JPS6260057B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to Stevia rebaudiana of the Asteraceae family.
This invention relates to a method for extracting and refining the natural sweet substances contained in Bertoni.

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-mentioned extract contains a large amount of impurities such as bitter substances, colored substances, and odorous substances when used as it is, and when performing the above-mentioned treatment, it places a large load on ion exchange resins and adsorption resins, impairing the functions of these resins. This was causing deterioration and 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 or calcium chloride 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.・After extracting Rebaudeiana Bertoni with water or alcohol and adding a PH regulator to the resulting extract to adjust the PH of the extract to 4 or less,
A method for purifying a stevia sweet substance is characterized in that impurities in an extract are precipitated and removed by adding calcium hydroxide.

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 considered to be 50-80℃.

The pH of the above extract or its concentrate obtained by extracting sweet substances from Stevia leaves or stems is usually 5 to 5.
7, and add a PH adjuster to this extract to adjust the PH.
By adjusting the pH to 4 or less and then adding calcium hydroxide, a much larger amount of impurities can be precipitated and removed than when calcium hydroxide is added when the pH is over 4. .

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 will not precipitate in particularly large amounts even if it is lowered excessively.

The amount of calcium hydroxide added depends on the concentration of the above-mentioned extract, but if it is too small, impurities will precipitate or the amount of coagulation and precipitation will be small, so it is usually 0.5% by weight or more based on the extract whose pH has been adjusted to 4 or less. It is said that
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.

In order to purify the stevia sweet substance by the purification method of the present invention, first, as described above, stevia is extracted with water or alcohol, and a PH adjuster such as hydrochloric acid is added to the obtained extract to adjust the PH to 4 or less. Depending on the concentration and pH of the extract, a small amount of impurities usually precipitate. Furthermore, when calcium hydroxide is added to this solution, a large amount of impurities in the extract precipitate, but since this precipitate is generally a large floc-like substance, it is easy to separate it by filtration, and paper is generally used as a filtration membrane. is used, and pressurization and depressurization are performed as appropriate to increase the overspeed.

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, compared to the conventional method of adding calcium hydroxide or calcium chloride to the extract obtained by extracting stevia, , impurities in the extract can be precipitated and removed at a high rate.

Therefore, when stevia sweet substances are further purified 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: Model 660 manufactured by Nippon Waters Co. Column: μ Bondabac/ _NH2 Eluent: Acetonitrile/Water (volume ratio 80/20) Detector: UV-210nm Example 1 Leaves of Stevia rebaudiana Bertoni
8.5 kg of water was added to 1.5 kg, heated to 60°C, left for 2 hours, and the stevia leaves were removed by centrifugation to obtain 7 kg of extract. 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 2.00g from the above extract and add hydrochloric acid to pH
When adjusted to 1.2, a small amount of precipitate was deposited.
Furthermore, 3.20 g of calcium hydroxide was added to this solution to produce a large amount of precipitate, which was then removed by filtration. The weight of the precipitate was 7.20 g. The sweetness component in the liquid was 3.035g (yield 99.5%).

Therefore, it was calculated that the amount of impurities removed from the extract by the above pH adjustment and addition of calcium hydroxide was 4.0 g or more, and the impurity removal rate was 45% or more. The color of the obtained liquid was light brown.

Example 2 The same treatment as in Example 1 was carried out, except that 2.00 g of the extract collected in Example-1 was added with hydrochloric acid to adjust the pH to 3, and then 2.00 g of calcium hydroxide was added. When this was done, 5.55 g of precipitate was produced.
In the same manner as in Example 1, the impurities removed were 3.55
g or more, the impurity removal rate was calculated to be 40% or more. The color of the obtained liquid was light brown.

Example 3 After adjusting the pH of the fractionated extract to 2, 5.65 g of precipitate was produced in the same manner as in Example 1, except that 2.00 g of calcium hydroxide was added. The amount of impurities removed was 3.65g in the same manner as in Example 1.
As described above, the impurity removal rate was calculated to be 41% or more. Moreover, the color of the obtained liquid was light brown.

Comparative Example 1 2.00 g was taken from the extract obtained in Example 1, and hydrochloric acid was added to this liquid to adjust the pH to 2, resulting in a small amount of precipitate (0.48 g). 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 2.00 g of the extract obtained in Example 1 was taken, and 2.00 g of calcium hydroxide was added to the extract without adjusting the pH of the solution to form a precipitate (4.44 g). In the same manner as in Example-1, the amount of impurities was calculated to be 2.44 g or more, and the impurity removal rate was calculated to be 27.5% or more. The color of the obtained liquid was brown.

Comparative Example 3 2.00 g was taken from the extract obtained in Example 1, 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 green.

Claims (1)

[Claims] 1. Stevia rebaudiana Bertoni is extracted with water or alcohol, and the resulting extract is
A method for purifying a stevia sweet substance, which comprises adding a pH adjuster to adjust the pH of the extract to 4 or less, and then adding calcium hydroxide to precipitate and remove impurities in the extract. 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.