KR920003049B1 - Process for refining sweetings from stevia - Google Patents

Abstract

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Description

Method of preparing stevia sweetener

The present invention relates to a purification method for preparing stevia sweetener by extracting stevioside and rebaudioside A from a stevioside-containing plant, and effectively removing impurities using tannins or tannic acid.

Stevia is a perennial plant of the Asteraceae, which is known to be native to parts of Brazil, mainly in Paraguay in South America, and is called Stevia Rebaudiana BERTONI (hereinafter abbreviated as Stevia). It is known to contain a large amount of glycosides such as rebaudioside A, B, C, D, E and steviol side. Stevia is a substance that is stable against heat and pH, and sweetener is a natural extract sweetener that is 200-300 times calories 1/300 of sugar and is expected to be expected in the future. Known purification methods for Stevioside and Rebaudioside A (hereinafter abbreviated as Stevio) currently contained in Stevia leaves include (1) removal of impurities by flocculants and the like, (2) crystal precipitation of Stevio by organic solvents. (3) method of separating stevio by adsorbent, (4) removing impurities by molecular filtration such as dialysis, ultrafiltration membrane, gel filtration, (5) purification method by ion exchange resin, (6) stevio transition There are ways.

However, such a known purification method is difficult when the high purity purification for commercialization of the product does not economically remove the pigment and a large amount of impurities contained in the stevia extract. Therefore, a typical manufacturing process is as follows.

In other words, the stevia extract has a large amount of protein, low-molecular sugars and pigments in the stevia extract in the conventional manufacturing process, and thus acts as an obstacle to the fine filtration using ion exchange resins, dialysis and ultrafiltration membranes, concentration and crystallization for recovery For this reason, it is known that impurities in the extract are first agglomerated, precipitated and removed by using a metal salt or the like.

Therefore, the inventors of the present invention, while continuing research on an effective purification method of stevia, knew the following facts.

In other words, as a pretreatment operation of stevia, tannin or tannic acid was found to have excellent coagulation effect while experiments were performed to aggregate and treat impurities such as calcium compounds, aluminum compounds, polyaluminum chloride (PAC), and alum.

Tannins are contained in the fruits of plants such as persimmons, tangerines, and acorns, and although often reported to be effective for protein separation, the present inventors experimented by adding them as a coagulant to the stevia extract, resulting in pigments, impurities, It was found that the cohesive force to coagulate and precipitate proteins and heavy metals was excellent.

The mechanism of precipitation formation in tannin or tannic acid is not known, but tannin has astringent properties, and has a characteristic taste. It has a general taste such as deterioration and precipitation of fruit wine and beer, and inhibition of enzyme activity. It is known as a factor causing deterioration of food quality. In addition, it is widely used for the detection of proteins using the astringent properties of tannin or tannic acid, analytical means for quantifying differential tannins, purification of enzymes, and protein removal of sake.

Hereinafter, the structure of the present invention will be described in detail, and the leaves and stems of dry stevia are pulverized, and an extract is obtained by water, an organic solvent or a combination of water and an organic solvent, and then tannin or tannic acid is added to the extract. Precipitation was produced by stirring at room temperature, and the polymer co-coagulant was added, followed by stirring for 1 hour.

At this time, the amount of tannic acid to be added is more than 0.3% (bubble volume), and as the coagulant, it is required to add 1.5% or more of the amount of tannic acid to be added as a -CH group high molecular organic compound.

When tannin acid is added below, cohesion decreases, and even when 5% or more is added, the process effect does not increase. When flocculation, pH should be adjusted properly to 5.0-11.0, and calcium hydroxide, quicklime, calcium carbonate, caustic soda, etc. are used as pH adjusting agent. Next, the precipitate formed by standing for 1 hour is removed.

Removal of the precipitate uses known methods. That is, the precipitate can be easily removed using a centrifugal separator, a filter press, a diatomaceous earth coated continuous filter, and a light brown liquid is obtained after removing the precipitate, wherein the discoloration rate is 98% and the impurity removal rate is 90% or more.

Table 1 is an experimental result comparing the discoloration rate and the impurity removal rate between the coagulation precipitation according to the present invention and the coagulation precipitation of the conventional method, it can be seen that the method of the present invention is much more effective than the conventional method. In addition, in the process of the present invention, the loss of sweet components of Stevioside and Rebaudioside A is very small, and more than 98% is recovered in the separation liquid.

TABLE 1

After the precipitation of the impurities is finished, the extract is removed by dialysis or ultrafiltration membranes to remove low molecular weight substances such as salts that have not been removed by coagulation, and are purified with high purity using an ion exchange resin.

That is, impurities are removed by selective adsorption and washing in the polystyrene porous adsorption resin, eluted with an organic solution, and then residual impurities are removed using a weakly alkaline anion exchange resin and a strong acid cation exchange resin. At this time, when the liquid passed through, a colorless liquid almost completely decolorized is obtained. After concentrating this and drying by lyophilization or spray drying, a product having a stevio content of 93% or more is obtained. The product was analyzed in addition to stevio, a small amount of water, ash and steviol derivatives, glucose and the like.

When purifying the treatment liquid obtained by treating tannin or tannic acid according to the present invention, the purification effect is the same even when using other well-known methods as well as membrane, dialysis, ultrafiltration membrane and ion exchange resin treatment. It will be described in detail in the following Examples.

Example 1

Hot water is added to 500 g of stevia dry leaves, and the residue is washed to obtain 10 liters of the extract. 120 ml of tannic acid and 2 ml of organic co-coagulant were added thereto, and then, the mixture was adjusted to pH 9.2 with Ca (OH) 2 with stirring, and allowed to stand for 30 minutes, followed by centrifugation to obtain 8.9 liters of light brown extract.

At this time, the decolorization rate (measurement of 420 nm) was 98.5% when measured by absorbance, 90.4% removal of impurities (excluding stevio content), and 98% recovery of stevio. 1,000 ml of a liquid having a content of 4.7% was obtained.

Example 2

Hot water was added to 1 kg of stevia dried leaves, extracted twice at 60 ° C. for 2 hours, and separated by a high-speed separator to obtain 19.2 liters of stevia extract. 8 ml of tannin 350ml organic polymer coagulant was added thereto, adjusted to pH 9.5 with CaO, stirred for 1 hour at 20 ° C, and filtered through a diatomaceous earth filter to obtain 18 liters of light brown extract. The decolorization rate was 99.1%, the impurity removal rate was 92.5%, and the stevio recovery rate was 99%. The impurities were removed by ultrafiltration membrane, selectively adsorbed by passing through 400 ml of porous adsorbent resin with SV = 3, washed with 5 liters of purified water, eluted with 50% -isopropanol solution, and then 200 ml of weak base. A colorless liquid was obtained by passing SV = 5 through the anion exchange resin and the strongly acidic cation exchange resin. It was spray dried to obtain 121.6 g of a white powder product, its stevioside content was 69.8% stevioside and 22.7% rebaudioside A2.

Claims (4)

A method for purifying a stevia sweetener, characterized by adding tannin or tannic acid to a stevia leaf extract containing stevioside and rebaudioside A to coagulate and precipitate impurities. The method of purifying a sweetener for stevia according to claim 1, wherein 0.3% to 5% of tannin or tannic acid is added. The method of claim 1, wherein the extract is pH 4.0 to 11.0 purification method of stevia sweetener. The method of purifying a sweetener for stevia according to claim 1, wherein an organic polymer having a -CH group is added as a coagulant.