DE2248921B2 - Process for the production of a mixture of vegetable and animal oils or fats and fatty acid ester esters - Google Patents

Description

draws that sterol-shark plant conditions are subjected to 10

and / or animal oils and fats, based on their content of free sterols, 1.0 to 1.1 Equivalent fatty acid ester of monovalent, aliphatic Adds alcohols with 1 to 4 carbon atoms and the mixture with simultaneous removal of the released, monohydric alcohols transesterification

The invention relates to a method for converting vegetable and animal oils and fats contained sterols with free hydroxyl groups, so-called free sterols, in their fatty acid esters with Help of transesterification.

Vegetable and animal oils and fats contain as natural accompanying substances sterols, which are partly in bound form as fatty acid esters, partly in free form, d. H. with free hydroxyl groups. According to their origin, a distinction is made between phytosterols and Zoosterols. The most important representative of the latter group is cholesterol. Widely used Phytosterols are sitosterols, stigma ine, brassicasterine and campesterine. Another group are the mycosterols, which occur particularly in fungi, yeasts and lower plants, of which E ^r £ 3sterol is the most important representative. Cholesterol has recently also been found in various vegetable fats and oils, so that the above, traditional classification only applies to certain Restrictions are valid Some information about typical sterling contents of the most important oils and fats is compiled below

mg sterols in 100 g free bonded entire 75-125 0-1 Lard 75-125 72 3 Beef tallow 75 170 170 Fish oil (Peruvian) 340 272 243 Cod liver oil 515 63 17th Coconut oil 80 210 UO Soybean oil 320 200 130 Sunflower oil 330 195 55 Peanut oil 250 50 295 Rapeseed oil 345

It is known that when processing Edible oils and fats can change their sterols in an undesirable way, primarily the Free sterols are affected, while changes in the sterol fatty acid ester are not or only partially occur on a small scale. In the case of the one usually undertaken in the course of refining raw fats Activated bleaching earths, inter alia, cause bleaching. Dehydration of free sterols and thus the formation corresponding downstream products.

From cholesterol z. B. thus arise di- (cholesten- (5) -yl- (30) -ether (Dicholesleryli ether) 1 nd 3,5 cholestadiums. Aus / 3-sitosterol, stigmasterin and Brassicasterin also form the corresponding Dieters and Hydrocarbons. In addition, further polar and non-polar follow-up compounds could be detected, the identification of which is still pending. The hydrogenation reaction can also be used in fat hardening lead to irreversible side reactions to free sterols and thus to the formation of undesirable by-products, such as cholestanol (dihydrocholestcrin). Coprostanone. Coprostanol, epicholecstanol and others.

In this context it has already been suggested that the free sterols contained in oils and Feiten before curing with esterifying agents known per se, such as organic monocarboxylic acids, monocarboxylic acid anhydrides or monocarboxylic acid chlorides (see DE-OS 1617 035). The unfavorable working conditions of this type of treatment, namely high temperatures, long reaction times and corrosive properties of the esterification agents or catalysts, but should oppose a practical application. It has long been known that phytosterols and

their esters are strong when added to vegetable oils hypocholesterolemic effect, i.e. a decrease in blood cholesterol level or an inhibition the formation of blood cholesterol unfold. A prerequisite for this effect, however, is a higher content of

the above-mentioned sterols, which are usually found in natural oils and fats. At about 0.5% excess Stefingehällefi remain oils Room temperature is not bright, but rather cloudy, as these sterols are rather difficult to dissolve in oil. In order to

fc'i the use value of such oils, z. B. as salad oils, for mayonnaise production and other purposes. It has therefore been suggested to use free phytosterols for this purpose

to use their fatty acid esters, which are easily soluble in oils at room temperature and therefore allow contents of 0.5 to 10 wt .-% sterols in the form of their esters (see DE-OS 20 35 069), According to this proposal, the sterol esters required are from free sterols produced by esterification with organic monocarboxylic acids after the free sterols have been obtained from oils and fats or other natural sources in a known manner. This way of working is of course quite cumbersome and time-consuming. ι ο

The object of the invention is now to obtain free sterols contained in vegetable and animal oils and fats simple and effective way to protect against possible changes during processing and also to convert higher proportions of added free sterols into an easily soluble form. It was found, that both demands are met with the help of a modified form of the uniestering procedure can.

The invention accordingly provides a process for the production of a mixture of vegetable and vegetable origin animal oils or Feiten and fatty suresterine esters by transesterification in a homogeneous phase and at a higher temperature in the presence of alkali metal alcoholates or Alkali metals as catalysts, which is characterized in that sterol-containing vegetable and / or animal oils and fats, based on their Content of free sterols, 1.0 to 1.1 equivalents of fatty acid esters of monohydric, aliphatic alcohols with 1 up to 4 carbon atoms are added and the mixture is subjected to conversion conditions with simultaneous removal of the monohydric alcohols released

The oils and fats treated according to the invention can be used to produce hoarded (hydrogenated) Fats are used. The vegetable oils treated according to the invention can also be used as salad oils for Production of mayonnaise and as a component of fat blends for the production of margarine use.

With the help of the method according to the invention are contained in vegetable and animal fats free Sterols are quantitatively converted into their fatty acid esters, regardless of the amount of free sterols, so that additions of free sterols are also included. In the usual transesterification of Edible fats, on the other hand, are known to work without additives - apart from catalysts free sterols are only partially converted into their fatty acid esters. A particular advantage of the Invention, which comes to light especially with higher contents of free sterols, consists in the fact that the process products are practically free of partial glycerides, especially Diglycerides, are obtained if fatty acid monoesters, i. H. in the usual transesterification of edible fats, in an amount equivalent to the content of free sterols. Oils and fats containing partial glycerides have different properties Uses known to have disadvantageous properties.

The fatty acid monoesters required for the process according to the invention are obtained by alcoholysis of oils and Fetfeh or by the addition of fatty acids Easily accessible methanol, ethanol, propanols or butanols. If one uses the one to be treated Oil or fat corresponding monoesters (esters of their <· /> Total fatty acids), the fatty acid spectra of the respective starting material and process product remain same. Of course, monoesters of individual fatty acids or fatty acid mixtures are also different Composition useful. Under the conditions of the process according to the invention, 1 mole is free Sterol or sterling mixture equivalent to 1 mol fatty acid monoester or fatty acid monoester mixture, from which the proportions of fatty acid monoesters to be added can easily be calculated.

The crude oils and fats to be treated according to the invention are first degummed in the usual way, deacidified and dried; after carrying out the method according to the invention is so then for the purpose Removal of the catalyst, washed extensively with water, with small amounts (approx. 0.5% by weight) activated fuller's earth treated and then deodorized. Excess, unconverted fatty acid monoester is removed by deodorization. In the case of oils and fats to be hydrogenated afterwards bleaching and deodorization can also be carried out after curing.

To carry out the process according to the invention, use is made of closed, evacuable agitator vessels which, in addition to heating and cooling devices and the usual fittings, are provided with a connection for introducing nitrogen. After adding the oil or fat to be processed and the fatty acid monoester, if necessary after adding free sterol, the finely divided catalyst (approx. 0.2% by weight alkoxide or 0.02% by weight alkali metal) is introduced with the agitator running and then at 120 to 125 ⁰ C, heated while evacuating to a vacuum of mm below 20 Hg at 90 to 160 ⁰ C, preferably simultaneously, a weak stream of nitrogen until completion of the process to the removal of the released, monohydric alcohol and thus accelerating the reaction towards the desired end state. With native oils and fats, this is usually reached after 1 to 2 hours. Higher sterol additions require longer reaction times of up to a maximum of 6 hours. The process can also be carried out continuously or semi-continuously.

Since the initially mentioned free sterols with digitonin precipitated from their solutions as digitonides the smallest structural changes but cancel this precipitability, the quantitative determination can of the total and the free sterol, from the difference of which the bound sterol is calculated, to the analytical Control of the process and its products are used. To determine the content of With all of the sterols, the fat in question is first saponified and the unsaponifiable from the soap solution Ether or petroleum ether extracted. The sterols, the now all in free form, precipitated with digitonin (also in solution), separated and balanced. To determine the free sterols, an aliquot of the fat is dissolved without saponification and mixed with a digitonin solution. In this case, only the free sterols contained in the fat sample are precipitated then be isolated as above. The difference between the two determinations gives the fat content bound (in ester form) sterols. This corresponds to the method of M. Klostermann and H. Opitz, described in the Handbook of Food Chemistry, Berlin 1969, Springer Verlag, Volume IV: Fette jnd Lipoide, page 781. Of course, the known thin-layer chromatographic methods

to be used. In this way, any decomposition products of the sterols can also be detected may form during the specified processing. The DGF standard method is used to test for partial glycerides C-Vl 7 (Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart), from the possible contents of Diglycerides can be calculated.

The method according to the invention is fundamental Applicable to all industrially processed oils and fats and guarantees reliable protection against Changes in sterols, be it in the course of processing through bleaching and hardening, or in the case of the use; In particular, autoxidative changes should be mentioned here, compared with free ones Sterols are known to be more sensitive than their esters.

Bleached and hardened fats pretreated according to the invention are used as cooking, frying and baking fats and for the production of margarine. For enrichment with free sterols and their subsequent conversion into fatty acid esters, vegetable oils such as soybean oil, sunflower oil, corn oil, rapeseed oil and the like are primarily suitable. With contents of up to 10% by weight of sterols; ^? Like their esters, these oils retain their shiny appearance at room temperature. They can be used as salad and Kritier oils, to make mayonnaise and as an ingredient in margarine-fat blends. Their advantages are based on the stability of the sterol esters they contain and therefore primarily relate to their nutritional properties.

The invention is explained in more detail below with the aid of examples

example 1

1000 g each of degummed, deacidified and dried fish oil (Peruvian), soybean oil or sun table

35 flower oil with approximately 1.05 times the stoichiometric amount of the methyl esters of their total fatty acids, calculated according to the content of free sterols, as well as with 0.2 wt ° C and kept at this temperature for 2 hours while passing through a weak stream of pure nitrogen. Then was cooled to 90 ° C, washed to remove the catalyst three times with Wa I distilled water, dried in vacuo, and with 0.5 wt .-% activated bleaching earth treated for 20 minutes After filtering off the bleaching earth for 4 hours in vacuum deodorized at 5 mm Hg and 200 ° C in the usual way

The products of the process were then in the autoclave using a nickel-kieselguhr catalyst in an amount of 0.2% by weight nickel, calculated on the respective amount of oil, at 180 ° C hydrogenated until products with a melting point of 40 ° C were obtained.

For comparison purposes, n equal amounts of named degummed, deacidified and dried oils are bleached, deodorized and hydrogenated in the same way

The addition of fatty acid methyl esters and the content of sterols depending on the treatment are compiled in the table below, which means:

a) degummed, deacidified, dried oil (starting material);

b) transesterified with fatty acid methyl ester (treated according to the invention), bleached, deodorized Oil;

c) as under b) treated and hydrogenated oil;

d) bleached, deodorized oil;

e) hydrogenated OIL

Oil type Fatty acid methyl ester Type of treatment mg sterols in 100 g free bonded in% by weight entire 175 170 Fish oil - a) 345 2 340 0.15 b) 342 2 338 0.15 c) 340 12th 120 - d) 132 88 162 - e) 250 205 120 Soybean oil - a) 325 1 320 0.20 b) 321 1 310 0.20 c) 309 45 115 - d) 160 118 115 - e) 233 195 130 Sunflower oil - a) 325 1 320 0.20 b) 320 1 304 0.20 c) 305 102 118 - d) 220 116 122 - e) 248

The hydroxyl numbers of all products were around the 65 ment of the designated oils, their free sterols

Value 1, which has been converted practically completely into their esters with a content of about 1% by weight.

Diglycericien corresponds. At the same time it emerges from the experiments that the

Accordingly, contents of bound sterols (sterol esters) are achieved through the handling according to the invention

Bleaching and hydrogenation are only insignificantly reduced, so no structural change has taken place Has. In contrast to this, the contents, in particular of free sterols, are not according to the invention treated oils dropped considerably during further processing, which presumably leads to a a significant part of their structural changes can be traced back to.

Example 2

In 1000 g of degummed, deacidified, dried and dewaxed sunflower oil, 50 g / 3-sitosterol (pure, commercial preparation) and 42 g of sunflower oil fatty acid ethyl ester, corresponding to 1.1 times the calculated stoichiometric amount, were dissolved with heating. The mixture was then transesterified under the conditions of Example I while extending the reaction time to 6 hours. After selecting the catalyst, drying and deodoriser, a pale yellow oil was obtained which after Winteri sieren, ie after separation of the ^{triglycerides deposited at 5 to 7 C} C, which were practically free from sterol esters, remained bright when stored in the refrigerator. 100 g of the oil contained 4.84 g Gesamtsten ™ and 4.82 g bound sterols in the form of their esters, which corresponded almost to the theoretically calculated amount. The hydroxyl number of the oil was calculated to be 0.8, corresponding to 0.7% by weight of diglycerides.

A mixture of soybean oil with 9.8% by weight of cholesterol and 8.0% by weight of soybean oil fatty acid ethyl ester was treated in the same way. The oil contained 10.1 wt ⁰ / cholesterol bound as ester, was virtually free before diglycerides and remained winterization of oil storage in the fridge beirr blank.

Claims (1)

Claim: Process for the production of a mixture of vegetable and animal oils or fats and Fatty acid ester esters by transesterification in a homogeneous phase and at a higher temperature in Presence of alkali alcoholates or alkali metals as catalysts, thereby marked