GB1562794A - Method for the extraction of carotenes from palm oil - Google Patents

Description

(54) AN IMPROVED METHOD FOR THE EXTRACTION OF CAROTENES FROM PALM OIL (71) We, UNIVERSITI SAINS MALAYSIA, a body formed under the laws of the Federation of Malaysia, of Penang, Malaysia, and the governing body of the MALAYSIAN AGRICULTURAL RESEARCH AND DEVELOPMENT INSTITUTE, a body formed under the laws of the Federation of Malaysia, of Bag Berkunei 202, P.O. Universiti Pertanian, Serdang, Selanger, Malaysia, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an improved process for the extraction of carotenes from vegetable oils particularly palm oil.

The production of palm oil is growing very steadily and already contributes significantly to the world's supply of edible oils. It is also known that carotenes are present in palm oil in concentrations which vary from 250 to 1000 parts per million.

The average concentration of carotenes in Malaysian palm oil falls in the range of 400 to 700 parts per million. This, therefore represents a rich source of provitamin A for nutritional purposes. However, the present refining practice is to bleach the oil by a destructive process by using (a) Fuller's earth or (b) heating at about 2400C or (c) using a combination of heat and Fuller's earth at about 1500C. These processes destroy the carotenes present and hence represent the loss of a considerable potential source of vitamin A. It would, therefore, be useful if the carotenes could be extracted from the oil prior to refining without either destroying the oil or lowering its quality.

There are various methods of extraction of carotenes. These are (1) extraction by saponification, (2) the iodine method, (3) a urea process, (4) extraction using adsorbents, (5) extraction by selective solvents and (6) extraction by distillation.

The present invention is concerned with the extraction and subsequent recovery of carotenes from vegetable oils, particularly palm oil, using activated carbon. The extraction of carotenes from palm oil using activated carbon requires precautions to be taken to prevent oxidation as, if they are not taken, practically no carotene is obtained.

One method of overcoming the problem of oxidation has been described in British Specification No. 691,924 and comprised removing the oxygen present in the carbon by either treating the carbon with a reducing agent or by displacement with a gas, e.g. carbon dioxide, before effecting the extraction. This method suffers from the disadvantage that the reducing agent, when used, had to be removed from the carbon before extraction of carotenes could be effected and further that it is necessary to exclude oxygen during the extraction process.

The present invention overcomes these problems by treating the carbon with antioxidants which are acceptable to the food industry and which consequently may remain on the carbon during the extraction process. The antioxidants thus continue to operate during the extraction and the necessity of exclusion of oxygen is obviated.

The present invention provides a process for the extraction of carotenes from vegetable oils which comprises:- (a) contacting the oil, optionally in a solvent, at a pH of > 7 with an activated carbon which has been treated by contacting with a solution of one or more antioxidants selected from tocopherols, butylated hydroxy-anisile, butylated hydroxy-toluene and t-butyl hydroquinone, and (b) recovering the carotenes from the activated carbon by means of an organic solvent.

The antioxidants used to treat the activated carbon prior to carotene extraction, namely tocopherols, butylated hydroxy-anisole (BHA), butylated hydroxy-toluene (BHT) t-butyl hydroquinone (TBHQ) are all acceptable to the food industry and do not require removal from the carbon before the extraction of the carotenes. Tocopherols, particularly a-tocopherol, are the preferred antioxidants as they have a further advantage in that they assist the subsequent conversion of the carotenes to vitamin A.

Any convenient activated carbon may be used, for example, the carbons derived from saw dust or rubber wood.

The oil to be treated may be crude or refined, or a fraction e.g. an olein or stearin fraction, of the oil may be used. Treatment involves contacting the oil with the activated carbon, for example by stirring the two together in batch operation.

The preferred ratio of oil to activated carbon is from 2 to 50 parts by weight, preferably 10 parts by weight, of oil to 1 part by weight of activated carbon.

Alternatively the oil may be passed through a column or bed of the activated carbon in continuous operation. The proportion of carotenes extracted increases with increasing contact time, and suitable contact times likely to be within the range of la0 minutes, preferably 2030 minutes. Contact temperature should be preferably less than 50"C, although higher temperatures of 550C or above may be required when crude palm oil is treated without a solvent. Alternatively, the use of palm oil in an aliphatic solvent, e.g. petroleum ether enables the treatment to be carried out effectively at ambient temperature.

The treatment causes carotenes to be adsorbed by the activated carbon. After separation of the activated carbon from the oil, the carotenes are recovered by means of an aromatic solvent, for example, toluene or p-xylene. A preferred ratio of solvent to carbon is from 10 to 200 mls. of solvent per gram of carbon.

The overall recovery of carotenes from palm oil is about 40%. However, recovery from the activated carbon is quantitative.

The activated carbon is pretreated by contacting with the antioxidant(s), in solution, (preferably 2% based on weight of carbon) and it has been found that the adsorbent can be recycled for extraction as many as ten or twenty or more times without significant loss in its effectiveness. Adsorption of the antioxidants is almost quantitative. When the carbon loses its effectiveness it can be readily regenerated for further use by subjecting it to reduced pressure at 300C until constant weight is obtained, further treatment with antioxidants being unnecessary.

It has also been found that it is essential that the pH of the adsorbent be greater than 7 in order that the carotenes remain stable for extraction.

When the oil used is the olein fraction of Dalm oil treatment twice with activated carbon, as described heretofore, followed by concentration under reduced pressure to remove traces of solvent renders the oil sufficiently bleached for use as an edible oil.

It has also been found that the quality of the oil, particularly in terms of free fatty acid content and totox value (the totox value is defined as the anisidine value plus twice the peroxide value), is improved after treatment with activated carbon by the process of the invention. In a typical case the free fatty acid was reduced from 2.43% to 0.43% and the totox value from 50.65 to 21.33.

The carotenes can be freed from the recovery solvent by evaporation under pressure (for example initially at 500C and 60 mmHg pressure then at 40"C and 0.5 mmHg pressure). The temperature should be kept low. A solution of the carotenes in oil may thus be obtained in which the concentration is up to 6 times or more than that of the original concentration of the carotenes in the oil.

It is now known that a number of countries are turning to natural rather than synthetic carotenes for colouring and enriching the vitamin A content of food.

We think that there is much potential in this method which both extracts the carotenes for use as pro-vitamins for food and simultaneously bleaches the oil rendering it suitable for consumption.

The following benefits are consequent upon using the process as described.

(1) Carotenes which would otherwise be destroyed during the current practice of bleaching can be recovered without being oxidised, thus allowing exploitation of this rich source of pro-vitamin A.

(2) The side products resulting from heat bleaching are not present in the oils.

The following Examples illustrate the invention. The activated carbons used were obtained from Century Chemicals of Prai Penang, Malaysia.

Example 1.

A solution of crude palm oil (250 g.) in petroleum ether b.p. 60--80"C (1000 ml.) was stirred with activated carbon S511 (25 g.), which had been treated by contacting with 0.5% a-tocopherol in toluene (250 ml.) and had a pH of 10.8, for 30 minutes at room temperature (about 29"C). The solution was filtered and the carotenes adsorbed on the carbon were extracted with p-xylene (500 ml.). The carotene extract was obtained after removal of the solvent under vacuum initially at 50"C (P = 60 mmHg) and then at 40"C (P = 0.5 mmHg). The carotene extract was found to be four times more concentrated than the original crude palm oil as indicated in the results below: Results:

Sample Carotene Content (p.p.m.) Original Crude Palm Oil 604 Oil after Treatment 286 Carotene Extract 2520 Example 2.

A solution of olein (100 g.) in petroleum ether (400 ml.) was stirred with activated carbon S511 (10 g.) which had been treated by contacting with 0.5% atocopherol in petroleum ether (100 ml.) and had a pH of 10.8 for 30 minutes at about 29or. The olein was filtered and the carotene extracted with toluene (650 I.ll.) The oil loss was found to be 6% and the carotene concentration of the extract six times that of the original olein as shown in the results below: Results:

Carotene Content Lovibond 514fl Sample (ppm) column Original olein 649 77R 51Y Olein after treatment 48R 20Y Carotene extract 3916 Example 3.

A solution of olein (12.5 g) in petroleum ether (50 ml) was stirred with activated carbon S511 (6 g) which had been treated by contacting with 0.5% butylated hydroxy-anisole (BHA) in petroleum ether b.p. 60"--80"C (30 ml) and had a pH of 10.8 for 30 minutes at room temperature. The solution was filtered and the carotenes were extracted with 100 ml toluene. In further experiments the above procedure was repeated except that the antioxidant was replaced by either butylated hydroxy-toluene or t-butyl hydroquinone (TBHQ). In none of the cases did the product recovered show an oxidation peak at 325 nm.

WHAT WE CLAIM IS: 1. A processs for the extraction of carotenes from vegetable oils comprising: (a) Contacting the oil, optionally in a solvent at a pH > 7 with an activated carbon which has been treated by contacting with a solution of one or more antioxidants selected from tocopherols, butylated hydroxy-anisole, butylated hydroxy-toluene and t-butyl hydroquinone, and (b) recovering the carotenes from the activated carbon.

2. A process as claimed in claim 1 wherein the antoixidants used are tocopherols.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. Example 1. A solution of crude palm oil (250 g.) in petroleum ether b.p. 60--80"C (1000 ml.) was stirred with activated carbon S511 (25 g.), which had been treated by contacting with 0.5% a-tocopherol in toluene (250 ml.) and had a pH of 10.8, for 30 minutes at room temperature (about 29"C). The solution was filtered and the carotenes adsorbed on the carbon were extracted with p-xylene (500 ml.). The carotene extract was obtained after removal of the solvent under vacuum initially at 50"C (P = 60 mmHg) and then at 40"C (P = 0.5 mmHg). The carotene extract was found to be four times more concentrated than the original crude palm oil as indicated in the results below: Results: Sample Carotene Content (p.p.m.) Original Crude Palm Oil 604 Oil after Treatment 286 Carotene Extract 2520 Example 2. A solution of olein (100 g.) in petroleum ether (400 ml.) was stirred with activated carbon S511 (10 g.) which had been treated by contacting with 0.5% atocopherol in petroleum ether (100 ml.) and had a pH of 10.8 for 30 minutes at about 29or. The olein was filtered and the carotene extracted with toluene (650 I.ll.) The oil loss was found to be 6% and the carotene concentration of the extract six times that of the original olein as shown in the results below: Results: Carotene Content Lovibond 514fl Sample (ppm) column Original olein 649 77R 51Y Olein after treatment 48R 20Y Carotene extract 3916 Example 3. A solution of olein (12.5 g) in petroleum ether (50 ml) was stirred with activated carbon S511 (6 g) which had been treated by contacting with 0.5% butylated hydroxy-anisole (BHA) in petroleum ether b.p. 60"--80"C (30 ml) and had a pH of 10.8 for 30 minutes at room temperature. The solution was filtered and the carotenes were extracted with 100 ml toluene. In further experiments the above procedure was repeated except that the antioxidant was replaced by either butylated hydroxy-toluene or t-butyl hydroquinone (TBHQ). In none of the cases did the product recovered show an oxidation peak at 325 nm. WHAT WE CLAIM IS:

1. A processs for the extraction of carotenes from vegetable oils comprising: (a) Contacting the oil, optionally in a solvent at a pH > 7 with an activated carbon which has been treated by contacting with a solution of one or more antioxidants selected from tocopherols, butylated hydroxy-anisole, butylated hydroxy-toluene and t-butyl hydroquinone, and (b) recovering the carotenes from the activated carbon.

2. A process as claimed in claim 1 wherein the antoixidants used are tocopherols.

3. A process as claimed in either claim 1 or claim 2 wherein the antioxidant

used is a-tocopherol.

.

4. A process as claimed in any one of claims 1 to 3 wherein the activated carbon has been treated by contacting with up to 2% by weight based on the weight of the carbon of the antioxidant(s).

5. A process as claimed in any one of claims 1 to 4 wherein the ratio of the oil to the activated carbon is from 2 to 50 parts by weight.

6. A process as claimed in any one of claims 1 to 5 wherein the contact time of the oil and carbon is from 20-30 minutes.

7. A process as claimed in any one of claims 1 to 6 wherein the oil is palm oil or a fraction of palm oil.

8. A process as claimed in claim 7, wherein the palm oil is used in solution in petroleum ether.

9. A process as claimed in any one of claims 1 to 8, wherein the carotenes are recovered from the activated carbon by means of an aromatic solvent.

10. A process as claimed in claim 1 and substantially as hereinbefore described in any one of the Examples.

11. Carotenes whenever obtained by the process as claimed in any one of claims 1 to 10.