US2247280A - Stabilizing fatty compositions - Google Patents

Description

Patented Junezl, 1941 UNITED STATES PATENT OFFICE George D. Martin, mm. 'w. v... assignor to Monsanto Chemical Comp ny, St. Louis, 110., a corporation of No Drawing. Application Jilly 21, ms, x Serial No. 285,761

a claims. (c1. zs-zso) a This invention relatesto the treatment-of oils containing a fatty component and more particularly to the treatment of animal, vegetable and flshoils for the purpose of inhibiting rancidity and other undesirable eflects'associated therewith.

Animal, vegetable, ilsh and the like oils are fatty acid esters, as, fOr'e-x'ample fatty acid glycerides. As is well. known, oils .of this type are subject to changes characterized by the formation of malod'orous products which render them unsuitable for foodstuffs and for many other.

purposes. This condition is commonly referred to. as rancidity. Where the fatty acid compo nents of the oil comprise an unsaturated conrially enhanced. Rancidity is believed to result from the formation of aldehydes, ketones. peroxides andv similar oxidative degradation products of the oil and is usually further characterized by a bleaching action due to the peroxide content. For example olive oil is normally the familiar light golden color-whereas therancid product is colorless and possesses a decidedly unpleasant taste and odor. e transformation to the latter condition is accelerated by heat, light and various chemical agents and in general special precautions are necessary in handling and storing vegetable, animal .and fish 'oils, especially where intended for human consumption.

It is an object of this invention to stabilize vegetable, animal, fish and the like oils and more particularlyto prevent the development of ranv L One of the specific objects of this invention is to provide a rancidity inhibiting or retardin stituent the susceptibility, to rancidity is mate- Typical examples of the preferred class of'stabilizers comprise tri o-phenylene phosphate of.

the formula several days in an oven maintained at 50 C.

After various intervals of time the aged samples are tested in a manner analogous to that described-by D. H. Wheeler, Oil and Soap, Vol. 9, page 93, 1932. Thus, iive grams of the oil are dissolved in 50 c. c. of solvent mixture (60 percent of glacial acetic acid, 40 percent of chloroform) and 1 c. c. of saturated potassium iodide agent to be incorporated with the oil which is to be stabilized. A further obiect is to provide and oil composition stabilized against the development of rancidity. Other and further objects will be hereinafter shown. v

In accordance with present invntion it has been discovered that the neutral phosphates of polyhydric phenols are highly effective stabilizers of oils containing a fatty component. Estersof inorganic acids in which the inorganic acid nu- ,cleus is completely esterified, i. e. no replaceable hydrogen remains, are commonly termed "neutralesters" and it is'ln this sense that the term neutral is herein employed.

The preferred esters may be prepared by known methods from suitable esterifying agents solution added. After exactly oneminute from the time of the addition of potassiumiodide. 100 c. c. of water are added and the liberated iodine titrated with-0.0m sodium thiosulfate, cmploiing starch as indicator. Thetitration in cubic centimeters is a measure of the peroxide formation and consequently a measure of Y the stability of the oil. The so calledperoxide.'number" which is the usual basis 'of comparison is defined by Wheeler according to the equation 'T NX-500 M W I I where W is the. weight of j the oil and T is the milliters of thiosulfate of normality N. M is thus the millimols of-peroxide per kilogram or the peroxide number. '(See also CJH. Lee,

such as P201; and P001: and a polyhydric phenol.

- Neutral'phosphates derived from catechol, tertiary amyl catechol, tertiary butyl c'atechol, chlor catechol. pyrogallol, resorcincl, hydroquihone,-

' hydroxy hydroquinone 3,4 dioxy biphenyl. p,p'

dioxy biphenyl, 3,4,4 trio'xybiphenyl, 1,2 ;di oxy naphthalene, 1,5 dioxynaphthalene and ,the'like are included within the scope of this invention.

Rancidity in Edible Fats, page 108.) Obviously where a 5 gram sample of oil is titrated with .01Nthiosulfate the milliters required give the peroxide number directly.

I The followingare specific embodiments of the invention showing the useful and valuable properties of the preferred class of stabilizers and are to be understood as illustrative of the invention but in nowise'limitatwe thereof. r ,A small proportion, 0.1% of the stabilizing agent, was incorporated into an unstable oil. The peroxide number was determined as described above and compared with the untreated oil. i Typical results obtained upon testing the preferred class of neutral esters are set forth below:

Peroxide num- Cottonseed oil stabilizing agent be: after 30 a y as s Tri i-hydroxy o-phenylene phosphate 6.0 Trl 3-1: droryohenylene; hosghste 2.0 Tri 4-K any] o-p {lump osp ate. 1.0 Tri 6- ydroxy l-nap thyl)phosphate- 0.6 Blank 390.0

As further illustrative of the desirable properties of the preferred class of stabilizers, the peroxide numbers of typical oils stabilized by the addition of 0.1% of tri(o-phenylene) phosphate as compared with the peroxide number of the untreated oil (Blank) are given below.

Peroxide numbers after aging ior- Oil 10 days Cottonseed 8 an! (cottonseed) The following data show the peroxide numbers of oleic acid stabilized with 0.1% or tri(4- "tertiary amyl o-phenylene)phosphate as compared with the untreated product.

Peroxide nnrfnbers after aging or 21 days 34 days 53 days Treated product 2. 7 1. 4 E. Blank.-. 21.0 24.0 29. 7

2,247,2ao V From the data set forth above it is shown that the preferredstabilizing agents possess exceptional rancidity inhibiting properties when incorporated in unstable oils, as for example animal, vegetable and fish oils.

The amount of stabilizing agent which may be added'to an unstable oil may be varied within wide'limits but in general it will be found that good results may be obtained by adding, upon a weight basis from 0.01% to 1.0% of the stabilizing agent.

Other-methods of testing the stability of unstable oils than those specifically disclosed may 'Ffrom 0.01% to 1.0% of a be employed as is well known to those skilled in the art to which the present invention pertains.

The present invention is limited solely by the following claims attached hereto as part of the specification.

What is claimed is:

1. A fatty oil having incorporated therein a neutral phosphate of a polyhydric phenol in an amount sufficient to preserve said fatty oil.

2. A fatty oil havingincorporated therein a tri (o-arylene) phosphate in an amount sufficient to preserve said fatty oil.

3. A fatty oil having incorporated therein a tri (o-phenylene) phosphate in an amount sufficient to preserve said fatty oil.

4. A fatty oil having incorporated therein tri (4-tertiary amyl o-phenylene) phosphate in an amount sufficient to preserve said fatty oil.

5. A fatty oil having incorporated therein tri (4-hydroxy l-naphthyl) phosphate in an amount suflicient to preserve said fatty oil.

-6. A: fatty oil havingincorporated therein neutral phosphate of a polyhydric phenol I r GEORGE D. MARTIN.