Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Plant material is basic ingredient other than extract,...
Reexamination Certificate
2000-02-17
2001-03-20
Sayala, Chhaya D. (Department: 1609)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Plant material is basic ingredient other than extract,...
C426S002000, C426S080000, C426S489000, C426S492000, C426S635000, C426S807000, C554S012000, C514S558000, C514S560000
Reexamination Certificate
active
06203843
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a new use of conjugated linoleic acid in animal feeds. The conjugated linoleic acid is manufactured in an industrial scale process from seed oils such as sunflower oil and safflower oil, which contain non-fatty acid residues low enough to avoid final purification by distillation, but still pure enough to be safely fed to animal in bulk feed.
BACKGROUND OF THE INVENTION
Processes for the conjugation of the double bonds of polyunsaturated unconjugated fatty acids have found their main application in the field paints and varnishes. Oils comprised of triglycerides of conjugated fatty acids are known as drying oils. Drying oils have value because of their ability to polymerize or “dry” after they have been applied to a surface to form tough, adherent and abrasion resistant films. Tung oil is an example of a naturally occurring oil containing significant levels of conjugated fatty acids.
Because tung oil is expensive for many industrial applications, research was directed towards finding a substitute. In the 1930's, it was found that conjugated fatty acids were present in oil products subjected to prolonged saponification, as originally described by Moore, J. Biochem., 31: 142 (1937). This finding led to the development of several alkali isomerization processes for the production of conjugated fatty acids from various sources of polyunsaturated fatty acids.
In alkali isomerization the fatty acids are exposed to heat, pressure and a metal hydroxide or oxide in nonaqueous or aqueous environments, resulting in the formation of conjugated isomers. Other methods have been described which utilize metal catalysts, which is not as efficient in the production of conjugated double bonds. It was found that isomerization could be achieved more rapidly in the presence of higher molecular weight solvent. Kass, et al., J. Am. Chem. Soc., 61: 4829 (1939) and U.S. Pat. No. 2,487,890 (1950) showed that replacement of ethanol with ethylene glycol resulted in both an increase in conjugation in less time. U.S. Pat. No. 2,350,583 and British Patent No. 558,881 (1944) achieved conjugation by reacting fatty acid soaps of an oil with an excess of aqueous alkali at 200-230 degrees C. and increased pressure.
Among the processes known to effect isomerization without utilizing an aqueous alkali system, is a nickel-carbon catalytic method, as described by Radlove, et al., Ind. Eng. Chem.38: 997 (1946). A variation of this method utilizes platinum or palladium-carbon as catalysts.
Purified conjugated linoleic acid (“CLA”) has recently been shown in several studies to have unique properties when used as a food additive. Purified CLA appears to affect fat deposition in animals. Purified CLA both increases the lean to fat ratio, effectively reducing body fat, and increases feed conversion efficiency. An additional advantage of feeding CLA is that it appears to modulate immune responses under certain conditions. In laboratory animal studies CLA has been shown to prevent weight loss due to immune stimulation and to treat immune hypersensitivity.
The purified CLA utilized in prior studies as an animal feed additive was obtained by small scale laboratory procedures involving production of CLA from highly purified linoleic acid. Laboratory and pilot scale oil refining systems have been described for preparation of purified seed oils. For example Sullivan, J. Am. Oil Chemists' Soc., 53: 359 (1976), describes a laboratory semi-pilot steam refining system made entirely of glass.
While these systems are adequate for producing quantities of conjugated fatty acids for laboratory studies, or even clinical trials, they are not suitable for commercial scale bulk production. On the other hand, the large scale systems available to produce industrial quantities of conjugated acids, as in classical drying oils, cannot be run inexpensively enough to produce material for bulk animal feeds. The standard degumming, refining, and dehydration steps necessary to obtain nutritionally safe edible conjugated oils for livestock feeding, are prohibitively complex and expensive. (See Braae, J. Am. Oil Chemists' Soc., 53: 353 (1976) for a discussion of complex degumming processes as practiced on a commercial scale in Europe). Also there are significant losses of product through polymerization of conjugated fatty acids or their precursors at high temperatures.
Economical CLA production in commercial quantities for use in domestic food animal feeds is a desirable objective in light of the nutritional benefits realized on a laboratory scale. Preferably, the CLA is produced directly from a source of raw vegetable oil and not from expensive purified linoleic acid. Further, the process must avoid cost generating superfluous steps, and yet result in a safe and wholesome product palatable to animals.
SUMMARY OF THE INVENTION
In the present invention, a feed safe conjugated linoleic acid is manufactured according to a method otherwise used for producing an industrial grade conjugated product for use in paint and varnish. Typically, residues (i.e. the chemically modified end products resulting from heat and pressure) derived from non-oil components of seed oils, such as sterols and phosphatides, form unpalatable, or even toxic by-products under processing conditions. Generally seed oils such as corn or soy bean oil must be extensively degummed, and the sterols and phosphatides are meticulously removed in a series of purification steps to avoid fouling of equipment, and to recover a wholesome product. In addition to removal of impurities and by-product polymerized or carmelized material during processing, it is necessary to acidify and finally distill the oil to obtain product of requisite purity for use in food. Subjecting the oil to isomerization causes further impurities, and requires even more rigorous decontaminating and by-product removal.
Surprisingly, the Applicant has discovered that a complex purification scheme for producing a feed safe conjugated linoleic-containing oil is not necessary, if the starting material is an oil having less than 0.5 percent phosphatides, and an unsaponifiable sterol fraction containing less than 20 percent each of campesterol and stigmasterol. According to this criteria, sunflower and safflower oil are suitable starting oils for production of the present feed safe CLA enriched oil, but soybean oil or corn oil are not suitable because of the high unsaponifiable content, and also high levels of linolenic acid that tends to readily polymerize. It is further desirable to have a starting oil with a high linoleic acid content, so that the final product has a correspondingly high CLA content.
The present invention encompasses the new use in domestic animal feed of conjugated linoleic acid produced from a seed oil, especially sunflower and safflower oils, but not soybean or corn oils, having a linoleic acid content of at least 50 percent produced by an industrial scale process in which the crude oil is subjected to the steps of solvent extracting, as with hexane, alcohols, or polyols known in the art, fat splitting, treating with aqueous alkali to effect at least 50 percent isomerization of the double bonds of linoleic acid to form conjugated linoleic acid at low temperatures below about 230 degrees F., and preferably below about 215 degrees F., acidifying with a mineral acid, and separating the oil fraction from the majority of the aqueous fraction without a distillation step.
In the conjugation of linoleic by isomerization of the double bonds, the fat splitting step releases the free fatty acids from the glycerol backbone molecule. After the alkali treatment step followed by acidification, several water wash steps may be required to remove salts, and then the water content of the oil fraction can be reduced (after simple decanting the upper fat layer) by conventional centrifugation methods to a content of less than 10 percent. The presence of some water will not interfere with animal feed formulating. In fact, the presence of some water aids the mixing and homog
Natural Nutrition Ltd.
Sayala Chhaya D.
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