingredients used for this purpose were, on the one hand, 4.83 kg of malto-dextrin and, on the other hand, 29 g of a fraction A, 268 g of a fraction B with a dry matter content of 32% and 157 g of a fraction C with a dry matter content of 34% obtained from 1.5 kg of black pepper in accordance with Example 6.