CS261464B1 - Process for producing monoacylglycerols - Google Patents

Abstract

The solution relates to the production of food emulsifiers, namely monoacylglycerols of aliphatic monocarboxylic acids by catalytic glycerolysis of fats at 230 °C and deactivation of the catalyst (CaO) defined by the amount of orthophosphoric acid at the reaction temperature, aegaration of the deactivated catalyst by shot peening at 120 to 125 °C and isolation of monoacylglycerols by molecular distillation. The method allows multiple repeated use of unreacted and by-products of glycerolysis.

Description

The invention relates to monoacylglycerols of aliphatic monocarboxylic acids 0 ₁₂ ^C 24* ^{Ϊ3Γί ;0 monoacylglycerols are} surface-active substances that ^are used as emulsifiers, especially in the food industry.

The most common industrial production of monoacylglycerols of aliphatic monocarboxylic acids is based on the alcoholysis of fats with glycerol. This is a reversible reaction usually occurring at temperatures of 200 - 280 °C, or even higher, and usually in the presence of a catalyst, which is usually a hydroxide or oxide of an alkali metal or alkaline earth metal. Monoacylglycerols are obtained from the reaction mixture, usually after neutralization of the catalyst, for example by molecular distillation or extraction. The attempt is made to reuse unreacted or by-products of alcoholysis. The production processes are mostly discontinuous, but continuous processes are also described, in which the emphasis is placed on intensive mixing of the reaction mixture.

A disadvantage of the known methods for producing monoacylglycerols of aliphatic monocarboxylic acids is that the neutralization of the catalyst produces a finely dispersed salt that is very difficult to remove, which reduces the possibility of reusing unreacted fractions and by-products of alcoholysis.

These disadvantages are eliminated by the method of producing monoacylglycerols of aliphatic monocarboxylic acids 0 ₁₂ - 0 ₂ ^ according to the invention, in which fat reacts with glycerol, the weight ratio of fat to glycerol is 3:1, in the presence of 0.02 - 0.2% by weight of calcium oxide as a catalyst (based on fat), with the reaction temperature being 220 - 250 °C. After the reaction is complete, the calcium oxide is deactivated with a precisely defined amount of orthophosphoric acid and separated from the reaction mixture, from which the monoacylglycerols are then isolated by at least two-stage molecular distillation. The procedure is as follows: in the first stage of molecular distillation, which may be several stages forming its first phase, the glycerol residue and the fat fraction consisting mainly of monoacylglycerols and free aliphatic monocarboxylic acids are removed, and in the second stage the final product is obtained as a distillate containing at least 90% by weight of monoacylglycerols. The distillation residue contains at least 70% by weight of diacylglycerols. The procedure is characterized by

- 2 261 464 in that the deactivation of calcium oxide is carried out at a reaction temperature of 220 - 250 ° C by adding orthophosphoric acid (H ^ PO ^), with 0.7 mol of orthophosphoric acid per mole of calcium oxide, preferably using an acid with a concentration of at least 75% by weight. The reaction mixture is then cooled to 120 - 140 ° C and at this temperature free glycerol undissolved in the fat phase and sludges containing deactivated calcium oxide in the form of orthophosphoric acid salts are removed by centrifugation. The free glycerol obtained by centrifugation and / or molecular distillation and / or the fat fraction obtained by molecular distillation and / or the distillation residue from the previous batch are added to the starting reaction mixture of the next batch, whereby this reuse, preferably of all the above-mentioned unreacted and by-products, can be carried out at least six times in succession. The glycerol from the previous batch constitutes a maximum of 70% by weight of the total glycerol content in the fresh reaction mixture, and the fat fraction obtained during molecular distillation and/or the distillation residue from molecular distillation always constitutes a maximum of 50% by weight of the total fat fraction in the fresh reaction mixture.

The advantage of the method for preparing monoacylglycerols of aliphatic monocarboxylic acids according to the invention is that it is operated at lower temperatures, unreacted fractions and by-products can be reused, and the formation of polyglycerols and the decomposition of glycerol are reduced. This reduces the total consumption of raw materials on average by more than 10% by weight. Due to the method of deactivation and removal of calcium oxide, no deposits are formed on the distillation equipment. The distillation residue from molecular distillation is itself a high-quality semi-product for the preparation of food emulsifiers.

The method for producing monoacylglycerols according to the invention is further illustrated by the following examples.

Example 1

A 4.5-liter glass flask was charged with 3 kg of a reaction mixture containing 75 parts by weight (wt.) of fully solidified tallow (tallow) and 25 parts by weight of glycerol. After heating the mixture to 230 °C, 0.05% by weight of calcium oxide (based on tallow) was added in the form of a suspension in glycerol.

After an hour, the calcium oxide was deactivated at 230°C by adding 75 percent orthophosphoric acid to the reaction mixture, with 0.7 moles of orthophosphoric acid per mole of calcium oxide.

- 3,261,464

The reaction mixture was then cooled to 120 °C and at this temperature undissolved glycerol and sludge containing calcium oxide deactivated with orthophosphoric acid (hereinafter referred to as sludge) were separated from the mixture in a centrifuge. The remaining reaction mixture contained 9>4% by weight of free glycerol, 51>4% by weight of monoacylglycerols of aliphatic monocarboxylic acids (hereinafter referred to as MAG), 1.3 · 10 ^J $ by weight of calcium oxide and its color was characterized by level 8 of the colorimetric scale according to ČSN 58 0101 (hereinafter referred to as the colorimetric scale). This was followed by a two-stage molecular distillation. In the first stage, the rest of the free glycerol and the fat fraction (hereinafter referred to as TP) containing monoacylglycerols, free aliphatic monocarboxylic acids and a small amount of diacylglycerols and triacylglycerols were distilled off at a temperature of 175 - 180 °C. In the second stage, a distillate containing 96.4% by weight of MAG, 1.5· ¹⁰⁴ % by weight of calcium oxide, 0.2% by weight of glycerol was obtained at 190-200°C, and its color was characterized by a colorimetric scale of level 4. The distillation residue contained 7.3% by weight of MG, 80.4% by weight of diacylglycerols (hereinafter referred to as DAG), 12.3% by weight of triacylglycerols (hereinafter referred to as TAG) and 2.3·10“^$ by weight of calcium oxide, and its color was characterized by a colorimetric scale of level 12.

Example 2

A glass flask with a volume of 4.5 l was charged with 3 kg of the reaction mixture consisting of 35.7 wt. d. tallow and 14.3 wt. d. glycerol, and all the return fractions from the previous batch processed by the procedure given in Example 1, i.e. 7.1 wt. d. TP from the first stage of molecular distillation, 32.2 wt. d. distillation residue, 4.3 wt. d. glycerol from the centrifuge and 7.8 wt. d. glycerol from the first stage of molecular distillation. The reaction temperature and the catalyst deactivation temperature (CaO) were 220 °C, the temperature during the glycerol and sludge blasting was 125 °C. Otherwise, the procedure was identical to the procedure given in Example 1. The distillate contained 94.2 wt. % (hereinafter referred to as wt.) MG, 0.3 wt. % glycerol, 1.1 ♦ 10~ ⁴ % &*· calcium oxide, color - level 4 on the colorimetric scale.

Example 3

3 kg of the reaction mixture consisting of 39.7 wt. % tallow and 8.4 wt. % glycerol, as well as all the return fractions from the previous batch, were placed in a glass flask with a volume of 4.5 l.

- 4 "

261 464 processing is given in example 2, namely 6.7 wt. d. TP from the first stage of molecular distillation, 28.6 wt. d. distillation residue, 8.3 wt. d. glycerol obtained by centrifugation and 7.8 wt. d. glycerol from molecular distillation. The reaction temperature and the temperature during deactivation of calcium oxide were 250 °C, the temperature during centrifugation was 140 °C. Otherwise, the procedure was identical to the procedure in example 1. The reaction mixture after centrifugation contained 9.6 wt. % glycerol, 51.4 % — 7 wt. BG, 2.0 . 10 wt. % calcium oxide, color - level 11 of the colorimetric scale. The distillate contained 95.6 wt. % MAS, 0.1 wt. % glycerol, 0.7 . 10 wt. % of calcium oxide, color - degree 4 of the colorimetric scale. The distillation residue contained 80.3 wt. % DAS, 13.9 wt. % TAS, 5.7 wt. % MS and 5.1 . 10~^ wt. % calcium oxide, color - degree 15 of the colorimetric scale.

Example 4

A fresh reaction mixture containing 38.2 wt. d. tallow and 10.1 wt. d. glycerol, as well as all return fractions from the previous batch, the processing of which is given in example 3, was placed in a glass flask with a volume of 4.5 l, namely 5.5 wt. d. TP from molecular distillation, 31.3 wt. d. distillation residue, 8.1 wt. d. shot-off glycerol and 6.8 wt. d. glycerol from molecular distillation. The reaction mixture was processed according to the procedure given in example 1. The distillate contained 95.1 wt. % MS, 0.2 wt. % glycerol and 1.3 10^ wt. % calcium oxide, color - level 4 of the colorimetric scale.

Example 5

A fresh reaction mixture containing 40.8 wt. % tallow and 10.1 wt. % glycerol was placed in a glass flask with a volume of 4.5 l, as well as all the return fractions from the previous batch, the processing of which is given in Example 4, namely 4.0 wt. % TP from molecular distillation, 30.2 wt. % distillation residue, 7.5 wt. % glycerol obtained by centrifugation and 7.4 wt. % glycerol from molecular distillation. The processing procedure was identical to the procedure given in Example 1. The reaction mixture after centrifugation of glycerol and sludge contained 10.0 wt. % glycerol, 52.2 wt. % MS, 2.7 10*”^ wt. % calcium oxide and its color corresponded to level 14 of the colorimetric scale. The distillate contained 94.8 wt. % MS, 0.3 wt. % glycerol, 1.1 10“^ wt. % calcium oxide, color - level 4 of the colorimetric scale. The distillation residue contained 72.7 wt. % DAG, 17.0 wt. % MAG, 10.3 wt. % TAS and 1.0 10 calcium oxide, color - level 17 of the colorimetric scale.

- 5 Example 6 261 464

A 4.5 l glass flask was charged with 3 kg of the reaction mixture containing 39.8 wt. d. of tallow and 10.2 wt. d. of fresh glycerol and all the return fractions from the previous batch, the processing of which is given in Example 5, namely 3.7 wt. d. of TP from molecular distillation, 31.4 wt. d. of distillation residue, 6.9 wt. d. of glycerol separated in a centrifuge and 7.9 wt. d. of glycerol from molecular distillation. The processing procedure was identical to the procedure given in Example 1. The distillate contained 93.7 wt. % MAG, 0.1 wt. % glycerol and 1.4 10 wt. % calcium oxide, color - level 5 on the colorimetric scale.

Example 7

A 4.5 l glass flask was charged with 3 kg of the reaction mixture containing 41.5 wt. % tallow and 9.7 wt. % glycerol, as well as all the return fractions from the previous batch, the processing of which is given in Example 6, i.e. 3.0 wt. % TP from molecular distillation, 30.5 wt. % distillation residue, 7.5 wt. % glycerol separated in a centrifuge and 7.7 wt. % glycerol from molecular distillation. The processing procedure was identical to the procedure given in Example 1. After centrifugation of undissolved glycerol and sludge, the reaction mixture contained 10.0 wt. % glycerol, 52.0 wt. % BG, 2.7 10~^ wt. % calcium oxide and its color corresponded to level 7 of the colorimetric scale. The distillate contained 92.9 wt. % MAG, 0.1 wt. % glycerol and 1.2 10 * wt. % calcium oxide, color - grade 5 according to the colorimetric scale. The distillation residue contained 80.0 wt. % DAG,

6.6% by weight MAG, 13.4% by weight TAG and 1.6 10 ² % by weight calcium oxide, colour - level 18 on the colour scale.

Example 8

Quarterly operational preparation. 60 kg of the reaction mixture containing 75 wt. % tallow and 25 wt. % glycerol was placed in a kettle with a volume of 80 l. After heating the mixture to 230 °C, 0.05 wt. % calcium oxide (based on tallow) was added to the mixture in the form of a suspension in glycerol. After an hour, the calcium oxide was deactivated at 230 °C by adding 70% orthophosphoric acid to the reaction mixture, with 0.7 mol of acid per 1 mol of calcium oxide. The reaction mixture was then cooled to 120 °C and at this temperature, sludge and undissolved glycerol with a residual content of 0.02 wt. % calcium oxide were separated in a LAPX 202 self-cleaning plate centrifuge. The remaining reaction mixture containing 9.3 wt. % free

- 6 261 464 glycerol, ·51.4 $ wt· MG and 1.5 · 10”^ % wt. calcium oxide was subjected to two-stage molecular distillation under the conditions given in Example 1. The distillate contained 97»3 % wt. MG, 0.1 $ wt. glycerol and. 1.3 · ÍO' ² *' .% wt. calcium oxide, color - grade 4 of the color scale. The distillation residue contained 8.5 % wt. MG, 79.7 % wt. DAG, 10.8 % wt. TAG and 2.5 . 10~ ² # wt. calcium oxide, color - grade 12 of the color scale. The returnable fractions, i.e. TP from molecular distillation obtained in its first stage, the distillation residue, glycerol separated in the centrifuge and glycerol from the first stage of molecular distillation were used in the batch of the following batch, repeatedly as in examples 2 to 7·

The method for producing monoacylglycerols of aliphatic monocarboxylic acids according to the invention will be applied particularly in the fat industry in the production of emulsifiers usable in many areas of the food industry.

Claims (2)

SUBJECT OF THE INVENTION 261,464 1. A method for producing monoacylglycerols of aliphatic, monocarboxylic acids 0^ ₂ ^{by reacting} fat with glycerol at a weight ratio of fat to glycerol of 3:1, at a temperature of 220 to 250 °C using calcium oxide as a catalyst, deactivating the catalyst and removing it from the reaction mixture together with a part of the free glycerol, multi-stage molecular distillation of the remaining reaction mixture, in which the rest of the free glycerol and the fat fraction containing free aliphatic monocarboxylic acids are removed and monoacylglycerols in the form of a distillate and diacylglycerols in the form of a distillation residue are obtained, characterized in that the deactivation of calcium oxide is carried out by adding orthophosphoric acid to the reaction mixture at a temperature of 220 to 250 °C, preferably 230 °C, with 0.5 to 0.8 moles, preferably 0.7, per 1 mole of calcium oxide mole of orthophosphoric acid, preferably with a concentration of at least 75 by weight, the reaction mixture is then cooled to 120 to 140 °C, preferably to 120 to 125 °C and the deactivated calcium oxide and part of the free glycerol are removed by centrifugation at this temperature, followed by molecular distillation of the product, after which the free glycerol obtained by centrifugation ε/or the free glycerol removed by molecular distillation and/or the fat fraction containing free aliphatic monocarboxylic acids, removed by molecular distillation and/or the distillation residue from one or more previous batches are returned to the starting reaction mixture of the following batch. 2. A method for producing monoacylglycerols according to item 1, characterized in that the returned glycerol constitutes up to 70% by weight of the total glycerol content in the reaction mixture and the returned fat fraction removed by molecular distillation and/or the returned distillation residue constitutes up to 50% by weight of the total fat fraction in the reaction mixture, wherein the return of said fractions is carried out at least six times in succession.