US3284213A

US3284213A - Process for inhibiting breakdown in heated cooking oils

Info

Publication number: US3284213A
Application number: US309338A
Authority: US
Inventors: Leon A Van Akkeren
Original assignee: Armour and Co
Current assignee: Armour and Co
Priority date: 1963-09-16
Filing date: 1963-09-16
Publication date: 1966-11-08
Anticipated expiration: 1983-11-08

Description

United States Patent 3,284,213 PROCESS FOR INHIBITING BREAKDOWN IN HEATED COOKING OILS Leon A. Van Akkeren, Lombard, Ill., assignor to Armour and Company, Chicago, Ill., a corporation of Delaware No Drawing. Filed Sept. 16, 1963, Ser. No. 309,338 1 Claim. (Cl. 99-118) This invention relates .to a process for inhibiting breakdown in heated cooking oils, and more particularly to the treating of vegetable and animal triglyceride oils to reduce polymer formation therein, for reducing foaming, and for increasing the useful life of the cooking oils.

Cooking oils, as, for example, deep fat frying oils, are subject to foaming by reason of polymer formation therein. Further, polymer formation in the heated oils re sults in the formation of objectionable color so that the oil is frequently discarded.

An object of the present invention is to provide process steps for overcoming the above-described defects in heated oils and for inhibiting the breakdown in such oils when the same are heated, as in cooking. A further object is to provide a method for reducing polymer formation and thereby foaming when the cooking oils are heated. Other specific objects and advantages will appear as the specification proceeds.

In one embodiment of my invention, phosphoric acid is dispersed in a cooking oil, such as a vegetable or animal oil, and the oil is then heated slowly to a temperature of about 100 C. Acid bleaching clay is then suspended in the oil and the temperature raised to about 120 C. and held at 120 C. for 20 minutes. After cooling and filtering the product, the oil is subjected to any suitable procedure for the removal of undesirable impurities. I prefer to subject the oil to heating at temperatures in the neighborhood of 220-225 C. and under reduced pressure for the removal of volatile compounds and to prevent discoloration of the oil. The resulting product has a substantial reduction in polymer content, compared toan untreated sample of the oil. During heating, as in the cooking operation, color formation in the treated sample is less than in an untreated sample, foaming is reduced, and the oil has a long useful life.

In the treating operation, it is important that agitation be slower after the phosphoric acid is added because rapid I agitation will cause the formation of free acid in the oil.

By slow or gentle stirring, effective treatment of the oil is brought about without the formation of free acid.

It is important that ail phosphoric acid be removed from the treated oil before the final high heating stage at 220-225 C., and for removal I employ an acid bleaching clay. The acid bleaching clay is particularly effective for removing any phosphoric acid or phosphate in the oil, and there is, therefore, no tendency for the oil to darken when subjected to the high temperature range of 220-225 C.

The phosphoric acid may be added at variable levels. I prefer to use about 0.05 to 3.5 weight percent of concentrated phosphoric acid based on the weight of the oil. As a specific example, I have found that optimum results are obtained through the use of 0.25 percent of 85 percent phosphoric acid (v./w.). With 100 grams of oil, A of a mi. of 85 percent phosphoric acid was used and excellent results were obtained, as described in Example I.

The acid bleaching clay under temperatures of 100- 130 C., and preferably about 120 C., is extremely effective in removing all phosphoric acid material from the treated oil, with the result that in the subsequent high heating of 220225 C. there is no discoloration or darkening of the treated oil. The oil containing the bleaching clay is preferably held for 15 to 30 minutes at the selected higher temperature, and then cooled and filtered so that the phosphoric acid and reaction products are effectively removed.

Specific examples illustrative of the process may be set out as follows:

Example I 0.25 percent of percent phosphoric acid (v./w.) was dispersed into refined, unbleached, undeodorized cottonseed oil by rapid stirring, after which the product was heated with gentle stirring to C. One-half percent of acid bleaching clay (Super Filtrol) was suspended in the oil, and the temperature raised to C. and held for 20 minutes. The product was cooled and filtered, after which it was heated for 2 hours at 220-225 C., using less than one-half mm. pressure.

The product was found to have about 25 percent reduction in polymer content as compared with an untreated sample. When used in a deep fat fryer, there was substantially no foaming and no discoloration.

Example II A cottonseed oil sample treated with H PO was heated at -195 C. for 96 hours (with stirring), and a similar sample of cottonseed oil not treated with H PO was similarly heated at 185195 C. for 96 hours (with stirring). The treated oil gave a 24 percent reduction in polymer content compared to the untreated sample.

Example III TABLE 1 Heating Time in Hours 0 48 96 Sample Polymer content of tallow 1. Untreated 2. H PO4 treated While in the foregoing specification I have set forth steps of procedure in considerable detail for the purpose of illustrating embodiments of the invention, it will be understood that such detail or details may be varied widely by those skilled in the art without departing from the spirit of my invention.

I claim:

In a process for treating heated triglyceride cooking oils to inhibit breakdown during heating and to prevent foaming, the steps of adding about 0.05 to 3.5 percent of concentrated phosphoric acid to the oil, heating the oil slowly to a temperature of about 100 C. while stirring slowly to prevent the formation of free acid in the oil, adding bleaching clay to the oil When the same has reached about 100 C. and "heating the mixture to about 120 C. for about 15-30 minutes, cooling and filtering the oil to remove the clay and phosphoric acid material, and then heating the oil filtrate to about 220225 C. under reduced pressure.

References Cited by the Examiner UNITED STATES PATENTS 1,982,907 12/1934 Eckey 99-163 4 FOREIGN PATENTS 326,539 3/1930 Great Britain. 377,336 7/1932 Great Britain.

5 OTHER REFERENCES Andersen: Refining Oils and Fats for Edible Purposes, Pergamon Press, N.Y., 2nd ed., 1962, pp. 158 and 159.

A. LOUIS MONACELL, Primary Examiner. 1O MAURICE W. GREENSTEIN, Assistant Examiner.