GB2031939A

GB2031939A - Method of stabilizing oils and fats

Info

Publication number: GB2031939A
Application number: GB7931986A
Authority: GB
Original assignee: Showa Sangyo Co Ltd
Current assignee: Showa Sangyo Co Ltd
Priority date: 1978-09-16
Filing date: 1979-09-14
Publication date: 1980-04-30
Also published as: FR2436178A1; NL7906878A; DE2937327C2; DE2937327A1; GB2031939B; FR2436178B1; CA1127447A

Abstract

A method of stabilizing an animal or vegetable oil or fat, comprises mixing the oil or fat with at least one cereal and/or starch and/or protein, and holding the resulting mixture at a temperature above 150 DEG C. The heated mixture produced, or a volatile material generated during heating, may be added to an animal or vegetable oil or fat to be stabilized. The stabilizers produced overcome certain disadvantages found when using chemically-synthesised antioxidants.

Description

SPECIFICATION Method of stabilizing oils and fats This invention relates to the stabilization of edible animal and vegetable oils and fats against oxidation by atmospheric oxygen, and more specifically to a method of stabilizing oils and fats by heating the oils and fats with cereals and/or starch and/or protein at atemperature above 1500C.

Anti-oxidants such as 2(3) - butyl - 4 - hydroxyanisole (BHA) and 2,6 - di - tert - butyl -p - cresol (BHT), most of which are chemically synthesized products, are generally used to stabilize oils and fats, especially edible oils and fats, and to prevent them from deterioration. These anti-oxidants are used for these purposes in accordance with regulations concerning food additives. If the stabilizing effect for oils and fats can be achieved by natural, non-toxic substances, especially at moderate cost, this method of stabilization may become more useful and the value of the product prepared according to the method may be elevated nominally and virtually as edible oils and fats.

There has recently been a tendency to seek natural non-toxic substances as an anti-oxidant for stabilizing oils and fats. We have studied the stabilizing effect of an anti-oxidant derived from natural substances on edible fats and oils and have found that such effect can be obtained by heating these oils and fats with cereals and/or starch and/or protein at a temperature above 1500C.

The present invention provides a method of stabilizing an animal or vegetable oil or fat, which comprises mixing the oil or fat with at least one cereal or with starch and/or protein, and holding the resulting mixture at a temperature above 1 500C. A mixture of starch and protein may be added in the form of cereal or a particulate cereal product to the animal or vegetable oil or fat.

In an embodiment of the invention using starch and/or protein, soybean oil, rape seed oil, lard and palm oil were selected as the samples to be treated.

Potato starch, powder of wheat gluten and a mixture of equal amounts of the starch and gluten were added to the oils and fats.

The amount of starch, gluten and their mixture to be added to the oil was 20% by weight of each oil.

The mixture of oils and additives was kept agitated and heated at a temperature of 250"C for 30 minutes and then the solid matter was filtered off. The stability of the filtered oil is illustrated in Table 1 below as hours measured by A. O. C. S. Official Method CD 12-57 (Active Oxygen Method), as reapproved 1973.

The samples of oils and fats used in the test were obtained by refining crude oil by conventional refining processes such as deacidification, decolourization and deodorization. No anti-oxidant was added to these oils.

Table 1 after after heating with heating the mixture of without the same amount before starch and potato wheat of potato starch heating protein starch gluten and wheat gluten soybean more than more than more than oil 15.5 9.0 100 100 100 rape seed more than more than more than oil 18.0 14.0 100 100 100 more than morethan more than lard 4.5 1.0 100 100 100 more than more than more than palm oil 72.0 65.0 200 200 200 As shown in Table 1, the AOM hours of oils heated with starch and/or protein were remarkably increased and the stability of the treated oils was greater. The stability was naturally decreased when the oils were heated without starch and/or protein.

Starch and/or protein have a stabilizing effect on oils and fats only when these oils and fats are heated with the starch and/or protein. If starch and/or protein are heated beforehand and then added to the oil, no stabilizing effect can be observed in the oil.

The stabilizing effect of the invention was heretofore not known and is significant not only because of its technological advance but also because of its industrial availability.

The factors which have an influence on the stabilizing effect of the invention are described as below.

(1) Starch and protein In the present invention, starch, protein or the mixture of starch and protein in a suitable ratio is heated with oils and fats.

The starch which has been found effective in the method of the invention may be derived from plants differing greatly in their botanical classifications, such as wheat, corn, potato or sweet potato, and it goes without saying that a similar stabilizing effect is also observed when starches of other origin are used. The starches are desirably purified in order to obtain sufficient stabilizing effect sufficiently.

The proteins which have been found effective in the method of the invention can be selected from a group of wide range consisting of vegetable protein derived from soybean, wheat and the like, and animal protein derived from meat, fish, egg and the like.

The above-mentioned starch and protein can be used independently or as a mixture thereof in a suitable ratio. The stabilizing effect of the invention varies according to the mixing ratio of the components.

It is always greater in the oil treated with the method of the invention than that in the non-treated oil regardless of the mixing ratio of the components.

The relationship between the mixing ratio of starch and protein, and the stabilizing effect in a test is shown in the accompanying drawing.

In a test, 20% by weight of the mixture of wheat starch and isolated soybean protein (95% protein) based on the oil was added to the soybean oil (500 g) and the mixture was heated for 30 minutes at a temperature of 250"C and then the oil was separated by filtration. The mixing ratio of starch and protein was varied from 0 to 100%. The stability of the resulting oil was measured by the above-mentioned Active Oxygen Method. The accompanying drawing shows the result of the test.

The stability of soybean oil which was nottreated with the method of the invention is shown by line (A), and the stability of the oil treated by the method of the invention was elevated remarkably regardless of the mixing ratio of starch and protein.

As shown in the drawing, when the mixing ratio was above 50%, the stability of the oil was excellent.

Similar effects can be observed when other kinds of starch and protein or mixtures of two or more of these components are used. Moreover, we have found that the stabilizing effect of the invention is far superior to that of the oil which was heated with protein and sugars.

(2) The amount of starch and protein to be added to the oil.

The stabilizing effect of the invention varies according to the ratio of the amount of starch and/or protein to the oils and fats. The higher the ratio is, the more the stabilizing effect increases. The stabilizing effect increases when the amount of oils and fats increases with an unchanged ratio. The amount of starch and/or protein to be added to oils and fats is preferably from 0.002 to 9 parts of starch and/or protein for 1 part of oils and fats.

(3) Manner of heating 1) Temperature: The stabilising effect of the invention appears under heating at about 1 500C and the practically preferable temperature is above 1600C. Higher temperatures can produce even better results. The maximum temperature depends on the heating conditions such as whether the heating is performed in the open air under normal atmospheric pressure or in an inert gas under reduced pressure. It is about 300 C when the heating is performed in the open air.

2) Time of heating: Longer heating times are usually more advantageous for the stabilization of oils and fats. Excessive heating times, however, are not desirable. The time of heating is generally up to 300 minutes according to the temperature, and less than 300 minutes are practically preferable. Longer heating times may, of course, be required when heating is performed under special conditions.

For example, 20% by weight of starch and/or protein is added to the oil and the mixture is heated at a temperature of 250"C. The stabilizing effect in the oil appears after heating for 5 minutes. When the mixture is heated at a temperature of 160"C under reduced pressure, the effect appears after heating for 3 hours.

3) Heating conditions: The operation of heating can be selected from treatments under normal pressure, in the open air, under reduced pressure and in a stream of an inert gas. It is preferable to heat oils and fats with starch and/or protein under reduced pressure or in an inert gas in order to prevent the oils and fats from degradation caused by the contact of the oils and fats with air (oxygen). Such operation under reduced pressure or in an inert gas can significantly inhibit the coloration and the gen eration of odour in the heated oil.

Agitation during heating is not always necessary, but the agitation of the mixture is practically preferable to perform heat treatment homogeneously and efficiently.

The oils are usually filtered or clarified after heat treatment by conventional methods of filtration or centrifugation.

In special cases, clarification after heat treatment is not performed and the suspension of insolubles in the oil can be used for stabilizing oils.

When a large amount of starch and/or protein is added to oils and fats, for example, 9 parts of starch and/or protein is added to 1 part of oils and fats, the oil can be separated from the heated mixture by a centrifuge or the heated mixture as it is can be dispersed in the oils and fats which are to be stabilized without separating heated starch and/or protein from the oil. The stabilized oil is dissolved or transferred into the untreated oil and thereafter the insoluble residue is separated and removed from the oil.

The stabilizing effect of the oil can be improved in a desired degree, if a suitable amount of the heated mixture is added to the untreated oil.

In an embodiment of the invention using cereals, soybean oil, rape seed oil, lard and palm oil were selected as the samples to be treated and wheat flour, defatted soybean flour and rice flour were added as cereals to the oils and fats. Each amount of cereals was 20% by weight of each oil. The mixture of oils and cereals in the vessel was kept at a temperature of 250"C for 30 minutes under agitation and then the solid matter was filtered off. The stability of the filtered oil is illustrated in Table 2 below as hours by the AOM (Active Oxygen Method) test method (Oil & Soap, 10, 105-9,1933). The samples of oils and fats to be treated were obtained from the oil refined by conventional refining processes such as deacidification, decolourization and deodorization.

No anti-oxidant was added to these oils.

Table2 AOM (hours) before after heating after heating with heating without wheat defatted rice cereals flour soybean flour flour soybean oil 16 8 84 64 54 rape seed more than more than more than oil 20 17 100 100 100 more than more than more than lard 8 4 100 100 100 more than more than more than palm oil 64 50 100 100 100 As shown in Table 2, the AOM hours of the oils which were heated with cereals were remarkably increased and the stability of the treated oils was greater, although some differences were found in AOM hours among the cereals used. The AOM hours were naturally less when the oils were heated without cereals.

Cereals have a stabilizing effect on oils and fats only when these oils and fats are heated with the cereals. If the cereals are heated beforehand and then added to the oil, no stabilizing effect can be observed in the oil. For example, cereals such as wheat flour, defatted soybean flour and rice flour are each heated at a temperature of 250"C for 30 minutes. These heated cereals themselves or the extracts of these cereals with solvents such as chloroform, acetone or normal hexane are added to the aformentioned soybean oil and the AOM test is carried out on the oil. The result of the test is shown in Table 3 below.

The amount of the heated cereals or the extracts which is added to the oil corresponds to an amount of cereals which is 20% by weight of the oil and is added to the oil as shown in Table 2.

Table3 AOM hours Control, Added with extracts heated with Added with of heated cereals cereals heated extracted with and oils cereals chloroform n-hexane acetone Wheat flour 84 17 16 16 16 Defatted soybean flour 64 16 16 16 16 Riceflour 54 16 16 16 16 It is evident from Table 3 that the heated cereals or the extracts thereof with solvent do not improve the stability of oils and fats. We have found that the stabilizing effect of the invention can only be obtained by heating cereals with oils and fats. The stabilizing effect of the invention was heretofore not known and is significant not only because of its technological advance but also because of its industrial availability.

The factors which have an influence on the stabilizing effect of the invention are described below.

1. The kind, state and amount of cereals to be used.

As stated above, the cereals include those which have a very wide range and are generally known as cereals such as wheat flour, defatted soybean flour, rice flour, corn flour, barley flour, rice bran, wheat bran, rice, barley, wheat, corn or the like. These cereals can be used not only as powders or grains but also as roughly crushed particles. They can be used as a mixture of two or more kinds of cereals.

All kinds of cereals seem to have a stabilizing effect on oils and fats although some differences in the effect exist among these cereals and the stabilizing effect can be increased according to the amount of cereals to be added to oils and fats. The amount of cereals to be added to oils and fats is generally from 0.002 to 9 parts of cereals for 1 part of oils and fats.

2. Heating (1) Temperature: The stabilizing effect of the invention appears in the heating treatment at a temperature of about 1 500C and the practically preferred temperature is more than 160 C. Higher temper- ature can obtain a better result. The maximum temperature depends on the heating conditions, such as whether the heating is performed in the open air under normal atmospheric pressure or in an inert gas under reduced pressure. It is about 300"C when the heating is performed in the open air.

(2) Time: Longer times of heating are usually more advantageous for the stabilization of oils and fats. An excessive time of heating, however, is not desirable The time of heating is generally selected within 300 minutes according to the temperature, and a time of less than 300 minutes is practically preferable. Longer times of heating may, of course, be required when heating is performed under special conditions.

For example, 20% by weight of wheat flour is added to the oil and the mixture is heated at a temp erature of 250"C. The stabilizing effect in the oil appears after heating for 5 minutes. The same amount of wheat flour is used and thereafter heated at a temperature of 160"C under reduced pressure.

The effect appears after heating for3 hours.

(3) Condition: The heating conditions can, for example, be selected from treatments under normal pressure, in the open air, under reduced pressure and in a stream of an inert gas.

It is preferable to heat cereals and oils under reduced pressure or in an inert gas in order to preventthe oils from oxidation caused by the contact of the oils with air (oxygen). Such heat treatment under reduced pressure or in an inert gas can significantly inhibit the coloration and odour formation in the heated oil.

Agitation during heating is not always necessary, but agitation of the mixture is practically preferable to perform the heat treatment efficiently.

The oils are usually filtered or clarified after heat treatment by the conventional methods of filtration or centrifugation and the like.

In special cases, clarification after heat treatment is not performed and the suspension of insoluble heated cereals in the oil can be used for stabilizing oils.

When a large amount of cereals is added to the oil, for example, 9 parts of cereals are added to 1 part of oil, the oil can be separated from the heated mixture by a centrifuge or the heated mixture can be dispersed in the oil to be stabilized without separating heated cereals. Thus, the stabilized oil is dissolved or transferred into the untreated oil and thereafter the insoluble residue is separated and removed from the oil. The stabilizing effect of the oil can be improved in a desired degree if a suitable amount of the heated mixture is added to the untreated oil.

If stabilized oils and fats are prepared according to the method of the invention and are treated under suitable conditions they are far superior in their stability to those prepared by the addition of conventional synthetic antioxidants. The activity of the conventional synthetic antioxidants in the oil will decrease or disappear owing to decomposition during heating such as frying. On the other hand the stabilized oils of the invention have a high resistance to heat and these oils and the effective constituents assumed to be formed in the oil do not evaporate or decompose during heating, so that the oxidation of oil during heating is avoided.

The stabilizing effect of the invention can, of course, be observed in products fried with the stabilized oil, and the stability of the product is far superior to that of the same product fried with the oil in which conventional antioxidants are incorporated.

It is one of the advantages of the invention that the highly stabilized oil can be obtained by adding a desirable amount of the heated oil according to the method of the invention to the untreated oil, and the resulting oil is far superior in its stability to the oil mixed with synthetic antioxidants.

Of course, the oil treated according to the method of the invention can also be employed simultaneously with conventional antioxidants.

The oils and fats to be treated according to the method of the invention include a very wide range of animal and vegetable oils and fats, such as soybean oil, rape seed oil, lard, palm oil, rice oil, corn oil, sunflower oil, cotton seed oil, safflower oil, coconut oil, palm kernel oil, olive oil, cacao butter, beef tallow, mutton tallow, fish oil, whale oil and the like.

Crude oils, deacidified oils, or decolorized oils obtained in the refining steps, hydrogenated oils and fractionated oils can be used as the oils to be treated in the invention.

We have also found that the stabilizing effect of the invention can be obtained by adding the volatile substance generated in the course of heating cereals and/or starch and/or protein with oils and fats to the untreated fresh oil.

When oils and cereals and/or starch and/or protein are heated in a flask, the volatile material released from the hot mixture is recovered and collected in a cooler. The stability of fresh oil to which the distillate and the oil remaining in the flask are added is significantly improved. The cereals and/or starch and/or protein, the amount of oil and the heating conditions to collect the volatile material are the same as described above and the condensation and collection of the volatile material can be carred out under normal pressure, reduced pressure or in a stream of an inert gas. The volatile material in the form of a gas can also be introduced directly into the fresh oil. The degree of stabilizing effect of the oil can be controlled by varying the amount of the volatile material added to the fresh oil.

The invention is illustrated by the foliowing Examples.

Example 1 Refined oils and fats free from conventional antioxidants were mixed with starch and/or protein and heated in a flask. The amount of starch and/or protein and the combination of the oils with starch and/or protein are illustrated in Table 4. The stability of the resulting oil was measured by the AOM test.

The conditions of heat treatment are as follows: The amount of treated oil: 500 g Heat treatment was carried out at 250"C for 30 minutes in an open flask with stirring at400 r.p.m.

Stability test: each sample was then cooled to about 60"C and centrifuged. The clear supernatant was tested for oxidation resistance by the AOM test method.

The results are shown in Table 4.

Table 4

AOM stability (hours) Sample amount soybean rape oil corn refined lard (%) salad oil salad oil salad oil palm oil control * - 9 14 16 65 1 wheat starch (I) 20 151 7 206 215 more than 120 300 isolated soybean protein (II) 20 196 238 285 more than 165 300 I(25) + II(75) 20 165 210 230 more than 133 300 I(50) + II(50) 20 130 189 186 more than 120 300 I(75) + II(25) 20 120 160 170 more than 106 300 I(20) + wheat gluten-(25) 10 115 148 189 240 88 corn starch (80) + II(20) 10 75 90 95 286 68 I (50) + fish meal (50) 30 180 210 273 more than 215 300 corn starch(50)+ egg white (50) 5 58 76 90 255 49 * Heat treatment was carried out without adding starch and/or protein under the same condition.

As shown in Table 4, although there are differences in some degree among different kinds of fats and oils, and mixing ratios of starch with protein and of starch and/or protein to oils and fats, the resulting oils treated with the method of the invention have a remarkably improved stability in comparison with those treated without starch and/or protein.

Example 2 One part each of soybean salad oil treated as described in Example 1 was added to ten parts of untreated soybean salad oil, mixed and dissolved.

The AOM hours of the mixture was examined and the stability values were elevated to more than 40 hours.

Example 3 500 g of decolorized corn oil and 100 g of the mixture of the same amount of wheat starch and isolated soybean protein powder were placed in a threenecked flask equipped with a stirrer, water cooler and thermometer. The mixture was agitated at a temperature of 270"C for two hours. The volatile material generated during heating was condensed and collected.

All of the distillate was added to 100 g of soybean salad oil. The AOM stability value of fresh soybean salad oil was 16 hours and it was improved to more than 75 hours after addition of the distillate.

Example 4 Wheat, wheat flour, wheat bran, rice flour, rice bran, corn flour, soybean flour and defatted soybean flour extracted at low temperature were added respectively to 500 g of soybean salad-oil, rape seed salad-oil, corn salad oil, refined palm oil and lard (not containing anti-oxidant) as shown in Table 5.

The amount of cereals added to the oils and fats is also shown in Table 5. The heat treatment was carried out in a 1 litre beaker at 2500C for 30 minutes in the open air under agitation by a small agitator at 400 r.p.m. After heat treatment, each sample was cooled down to about 60"C and centrifuged, so that the clarified oil was obtained. The stability of the oil was examined by the AOM test. The resu Its are shown in Table 5.

Table 5

AOM stability (hours) Sample amount soybean rape corn refine 'I ($) salad oil salad oil salad palm lard I oil oil control* 8 17 19 50 4 wheat 20 25 81 96 more more than than 100 100 wheat flour 20 84 more more more more than than than than 100 100 100 100 wheat bran 10 40 more more more more than than than than 100 100 100 100 rice flour 20 54 more more more more than than than than 100 100 100 100 rice bran 10 40 more more more more than than than than 100 100 100 100 corn flour 20 53 more more more more than than than than 100 100 100 100 soybean flour 10 42 more more more more than than than than 100 100 100 100 defatted 20 64 soybean flour at low 100 100 100 100 temperature * Heat treatment is carried out under the same conditions but without adding cereals.

As shown in Table 5, although there are some differences among kinds of fats and oils, and the kinds and forms of cereals, oils and fats treated with the method of the invention have a remarkably improved stability in comparison with those treated without cereals.

Example 5 The heat treatment was applied to soybean salad oil with differing amounts of wheat flour under the same conditions as in Example 4. The results of the AOM test are shown in Table 6.

Table6 amount of AOM stability in wheat flour soybean salad oil (%) (hour) 1 16.0 2 21.5 5 35.0 10 55.0 20 84.0 40 100.0 As clearly shown in these results, the stability of oils and fats can be obtained by the addition of a wide range of the amount of cereals and it is promoted by increased amounts of cereals.

Example 6 Soybean salad oil and wheat flour which were used in Example 4 were mixed intimately in a ratio of 1 to 1,1 to 2 and 1 to 5, based on the weight of oil and flour. These mixtures were heated for ten minutes in a frying pan, maintaining the temperature of the mixture at2300C under agitation.

The mixture was left standing to cool and was filtered with filter paper. One part of each heat-treated oil was added to ten parts of untreated oil and mixed, and the AOM stability was examined on the heat-treated oil and on the mixture of the heattreated and untreated oil. The results of the test are shown in Table 7.

Table 7 Sample A OM stability (hours) Heat treated oil (1) oil:flour = 1:1 more than 100 Heat treated oil (2) oil:flour = 1:2 more than 100 Heattreated oil (3) oil:flour = 1:5 more than 100 Mixed oil of 1 part of the oil (1) with 10 parts of untreated oil 50 Mixed oil of 1 part of the oil (2) with 10 parts of untreated oil 78 Mixed oil of 1 part of the oil (3) with 10 parts of untreated oil more than 100 As shown clearly in Table 7, even when the increased amount of cereals was added to the oil, the stability of the oil was significantly promoted, and it was also greatly improved by adding these heat-treated oils to the untreated oil.

Example 7 500 g of decolorized corn oil and 50g of wheat flour were put into a three-necked flask with an agitator fan, condenser (water-cooled system) and thermometer. The contents were agitated at a temperature of 270"C for two hours. The volatile substance produced in the process of heating was introduced and condensed in the condenser and was collected there. The yield of the volatile substance was 3.12 g.

All of the volatile substance was added to soybean salad oil (used in Example4,AOM 16 hours) and the AOM stability was measured and found to be improved to 39 hours.

Example 8 Defatted soybean oil extracted at low temperature was added to decolorized rape seed oil and the mixture was heated under the reduced pressure of 1-2mmHg. The temperature and the period of heating are shown in Table 8.

Table 8 AOM stability (hours)

Heating time (minutes) temperature 60 | 120 180 300 140 14 15.5 17.5 18.5 200 15 23 28 40 260 38 46 62 95 The AOM stability of decolorized rape seed oil before heating was 14 hours.

Example 9 Rice cracker was fried with the heat-treated soybean salad oil prepared in Example 4. Soybean salad oil before heat treatment (control 1), and the oil of control 1 added with 200 ppm of BHA (control 2) were also used for frying rice cracker. The conditions of frying rice cracker are shown in Table 9.

Table 9 conditions of frying rice cracker the weight of material for frying rice cracker 2.5g/piece temperature of frying 260"C period of frying 4.5 seconds/piece The fried rice cracker was preserved at a temperature of 30"C and the change of flavour and the peroxidle value of the products were observed. The results of the observation are given in Table 10.

Table 10 Results of observation during storage after 1 month after 2 months after 4 months after 6 months

change of fresh flavour fresh flavour fresh flavour fresh flavour flavour Fried cracker fried with the oil according to the invention POV 1.2 2.3 3.4 5.8 whang of somewhat fatty strong rancid Fried cracker fried lavour taste, edible odour, not control l palatáble POV 25.l 89.9 ~ hange of somewhat fatty strong rancid Fried cracker fried lavour taste, edible odour, not ~ with the oil of palatable control 2 OV 22.8 93.6 ~ POV (peroxide value) : me/Kg As shown in the Table, the fried product fried with the oil prepared by the method of the invention has far superior stability to the product fried with the oil incorporating the conventional antioxidant.

Claims

1. A method of stabilizing an animal or vegetable oil or fat, which comprises mixing the oil or fat with at least one cereal or with starch and/or protein, and holding the resulting mixture at a temperature above 1 50 C.

2. A method for stabilizing an animal orvegetable oil or fat, which comprises mixing starch and/or protein with an edible oil or fat and holding the resulting mixture at a temperature above 1 50 C.

3. A method for stabilizing an animal or vegetable oil or fat, which comprises mixing starch and/or protein with an edible oil or fat, holding the resulting mixture at a temperature above 1 500C, and adding the heated mixture orthe oil or fat separated from the heated mixture to an animal or vegetable oil or fat to be stabilized.

4. A method for stabilizing an animal orvegetable oil or fat, which comprises mixing the starch and/or protein with an edible oil or fat, holding the resulting mixture at a temperature above 1 50 C, and adding a volatile material generated during heating to an animal or vegetable oil or fat to be stabilized.

5. A method for stabilizing an animal orvegetable fat or oil which comprises mixing the fat or oil with at least one cereal and heating the mixture so formed at a temperature above 1 50 C.

6. A method as claimed in claim 5, wherein the cereal is wheat flour, defatted soybean flour, rice flour, corn flour, barley flour, rice bran, wheat bran, rice, barley, wheat or corn.

7. A method for stabilizing an animal or vegetable fat or oil, which comprises adding the heated mixture prepared according to the method as set forth in claim 5 or the fat or oil separated from said mixture to said animal or vegetable fat or oil which is to be stabilized.

8. A method for stabilizing an animal or veget able fat or oil, which comprises adding a volatile substance generated during heating according to the method as set forth in claim 5 to said animal or vegetable fat or oil which is to be stabilized.

9. A method as claimed in any one of claims 1 to 8, wherein the temperature of heating is 150"C-300"C.

10. A method as claimed in any one of claims 1 to 9, wherein 0.002 to 9 parts by weight of cereal and/or starch and/or protein are mixed with 1 part by weight of the fat or oil.

11. A method of stabilizing an animal orvegetable fat or oil against oxidation by atmospheric oxygen which comprises: (a) mixing at least one particulate cereal and/or starch and/or protein with an edible fat or oil; (b) holding the resulting mixture at a temperature above 1 500C until an anti-oxidant is formed by reaction of said cereal and/or starch and/or protein with said edible fat or oil; (c) separating said anti-oxidant from said cereal and/or starch and/or protein; and (d) mixing an effective amount of said anti-oxidant with the animal or vegetable fat or oil to be stabilized.

12. A method as claimed in claim 11, wherein said anti-oxidant is capable of being distilled at about 270"C without loss of the anti-oxidant effect thereof.

13. A method as claimed in claim 1, substantially as hereinbefore described with reference to any of the Examples and/or the accompanying drawing.

14. Stabilized animal or vegetable oil or fat prepared by a method as claimed in any one of claims 1 to 13.