Method for the chromatographic isolation of vitamin E isomers

Details Method for the chromatographic isolation of vitamin E isomers Method for the chromatographic isolation of vitamin E isomers

2001-02-02

2003-12-02

Therkorn, Ernest G. (Department: 1723)

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

C210S656000, C210S659000, C210S634000, C549S413000, C554S174000

Reexamination Certificate

active

06656358

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to methods for the chromatographic isolation of vitamin E isomers. In particular to methods of isolating individual vitamin E isomers such as &agr;-tocopherol, &bgr;-tocopherol, &ggr;-tocopherol, &dgr;-tocopherol, &agr;-tocotrienol, &agr;-tocotrienol, &ggr;-tocotrienol, &dgr;-tocotrienol and the like from vitamin E containing mixtures such as crude palm oil, palm oil products, palm oil by-products, vegetable oils, and the like.
BACKGROUND OF THE INVENTION
Tocols are vitamin E compounds that include tocopherols (T) and tocotrienols (T
3
) that are found in vegetable oils in varying quantities (See, e.g., Table A). The tocols present in most vegetable oils are typically in the form of tocopherols (&agr;-, &bgr;-, &ggr;-, and &dgr;-tocopherols). Palm oil, however, is unique since the tocols are present mainly in the form of tocotrienols (&agr;-T
3
, &ggr;-T
3
, and &dgr;-T
3
). Each of the tocols exhibits interesting physiological properties.
TABLE A
Tocopherols Amounts in Vegetable Oils (mg/kg)
Oil
&dgr;-T
&bgr;-T
&ggr;-T
&dgr;-T
&agr;T
3
&ggr;-T3
&dgr;-T
3
Castor
28
29
111
310
—
—
—
Cocoa butter
11
—
170
17
2
—
—
Coconut
—
—
—
2-4
20
—
—
Corn
134
18
412
39
—
—
—
Cottonseed
573
40
317
10
—
—
—
Groundnut
169
5
144
13
—
—
—
Linseed
—
—
—
—
—
—
—
Mustard
75
—
494
31
—
—
—
Olive
93
—
7
—
—
—
—
Palm from fibers
1662
—
—
—
456
485
142
Palm
150
—
—
—
1127
297
80
Palm
279
—
61
—
274
398
69
Rape
70
16
178
7
—
—
—
Rice bran
324
18
53
—
236
349
—
Safflower
477
—
44
10
—
—
—
Sesame
12
6
244
32
—
—
—
Soyabean
116
34
737
275
—
—
—
Sunflower
608
17
11
—
—
—
—
Wheat germ
1179
398
493
118
tr
—
—
Both tocopherols and tocotrienols act as powerful nutritional antioxidants and help to reduce cellular damage due to free radicals arising from the body's normal oxidative energy metabolism or from the action of toxic chemicals and pollutants in our environment. Free radicals have been implicated in aging, chronic degenerative diseases, and cancer.
Vitamin E is also a natural antioxidant, present at approximately 600-1000 ppm in crude palm oil; the major component being &ggr;-tocotrienol. Recently it has been reported that &ggr;-tocotrienol has anti-cancer properties in addition to its known antioxidant activity. Tocotrienols have been found to lower blood cholesterol.
U.S. Pat. No. 5,190,618 discloses a process for extracting vitamin E from palm fatty acid distillates (PFAD). The process involves converting the PFAD into methyl esters and distilling the methyl esters followed by ion-exchange chromatography and molecular distillation to get a vitamin E concentrate of more than 90%.
U.S. Pat. No. 5,157,132 discloses a process for extracting vitamin E from crude palm oil (CPO) by converting the CPO to methyl esters and then removing the esters by molecular distillation to yield carotene-rich and vitamin E-rich fractions.
GB 2,218,989 discloses converting crude palm oil into methyl esters followed by chromatographic separation of the methyl esters, on an adsorbent in the presence of solvents, to yield carotene-rich, vitamin E-rich, and sterol-rich fractions.
These patents only describe the isolation of vitamin E-rich fractions from palm oil and do not disclose the isolation individual vitamin E isomers which may exhibit important physiological properties. Thus, all of the previously known methods that involve in the adsorption/desorption chromatographic separation only isolate mixtures of vitamin E isomers rather than individual isomers. Moreover, these methods all use solvents that are costly and hazardous.
There is a need for methods to separate and isolate vitamin E isomers that avoids or eliminates the sole use of solvents and consequently, renders the process “non-hazardous.”
SUMMARY OF THE INVENTION
The invention relates to a method for the chromatographic separation of vitamin E isomers from a vitamin E containing mixture. The method involves the steps of combining the vitamin E mixture with an adsorbent to effect adsorption of the vitamin E isomers on the adsorbent and selectively desorbing the vitamin E isomers from the adsorbent with a solvent under supercritical conditions.
The vitamin E isomers may be one or more of &agr;-tocopherol, &bgr;-tocopherol, &ggr;-tocopherol, &dgr;-tocopherol, &agr;-tocotrienol, &bgr;-tocotrienol, &ggr;-tocotrienol and &dgr;-tocotrienol. The adsorbent may be silica gel, reverse phase C-18 silica gel, or a mixtures thereof. The solvent may be CO
2
, propane, propene, or ethylene. Preferably, the solvent is CO
2
. The solvent may optionally further include an entrainer such as an alcohol. In one embodiment the separation is performed at a temperature of about 20° C. to 150° C. and a pressures of about 20 kg/cm
2
to 800 kg/cm
2
. The vitamin E containing mixture may be crude palm oil, palm oil products, palm oil by-products, vegetable oils, and a vitamin E concentrate.
When the vitamin E containing mixture is a vitamin E concentrate the vitamin E concentrate may be formed by esterifying free fatty acid components of the vitamin E containing mixture with one or more monohydric alcohols to provide esters followed by removing the esters to form the vitamin E concentrate, or by trans-esterifying glyceride components the vitamin E containing mixture with one or more monohydric alcohols to provide esters and then removing the esters to form the vitamin E concentrate. The alcohol may be a C
1
to C
8
alcohol, such as methanol.
The free fatty acid components of the vitamin E containing mixture may be esterified using a catalyst selected from the group consisting of a solid alkali metal bisulfate acid, a solid alkali metal sulfate acid, a strongly acidic ion exchange resin, and an enzyme. The glyceride components of the vitamin E containing mixture may be trans-esterifed using a basic catalyst or an enzyme.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a method for the chromatographic separation of vitamin E isomers from vitamin E containing mixtures.
The phrase “vitamin E containing mixtures,” as used herein, means any mixture or combination of compounds that includes vitamin E. Preferably, the vitamin E containing mixture is one or more of crude palm oil (CPO), palm oil products, palm oil by-products, or other vegetable oils and fats. More preferably, the vitamin E containing mixture is one or more of crude palm oil.
In particular the present invention uses a supercritical fluid (such as SC—CO
2
) in combination with one or more adsorbents to effect adsorption and desorption of the vitamin E isomers resulting in the vitamin E isomers being separated from the other compounds in the vitamin E containing mixture. Preferably, the individual vitamin E isomers are also separated from each other.
In one embodiment the present invention involves isolating vitamin E isomers from a vitamin E concentrate. The phrase “vitamin E concentrate,” as used herein means a vitamin E containing mixture that has been treated chemically and/or physically to increase the concentration of vitamin E. Preferably, the vitamin E concentrate may be prepared, for example,
a. from crude vegetable oil esters via catalytic alcoholic esterification/transesterification of the vegetable oils and distilling the esters to yield the vitamin E concentrate; or
b. from unsaponifiable matters of vegetable oils and fats by a saponification process;
c. by any process, such as chromatography (solvent and supercritical) and supercritical fluid extraction.
An important feature of the invention is that liquefied gas at supercritical conditions is used in the separation. Using a supercritical fluid avoids or reduces the prior requirements for hazardous solvents. To date, there has not been disclosed any method that uses a supercritical fluid for the adsorption/desorption chromatographic isolation/separation of Vitamin E isomers from plant sources such as crude palm oil, palm oil products, palm oil by-products, and other vegetable oils and fats.
The method of the invention for the chromatographic isolation of vitamin E isomers from crude palm o

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