Methods for treating deodorizer distillate

Details Methods for treating deodorizer distillate Methods for treating deodorizer distillate

2001-09-04

2004-06-15

Carr, Deborah D. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

C422S082090

Reexamination Certificate

active

06750359

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to methods for treating distillates obtained during the process of deodorizing various oils. More particularly, this invention relates to methods for recovering fatty acids, tocopherols, and sterols from a distillate obtained from the deodorizing of various oils.
BACKGROUND OF THE INVENTION
Oils derived from plants and animals are valuable sources of fatty acids, tocopherols, and sterols. During the process of refining such oils, however, significant amounts of these components, especially the tocopherols and sterols, are lost to various intermediate byproducts and waste streams, which include acidulated soapstocks, deodorizer distillates, or both, depending on the refining method selected. Accordingly, numerous methods have been proposed for recovering fatty acids, tocopherols, and sterols from various refining intermediates, including deodorizer distillates that are obtained as byproducts of a high-temperature distillation step (commonly termed deodorization) during the production of oils and fats.
Deodorization is usually the final step in producing oils and fats from plant and animal sources. Vegetable oils such as soybean oil typically contain volatile impurities that can impart objectionable odor and taste. These volatile compounds generally must be removed to produce edible oils. Deodorization generally involves a steam stripping process wherein steam is contacted with oil in a distillation apparatus operating at low pressure and a temperature sufficient to vaporize objectionable volatile impurities at the operating pressure. This process, commonly known as vacuum-steam deodorization, relies upon volatility differences between the oil and the objectionable impurities to strip the relatively more volatile objectionable impurities from the relatively less volatile oil. In a typical vacuum-steam deodorizing process, vegetable oil is introduced into a distillation apparatus having a plurality of vertically spaced trays, commonly termed stripping trays. Within each stripping tray, steam injected into the vegetable oil entrains objectionable volatile impurities. The combined steam and entrained distillation vapors are usually collected and condensed to form a distillate that can be disposed of or processed further to recover valuable materials.
The major constituents of deodorizer distillates are fatty acids, tocopherols, and sterols, which are present in various relative amounts depending on the oil source and the refining steps the oil is subjected to prior to deodorization. Deodorizer distillate itself has a certain commercial value. However, greater value can be realized when deodorizer distillate is split into a fatty acid-enriched fraction and a fraction enriched in sterols and tocopherols.
Fatty acids isolated from deodorizer distillates are utilized in several nonfood applications and are particularly useful as fluidizing agents for lecithin. Such fatty acids also can be utilized as precursors in a wide variety of molecular synthesis schemes. Typically, the fatty acid portion of deodorizer distillate comprises C
10
-C
22
saturated and unsaturated fatty acids. Soybean deodorizer distillate in particular contains about 50 percent by weight fatty acids.
Deodorizer distillates also contain sterols, which are valuable precursors in the production of hormones. Stigmasterol is used in manufacturing progesterone and corticoids. Sitosterol is used to produce estrogens, contraceptives, diuretics, and male hormones. Soybean deodorizer distillate in particular contains from about 10 to about 18 percent by weight total sterols, of which about 50% is sitosterol, about 20% is stigmasterol, about 20% is campesterol, and about 10% is other minor sterols.
The final major component of deodorizer distillates is tocopherol. Tocopherols are valuable natural antioxidants that help prevent oxidation and spoilage. Tocopherols are also utilized in the production of Vitamin E. Distillates obtained from soybean oil deodorization generally contain a mixture of &agr;, &bgr;, &ggr;, and &dgr; tocopherol isomers in a ratio of about 15:5:30:50. Alpha tocopherol has the most powerful biological Vitamin E activity. The other tocopherols have weaker Vitamin E activity but stronger antioxidant activity. If maximum Vitamin E activity is desired, non-alpha tocopherols can be converted into the alpha form by well-known techniques, such as methylation.
In the past, recovering tocopherols and sterols from deodorizer distillates and related mixtures has proved complicated and expensive. One difficulty associated with isolating one or more distillate fractions enriched in fatty acids, tocopherols, and/or sterols from deodorizer distillates is that the boiling points of sterols and tocopherols are roughly in the same range. Another difficulty is that deodorizer distillate can undergo thermal degradation if it is processed for extended periods at the temperatures at which sterols and tocopherols vaporize, such temperature conditions which can cause fatty acids to convert into undesirable trans isomeric forms.
Numerous methods have been proposed for treating deodorizer distillates to isolate and recover one or more components. In many of these methods, a first essential process step involves subjecting the fatty acids to an esterification or saponification reaction. For example, U.S. Pat. No. 3,153,055 teaches a process for isolating sterols and tocopherols from deodorizer distillate by esterifying the fatty acids with a monohydric alcohol under strongly acidic conditions. The sterols and tocopherols are then fractionally extracted from the esterification product mixture with a combination of polar and nonpolar solvents.
In an alternative esterification method, U.S. Pat. No. 5,487,817 teaches esterifying the sterols with the fatty acids and then distilling the resulting mixture to obtain a residue containing sterol esters and a distillate containing tocopherols. Sterols are then isolated from the residue by subjecting the sterol esters to cleavage under acidic conditions.
U.S. Pat. No. 2,349,270 discloses that deodorizer distillate can be treated with lime soap to saponify the fatty acids, followed by extraction of the unsaponifiable fraction (tocopherols and sterols) with acetone, in which the saponification products are insoluble. The extract is then washed and concentrated, as for example by solvent distillation, and then cooled to crystallize sterols which are removed by filtration, leaving a high purity tocopherol fraction. The fatty acid soaps formed by the process can be acidulated and converted into free fatty acids.
Extractive separation methods also have been employed in treating deodorizer distillates to isolate one or more components. For example, U.S. Pat. No. 5,138,075 describes a method for recovering tocopherols from a deodorized distillate which comprises contacting the distillate with liquid water at elevated temperature and pressure, thereby producing a raffinate phase stream having a relatively high concentration of tocopherols and an extract phase stream having a relatively high concentration of fatty acids. The raffinate stream and the extract stream are then cooled to a temperature at which the organic components thereof are immiscible with liquid water, whereupon removal of water produces a tocopherol-enriched fraction and a fatty acid-enriched fraction, respectively.
None of the above methods for isolating one or more components from a deodorizer distillate has proved satisfactory, however. Methods employing an esterification step or saponification step introduce processing complexity and require later processing steps that often involve use of strong mineral acids in order to convert the respective esters or soaps into free sterols and free fatty acids. Mineral acids can be dangerous in handling and can induce discoloration or other degradation of distillate components. Methods requiring extractive steps are expensive and create the potential for contamination by residual solvent.
Previously known methods for isolating one or more components

Affiliated with

Also associated with

Rating

Methods for treating deodorizer distillate does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Methods for treating deodorizer distillate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods for treating deodorizer distillate will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3298242