FIELD OF THE INVENTION

The present invention is directed to purifying fatty acid compositions, specifically methods of making purified fatty acid compositions having improved color values and/or color stability over time.

BACKGROUND OF THE INVENTION

Fatty acids are produced by hydrolyzing natural fats, that is, glyceryl esters of fatty acids, into a mixture of fatty acids and glycerin, and separating the fatty acids from glycerin. While natural fats consist predominantly of glyceryl esters, natural fats also contain impurities or substances which, when exposed to heat and/or atmospheric conditions, become darkened in color. Also, commercial fatty acids generally are derived from more impure, inedible oils and fats which in and of themselves are of dark color. Thus, a batch of fatty acids produced commercially by hydrolysis is usually brown in color, or darker, depending upon the quality of the feed stock put into the hydrolyzer. These crude/raw fatty acids sometimes are bleached by addition of bleaching earth capable of adsorbing at least some of the dark colored components. Bleaching of fatty acids is accomplished by mixing with the fatty acids an amount of bleaching earth required to give the desired color, usually 1-3 percent by weight, and agitating from 15-30 minutes at a temperature of approximately 70 degrees Celsius. Thereafter, the bleaching agent is removed by filtration.

There is a continuing need to select bleaching agents in methods of making purified fatty acid compositions specifically as it relates to the reduction of color.

SUMMARY OF THE INVENTION

The present invention is based, at least in part, upon the surprising observation that acid activated bleaching earths characterized herein, provides purified fatty acid compositions having desirably reduced color values. That is, the use of these certain bleaching earths can reduce the resulting Lovibond color values thereby indicating a higher degree of purification in purified fatty acid compositions. Accordingly, an aspect of the invention provides for a method of making a purified fatty acid composition comprising the step of combining a raw fatty acid composition with a bleaching earth having a pH less than 3.9. The pH of the bleaching earth is assessed by a 10 percent by weight suspension of the bleaching earth and distilled water filtered through polytetrafluoroethylene filter paper, and at 25 degrees Celsius. Optional additional steps may include mixing the combined raw fatty acid composition and bleaching earth and/or filtering the (mixed) combined raw fatty acid composition and bleaching earth to remove the bleaching earth.

An advantage of the present invention is stabilization of the purified fatty acid composition against color deterioration during storage or during use.

An advantage of the present invention is minimizing the use of the subject bleaching earth.

An advantage of the present invention is avoiding the need for nitrogen blanketing in the handling, storage, and/or transportation of the purified fatty acid composition.

An advantage of the present invention is avoiding, or at least minimizing, the need for expensive capital equipment and/or energy demands (e.g., hydrogenation requires pressured vessels, higher temperatures, catalyst, and/or re-distillation)).

