Method for producing of stevioside

FIELD: food-processing industry.

SUBSTANCE: method involves extracting ground dry leaves of Stevia Rebaudiana B. plant by liquefied CO₂ in sub-critical or above-critical state; providing aqueous extraction of leaves at temperature of 30-90°C in rotary-cavitational type extractor with cavitation index K=0.8-1.9; separating extract from solid residue by centrifuging process, with following separation thereof for separating of suspensions; providing ultra-filtering cleaning of extract at temperature of 20-95°C, under pressure of 0.1-2.0 MPa and liquid flow rate of 1.0-8.0 m/s above membrane; subjecting resultant concentrate to diafiltering by means of membranes with average pore size of 25-500 Å; after diafiltering, concentrating extract by back osmosis process and subjecting to additional cleaning procedure on ion-exchange columns; concentrating clean concentrate in thin-film vacuum evaporation apparatus at temperature of 45-95°C and drying concentrate in sprayer-type drier at temperature of 100-160°C until residual moisture content of powder is below 10%.

EFFECT: high extent of cleaning of extract, reduced loss of stevioside, increased yield and purity of ready product.

4 cl, 2 ex

The invention relates to food industry, namely the method of producing reveal from the leaves of the plant Stevia Rebaudiana Century, which can be used in the food industry as sweeteners.

There is a method of isolation and purification of the reveal, including water extraction of the leaves of Stevia Rebaudiana Century in a weak alkaline medium, purification of the extract column chromatography using nonpolar porous polymer resin, the selection of reveal the elution (JP, 55-40596, 1980).

The disadvantage of this method is its high energy and labor to restore polymer resin.

A method of obtaining the reveal from vegetable raw materials, including water extraction of dried plant material of Stevia Rebaudiana Century at a temperature of 20-65 ° With removal of impurities by treating the extract of CA(Oh)₂, filtration, ion exchange purification through a column of strongly acidic resin to the desired purity, concentration and drying (EP 0302948,1987).

The disadvantage of this method is the complexity and high cost of the process.

Closest to the claimed is a method for the reveal, which includes water extraction of crushed dried leaves of the plant Stevia Rebaudiana Century, the separation of the extract from the solid residue, purification of the extract by ultrafiltration and concentration (authors the first certificate of the USSR No. 1741737, publ. 1992).

The disadvantages of the method include loss of the target product in the process of retrieval, and a significant content of impurities, representing pigments, protein and pectin substances, which reduce the quality indicators of the finished product.

The present invention aims to improve the purification efficiency and reduction of losses reveal in the course of its processing.

This technical result is achieved in that in the method of producing reveal, including water extraction of crushed dried leaves of the plant Stevia Rebaudiana Century, the separation of the extract from the solid residue, purification of the extract by ultrafiltration, its concentration and drying, provide that before water extraction of crushed dried leaves of the plant Stevia Rebaudiana Century is subjected to extraction for 5-120mm minutes liquefied CO₂located in the subcritical or supercritical state, with periodic pressure relief extractors with subsequent restoration to its initial value, and water extraction was carried out at a temperature of 30-90°With the rotary extractor-cavitation-type when the cavitation index K=0.8 to 1.9, and is separated from the solid residue by centrifugation when the separation factor F_R=100-2000 with subsequent separation, ultrafiltration wire is t at a temperature of 20-95° Since, the value of the working pressure 0.1-2.0 MPa and speed of flow of liquid over the membrane 1,0-8,0 m/s to remove from the extract of pigments, protein and pectin substances with subsequent diafiltrate the resulting concentrate, using membranes with an average pore size 25-500 And, moreover, the concentration of the extract is carried out by reverse osmosis at a temperature of 20-95° C, working pressure up to 8.0 MPa on the membranes, with 95-99%selectivity for sodium chloride, to the content of the reveal in the obtained extract not less than 100 mg/l, and the extract is subjected to additional cleaning on ion exchange columns, after ionoobmennoi cleaning implement additional concentration of purified extract in thin film vacuum evaporation apparatus at a temperature of 45-95°to content reveal the solution is not less than 200 mg/l, and drying of the concentrate is carried out in a spray dryer at a temperature of 100-160 °C to a residual moisture content of the obtained powder is not more than 10%.

In addition, during the extraction of liquefied CO₂in addition, you can perform ultrasonic processing of raw materials at a frequency 16-120 kHz for a period of not more than 30 minutes.

If diafiltration can use drinking water to the dilution factor of 10-15.

Before water extraction can be performed more grinding raise inogo raw materials.

These characteristics are interrelated with the formation of a stable set of essential features, sufficient to obtain the desired technical result.

The method is as follows.

Dry plant material representing the leaves of the plant Stevia Rebaudiana Century, is directed to apparatus for grinding raw material, which is preferably carried out until the particle size 1.0-2.0 mm, followed by processing in the mill with the formation of petals with a thickness of 0.1-0.2 mm

Then the crushed raw materials are weighed and loaded into the extractor. In the loaded extractor serves liquefied CO₂and begin the process of extraction of raw data extractant in its subcritical (t=0-30°C, R=3,5-7,2 MPa) or in a supercritical state (t=32-72°C, P=8.0 To 40 MPa). The extraction process is carried out in the course of the 5-120mm minutes depending on the content in the original plant material of essential oils, fatty acids, lipids and pigments, polluting the obtained target product is stevioside. The extraction process are periodically reset the pressure in the extractor are one order of magnitude (10 times) and then restoring the original values of the pressure, by submitting the extractor new portions of the liquefied gas.

Such pulsations are an integral part of the process. They allow to increase the purity of the target issue for lighting the th product and significantly reduce the duration of the process of its receipt.

In the course of CO₂extraction to improve its efficiency possible the implementation of ultrasonic influence on vegetable raw materials. Ultrasonic treatment is carried out mainly at a frequency 16-120 kHz for a period of not more than 30 minutes, which allows for increased pollutant target product and reduce the duration of the process.

After completion of the CO₂extraction purified from essential oils, fatty acids, polyphenols, lipids and other substances of vegetable raw material is subjected to aqueous extraction, which is carried out at a temperature of 30-90°and water ratio mixture, mainly 1:5, extracter rotary cavitation type when cavitation index K=0.8 to 1.9. If necessary, the mixture is alkalinized with lime milk to pH 8.0, and 9.0. In the process of water extraction get a lot with the particle size of the solid phase 1-100 μm. In the cavitation effect is the destruction of cell walls of plant material, which allows to fully extract the target product.

To intensify the process of water extraction may further grinding plant, past CO₂extraction.

For coarse separation of the mass into solid and liquid fractions is carried out by centrifugation when the separation factor F_R= 100-2000. The separation factor is chosen in C is depending on the type centrifuge (model, brand, modification). Separated by centrifugation of the liquid fraction is subjected to separation to increase the degree of its purification from the contained sediment.

Obtained after separation of the extract reveal purified by ultrafiltration, which is carried out at a temperature of 20-95°C, the value of the working pressure 0.1-2.0 MPa and speed of flow of liquid over the membrane 1,0-8,0 m/s to remove from the extract 90-95% of pigments, protein and pectin substances. To reduce losses reveal during technological processing immediately after the ultrafiltration membrane installation toggle diafiltration in its path add fresh servings of drinking water. The process parameters of diafiltrate the same parameters of the ultrafiltration process. The dilution factor when diafiltration equal to 10-15. Using diafiltration allows to increase the output of the reveal 2.0-2.5 times.

For carrying out the ultrafiltration process and diafiltration use membranes with an average pore size 25-500.

The wide limits of settings ultra and diafiltration determined depending on the type of membranes, their material and type of substrate. So, at a temperature of 20°for ultra - and diafiltration use membrane UAM-20 POINTS, while at a temperature of 95° - UPM-20.

NASM is rubbing on something that stevioside is a substance not thermolabile, raising the temperature to 95°caused by an increase in the performance of the process.

Because in the process of diafiltration the total amount of purified extract increases, carry out the process of its concentration to the content of the reveal in it not less than 100 mg/L.

Concentration is carried out using the reverse osmosis process at a temperature of 20-95°C, working pressure up to 8.0 MPa using membranes, preimushestvenno MGA-P-T, with 95-99%selectivity for sodium chloride.

Final purification of the concentrated extract is performed on ion-exchange columns to content in the extract of at least 90% of the reveal.

For more effective cleaning of the extract is cleaned by sequential passage through ion exchange columns filled with initially strong anyone - and cation-exchange materials, and then weak katiana - and anion-exchange materials.

This terminology is commonly used in industry. For the practitioner it is identifiable. However, to bring it in line with the generally accepted technical literature under strong anyone - and cation-exchange materials should be same strong-base anion exchange resin and a strongly acidic cation exchangers, and under weak Catino and anyoneeven and materials - weak acid cation exchangers and weakly basic anion exchange resin.

As a weak acid cation exchange materials are used mainly amberlite resin IRC-50, as the strongly acidic cation-exchange materials - IR-120. As a strongly basic anion-exchange materials are used mainly amberlite resin IRA-410, and as weakly basic - IRA-458.

The process of ion-exchange treatment is carried out to obtain an extract containing not less than 90% of the reveal. Ion-exchange purification allows you to remove from the extract of the free amino acids, vitamins, mineral admixtures.

Purified on ion-exchange columns extract additional focus to the content reveal the solution is not less than 200 mg/l in thin film vacuum evaporation apparatus at a temperature of 45-95°that reduces the degradation of reveal in the process of spray drying, and the load on the drying installation.

Drying of the concentrate is carried out by spray drying at a temperature of media, preferably air, 100-160°C. the Spray drying process reduces the degradation of the target product. Drying lead to a residual moisture content of the finished product not more than 10%.

Formed at the stage of diafiltration by-product - pigment-carbohydrate concentrate, containing almost the entire original complex vitamins to anti scar is new, mineral and protein substances leaves of the plant Stevia Rebaudiana Century, has high nutritional and bioactive properties and can be used in natural or dried form in the manufacture of various food items traditional or medicinal purposes, and in the production of dietary SUPPLEMENTS.

The method is illustrated by the following examples of its implementation.

Example 1.

Dry plant material representing the leaves of the plant Stevia Rebaudiana Century, is directed into a hopper apparatus for grinding raw material, which is preferably carried out until the particle size 1.0-2.0 mm, followed by processing in the mill, with the formation of petals with a thickness of 0.1-0.2 mm

Then the crushed raw materials in the amount of 100 kg loaded into the extractor in cassettes stainless mesh. In the loaded extractor serves liquefied CO₂in the amount of 900 kg and start processing raw data extractant under the following process parameters: t=20°C, P=5.7 MPa. The treatment is carried out for 60 minutes, the rate of pressure relief for the implementation of the pulsating explosions - 2.0 MPa/min. Residual pressure in the extractor 0.3 MPa, the frequency of discharge of miscella in the receiver - once in 5 minutes.

After that cleared the meal is subjected to aqueous extraction, which is carried out at a temperature of 60°With the rotary extractor-CAW is operating type, when the cavitation index K= 0.8, the water ratio mixture of 1:5 and pH 8.5. The process is conducted within 45 minutes.

For the Department received the extract from the solid phase carry out the centrifugation of the slurry in the separation factor F_R=1000, and then separation of the separated extract to remove most of the suspended solids.

Extract reveal then purified by ultrafiltration, which is carried out at a temperature of 40°With, the working pressure of 0.2 MPa and speed of flow of liquid 3.0 m/s over the membrane UPM-10. Focusing initial volume of the extract in 10 times, ultrafiltration installation switch mode diafiltration, which is carried out at a temperature of 20-95°C, the value of the working pressure 0.1-2.0 MPa and speed of flow of liquid on the membrane of 1.0-8.0 m/s, while the process is conducted drinking water to the dilution factor of 10-15.

In its path add fresh servings of drinking water to the original volume of the solution. For carrying out the ultrafiltration process and diafiltration use membranes with an average pore size 25-500. Because in the process of diafiltration the total amount of purified extract increases, hold his concentration using reverse osmosis on the membranes of the brand OPM-KM at a temperature of 40°and an operating pressure of 5.0 MPa to content in the eating of the reveal of 150 mg/L.

Final purification of the concentrated extract is carried out at a temperature of 55°With ion-exchange columns beginning with a strong anyone- (IRA-410) and cation exchange (IR-120) and then with a weak katiana- (IRC-50) and anion exchange (IRA - 458) materials to content in the extract 90% of the reveal.

The extract obtained additional focus to the content of the reveal in a solution of 250 mg/l in thin film vacuum evaporation apparatus at a temperature of 60°C.

Drying of the concentrate is carried out by spray drying at a temperature of inlet air 140°and at the output 80°C.

The final product of the process is a dry powder of the reveal with a moisture content of 8.0%, yellowish-white, purity 90%, degree of sweetness relative to sucrose 1:250.

Example 2.

The example is carried out in accordance with example 1, except that the amount of raw material is 20 kg, and the quantity of liquid carbon dioxide - 400 kg

In addition, the process carbon dioxide extraction is carried out at supercritical extractant, while during the process along with the pulsator, optionally use the ultrasonic generator. After impregnation solvent sudden release of pressure carried out with a speed of 6.0 MPa/min Parameters of the extraction process: temperature 60°C, a pressure of 20 MPa, deletelines the ü - 30 minutes, the frequency of discharge of miscella - once in 6 minutes. The oscillation frequency of the ultrasound 100 kHz, the processing time of the raw ultrasound - 25 minutes.

The process of water extraction is carried out at a water ratio mixture of 1:8, a temperature of 55°C, pH of 8.2, when the cavitation index K= 1,9 within 30 minutes. Centrifugation is carried out at the separation factor F_R=1800.

The ultrafiltration is carried out at a temperature of 50°With, the working pressure of 0.5 MPa and speed of flow of liquid to 4.0 m/s over the membrane BTU-PSA-5.

Switching mode diafiltration carried out after reducing the original volume of the extract 11 times.

Concentration is performed on the membranes of the brand there-KM at a temperature of 45°and an operating pressure of 5.0 MPa to content they reveal to 200 mg/L.

Final purification of the concentrated extract is carried out at a temperature of 55°With ion-exchange columns beginning with a strong anyone- (IRA-410) and cation exchange (IR-120) and then with a weak katiana- (IRC-50) and anion exchange (IRA - 458) materials to content in the extract 93.5 per cent of the reveal.

The extract obtained with purity of 93.5% extra focus to content in the reveal of 300 mg/l in thin film vacuum evaporation apparatus at a temperature of 60°C.

Drying of the concentrate is carried out by spray drying oven at a temperature on the I is de 130° C, and the output is 75°C.

The final product of the process is a dry powder of the reveal with a humidity of 10%, white color, purity of 93.5%, a degree of sweetness relative to sucrose 1:280.

1. The method of producing reveal, including water extraction of crushed dried leaves of the plant Stevia Rebaudiana Century, the separation of the extract from the solid residue, purification of the extract by ultrafiltration, its concentration and drying, characterized in that before the water extraction of the crushed dry leaves of the plant Stevia Rebaudiana Century is subjected to extraction for 5-120mm min liquefied CO₂located in the subcritical or supercritical state, with periodic pressure relief extractors with subsequent restoration to its initial value, and water extraction was carried out at a temperature of 30-90°With the rotary extractor-cavitation-type when the cavitation index K=0.8 to 1.9, and is separated from the solid residue by centrifugation when the separation factor F_R=100-2000 with subsequent separation, ultrafiltration is carried out at a temperature of 20-95°C, the value of the working pressure 0.1-2.0 MPa and speed of flow of liquid over the membrane 1,0-8,0 m/s to remove from the extract of pigments, protein and pectin substances with subsequent diafiltrate the resulting concentrate using membranes with an average pore size 25-500 moreover , the concentration of the extract is carried out by reverse osmosis at a temperature of 20-95°C, working pressure up to 8.0 MPa on the membranes, with 95-99%selectivity for sodium chloride content of the reveal in the obtained extract not less than 100 mg/l, and the extract is subjected to additional purification on ion-exchange columns, after the ion-exchange purification of implementing the additional concentration of purified extract in thin film vacuum evaporation apparatus at a temperature of 45-95°to content reveal the solution is not less than 200 mg/l, and drying of the concentrate is carried out in a spray dryer at a temperature of 100-160°C to a residual moisture content of the obtained powder is not more than 10%.

2. The method according to claim 1, characterized in that in the process of extraction of the liquefied CO₂additionally, by ultrasonic processing of raw materials at a frequency 16-120 kHz for a period of not more than 30 minutes

3. The method according to claim 1, characterized in that when diafiltration use drinking water to the dilution factor of 10-15.

4. The method according to claim 1, characterized in that before water extraction spend additional grinding plant.