JPS6257296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting and purifying natural sweet substances contained in Stevia rebaudiana Bertoni, a member of the Asteraceae family.

Stevia rebaudiana Bertoni (hereinafter referred to as stevia) stems, mainly leaves, contain steviosides such as ribaudioside A, ribaudioside C, ribaudioside D, ribaudioside E, and zurcoside A. It contains a sweet substance with a similar chemical structure (hereinafter referred to as stevia sweet substance).

To extract and purify stevia sweet substances from stevia, stevia leaves are extracted with water or hydroalcohol, and the resulting extract is treated with an ion exchange resin to remove impurities, or the extract is made non-polar. Generally, Stevia sweet substances in the extract were selectively adsorbed by treatment with an adsorbent made of a synthetic resin, and then desorbed.

However, the above extract contains a large amount of impurities such as bitter substances, colored substances, and odorous substances when used as is, and when performing the above treatment, it places a large load on ion exchange resins and adsorption resins, resulting in a decrease in the functionality of these resins. and caused deterioration.

Therefore, in order to reduce the load on the resin, various methods have been proposed to remove impurities from the extract in advance. For example, a method of adding calcium hydroxide, calcium chloride, etc. to the extract is known. However, even with the above method, the removal of impurities in the extract is not sufficient, and clogging and contamination of the ion exchange resin and adsorption resin have not been sufficiently eliminated.

The present invention has been made in view of the above-mentioned current state of the purification method for stevia sweet substances, and aims to provide a purification method that can precipitate and remove impurities in a stevia extract with higher efficiency than before.・Extract Rebaudiana Bertoni with water or alcohol, add a PH regulator to the resulting extract to bring the pH of the extract to 4 or less, and then add calcium hydroxide to remove impurities in the extract. A method for purifying a stevia sweet substance is characterized in that it is precipitated and separated, and a water-soluble organic solvent is added to the obtained liquid to precipitate and remove impurities in the liquid.

The present invention will be explained in more detail below.

Stevia extraction treatment with water or alcohol is usually carried out by immersing 1 kg of stevia leaves in 2 to 15 kg, preferably 3 to 10 kg of water or aqueous alcohol, and in most cases heating, but of course, stevia leaves are immersed in warm water from the beginning. You may. The stevia to be subjected to the extraction treatment may be a mixture of leaves and a portion of the stem, or the whole stevia plant may be appropriately crushed using a doji crusher, a corn crusher, or the like. The higher the extraction temperature, the higher the efficiency of extracting stevia sweet substances, but on the other hand, the amount of impurities extracted also increases.
It is said to be 50-80℃.

The pH of the extract or its concentrate obtained by extracting sweet substances from the leaves or stems of Stevia is usually about 5 to 7, but in the present invention, a PH regulator is added to the extract or concentrate. In addition, the pH is adjusted to 4 or less, and then calcium hydroxide is added.

Suitable examples of pH regulators include hydrochloric acid and phosphoric acid, and in some cases it is also possible to use metal chlorides, but using a small amount can lower the pH of the extract to 4 or less. Hydrochloric acid is most preferred because of its availability and ease of use. The pH of the extract just before adding calcium hydroxide is preferably from 1 to 3.5 in consideration of economic efficiency, since impurities do not precipitate in particularly large amounts even if the pH is excessively low.

The amount of calcium hydroxide added depends on the concentration of the above-mentioned extract, but if it is too small, the precipitation of impurities or the amount of coagulation and precipitation will be small, so it is usually 0.5% by weight or more for the extract whose pH has been adjusted to 4 or less. If the amount is too high, the pH of the extract may become too high and the stevia sweet substance may be decomposed, so the amount is usually set so that the pH of the extract does not exceed 13, preferably 12.

The precipitate formed by the addition of calcium hydroxide is generally a large floc and is easily separated and removed by filtration. Paper is generally used as the membrane, and pressurization and depressurization are carried out as appropriate to increase the overspeed.

A water-soluble organic solvent is added to the liquid obtained by separating the precipitated impurities, to further precipitate the impurities in the liquid.

Specific examples of water-soluble organic solvents include methanol,
Ethanol, propanol, acetone, etc. can be mentioned, and methanol, ethanol, and propanol are preferably used, and methanol is particularly preferably used. If the amount of the organic solvent added is too large, there is a risk that part of the stevia sweet substance will be lost when separating the precipitated impurities, and if it is too small, the impurity precipitation effect due to the addition of the solvent will not be achieved. The amount is preferably 5 to 50% by weight, more preferably 10 to 30% by weight based on the liquid.

In addition to the stevia sweetening substance, the liquid often contains impurities mainly consisting of various salts with smaller molecular weights, so either the liquid is further treated with an ion exchange resin to remove the remaining impurities, or Alternatively, it may be treated with a synthetic resin adsorbent to selectively adsorb the stevia sweet substance in the liquid and then desorb it.

The method for purifying a stevia sweet substance of the present invention is configured as described above, and according to the present invention, impurities in the stevia extract are significantly reduced compared to the conventional method of adding calcium hydroxide or calcium chloride to the stevia extract. By removing the precipitate at a high rate, a purified stevia sweet substance with a low degree of coloring can be obtained.

Furthermore, when purifying Stevia sweet substances using ion exchange resins or adsorption resins, the load on these resins can be reduced and the deterioration in function can be minimized.

Examples and comparative examples of the present invention are shown below.

% simply indicates weight %.

Separation and quantification of sweet substances was carried out by liquid chromatography under the following conditions.

Equipment: Nippon Waters Co., Ltd. 660 type column: μ Bondapack/NH ₂ Eluent: Acetonitrile/water (volume ratio 80/20) Detector: UV-210mm Example 1 Stevia rebaudiana Bertoni leaves
Add 8.5 kg of water to 1.5 kg, heat to 60℃, leave for 2 hours, remove Stevia leaves by centrifugation, and add 7.5 kg of water.
Kg of extract was obtained. The color of the extract is dark green, and the concentration of solids, sweet ingredients, and impurities vary.
They were 5.955%, 1.525%, and 4.430%.

Take 200g of the above extract and add hydrochloric acid to pH
When the temperature was adjusted to 3, a small amount of precipitate was deposited. Further, 2.00 g of calcium hydroxide was added to this solution to produce a large amount of precipitate, which was then removed by filtration. The weight percent of the precipitate was 5.55 g.

60 g of methanol was added to the resulting solution to further form a precipitate, and the precipitate was removed by filtration. The total weight of the precipitate, including that from the above separation, was 7.09 g. The sweet component in the final solution was 3.02 g (yield: 99%).

Therefore, it was calculated that the amount of impurities removed from the extract by the above pH adjustment and addition of calcium hydroxide and methanol was 5.09 g or more, and the impurity removal rate was about 57% or more.

The color of the liquid finally obtained was pale yellow.

Example 2 200 g of the extract obtained in Example 1 was taken, hydrochloric acid was added to adjust the pH to 2, and 2.00 g of calcium hydroxide was added to form a precipitate, which was separated.
20 g of methanol was added to the resulting liquid to further form a precipitate, which was removed. The total amount of sediment is 6.31
It was hot at g. In the same manner as in Example 1, the amount of impurities was calculated to be 4.31 g or more, and the impurity removal rate was calculated to be 48% or more.

The color of the obtained liquid was pale yellow.

Comparative Example 1 When 200 g was taken from the extract obtained in Example 1 and the pH was adjusted to 2 by adding hydrochloric acid, a small amount of precipitate (0.48 g) was precipitated. Based on the amount of sweet components in the liquid after separation, it was determined that all of the precipitates were impurities, and the impurity removal rate was calculated to be 5.4%.
The color of the obtained liquid was brown.

Comparative Example 2 200g of the extract obtained in Example 1 was collected,
calcium hydroxide without adjusting the pH of this solution.
Addition of 2.00g resulted in a precipitate (4.44g).
In the same manner as in Example 1, it was calculated that the amount of impurities was 2.44 g or more and the impurity removal rate was 27.5% or more. The color of the obtained liquid was brown.

Comparative Example 3 200 g of the extract obtained in Example 1 was taken, and 2.00 g of calcium chloride was added to this solution to form a precipitate (2.85 g). In the same manner as in Example 1, it was calculated that the amount of impurities was 0.85 g or more and the removal rate was 9.6% or more. The color of the liquid was blackish brown.

Comparative Example 4 In Comparative Example 2, instead of adding 2 g of calcium hydroxide, 2 g of calcium chloride was added and then 30 g of methanol was added for treatment. The amount of precipitate produced was 3.28 g. In the same manner as in Example 1, it was calculated that the amount of impurities was 1.28 g or more and the impurity removal rate was 14.4% or more. The color of the obtained liquid was dark green.

Claims (1)

[Claims] 1. Stevia rebaudiana Bertoni is extracted with water or alcohol, and the resulting extract is
After adding a PH regulator to adjust the pH of the extract to 4 or less, calcium hydroxide is added to precipitate and separate impurities in the extract, and a water-soluble organic solvent is added to the resulting liquid. A method for purifying a stevia sweet substance, which comprises removing impurities in the liquid by precipitation. 2. The purification method according to item 1, wherein the PH regulator is hydrochloric acid or phosphoric acid. 3 PH of extract after adjusting by adding PH adjuster
The purification method according to item 1 or 2, wherein is 1.0 to 3.5. 4. The purification method according to any one of Items 1 to 3, wherein the water-soluble organic solvent is at least one of methanol, ethanol, and propanol. 5. The purification method according to items 1 to 4, wherein the amount of the water-soluble organic solvent added is 5 to 50% by weight based on the liquid after addition.