RU2585193C2 - Method of producing natural colouring agent from larch bark - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing natural colouring agents from natural raw materials and can be used in food, as well as in perfume and textile industry. Larch bark is used as raw material (usually Gmelin larch). Method involves grinding larch bark and water purification, followed by primary extraction in melted water at temperature of 18±2 °C for 12±2 hours and secondary extraction without use of chemical additives at 80±10 °C for 45-60 min, and ratio of water to bark by weight of 1:10 to 1:8. Further, method includes hot filtration of extract and drying to a dry residue at temperature of 15±2 °C to 70±2 °C for 22-24 hours depending on required colour gamma of obtained dye. Evaporated dry residue is crushed to a powder and packaged in said form. Furthermore, after cooling, extract may be stored in liquid form in a closed opaque container.

EFFECT: according to disclosed solution at minimum power consumption ecologically clean and stable dye is obtained, wherein without using additional chemical reagents and with preservation of biologically active substances, and used bark can be used for fertiliser or mulching of depleted soils, which contributes to cleaner technological process.

1 cl, 2 tbl

Description

The invention relates to methods for producing natural dyes from natural raw materials and can be used in food, as well as in the perfumery and textile industries.

A known method of producing a modified anthocyanidin dye (see RU No. 2202575, C09B 61/00, publ. 04/20/2003) from the bark of coniferous wood (fir or larch), where the extraction of crushed bark is carried out in the presence of non-polar solvents, ethyl alcohol containing hydrochloric acid. The dye obtained in this way requires significant energy consumption and the use of chemical reagents in the technological process does not allow the bioactive substances present in natural raw materials to be stored in the dye.

A known method for producing quercetin dye (see RU No. 2264422, СВВ 61/00, published on November 20, 2005), where onion husks and ground coniferous bark are mixed, the mixture is extracted with an extractant in the form of liquid ammonia at a pressure above atmospheric. The process of obtaining dye in this way is energy-consuming, while the use of liquid ammonia does not allow you to save biologically active substances in the composition of the dyes and get a completely natural product.

A known method of obtaining dyes and tanning substances (tannins) from the remains of plant materials (see RU No. 2126025, C09B 61/00, publ. 02/10/1999), where the extraction is carried out under certain phases of pulsating countercurrent flow followed by twenty-fold recirculation through ultrafilters and continuous concentration of the extract. However, the dye obtained by the proposed method does not ensure the purity of the tone when staining, since the residues of plant materials are used for extraction, and the amount of dyes decreases as a result of repeated recycling of liquid filtrates and their return to the technological process.

Closest to the proposed method is a method for producing a natural dye from onion peel (see RU No. 2021310, СВВ 61/00, publ. 10/15/1994), which provides for the extraction of ground natural raw materials in the presence of citric acid, followed by filtration of the cooled extract and its concentration in various modes under pressure. The method is expensive when used, because food acids are used to completely isolate the coloring pigment, and pressure concentration is required to concentrate the extract.

The problem to which the claimed invention is directed, is expressed in ensuring maximum yield and concentration of anthocyanins from natural raw materials without the use of chemical additives to obtain a natural dye.

The technical effect obtained by solving the problem is expressed in the production of environmentally friendly and sustainable dye from natural raw materials without the presence of chemical reagents, while preserving biologically active substances and with minimal energy consumption.

To solve this problem, a method of obtaining a natural dye from larch bark involves grinding natural raw materials (larch bark) and its water purification followed by primary (cold) extraction in melt water at a temperature of 18 ± 2 ° C for 12 ± 2 hours and secondary (hot ) extraction without the use of chemical additives at a temperature of 80 ± 10 ° C for 45-60 minutes, while the ratio of the amount of bark to water by weight is from 1:10 to 1: 8. Next, the hot extract is filtered and dried to obtain a dry residue at a temperature of 15 ± 2 ° C to 70 ± 2 ° C for 22-24 hours in a ventilated room, depending on the desired color scheme of the resulting dye. The evaporated dry residue is crushed to a powder state and packaged in this form. In addition, the extract after cooling can be stored in liquid form in a closed, opaque container.

A comparative analysis of the features of the claimed solution with the signs of the prototype and analogues indicates the conformity of the claimed solution to the criterion of "novelty."

The invention allows to expand the raw material base of dyes (waste from wood processing enterprises is used), to ensure maximum yield and concentration of anthocyanins from natural raw materials without the presence of chemicals with minimal energy consumption while preserving biologically active substances in the dyes. The exclusion of chemical additives in the production of natural dyes can improve the coloring of dyes and get an environmentally friendly product.

The features of the characterizing part of the claims provide the solution to the following functional problems.

Water purification of natural raw materials helps in obtaining further the purity of the tone of the dye.

The use of melt water instead of food acids to dissolve impurities in aqueous extracts of natural raw materials and its cold extraction at a temperature of 18 ± 2 ° C for 12 ± 2 hours is necessary to ensure complete dye release, preservation of bioflavonols due to the accelerated process of dissolution of salts in impurities of aqueous extracts extracts. Moreover, at this stage there are no additional costs, which generally reduces the cost of the production process.

According to the physicochemical properties, melt water does not contain chlorine and its compounds, salts of heavy metals, nitrates, pesticides, bacteria, fungi, organic substances. Moreover, the degree of surface tension of water is 43 dyne / cm, in contrast to the water supply (73 dyne / cm). The acidity of melt water is pH> 7, which relates it to a slightly alkaline medium, and the redox potential (OKP) corresponds to the OKP of intercellular fluid, i.e. in the range from -100 to -200 millivolts (mV), in contrast to the OKP of tap water, which ranges from +300 to +400 mV (see Serebryakov R.A., Stepanov A.P. Stekhin A.A., Sysina A.I. Structured water in agricultural technologies // Proceedings of the international scientific and technical conference "Energy Supply and Energy Supply in Agriculture", vol. 1, p. 3-9).

Melt water can have various properties due to the ordered internal interaction in associates (clusters), consisting of 43, 53 molecules. Therefore, by changing water clusters through various interactions, it is possible to control its properties.

According to the results of experimental studies, water was chosen whose structure ensured the maximum solubility of salts and, as a result, increased the coloristic concentration of the pigment (see table 1).

The results of experimental studies have confirmed the influence of the water structure on the solubility of salts in pastes and the relative coloring ability of organic pigments (see Utrobin N.P., Leontyeva A.I. Nanostructured materials as catalysts and initiators of organic synthesis // Vestnik TSTU. 2008. Volume 14. No. 4. - S. 827-828).

Melt water (extractant) is obtained by freezing tap water and thawing, which contributes to the acquisition of a certain cluster structure, which allows to increase the degree of dissolution of salts in the impurities of extracts, which, in turn, contributes to a greater yield of coloring substances from natural raw materials while preserving natural bioactivators in natural dyes.

According to experimental data, the maximum extraction of natural dye without the use of chemicals is achieved at a temperature of 80 ± 10 ° C for 45-60 minutes. At the same time, the hot extract is filtered once.

The ratio of the amount of bark to water by weight is from 1:10 to 1: 8, which is optimal for maximum extraction and subsequent evaporation of the dry residue.

Drying the extract at various temperature conditions to obtain a natural dye in the form of a powder in combination with the hot extraction step allows you to control the color scheme of the dye obtained from light yellow to dark brown and black, for example, when drying for 22-24 hours at a temperature of 70 ± At 2 ° C, the most saturated colorant (dark brown, black) is obtained, and at 15 ± 2 ° C, a less saturated shade of light yellow is obtained.

The proposed method for producing natural dye is as follows.

As a natural raw material, larch bark is used (most often Gmelin larch, as the most common type in the forest fund of Yakutia), which is crushed with a crusher to a fraction of 0.2 / 0 mm and subjected to water purification. The washed particles are placed in a container for cold extraction (soaking) in melt water at a temperature of 18 ± 2 ° C for 12 ± 2 hours. Melt water is preliminarily obtained by freezing and thawing in natural cold conditions at a temperature of minus 10-50 ° C. The resulting cold extract together with the bark is loaded into the boiler with a stirrer, where hot extraction is carried out with constant stirring of the stirrer at a temperature of 80 ± 10 ° C for 45-60 minutes. The ratio of the amount of bark to water by weight should be in the range from 1:10 to 1: 8.

Table 2 shows the dependence of obtaining a certain degree of extraction on the use of various types of extractants, which allows us to conclude that the use of various extractants at certain temperatures changes the degree of extraction of natural raw materials. When choosing melt water as an extractant, the degree of extraction of larch bark increases by an average of 9%, pine bark - by 11%.

After extraction, the hot solution is filtered, followed by squeezing the bark to completely extract the aqueous extract. Cooled liquid natural dye is poured through the filter into an opaque container or poured into hollow containers and dried in a ventilated room for 22-24 hours to obtain a dry residue at different temperature conditions, for example 70 ± 2 ° C or 40 ± 2 ° C or 15 ± 2 ° C. The resulting dry mass is ground to a powder and sieved.

The concentrated dry dye is dark brown and odorless. Its packaging can be carried out in paper bags.

To use the dye, the powder is dissolved in water, while it is recommended to use distilled and heated (up to 30 ° C) water. The amount of soluble dye powder is determined visually depending on the material to be painted, and the desired color saturation.

Natural dye in dry form can be stored up to 3 years, and in liquid form - for 1.0-1.5 years in a cool room (up to + 18 ° C). At the same time, the dye retains not only high coloristic properties, but also biologically active substances.

Used bark can be used to fertilize or mulch depleted soils, which contributes to a waste-free process.

The color of the natural dye depends on the type of bark, the degree of concentration of the extracts in various temperature conditions.

The proposed method is economical to obtain a natural vegetable dye, as it does not require the use of additional chemicals and expensive equipment.

Claims (1)

A method of obtaining a natural dye from larch bark, including crushing the bark, its aqueous purification and extraction in water, characterized in that the primary extraction is carried out in melt water at a temperature of 18 ± 2 ° C for 12 ± 2 hours, followed by secondary extraction in water without the use of chemical additives at a temperature of 80 ± 10 ° C for 45-60 minutes and filtering the resulting extract, while the ratio of the amount of bark to water by weight is from 1:10 to 1: 8, after which the extract is dried for 22-24 hours to floor cheniya dry mass at a temperature range of 15 ± 2 ° C and 70 ± 2 ° C depending on the desired dye color gamut, while the resulting dry mass ground to a powder.