US2064158A - Treatment or conditioning of cottonseed meats and pressing oil from same - Google Patents

Description

Patented Dec. 15, 1936 2,064,158 PATENT OFFICE TREATMENT on CONDITIONING OF 001- TONSEED MEATS' AND -PRESSING OIL FROM SAME Thomas J. Harrell and Worth, Tex.,

Charles W. McMath, Fort assignors to Traders Oil Mill Company, Fort Worth, Tex., a corporation of Texas No Drawing. Application January 18, 1936, Serial No. 59,788

v to produce a pressed cake or meal palatable in flavor, pleasing in appearance, and substantially free from toxic principles so that it can be used safely for feeding to animals, or even as a human food after being reduced to a fiourof extreme fineness. I

The usual process of preparing cottonseed and pressing the crude oil from same as ordinarly carried out in hydraulic presses or other types of presses is so well known as not to need description here. In securing the maximum yield of oil, a great deal depends on the proper cooking of the meats and on theirmoisturecontent on leaving the cooker and going to the press. The cooking operation apparently softens or bursts the oil cells so as to greatly facilitate the subsequent expressing of the oil. There is an optimum -moisture range for the meats asfedto the press, in order to secure the maximum yield of oil with a minimum of difiiculty in pressing, this optimum range being usually considered to be between 5.0 and 5.5 per cent in ordinary milling practice. Higher moisture tends to cause the meats to "crawl, or squeeze out, in pressing. Cottonseed as received at the mill varies considerably in moisture con-' tent so that in' order to obtain uniformly efiicient results in pressing, if the meats are too wet they are dried out in the cooker, while if they are too dry water or steam is added to them, usually before heating, but sometimes during cooking. In no case,.however, is excess water intentionally added at a high temperature to the extent de-- scribed below and then subsequently removed by evaporation, as this would involve an apparently unnecessary and purposeless expense, and up to this time it has not been known that any beneficial results would be thereby obtained. Our process is concerned mainly with the process of cooking the m'eats, or conditioning them, pres paratory to pressing the oil from same.

The crude oil expressed from cottonseed inthe usual procedure is of a deep red or brown color and contains in solution or in colloidal suspension noticeable percentages of non-fatty matter which, together with the naturallyoccurring free fatty acids of the oil, must-be subsequently removed in the refining operation in order to pro- 4 duce a light colored, neutraland palatable refined oil suitable for edible use or most other purposes.

Thisso-called "non-fatty matter, although containing some combined fatty acids, is of' a totally different nature from .the true fatty matter constituting the essential portion of the oil, and is characterized by being insoluble in acetone but We will refer to it soluble in petroleum ether. herein as the acetone-insoluble matter. The refining is accomplished by treating the crude oil with caustic soda solution, but this, besides removing the freefatty acids and the above men- 'tioned acetone-insoluble matter, unavoidably causes also a considerable loss of neutral oil due largely to the presence of the acetone-insoluble matter, which has the undesirable property of entraining or emulsifying neutral oil so as to increase the refining loss by several times its own weight. Any neutral; or refined, oil thus lost goes into the foots produced as a by-product of refining and has a much lower value in this form than if available as refined oil. This acetone-insoluble matter is so altered by our treatment that it is partly prevented from passing into the crude oil and partly separated from the crude oil by subsequent cooling and settling or filtering. thus 20 yielding a crude oil refining loss.

The ordinary cake or meal obtained from the usual pressing operation of cottonseed is well known to contain a toxic principle in varying amounts, commonly known as gossypol, and cake 'or mealcontaining noticeable amounts. of this with a considerably reduced toxic principle is considered to be unsafe for use as a feeding material for hogs, except under cer-' ing the heating with water for a suflicient time,

two things are accomplished; active gossypol of the meats is destroyed or converted into an innocuous form, and at the same time the acetone-.

insoluble matter which normally passes into the crude oil is changed so that it is either rendered insoluble'in'the oil as pressed, or separates readily from same by merely cooling and settling. After this stage of the treatment the moisturecontent of the meats is reduced, while still in the cooker, just sufficiently to permit pressingin the usual form of hydraulic press or other type of press.

In carrying out our invention we proceed as follows: After the seed are-cleaned and delinted, and the hulls separated in the usual way, leaving the proper percentage of hulls to produce a pressed cake or: meal of the required protein content, we crush or roll the kernels or meats about 190 F. to 205 Each ring is equipped with a steam jacket and a mechanical stirrer. In

the top ring the temperature of the kernels or meats is first raised as rapidly as possible to F. At about 190 F. or higher, sufficient water and/or steam is. introduced to bring the moisture content of the meats up to at least about eleven per cent, and preferably twelve per cent or a little higher. It isnot advantageous nor desirable to have more than twenty per cent of moisture. In practice a considerable mass of meats is maintained at all times in the ring at 190-205 F. with fresh meats and water flowing in continuously in the proper proportions, while from this ring to the next lower one and so on, as needed for filling the presses. The heating of the meats is continued and theypass successively from one ringto the next lower while the temperature of the meats in each ring progressively increases so that the temperature of the meats in the bottom ring will reach about 220 F. to 235, F.; 222 is about the ture for good-quality oil and efiicient pressing,

' and 228 is approximately the best for our purpose. the jackets of a three ring cooker of about sixty minutes, approximately equally divided in the. different rings in the ordinary operation of the but we are not limited to these time or more is usually consumed in process,

I heating from 190 ing to about F. than meats or adding the required water before heat-- This usually requires steam pressures in to sevent five pounds, in the first ring, forty to fifty pounds in the second, and fifteen to twenty-five pounds in. the third or bottom ring. The total time of passing through a cooker of this type will usually be from about seventy-five to about one hundred and ten minutes, or commonly in the neighborhood of one hour and forty periods. An hour F. to 235 F. Under these conditions the moisture begins to be reduced in the second ring and rea lies its desired final condition in the last ring, where the temperature reaches its maximum. The added water seems to accomplish its purpose in the first and second rings, and it should then be reduced.- promptly in order to avoid darkening of the meats, which occurs if wet meats are heated too long. An exhaust fan may be used on any or all of the rings after the first to assist in removing moisture. We so reguiatetemperature and time of heating that the moisture content of the meats is reduced only to a point that will just permit having the meats crawl, or

pressing without the press cloth. This 15 ususqueeze out from ally about 5.5 per cent to 7.5 percent moisture crude oil of darker color and higher refining loss,

whilehigher moisture causes crawling and prevents proper pressing. 'We have obtained better results by adding the required amount of water to the relatively dry meats after first heatby starting with wet ing. Even with wet meats containing for example eleven or twelve per cent moisture we find it advantageous to add one or two per cent additional moisture at'about 190 Freven though this i brings the total moisture somewhat above the point otherwise desired.

The cooking period'can be reduced from the 1 above mentioned figures if the type of equipment the wet meats are withdrawn lowest practicabletemperapermits more rapid heat transfer, but the temperature of the meats when water is added, the amount of water added, the maximum temperature, and the temperature and moisture content at the end of the cooking operation remain substantially as stated.

The meats are then delivered from the cooker to a former, wrapped in. cloth and pressed, preferably in a hydraulic press of the usual type, the pressure gradually rising to a maximum of about 3500 to 4000 pounds per square inch onthe ram, equivalent to about 2000 pounds per square inch maximum on the cake itself, and the pressure being maintained at approximately the maximum for about ten to thirty minutes or until the maximum amount of oil has been expressed in accordance with usual oil mill practice. The pressed cakes are then removed from the press. The crude oil is then allowed to cool and settle thoroughly, during which period a considerable amount of settlings separate out from the oil, which settlingsf contain most of the acetoneinsoluble matter previously mentioned, leaving a settled crude oil of unusually light color and low refining loss. The crude oil may also be filtered if desired, yielding an oil of still lower refining loss, in which case little or no settling is needed. The acetone-insoluble matter separates far more readily and completely from crude oil produced by our process either by settling or filtering than from. crude oil as ordinarily produced from similar seed. The settlings may be returned to the ress with fresh meats for re-pressing if desired. Similar improved results may be obtained by centrifuging the crude oil instead of filtering.

The cake obtained as abovedescribed may. be ground to meal if desired, and if it is to be used :as a flour for human food we grind it to extreme fineness and separate the contained hulls and lint completely at this point by suitable means such, for example, as an air separating device which practically completely eliminates the hulls and lint, leaving pure meal or flour having a protein content which may be as high as fifty-three per cent, depending of course on the original protein content of the kernels. This meal, or the cake from which it is ground, is a palatable food and is entirely non-toxic as has been proven by extensive feeding tests on animals of various kinds, and the flour has also been proven by extensive tests to be not only palatable and wholesome but 'entirely safe and suitable in every way for use as a human food. This meal and fiourare further described in our copending application Ser. f No. 10,694. Cake produced-by our process can be easily ground to fiour of any desired fineness. The oil content of the cake produced in this way is about the same as is produced with ordinary cooking and milling procedure.

It is understood that we are not limited to the use of any particular kind of equipment, but that ,any of the usual types of equipment used in cottonseed oil mills may be used in carrying out our process. 1

If producing a flour for human consumption, which must be entirely free from 'hulls'and lint,

we find that we can obtain practically identical products either by leaving a moderate percentage of'hulls in the meats when pressed and separating them afterwards, as above described, or by making.a complete separation of hulls from the meats before cooking, and then cooking and pressing the hull-free meats. A product com-.

ordinary crude cottonseed oil but which is largely eliminated from the oil by. our process, this material is generally considered to consist of a mixture containing phosphatides, resins, and possibly other types of materials, and the amount of same presentin various crude oils can be determined analytically, as follows-Dissolve 10 grams of the crude oil in 100 c; c. of dry acetone which has previously been saturated with an electrolytesuch as sodium nitrate or, potassium iodide Add a level teaspoonful of kieselguhr to serve as a filter-aid'and filter with slight suction on an asbestos mat. Wash the residue fi-timeswith 20 c. c. of acetone (free from electrolyte) each time.

-Then dissolve the acetone-insoluble matter by Washing the filter with successive 20 ,c. c. portions of petroleum ether and collect this filtrate in a'weighed flask. 'Evaporate off the petroleum ether and .Weigh theresidue. I

The refining loss of a crude cottonseed oil when refined according to the ofiicial method of the American Oil Chemists Society depends primarily on its content of free fatty acids and acetone-insoluble matter. The lossdue to free fatty acids alone is found by experience tobe about 2 or 2.5 times the free fatty acids, while the loss due to the acetone-insoluble matter will be about 3 to 4 times their amount. Thus, an average filtered crude oil containing 1 per cent F. F. A. and l per cent of acetone-insoluble mat- .ter would have a refining'loss of about 5 to 6.5

This will betincreasecl by about 0.5

per cent. per cent or more in oil which has not been filtered, due to the presence of small amounts of moisture and settlings. It is apparent, therefore, that in refining crude oil having low percentages F. F. A. the acetone-insoluble matter has a greater efiect on the refining loss than the F. F. A., and hence any reduction in the acetoneinsoluble matter content of an oil will cause a noteworthy reductionin the refining loss with consequent increased economy. I

Our process produces a crude oil practically free from acetone-insoluble matter. The amount of this material in ordinary crude oils generally varies from about 0.50 per cent to about 1.50 per cent, whereas crude oil produced by our procedure will contain much. less than this, the amount rarely if ever exceeding 0.25 per cent. This difie'rence causes a marked reduction in the refining loss ofour oil. Forlexample, an average crude oil produced from good seed by the usual procedure'shows about as follows,

' Per cent Free fatty acids 0.6-0.7 Acetone-insoluble matter 0.5-1.5 Refining loss (unfiltered crude oil) 5.0-6.0

while an average of crude oil produced from similar seed by our improved process has the following characteristics:

The color .of the crude oil produced by our process is always lighter, and the refined oil is always at least as light or lighter than refined oil made from crude processed from the same seed in the usual manner, The free fatty acids in the crude oil, as determined by the ofiicial method of the American Oil Chemists Society, are slightly lower than in oil produced from the same seed by ordinary treatment.

While occasional lots of crude oil have been produced in the past by ordinary milling procedure with lower refining loss than shown in. the

first table above, this has been accidental and possibly due to seed' containing naturally an unusually low percentage of acetone-insoluble mat- ,ter; but even in such instances the refining loss has rarely if ever' approached the unusually low losses obtained in refining oil produced by our process (making due allowances for any difierences in free fatty acid content) and it has never heretofore been possible to produce crude cottonseed oil consistently, day after day, from .the usual run. of cottonseed, which will have low refining losses comparable with our oil. This result is made possible solely by our discovery of the necessary treatment and the controlling factors herein described. We find no'difiiculty in keeping the acetone-insoluble content of crude oil from our process well below 0.50 per cent, and usually below 0.25 per cent or even as low as 0.1 per cent, but have never seen oil containing-less than approximately 0.5 per cent when madeby the usual'milling process. The reduction in refining loss accomplished by our procedure will ordinarily amount to at least 2 per cent, and may Y be 3 per cent or more, as compared with the re-. fining loss on oil made from the same seed with out our treatment.

Having thus-described our. invention, what we claim as new and desire to secure by Letters Patent is? 1. The process of treating cottonseed meats-to produce a crude oil characterized by containing content of said meats from their original moisture content to approximately eleven per cent to twenty per cent, gradually raising. the temperature to about 222 to, 235 F.'while reducing the moisture content by evaporation to approximately 5.5 per cent to 7.5' per cent.

2. The processof treating cottonseed meats to produce a crude oil characterized by containing not over 0.50 per cent of acetone insoluble matter with a. resulting low refining loss, and a pressed cake free from toxic effects when used as a feeding material'for animals or as a human food. comprising crushing the meats, heating to around 190 F., without increasing their moisture con-' tent, then adding to said heated meats sufliclent meats from..their original moisture content to not less than eleven per cent, gradually raising the temperature to-222235 F. while at no time reducing the moisture content below 5.5 per cent and delivering the cooked meats for pressing with a moisture content notover 7.5 per cent. I

3. The process of treating cottonseed meats to produce a crude oil characterized by containing not over 0.50 per cent. of acetone-insoluble matter with a resulting low refining loss, and a pressed cake 'free from toxic effects when used as a feeding material for animals or-as a human food,

comprising crushing the meats, heating the crushed meats to about F., without increas- 7 'per cent, gradually raising the temperature to approximately 228 F. while reducing the moisture, content by evaporation to approximately 5.5 per cent to 7.5, per cent and delivering the cooked meats for pressing with said moisture content.

4. The process of treating cottonseed meats to produce a crude oil characterized by containing not over. 0.50 per cent of acetone-insoluble matter with a. resulting low refining loss, and a' finely divided palatable non-toxic food product, comprising separating the lint and most of the hulls from the meats, crushing the meats, heating said meats to approximately 190 F., without increasing their moisture content, then adding to said meats sufficient water to raise the moisture contentfrom the original amount to a point between about eleven per cent and twenty per cent, raising the temperature to about 222 to 235 F. while reducing the moisture by evaporation to approximately 5.5 per cent to 7.5 per cent, pressing said meats at a. pressure of approximately ,two thousand pounds per square inch on said meats, grinding the pressed cake to a finely divided meal and separating the remaining lint and hulls aiter grinding.

5. The process of treating cottonseed meats to produce a crude oil characterized by containing not over 0.50 per cent of acetone-insoluble matter with a resulting low refining loss, and a finely divided palatable non-toxic food product, comprising separating the lint and' hulls as completely as possible from the meats, crushing the meats, heating said meats to approximately 190 F., without increasing their moisture content,

then adding to said heated meats suincient water to raise the moisture content from the original amount to approximately eleven per cent to twenty per cent, raising the temperature to approximately 222 to 235 F. while reducing the moisture by evaporation to approximately f.

per cent to 7.5 per cent, pressing the meats; at a pressure of approximately two thousand pounds I .per square inch on the meats, and grinding the pressed cake to a finely divided meal.

6. The process oitreating cottonseed meats to produce a crude oil characterized by containing not over 0.50 per cent of acetone insoluble matter with a resulting low refining loss, comprising separating the lint and most of the hulls from the meats, crushing the meats, heating a portionof said meats to approximately 190 to 205 F.,

adding to said meats at this temperature sufilcient water to raise the moisture content from the original amount to a point between 11 per cent and 20 per cent, maintaining a mass of said meats thus heated and moistened, while continuously adding to same a relatively small proportion of fresh meats not previously moistened and malntaining the, temperature of said mass not lower than about 190 F. and simultaneously adding to same suflicient water to maintain the moisture content at a point between about 11 per cent and 20 per cent, continuously withdrawing a relatively small proportion 01 said heated and moistened meats from said mass, raising the temperature of the meats thus withdrawn to about 222 to 235 F. while reducing the moisture content by evaporation to approximately 5.5 per cent to 7.5 per. cent and delivering the cooked meats for pressing with said moisture content.

THOMAS J. HARRELL.

CHARLES W. MOMATH.