SK285747B6 - Method of phytosterol concentrates preparation - Google Patents

Abstract

The phytosterols concentrate is prepared from deodorant condensate by refining vegetable oils, so that the deodorant condensate is subjected to a distillation at a temperature between 130 and 200 °C and at a pressure between 1 and 400 Pa, an unevaporated portion is saponifed by an alkaline lye in methanol, the resulting soaps are decomposing by mineral acid and created organic layer is subjected to a distillation at a temperature between 130 and 200 °C and at a pressure between 1 and 400 Pa. The distilling remainder from this distillation is phytosterol concentrate with 50 to 80 % by weight at a recovery of the phytosterols above 80 %. The phytosterols concentrate is used in a pharmacy in synthesis of steroids, in a cosmetics and food production as a dietetic adjunct.

Description

Technical field

The invention relates to a process for the preparation of concentrates of natural phytosterols from by-products of vegetable oil refining. Phytosterols are alcohols with 27 to 29 carbons per molecule and are steroids characterized by a cyclopentanoperhydrophenanthrene backbone. In particular, a preferred starting material for the preparation of phytosterol concentrates is deodorizing condensate, which is produced as a by-product in the refining of vegetable oils during their deodorization and de-acidification by vacuum distillation. The content of phytosterols in vegetable oils ranges from 0.3 to 1.2% by weight, their content in deodorizing condensate is 5 to 20% by weight. The deodorizing condensate contains higher fatty acids, tocopherols, sterols, sterol esters, mono-, diatriacylglycerols, hydrocarbons, natural dyes and other minor substances. Trivial names such as β-sitosterol, campesterol, brassicasterol and stigmasterol are used to denote individual phytosterols. The preparation of phytosterol concentrates usually does not aim to isolate individual sterols but to isolate the phytosterol group as a whole.

BACKGROUND OF THE INVENTION

A number of processes for the preparation of phytosterol concentrates are described in the literature. Of practical importance are processes which use vacuum distillation to separate the deodorizing condensate alone or in combination with other physical or chemical operations. Distillation utilizes a different volatility of free fatty acids, tocopherols, sterols, and acylglycerols, which decreases, respectively. According to Ger. Offen. No. 2,656,208, the free fatty acids are removed from the deodorizing condensate by vacuum distillation and the distillation residue is transesterified with methanol and treated with CaCl ₂ to form sterol adducts which are then decomposed with mineral acid. The disadvantage of this procedure is the complicated process and low yield. The sterol esters present are not used. According to Jap. Kokai 74 05 959 is first de-esterified with methanol in the presence of an acid catalyst, then transesterified with methanol in the presence of an alkaline catalyst, and the methyl esters formed are distilled off in vacuo. The increased volatility of the methyl esters is utilized in comparison with the free acids. The disadvantage of the process is again its complexity with difficult catalyst replacement and low yield. Also known is CS 247 677 according to which the deodorizing condensate is separated by two-stage molecular distillation into a distillate fraction rich in fatty acids and into a distillate fraction enriched in sterols and tocopherols. This fraction was then dissolved in acetone and allowed to crystallize at -18 ° C. The disadvantage of this process is, in particular, the inability to use ester-linked sterols. In the process of U.S. Pat. No. 5,117,016, the deodorizing condensate is saponified, the soaps formed are decomposed with mineral acid, the liberated fatty acids are esterified with methanol to methyl esters, the water-methanol-heptane solvent system is added, and after cooling the precipitated sterols are filtered. The disadvantage is the large number of operations, the large consumption of chemicals and the need for complex regeneration of the multi-component solvent.

SUMMARY OF THE INVENTION

The disadvantages of the above processes are eliminated in the process for the preparation of the phytosterol concentrates according to the invention, which is characterized in that the deodorizing condensate is subjected to vacuum distillation at a temperature of 130 to 200 ° C and a pressure of 1 to 400 Pa, saponified, the resulting alkaline soaps are decomposed by mineral and the mixture is again subjected to vacuum distillation at a temperature of 130 to 200 ° C and at a pressure of 1 to 400 Pa, to obtain a phytosterol content of 50 to 90% by weight in the distillation residue.

The process for preparing the phytosterol concentrates of the invention has several advantages. Vacuum distillation of the initial deodorizing condensate separates a substantial portion of the free fatty acids present, so that the subsequent saponification concerns a considerably smaller amount of the substance. This results in lower consumption of alkaline lye for saponification, as well as lower consumption of mineral acid for decomposing soaps and formation of less salt. The saponification process also makes it possible to extract sterols bound in deodorizing condensate in the form of esters. The process is simple, resulting in a high concentration of phytosterols in the product fraction of about 80% and a high recovery in this fraction above 80%. Both distillation and saponification take place at relatively low temperatures, so that there is no thermal degradation of the natural substances present. It is advantageous to carry out the distillation in short-path evaporators with a wiped film at low pressure at tens of Pa. Under these conditions, in addition to the phytosterol concentrate, tocopherol concentrate (vitamin E) can be obtained by further operations, which in the process according to the invention are concentrated together with the phytosterols. The concentrations of phytosterols obtained are sufficient for subsequent use in pharmacy, but nothing prevents their further concentration, for example by crystallization from methanol or acetone. In the process according to the invention, there is no significant change in the proportion of phytosterols in the product compared to the initial deodorizing condensate.

Deodorizing condensate with a phytosterol content of 5 to 20 wt. with an acid number of 40 to 175 mg KOH / g, corresponding to a content of 20 to 85 wt. of free fatty acids, is subjected to distillation in a short-path evaporator with a wiped film at a temperature of 130 to 200 ° C at a pressure of 1 to 400 Pa. The distillate fraction is obtained as a fatty acid concentrate having an acid number of 160 to 190 mg KOH / g, with a phytosterol content of 0.5 to 3%, representing 20 to 75% of the starting deodorizing condensate, depending on the proportion of free fatty acids. The yield of phytosterols in this fraction is less than 10%, so the losses of phytosterols to this fraction are not significant. The content of phytosterols in the non-evaporated portion is increased accordingly after leaving the fatty acids. The vaporized portion with an acid number of 10 to 30 mg KOH / g is then saponified with an alkaline solution in methanol. The weight ratio of the evaporation fraction against methanolic liquor solution is 1: 1.5 to 1:

5. The concentration of the alkaline liquor NaOH or KOH is 5 to 40%. The saponification converts the acylglycerols present into alkaline soaps and liberates glycerol, as well as transforming the phytosterol esters into free phytosterols. The phytosterols content of the saponified deodorizing condensate is generally increased by several percent. The saponification is carried out at 50-100 ° C for 2-6 hours with stirring under reflux. After saponification, the reaction mixture is quenched with an equimolar amount of mineral acid in a slight excess over the alkali used, the organic layer is washed with water until neutral and dried. The material thus treated, having an acid number of 60 to 160 mg KOH / g, is subjected to repeated distillation in a short path evaporator under the same conditions as for the first distillation of the original deodorizing condensate. Again, the distillate fraction is a fatty acid concentrate and also contains a small fraction of phytosterols at 1 to 4 wt%, which represents a phytosterol recovery in this fraction of less than 10% relative to the phytosterol content of the deodorizing condensate feed. The phytosterol concentrate is a distillation residue from this operation which contains 50 to 80 wt. phytosterols at their recovery rates above 80%. The recovery evaluation is relative and does not reflect the increase in sterols resulting from the saponification of sterol esters.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

275 g deodorant condensate containing 18.1 wt. of phytosterols, with an acid number of 74.0 mg KOH / g, was distilled in a short-path evaporator with a wiped film at 160 ° C and 20 Pa. A front distillate fraction, representing 32% of the initial deodorizing condensate, an acid number of 188.4 mg KOH / g, a sterol content of 0.3%, a sterol yield of 0.5% was obtained. An evaporation fraction of 68% of the initial deodorizing condensate has an acid number of 25.7 mg KOH / g, a phytosterol content of 27%. It was mixed with 440 g of a 8 wt.% Solution of KOH in methanol, which represents a ratio by weight of the evaporation fraction to an alkali solution in methanol of 1: 2.7. The reaction mixture was stirred at reflux at 75 ° C for 4 hours, then 95 g of 35% HCl was added. The organic layer obtained after repeated washing with warm water was freed from methanol and water and had an acid number of 138.5 mg KOH / g. Distillation in a short path evaporator with a wiped film at 160 ° C and 30 Pa gave a distillate fraction representing 45% of the original deodorizing condensate and had an acid number of 180.9 mg KOH / g, contained 3.2% sterols at their yield. 8%. The distillation residue represents 23% of the initial deodorizing condensate, has an acid number of 34.8 mg KOH / g, a phytosterol content of 75.2% by weight, a phytosterol recovery of 95%.

Example 2

270 g of deodorizing condensate with a phytosterol content of 14.6% by weight, with an acid number of 130.0 mg KOH / g, was distilled at 160 ° C and 15 Pa. The front fraction with a 66% fraction of the starting deodorizing condensate had an acid number of 181.0 mg KOH / g, a sterol content of 0.5% by weight, a sterol yield of 2%. An evaporation portion of 34% of the starting material having an acid number of 16.3 mg KOH / g, a sterol content of 40.5% by weight, was mixed with 309 g of a 5.5% by weight solution of KOH in methanol. ratio of the evaporation fraction to methanolic liquor solution 1: 3.7, and heated to 70 ° C for 4 hours. 56 g of 35% HCl were used to decompose the soaps. The organic layer after washing and removal of water and methanol residues had an acid number of 98.5 mg KOH / g. Distillation at 160 ° C and 15 Pa yielded a distillate fraction with 15% of the original deodorizing condensate with an acid number of 185.0 mg KOH / g, a sterol content of 3.9%, a sterol yield of 3%. The distillation residue containing 19% of the initial deodorizing condensate contained 73.6 wt. phytosterols at 98% recovery.

Industrial usability

Phytosterol concentrates can be used in pharmacy in the synthesis of steroids, steroid hormones and anti-inflammatory preparations, in cosmetics and also in the food industry in the form of dietary supplements and in the fortification of food products.

Claims (2)

Process for preparing phytosterol concentrates from deodorizing condensates from edible oil refining, characterized in that from deodorizing condensate containing from 5 to 20 wt. the phytosterols are evaporated at a temperature of 130 to 200 ° C and at a pressure of 1 to 400 Pa at a rate of 20 to 80% of the starting amount, the vapourised portion is saponified and, after decomposition of the soaps with mineral acid, distilled at 130 to 200 ° C; at a pressure of 1 to 400 Pa, the distillation residue from this operation with a proportion of 5 to 30% of the original deodorizing condensate comprising 50 to 90 wt. phytosterols. Process for the preparation of phytosterol concentrates according to claim 1, characterized in that the saponification of the non-evaporated fraction of deodorizing condensate takes place in a mixture thereof with a solution of KOH in methanol in a weight ratio of 1: 1.5 to 1: 5 at a KOH concentration in methanol of 5 to 40%. weight. at 50-100 ° C for 2-6 hours.