CA1056645A - Method of obtaining a smoking agent - Google Patents

Abstract

A B S T R A C T
The present invention concerns a process of preparing a food smoke additive which comprises the steps of, destructively distilling cellulose and/or lignin material to form tar or smoke condensate, removing organic nit-ric bases from the condensate by means of an aqueous solution of a mineral acid or as a compound formed by reaction with an acid which is indecomposable at a temperature up to 250°C, distilling remaining tar or smoke condensate in two stages, a first said stage comprising distillation at a pressure of be-tween 20 - 30 mm Hg with the addition of zinc, aluminium or iron dust and col-lecting the fraction boiling below 100 - 110°C, and a second said stage com-prising distillation of said 100 - 110°C boiling fraction at a pressure not exceeding 20 mm Hg with the addition of polyhydric alcohol and collecting the fraction containing compounds-exhibiting a boiling point of up to 250°C at 20 mm Hg, heating the food smoke additive plus polyhydric alcohol thus col-lected to a temperature of 50° - 90°C to separate out an alcohol layer which is removed from the food smoke additive layer, said steps of removing organic nitric bases and said two-stage distillation of remaining tar or smoke con-densate being interchangeable.

Description

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This invention relates to a process for preparing a food smoke additive of aromatizing and preserving properties which, when added to pro-tein-fat articles of food, improves the taste and smell properties of the food imparts to the food t`eatures of smoked products, increases permanence and counteracts oxidation of the food.
It has long been known to impart to protein fat products the fea-tures of smoked products by direct subjection of said products to the action of curing smoke obtained by uncompleted combustion of cellulose-lignin mate-rial. The known method imparts to products the expected taste and smell of smoked articles of food but at the same time contaminates the food with super~
fluous and harmful components such as organic nitric bases and certain vola-tile acids. These harmful components impart a foreign smell tone, as well as carcinogenic hydrocarbons, ben~opyrene and ben~ophenathrene derivatives to the food.
Furthermore smoking by means of curing smoke on a large commercial scale is a technologically onerous process, di-fficult to standardization and automati ation of continuous production lines requiring expensive devices and ~ great stores of definite wood material which are indispensable for the pre-- paration of smoke.
The above disadvantages and inconveniences are the reason why the known method is more and more replaced by the so~called smokeless curing with the aid of food smoke additives or smoking agents which, when added to food, impart to the food taste and smell properties more or less similar to that of products smoked according to the classical method but containing neither carcinogenic nor ballast substances.
Smoking agents are obtained from products of destructive distilla-tion of wood or associated raw-materials which takes place without air access or with air excess, Such distillation products included tar and smoke formed during the pyrolysis of wood. There exists a series of methods of obtaining smoking agents from these raw-materials by way of distillation, extraction, fractionation or combination of said operations aiming at the removal of harmful and undesired components and retaining only compounds or gl`OUpS of ~ ; j,r : . . ' , compounds exhibiting ~uitahle taste ~mcl smell properties, antioxidant and bactericidal attrihutes.
From smoking agents very high quality requirements, such as provided by various State legislation are expected the fulfilment of which is a fundamental condition for the admittance of said agents to articles of food.
Furthermore they sllould impart to articles of food the typical desired taste and smell of smoked products, they should exhibit antioxidant and bactericidal properties, and they are not allowed to comprise carcinogenic compounds in a quantity exceeding 1 part by weight per one million parts by weight of the article of food and they should be used in quantities of from a dozen or so to several hundred parts by weight of the agent per one million parts by weight of the product.
From among known smoking agents only a few of them fulfil the said conditions. These agents are obtainable by fractional extraction with the aid of organic water-immiscible solvents, advantageously ethyl ether of the condensate of curing smoke obtained in the process of déstructive distillation of cellulose and/or lignin material, carried out in excess air.
In a prior art process, three usable fractions are isolated.
As the-first, the fundamental fraction, the fraction containing mainly phenol compounds of a molecular weight of above 140 is obtained. This fraction may be mixed with the second the terpene fraction obtained during the further course of the extraction and containing compounds that do not form salt type combinations in a medium of a pH value of about 12, 8, and with the third, the acid fractlon containing low:r carboxylic acids and forming the inished ;~
smoking agent. However, this method is technologically rather difficult and labour-consuming, and requires a complicated apparatus.
The method of obtaining the smoking agent according to the `
present invention makes it possible to produce the agent by a method which is simple both in respect of technology and apparatuses, is easy for automatiza-tion and provides work safety conditions. Furthermore this agent exhibits very good taste and smell properties fully imitating the aroma of smoked food articles. It exhibits also antioxidant and bacteriostatic properties, whereby ~ - 2 -5~
it is a very good agent for the preservation of protein-fat products and it is free from ~allast and unwholesome compounds.
According to the present invention, there is provided a process of preparing a food smoke addit;ve ~h;ch comprises tlle steps of) des-tructively distilling cellulose and/or lignin material to form tar or smoke condensate, removing organic nitric bases from the condensate by means of an aqueous solution of a mineral acid or as a compound formed by reaction with an acid which is indecomposable at a temperature up to 250UC, distilling remaining tar or smoke condensate in two stages in an inert atmosphere, a first said stage comprising distillation at a pressure of betw0en 20-30 mm Hg and collecting the fraction boiling below 100-110C, and a second said stage comprising distillation of said 100-110C boiling fraction at a pressure not exceeding 20 mm Hg and collecting the fraction containing compounds exhibiting a boiling ~
point of up to 250C at 20 mm Hg, heating the food smoke additive thus ~.
collected to a temperature of 50-90C to separate out an alcohol layer which is removed from the food smoke additive layer, said steps of removing organic nitric bases and said two-stage distillation of remaining tar or smoke condensate belng interchangeable. An aqueous solution of mineral acid with a concentration of 5-20%, in a quantity of 5-25% by weight in relation to the weight of the tar or smoke condensate, is preferably used in the extraction of organic nitric bases.
The extraction is performed once or several times by addition of portions of acid at room temperature, whereupon the upper layer containing the organic nitric bases and constituting the waste, is separated. A lower tarry layer is washed several times with water and with an aqueous solution of sodium bicarbonate or with a saturated aqueous solution of sodium chloride, ..,.-~
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whereupon it is sllb~ected to further ~r~atlllent. On -the other hclnd, the bind-ing of organic nitric bases with the aid of orthophosphoric acid is made by mixing the initial raw material with 0~5 - 5% by weight of 85 - 90% acid.
The raw material thus preliminarily purified is subjected to a two-stage distillation under reduced pressure in an atmosphexe of inert gas, e.g.
nitrogen, argon or carbon dioxide, advantageously with an addition of 1 - lU%
by weight, best 5%~ of zinc~ aluminium or iron dustu The application of dust allows to obtain a smoking agent of a light, amber colour, because it prevents the oxidation of the hydroquinone or quinonone system. Said dust may be add-ed in the first or in the second distillation phase.
In the -first distillation phase carried out at a pressure of 30 -; 20 mm Hg the forerunnings constitute a waste and the fraction containing sub-stances exhibiting a boiling point of below 110 - 100C are collectedO These are mostly low-molecular organic acids~ water~ hydrocarbons and other ballast substances.
; In the second phase of the distillation process the pressure is lowered to a pressure not higher than 20 mm Hg and the fraction containing compounds of a boiling point of up to 250C at 20 mm Hg is collected~ When using a pressure which is lower than 20 mm Hg, compounds of a correspondingly lower boiling point are distilled. This fraction is the finished smoking agen~.
The tails from the above distillation containing mainly pitch, and acid e.g. phosphoric acid is used~ also bound organic nitric bases are techno-logical waste. It has been found that it is much easier to remove the waste tails from the distilling apparatus if they are diluted by means of polyhydric alcohol~ It is there~ore of advantage to commence the second phase of the distillation process at a pressure of up to 20 mm Hg as an extractive dis-tillation with polyhydric alcohol vapours~ which alcohol also influences in a positive manner the distillation process i~self~ Advan~ageously, glycerol is used as the polyhydric alcoholO
Polyhydric alcohol is mixed with tar, deprived of the fraction of the boiling point of below 100C at a pressure of 2Q mm Hg, as well as of _ ~ ~

, organic nitric bases, or having nitric bases bound with the aid of acid, in a quantity of 1 - 10 parts by weight of alcohol per 1 part b~ weight of raw material, advantageously 5 parts of alcohol per 1 part of raw material. From this process the fraction exhibiting a boiling point of up to 250C at 20 mm Hg, or of` a correspondingly lower temperature at a pressure of beneath 20 mm Hg is collected. This fraction constitutes a mixture of polyhydric alcohol and compounds which form the smoking agent. The -fraction is then heated to a temperature of 50 - 90C in order to obtain automatic separation into two layers. The upper layer is the smoking agent, while the lower layer is the polyhydric alcohol which can be re-used for the distillation of the next por-tion of tar.
Researches have shown that positive results are obtainable also in the case of a certain modification of the method of obtaining the smoking agent according to the invention. In this modification, the sequence of the operations is changed in such a way that the raw distillation tar or the smoke condensate is first subjected to the two-stage distillation according to the process above described and with maintaining of the same technological para-meters, and only in the final distillate containing the smoking agent we re-move the organic nitric bases by extraction with the aid of the aqueous solu-tion of a mineral acid, advantageously sulphuric acid.
The smoking agent obtained according to the invention is a compli-cated mixture of organic compounds which contains at least 50% of components of phenol character, as well as higher fatty acids, terpene compounds and other ones, said agent being simultaneously deprived of substances of carcino-genic actionO This agent distinguishes itself by the typical desired smoked food aroma and when added to protein-fat products it imparts to them features of products smoked according to the draft method and increases their per~a nence and counteracts their oxidation. The yield of the process according to the invention calculated in the initial raw material, amounts to 15 - 40% by weight~
The process o~ the present invention may also be used for refining ~ .

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the ~ractions obtained according to Patent P-13~ 539, especiaLly the ~raction containing phenols oE a molecular weight of above 140, in order to improve both their taste and smell properties, and the degree of purity, especially as regards the decrease to a minimum the contents of noxious substances.
Particularly satisfactory quantitative and qualitative results were obtained by subjecting the above phenol fraction to additional technological treating consisting in distilling under reduced pressure, advantageously in the presence of an indecomposable acid at a temperature of up to 250C, especially orthophosphoric acid, added for binding the substances of organic bases character and ~or counteracting the polymerization-condensation processes, and/or in the presence of zinc or aluminium dust to prevent the oxidation.
The distillation process is conducted at a pressure not higher than 20 mm Hg at a temperature of up to 200C or a correspondingly lower one at a pressure being lower than 20 mm Hg, the acid being added in a quantity of up to 5% by weight, whereas the zinc or aluminium dust - in a quantity of 1 ~ ;
5% by weight in relation to the phenol fraction. ~dditional assurance against the possibility of oxidation and an improvement of the conditions of the run of the process can be obtained by conducting the disti11ation in an oxygen-free atmosphere. Considerable facilitation of the distillation conditions can be obtained by adding, prior to the beginning of the distillation, to the phenol fraction, polyhydric alcohol, advantageously glycerol in a quantity of 3-6 parts by weight of alcohol per one part by weight of the phenol fraction The yield of the phenol fraction refined according to the distillation method amounts to 60 - 90% by weight in relation to the weight of the raw anhydrous fraction.
The obtained distillate after its separation from alcohol is in the form of a thick yellowish oil and is characterized by high taste and smell values and contains only traces of ballast compounds noxious to health, parti-cularly carcinogenic ones. Instead of polyhydric alcohols as the additional substances in the distillation process it is possible to use also vegetable oils~ high_boiling aliphatic hydrocarbons or silicon oils which during the , ,~ :

distillation do not pass to the distillate. When -the distillation is carried out in a non~acid medium~ e.g. in the presence of polyhydric alcohol or oil~
it is of advantage to subject the raw or distilled phenol frac~ion to extrac-tion with the aid of a mineral acid such as e.g. sulphuric acid~ in order to remove substances of organic base character, and then carefully wash for neutralization purposes. It has been found that both in technical and econo-mical regards the most effective is the leading of the distillation process according to the continuous method.
To an identical refining operation by distilling under reduced pressure can be subjected also the third fraction of the smo~ing agent accord-ing to Patent P-134 539, which fraction contains lower carboxylic acids.
For increasing the effect of removing from the smoking agent the ~ ~
ballast and noxious compounds of the benzopiren type, dibenzoatracen and other ~ `
aromatic hydrocarbons, the agent is subjected to the operation of selective adsorption on absorption masses such as active carbon, wide porous silica gel, synthetic molecular sorbents etc. The process is performed in such a manner that the smoking agent is previously diluted in organic solvents such as lower aliphatic alcohols, dialkyl ethers, halogen hydrocarbons and other ones, or non-diluted it is heated to a temperature of 50 - 90C, and then it is passed through a column filled with a convenient adsorbent. Per 100 parts by weight of the agent, 10 - 50 parts by weight of absorption mass are used, sub-ject to its kind and selection activity. After the fluid has passed through the adsorption column, the solvent is, in case of need, removed by evaporation under normal or reduced pressure. A refined smoking agent in the form of a thick yellowish oil of intensive smoked food aroma and of a very high degree of purity, especially as regards carcinogenic compounds, is obtained.
The product of the present invention is not only oE very high purity, but also of excellent aromatizing and antioxidizing properties. This agent is a concentrate of very high concentration. Being used in food products in quantitiés from several to several hundred parts by weight per one million parts by weight o~ the product, it is necessar~ to dilute said concentrate ~`

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with the aid of suitable substaIlces of carrier character. As the carriers~
known substances are used, such as e-thyl alcohol, ethylene glycoI, glycerol~
animal ~`ats or vegetable fats, domestic sa]t, starch~ spices, pickling mix-tures9 water etc. Said dilution takes place, depending on the Icind of the carrier, either by dissolving the concentrate in the carrier or by saturating the solid carrier with the concentrate or by producing an emulsion o~ the con-centrate in the carrier. The smoking agent is diluted to a concentration of several per cent. The agent diluted in thc carrier is mixed with the food product or it is put on the surface of the latter according to known methods.
~or instance, a several per cent solution or the emulsion of the smoking agent in a carrier of low viscosity with the addition of a dye or without said ;~
addition is sprayed on the surface of the food product, advantageously using an electrostatic field, whereupon the evaporation of the carrier takes place automatisally.
The process according to the invention is more fully explained by ~ ~
the following examples: ;
EXAMPLE 1 ~ ~i .
Tar from dry distillation of hardwood is subjected at room tempera-ture to extraction by means of a 10% aqueous sulphuric acid solution used in a quantity of 10% by weight in relation to the weight of the initial tar. The separated upper water layer containing organic nitric bases unfavourably in-fluencing the aroma of the smoking agent, is rejected as waste, whereas the tarry layer is washed 4 times with water and with a 3% sodium bicarbonate solu~
tion to neutral reaction. The preliminarily purified tar is then subjected to fractional distillation in nitrogen atmosphere after 5% by weight of ~inc dust, calculated in tar7 have previously been added. The distillation is led under reduced pressure in two stages~ First the fraction of compounds exhibi-ting a boiling point of less than 100C at 20 mm Hg~ being a mixture of low molecular fatty acids and phenols as well as hydrocarbons negatively influenc-ing the aroma of the smoking agent~ and which is a waste~ is collected. Thenthe pressure is lowered up to 10 mm Hg and the fraction exhibiting a boiling . . ~ , .
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~os~s point of less than 180C at lO ~n Hg, constituting the smoking agent~ is collected. The yield of the smoking agent thus obtained amounts to 30% in relation to the initial tar.
EXAMPLE [I
Tar being the condensate of curing smoke obtained by destructive wood distillation led with air excess, liberated from nitric bases and com-pounds exhibiting a boiling point of less than 100C'C at a pressure of 20 mm ~;
Hg as in EXample I, is mixed with a quadruple quantity of glycerol and sub_ jected to extractive distillation in nitrogen atmosphere under a pressure not exceeding 20 mm Hg. A fraction exhibiting a boiling point of up to 250C at 20 mm Hg is collectedO The distilled mixture of glycerol and compounds con stituting the smoking agent is heated to 60C in order to separate into two layers The lower layer is glycerol, whereas the upper layer is pure smoking agent. The yield of the process amounts to 20% in relation to the quantity of the initial raw material.
EXAMPLE III
To tar originating from destructive distillation of wood, 2% byweight of 85% orthophosphoric acid is added and the mixture is subjected to ~
two-stage distillation in carbon dioxide atmosphere under reduced pressure. ~-The forerunnings containing compounds exhibiting a boiling point of less than 110C at a pressure of 25 mm Hg are collected. These forerunnings constitute a mixture of low-molecular fatty acids, phenols and hydrocarbons and is re-jected as waste. After distilling off the forerunnings, 5% by weight of alumi- ~;
nium dust is added to the residue and in a carbon dioxide atmosphere the smok-ing agent exhibiting a boiling point of up to 250C at 20 m~ Hg is distilled off. The yield of the smoking agent is the same as in Example I. Then this agent gets dissolved in ethanol in a proportion of l : 9 and it i5 passed at room temperature through a glass column filled with active carbon. From the obtained filtrate, after evaporation of the solvent~ one obtains an agent in .
3V form of thic~ yellowish oil of intensive smoked food aroma. The yield of the adaorption process amounts to 90%.

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~XA~P~E IV
Tar being the condensate of curing smoke obtained by dest~lctive ~ood-distillation led in air excess is subjected to two-stage distillation under reduced pressure~ as in Example II. The distillate obtained in th~
second phase after separation of the glycerol layer is subjected at room tem-perature to extraction with the aid of a 10% aqueous sulphuric acid solution used in a quantity of 7% by weight, the upper aqueous fraction containing organic nitric bases being rejected as waste. The lower fraction after wash- -ing with water and neutralization is the pure smoking agent.
~AMPI.E V :' To a raw phenol fraction obtained in the smoke condensate extrac-tion process with the aid of ethyl ether, aluminiu~ dust in a quantity of 5%
by weight is added and the fraction of a boiling point of 96 160C at a pressure of 10 mm Hg constituting the smoking agent, is distilled off. A
yield of the process of about 60% is obtained. Then this agent is diluted with the aid of diallcyl ether to a 10% solution which is then passed through a glass column filled with molecular aluminosilicate sorbent at room tempera-ture. After evaporation from the filtrate the solvent one obtains the pure smoking agent in form of a thick yellowish oil o~ intensive smoked food aroma.
The yield of the adsorption process amounts to 90%0 EXAMPLE V~[
To a raw phenol fraction obtained in the smoke condensate extrac-tion process with the aid of ethyl ether, 1% of 85% orthophosphoric acid iS
added and after thoroughly mixing, the forerunnings of a boiling point of be-low 110C at 40 mm Hg are distilled off. To the residue 4% of æinc dust are added and the distillation is continued. A fraction of a boiling point of 100 - 180C at 10 mm Hg in form of a yellowish oil of intensi~e smoked food aroma is obtainedO The yield of the process amounts to about 65%.
Ei~MPLE VII
Ra~ phenol fraction obtained as in ~xample V~ is extracted with the aid of 10% sulphuric acid used in a quantity of 25%, whereupon it is washed .,'''''.~ ~

with an aqueolls sodium ch.Loride solution to neutrill reaction~ then anhydrous glycerol in a proportion o.f 4 parts by weight of gl.ycerol to :I. part by weight phenol fraction is added and the distillation is led. A frac-tion of a boil-ing point o:f 40 - 166C at 10 mm Hg is received~ The obtained distillate after warming to 60C undergoes delamination. We separate the upper layer in form of a thick light-brown oil of an intensive smoked food aroma, being the pure phenol fraction. The yield of the whole process amounts to about 68%.

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Claims (20)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process of preparing a food smoke additive which comprises the steps of, destructively distilling cellulose and/or lignin material to form tar or smoke condensate, removing organic nitric bases from the condens-ate by means of an aqueous solution of a mineral acid or as a compound formed by reaction with an acid which is indecomposable at a temperature up to 250°C, distilling remaining tar or smoke condensate in two stages in an inert atmosphere, a first said stage comprising distillation at a pressure of between 20-30 mm Hg and collecting the fraction boiling below 100-110°C, and a second said stage comprising distillation of said 100-110°C boiling fraction at a pressure not exceeding 20 mm Hg and collecting the fraction containing compounds exhibiting a boiling point of up to 250°C at 20 mm Hg, heating the food smoke additive thus collected to a temperature of 50°-90°C
to separate out an alcohol layer which is removed from the food smoke additive layer, said steps of removing organic nitric bases and said two-stage distill-ation of remaining tar or smoke condensate being interchangeable.

2. A process of preparing a food smoke additive according to claim 1 further comprising the step of passing the food smoke additive of claim 1 in diluted or non-diluted form and heated to 50-90°C through active carbon, wide porous silica gel or synthetic molecular sorbents which removes any remaining organic nitric bases or other ballast compounds by selective absorption.

3 A process according to claim 1 or 2 wherein said mineral acid is sulfuric acid.

4. A process according to claim 1 or 2 wherein said acid which is indecomposable at a temperature up to 250°C is orthophosphoric acid.

5. A process according to claim 1 or 2 further comprising the step of washing the tar or smoke condensate which is obtained after removing organic nitric bases with water.

6. A process according to claim 1 or 2, characterized in that the removal of organic nitric bases is carried out at room temperature using an aqueous mineral acid solution of a concentration of 5-20%.

7. A process according to claim 6, characterized in that the mineral acid is introduced in a quantity of 5-25% by weight in relation to the quantity of tar.

8. A process according to claim 1, characterized in that said remaining tar or smoke condensate or tarry fraction which is obtained after removal of said organic nitric bases is washed with water and with an aqueous solution of sodium bicarbonate or with saturated sodium chloride solution.

9. A process according to claim 4, characterized in that the orthophosphoric acid is used in a quantity of up to 5% by weight for a 85-90%
acid.

10. A process according to claim 1 or 2, characterized in that the inert gas is nitrogen, argon or carbon dioxide.

11. A process according to claim 1 or 2, characterized in that zinc dust, aluminium dust or iron dust is used added to said remaining tar or smoke condensate in a quantity of 1-10% by weight in relation to the quantity of said remaining tar or smoke condensate, said dust being added at once in the first phase or only in the second phase of the distillation.

12. A process according to claim 1, wherein glycerol is added to said fraction boiling below 100-110°C during said second stage.

13. A process according to claim 12, characterized in that the glycerol is used in a quantity of 1-10 parts by weight per 1 part of tar.

14. A process according to claim 2, characterized in that prior to the selective adsorption process the smoking agent is diluted with the aid of organic solvents, advantageously lower aliphatic alcohols, dialkyl ethers or halogen hydrocarbons.

15. Method of obtaining a food smoke additive by extraction and distillation from tar obtained in result of condensation of smoke produced in the process of destructive distillation of cellulose and/or lignin material, conducted in air excess, characterized in that the fraction, obtained in result of extraction with the aid of organic solvents, containing phenols of a molecular weight of above 140, or the fraction containing lower carboxylic acids, is subjected to distillation under reduced pressure not higher than 20 mm Hg at a temperature of up to 200°C or correspondingly lower at a pressure lower than 20 mm Hg advantageously in the presence of a mineral acid, particularly orthophosphoric acid, and/or in the presence of zinc dust or aluminium dust, or in the presence of polyhydric alcohol, or in the presence of vegetable oils, or high boiling aliphatic hydrocarbons or silicone oils, the distillation process being advantageously led in an oxygen-free atmosphere, and then the pured fractions collected.

16. Method of obtaining an agent according to claim 15, character-ized in that as the mineral acid, orthophosphoric acid in a quantity of up to 5% by weight for a 85-90% acid is advantageously used.

17. Method of obtaining an additive according to claim 15, characterized in that zinc dust or aluminium dust is used in a quantity of 1-5% by weight of distilled medium.

18. Method of obtaining an agent according to claim 15, character-ized in that glycerol is used in a quantity of from 3 to 6 parts by weight per 1 part of the raw material being subjected to distillation.

19. Method of obtaining an agent according to claim 15, character-ized in that in case of carrying out the distillation in a non-acid medium, a raw or distilled phenol fraction is advantageously subjected to extraction with the aid of a mineral acid, whereupon it is subjected to neutralization.

20. Method as claimed in claim 15, characterized in that prior to the selective adsorption process the phenol fraction is diluted by means of organic solvents, advantageously by means of lower aliphatic alcohols, dialkyl ethers or halogen hydrocarbons.