RU2377280C1 - Vegetable oil refining method - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: invention refers to fat-and-oil industry. Method provides for elimination of phospholipids, waxes and wax-like substances, free fatty acids, dying compounds and acidification products on stage of gel persorption with following control stages of bleaching and freezing. Gel persorption is performed at 16-20°C, gel is made by equal distribution of citric acid in quantity 0.06-0.12% of oil weight in form of 40-60% water solution and following adding of sodium metasilicate solution obtained by dissolving powder of 9-water sodium metasilicate In water in ratio 1:(1.2-1.3) in quantity providing elimination of fatty acids with plenty up to 30%, oil is mixed. Reagents are added during 40-60 minutes. Mixture is maturated during 6-9 hours, oil is separated from gel sediment, additionally oil is separated from gel sediment at 18-30°C. After gel sorption stage substance separated from gel sediment is supplied to control bleaching which is performed during 30 minutes at 18-20°C with addition of adsorbent with pH 2-5 in quantity 0.35-0.55% from oil weight and further to control freezing with adding of 0.25-0.3% of adsorbent into the oil.

EFFECT: increased vegetable oil quality, increased durability while storage due to decreased content of acidification products and high content of tocopherols and decreased expenditure of supporting materials.

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Description

The invention can be used in the oil industry for the purification of vegetable oils.

A known method of refining vegetable oil, including the removal of phospholipids, waxes and wax-like substances by sequential treatment of the oil at 20-22 ° C with a 5-10% solution of phosphoric acid and a solution of sodium silicate with a density of 1.32-1.34 g / cm ³ in the amount of 0.7-0.75% by weight of oil with a ratio of phosphoric acid-sodium silicate 1: 1.3, exposure for 5-15 minutes and separation of the mixture in a centrifugal or gravitational field. "The technology of processing fats N.S. Harutyunyan, E.P. Kornen, L.N. Yanova and others. Pishchepromizdat, 1988, S. 122-123."

The disadvantage of this method is the removal of only wax substances and phospholipids remaining in the oil after hydration. All other stages of hydration, neutralization, washing, drying and bleaching of oil this method does not affect. Therefore, the inclusion of an additional stage of removing only wax substances in the general refining scheme does not solve the problem of low yield of the target product, large waste and losses, the need for wastewater treatment and high energy costs.

Closest to the claimed is a method of refining vegetable oil, including the removal of phospholipids, free fatty acids and wax-like substances by mixing crude oil with an aqueous solution of citric acid and sodium chloride concentration of 1-10% at a solids ratio of citric acid and sodium chloride (0.5 : 10) - (10: 0.5) in an amount that provides the ratio of the mass fraction of phosphatides: reagent (1:10) - (1: 2.5), exposure of the mixture for 0.5-2.0 hours, subsequent input 5-1 aqueous citric acid solution 5% in an amount of 0.5-2% by weight of oil and an aqueous solution of sodium silicate with a density of 1.05-1.35 g / cm ³ , exposure for 0.5-2.0 hours, re-introduction of an aqueous solution of sodium silicate with a density 1.05-1.35 g / cm ³ in an amount that ensures the neutralization of free fatty acids in excess of 10-15%, and exposure for 0.5-2.0 hours, while all operations on refining of oil and separation of refined oil from sediment produced in the field of gravitational or centrifugal forces at a temperature of 15-35 ° C (patent RU 2224786 C2; 05/13/2002).

The disadvantages of the method are its multi-stage, increased loss of neutral fat due to its emulsification, saponification and enthusiasm for soap and wax sediment, difficulties in separating oil from sediments, large waste and losses, low yield of the target product, high energy consumption.

The technical result of the invention is to increase the quality of the oil due to the deep removal of phospholipids, waxes and wax-like substances, free fatty acids and dyes under conditions that prevent oxidation of the oil, increasing the yield of the target product, reducing the consumption of auxiliary materials, reducing recyclable waste and reducing energy costs.

The technical result is achieved in that in a method for refining vegetable oil, including the removal of phospholipids, free fatty acids and wax-like substances by mixing unrefined oil with a hydrating reagent, exposure, treatment with an acidic reagent and sodium silicate, exposure and separation of vegetable oil from the sediment in a centrifugal or gravitational forces, excretion of phospholipids, waxes and wax-like substances, free fatty acids, coloring compounds and oxidation products occurs at the gel stage sorption with subsequent control stages of bleaching and freezing, while gel sorption is carried out at 16-20 ° C, and the gel is created by uniform distribution of citric acid in an amount of 0.06-0.12% by weight of oil in the form of 40-60% aqueous solution and the subsequent introduction of a solution of sodium metasilicate obtained by dissolving a powder of 9 aqueous sodium metasilicate in water in a ratio of 1: (1.2-1.3), in an amount that ensures the removal of free fatty acids, in excess of up to 30%, mix the oil and introduced reagents for 40-60 minutes, settling They are removed for 6-9 hours, the oil is separated from the gel precipitate, the oil is additionally separated from the gel precipitate at 18-30 ° C, then the oil after the gel sorption stage and separated from the gel precipitate are sent to control bleaching, which is carried out for 30 minutes at a temperature of 18-20 ° C with the introduction of an adsorbent with a pH of 2-5 in the amount of 0.35-0.55% by weight of the oil and then for the subsequent control freezing with the introduction of 0.25-0.3% of the sorbent into the oil.

The initial melting temperature of the low-melting fraction of sunflower oil waxes was experimentally determined, which amounted to 20.3-20.6 ° C. Therefore, the upper value of the temperature of gel sorption should not exceed 20 ° C, and the lower it is impractical to lower below 16 ° C due to an increase in the viscosity of the oil.

The dependence of the concentration of sodium metasilicate, the amount of silicic acid formed from metasilicate when interacting with citric acid, and the moisture introduced into the oil, on the chemisorption and sorption activity of silicate gel with respect to phospholipids, oxidation products, free fatty acids and dyes, waxes was experimentally established. and wax-like substances contained in sunflower oil. Based on this, the amount of citric acid and excess sodium metasilicate were selected. The same studies showed that the introduction of a large amount of water into the oil with solutions of citric acid and sodium metasilicate does not hold it with silicate gel, causes its hydrolysis and chemical reactions to neutralize free fatty acids with the formation of soap, causing emulsion formation, saponification, emulsification and entrainment Neutral fat in the sediment released from the oil. These disadvantages cause a decrease in the yield of the target product and make it difficult to solve the tasks. Therefore, the concentration of solutions of citric acid and sodium metasilicate is selected as maximum and sufficient for uniform distribution in the volume of oil. The silicate gel formed in this way is guaranteed to firmly bind water, has high activity for chemisorption and sorption processes to occur on its surface, and a high density necessary for its deposition in oil having a high viscosity at 16-20 ° C.

Thus, on the surface of a silicate gel, free fatty acids bind chemisorptively rather than chemically. Therefore, the oil carried away by the gel precipitate during its deposition is non-emulsified and can be easily isolated. The performance of this oil does not differ from the performance of the oil after the gel sorption stage, which allows us to direct it not to re-refining, but to further processing.

Studies have established that at temperatures below 20 ° C, oil oxidation practically does not occur. Therefore, the temperature during bleaching is reduced to 20 ° C. The inventive method is illustrated by examples.

Example 1. Under production conditions, 9850 kg of sunflower oil containing 0.70% phospholipids, 1.2% unsaponifiable substances, 0.2 oil-insoluble substances, 0.2% moisture, with an acid number of 3.26 mg were taken for refining KOH, peroxide value 4.2 _^1/2 O ₂ mmol / kg, 1.8 cu number anizidinovym In oil, cooled to 16 ° C. 0.12% of 60% citric acid and 112.5 L of sodium metasilicate were added (calculated taking into account the acid number of the oil with an excess of 30%) obtained by dissolving a powder of 9 aqueous sodium metasilicate in water in a ratio of 1: 1.2 . After stirring with the reagent for 60 minutes, settling for 9 hours, separating the oil from the gel precipitate, control bleaching for 30 minutes at 20 ° C with bleaching earth in an amount of 0.5% by weight of oil, control freezing for 9 hours with an input of 0 , 25% of the sorbent at a temperature of 6 ° C, by raising the temperature to 12 ° C immediately before filtration, the oil was deodorized for 60 minutes at a temperature of 210 ° C and a residual pressure of 5 mm Hg. Art. The results are shown in table 1.

Example 2 and 3. For examples 2 and 3 were taken oils, the indicators of which are shown in table 2. The oils were refined as described for example 1, taking into account the variable experimental conditions shown in table 2.

As follows from the data given in table 1, the industrial conditions confirm the achievement of high technical results of the proposed method for low-temperature refining of vegetable oil, including the stages of gel sorption, control bleaching, control freezing and production of high-quality vegetable oils, characterized by increased storage stability due to lower contents in them the products of oxidation and preservation of a high content of tocopherols in deodorized oil, with a high yield of target product, by reducing the consumption of auxiliary materials, such as bleached land and sorbents, recyclable waste and fuel and energy resources due to refining at low temperatures.

Table 1 No. p / p Indicators Source Oil for Examples Refined Oil for Examples one 2 3 one 2 3 one 2 3 four 5 6 7 8 one The amount of oil, t 9850 12473 11858 9508 12071 11590 2 Acid number, mg KOH 3.26 1.76 1.45 0.05 0.05 0.05 3 Mass fraction of phospholipids,% 0.70 0.65 0.63 Ots. Ots. Ots. four Mas. the proportion of unsaponifiable substances,% 1.20 1.20 1.13 0.71 0.70 0.73 5 Mas. the proportion of insoluble substances,% 0.20 0.13 0.10 Ots. Ots. Ots. 6 Mas. moisture content,% 0.20 0.12 0.10 Ots. Ots. Ots. 7 Chromaticity, units iodine 25 23 21 3 3 3 8

Peroxide value, 1/2

4.0 3.8 3.6 0.2 0.2 0.2 9 Anisidine number, cu 1.8 1.8 1.8 2.0 2.0 1.9 10 The number of totox, cu 9.8 9,4 9.0 2,4 2,4 2,3 eleven The content of diene compounds,% 0.20 0.18 0.16 0.18 0.16 0.14 12 The content of triene compounds,% 0,03 0.02 0.02 0.04 0,03 0.03 13 Induction oxidation period (hour 100 ° C, air

16.8 17.3 19.2 fourteen The content of tocopherols, mg% 76 74 78 52.6 56.3 61.0 fifteen The content of transisomers,% 0.41 0.40 0.38 0.40 0.38 0.36 16 The degree of transparency, fem 51 48 48 3 3 3 17 Oil yield - after all stages of low-temperature refining 96.68 97.5 97.89 - after deodorization 96.53 97.35 97.74

table 2 No. p / p Variable conditions in the examples for the implementation of the proposed method Example Values one 2 3 one Oil temperature during gel sorption, ° С 16 eighteen eighteen 2 The amount of citric acid,% by weight of oil 0.12 0.10 0.08 3 The concentration of citric acid,% 60 fifty 40 four The ratio of sodium metasilicate: water 1: 1,2 1: 1,2 1: 1.3 5 Excess sodium metasilicate,% thirty twenty 25 6 Gel sorption mixing, min 60 40 40 7 The duration of the sedimentation during gel sorption, hour 9 7 6 8 The amount of bleaching earth,% by weight of oil 0.55 0.50 0.35 9 The amount of sorbent during freezing,% by weight of oil 0.30 0.25 0.25 10 Freezing temperature, ° С 6 7 7 eleven The duration of freezing, hour 9 8 6

Claims (1)

A method of refining sunflower oil, including the removal of phospholipids, free fatty acids and wax-like substances by mixing unrefined oil with a hydrating reagent, exposure, treatment with an acid reagent and sodium silicate, exposure and separation of vegetable oil from the sediment in the field of centrifugal or gravitational forces, characterized in that removal of phospholipids, waxes and wax-like substances, free fatty acids, coloring compounds and oxidation products is carried out at the stage of gel sorption, followed by my control stages of bleaching and freezing, while gel sorption is carried out at a temperature of 16-20 ° C, and the gel is created by uniform distribution of citric acid in an amount of 0.06-0.12% by weight of oil in the form of 40-60% aqueous solution and the subsequent introduction of a solution of sodium metasilicate obtained by dissolving a powder of 9-aqueous sodium metasilicate in water in a ratio of 1: (1.2-1.3), in an amount that ensures the removal of free fatty acids, in excess of up to 30%, mix the oil and the introduced reagents for 40-60 minutes, stand for 6-9 hours, oil is separated from the gel precipitate, oil is additionally separated from the gel precipitate at 18-30 ° C, then the oil after the gel sorption stage and the precipitate extracted from the gel precipitate are sent to control bleaching, which is carried out for 30 minutes at a temperature of 18- 20 ° C with the introduction of an adsorbent with a pH of 2-5 in the amount of 0.35-0.55% by weight of the oil and then for control freezing with the introduction of 0.25-0.3% of the sorbent into the oil.