RU2264444C1 - Higher unsaturated fatty acid mixture preparation method - Google Patents

Abstract

FIELD: fat-and-oil industry.

SUBSTANCE: invention provides a method for preparing higher unsaturated fatty acid mixture for use in food processing, varnish-and-paint, and other industries. Method comprises distillation of fat feedstock, in particular sunflower oil, at 230-260°C and pressure 0.12-0.8 KPa to give distillate with acid number 130-160 mg KOH/g and subsequent reagent-free hydrolysis of distillate under autoclaving conditions (217-225°C and 2.0-2.5 MPa) for 3-4 h at fat-to-oil ratio 1:0.5. Method has following advantages: specific consumption of oils to prepare higher unsaturated fatty acid mixture is reduced by a factor 3-5; product preparation technology simplified owing to lesser number of process steps (from 3 to 2); total time of high-temperature action on far feedstock is reduced excepting second period of reagent-free hydrolysis; process is made wasteless because of elimination of bottom residues (goudrons) upon distillation of fatty acid.

EFFECT: enhanced process efficiency.

2 tbl, 2 ex

Description

The invention relates to the oil and fat industry, and in particular to methods of processing oil and fat raw materials in order to obtain a mixture of higher unsaturated fatty acids used in the food, paint, petrochemical and other industries.

A known method of producing a mixture of higher unsaturated fatty acids by non-reactive hydrolysis of a composition of vegetable oils, consisting of 20-80 wt.% High oleic sunflower oil and 20-80% mustard or rapeseed oil or a mixture thereof followed by distillation of the obtained fatty acids (A.S. RF No. 1373724, C 11 C 1/04, C 07 C 57/12, 1983).

The disadvantage of this method is the need for spending up to 100% edible vegetable oils and two-stage splitting in batch autoclaves with a total duration of 8 hours.

The closest in technical essence and properties of the obtained product to the present invention is a method for producing a mixture of higher unsaturated acids by non-reactive hydrolysis of a composition of vegetable oils under autoclaving in two stages in the presence of free fatty acids isolated from soap stocks corresponding to the formulation of vegetable oils, in a mass ratio of oil : fatty acids (3-10): 1 and subsequent distillation of the obtained fatty acids (A.S. RF No. 1664825, C 11 C 1/04, C 07 C 57/12, 1985).

This method is adopted as a prototype.

The disadvantages of the method are the significant consumption of edible oils - at least 75 wt.%, The technological complexity of the method due to the preservation of the regime of two-stage periodic splitting of oils in autoclaves, obtaining tar by-products from the distillation of fatty acids.

The task of the invention is to reduce the consumption of edible vegetable oils and simplify the method.

The problem is solved in that in the method of producing higher unsaturated fatty acids during the distillation of fatty raw materials and non-reactive hydrolysis in an autoclave, the sunflower oil is subjected to distillation at a residual pressure of 0.13-0.8 KPa and a temperature of 230-260 ° C, followed by the distillate splitting by the method non-reactive hydrolysis in one period at a temperature of 217-225 ° C and a pressure of 2.0-2.5 MPa for 3-4 hours at a ratio of fat: water 1: 0.5.

The proposed method for producing higher unsaturated fatty acids is carried out as follows: distillation is subjected to sunflower oil at a residual pressure of 0.13-0.8 KPa and a temperature of 230-260 ° C, followed by splitting of the distillate containing 65-80 wt.% Free fatty acids, periodically in autoclaves in one period at a temperature of 217-225 ° C and a pressure of 2.0-2.5 MPa for 3-4 hours at a ratio of fat: water 1: 0.5.

During the processing of oils with steam at low absolute pressure and a sufficiently high temperature, evaporation of free fatty acids, odorizing substances and other volatile compounds with steam is ensured and their subsequent separation from the oil stream and condensation of fatty substances from the gas-vapor mixture by irrigation with a cooled recirculating distillate. Excess distillate is automatically removed from the circulation circuit. During the distillation process, mechanical losses of oil are observed due to drip entrainment along with bubbling steam. The ablation is determined by the technological parameters of the process, the design and type of bubbling devices, as well as the method of distillate separation. Since the obtained distillate is a mixture of predominantly fatty acids and a neutral oil with a mass fraction of fatty acids of 60-80%, subsequent splitting of the high-acid mixture is possible in batch autoclaves in one period at a ratio of fat: water of 1: 0.5. It should be noted that during distillation of the oil, tocopherols in the amount of 1-3.5% are accumulated in the distillate as by-products, which are natural antioxidants that increase the stability of fatty acids to oxidation.

Vegetable oil, subjected to high-temperature distillation, is purified from impurities, acquiring additional nutritional value, and is not completely split, as in the method adopted for the prototype. In this case, no by-products such as tars occur during the distillation of fatty acids.

When the applicant conducted the analysis of the prior art, an analogue was not found that was characterized by the features of the claimed invention, and the definition of the prototype as the closest in the totality of the characteristics of analogues made it possible to identify the set of essential distinguishing features in the claimed object set forth in the claims.

We give examples of the proposed method and the method adopted as a prototype.

Example 1 (prototype)

A composition consisting of 75% sunflower oil and 25% fatty acids from rapeseed oil stocks with an acid number of 52.4 mg KOH / g is subjected to non-reactive hydrolysis at a temperature of 225 ° C and a pressure of 2.5 MPa in two periods with a change of water at a total ratio reacting components 1: 0.75 (1 period = 1: 0.45, II period = 1: 0.3). The split composition with an acid number of 184 mg KOH / g is distilled at a temperature of 230 ° C. and a residual pressure of 1.3 KPa. After distillation, fatty acids with an acid number of 186 mg KOH / g were obtained.

Example 2

Sunflower oil with an acid number of 2.4 mg KOH / g is distilled at a temperature of 230 ° C and a residual pressure of 0.13 KPa. The isolated distillate with an acid number of 130 mg KOH / g is subjected to non-reactive hydrolysis in an autoclave for 1 period at a temperature of 225 ° C, a pressure of 2.5 MPa and a fat: water ratio of 1: 0.5 for 3 hours.

After cleavage, fatty acids with an acid number of 186 mg KOH / g were obtained.

Examples 2, 3, 4 of the implementation of the proposed method in comparison with the prototype (example 1) are given in tables 1 and 2. Moreover, examples 2, 3, 4 confirm the possibility of implementing the inventive method, which is shown in the claims.

The transcendental values of the parameters of the oil distillation process in terms of absolute pressure of less than 0.13 KPa are impractical due to the sharply increasing costs of providing a vacuum; increasing the distillation temperature above 260 ° C is inappropriate to avoid undesirable side reactions - polymerization, thermal decomposition, oxidation, etc., leading to poor quality and lower yield of the resulting products.

Thus, the proposed method for producing a mixture of higher unsaturated fatty acids allows, in comparison with the prototype:

- eliminate the target oil consumption for the production of technological products;

- reduce the specific oil consumption for the production of a mixture of higher unsaturated fatty acids by 3-5 times;

- to simplify the technology of obtaining the finished product by reducing the total number of process steps from 3 to 2;

- reduce the total time of high-temperature exposure to fatty raw materials by eliminating the 2nd period with non-reactive hydrolysis;

- to ensure non-waste production of fatty acids due to the absence of bottoms (tars) from the distillation of fatty acids.

Claims (2)

1. The method of obtaining a mixture of higher unsaturated fatty acids, including distillation of fatty raw materials and non-reactive hydrolysis under autoclaving, characterized in that the distillation is subjected to sunflower oil at a residual pressure of 0.13-0.8 KPa and a temperature of 230-260 ° C, followed by splitting Nonreactive distillate by hydrolysis in one period at a temperature of 217-225 ^C and pressure of 2.0-2.5 MPa for 3-4 hours at a ratio of fat: water 1: 0.5. 2. The method according to claim 1, characterized in that the distillate transferred to the cleavage has an acid number of 130-160 mg KOH / g