CN101343298A - Preparation method of secondary purification of purple sweet potato anthocyanins by cation exchange resin - Google Patents

Abstract

The invention relates to a method for preparing purple sweet potato anthocyanins for secondary purification by cation exchange resins. The main technical feature is that the primary refined products of purple sweet potato anthocyanins are used as raw materials, and the primary refined products are adsorbed, removed and eluted with cation exchange resins. The secondary refined purple sweet potato anthocyanin product is obtained by freeze-drying, and the anthocyanin content of this product is more than 2 times higher than that of the primary refined product. In the present invention, the cation exchange resin technology is successfully used in the further purification of purple sweet potato anthocyanins. The obtained purple sweet potato anthocyanins are bright and natural in color, non-toxic, and have no special smell. They have various nutritional, pharmacological and health-care functions. The natural food pigment resource provides the possibility for the large-scale industrial secondary refining of purple sweet potato anthocyanin products with high biological activity, and lays the foundation for the further development and wide application of the obtained active products.

Description

Preparation method of secondary purification of purple sweet potato anthocyanins by cation exchange resin

technical field

The invention relates to the field of biochemistry, in particular to a preparation method for further purifying purple sweet potato anthocyanin from a primary refined product of purple sweet potato anthocyanin by using a cation exchange resin.

Background technique

Anthocyanin is one of the most widely used natural food colorings in the world. Because of its high safety, most countries such as China, Japan, the United States, the European Community and other countries allow it to be used for food coloring. Listed as colorants that do not require a license. The earliest person to use the name of anthocyanin was Marguart (1835). He extracted a blue pigment from cornflower flowers for the first time, so he called it anthocyanin.

Anthocyanins are composed of anthocyanins and sugars combined by glycosidic bonds, and belong to flavonoid polyphenols. Studies have shown that the carbon skeleton structure of natural anthocyanins is C ₆ C ₃ C ₆ . The polyhydroxy and methoxy derivatives of flavylium, see the carbon skeleton structure of anthocyanins in the figure below:

Most anthocyanins have substituted hydroxyl groups on the 3,5,7-carbon positions of anthocyanins. Due to the different numbers and positions of the substituents on each carbon position of the B ring——hydroxyl and methoxyl groups, various types of anthocyanins are formed. There are more than 250 kinds of anthocyanins known to exist naturally. Anthocyanins currently on the market mainly come from purple grape skins, black rice, black beans, etc., which are scarce resources. The rise of purple sweet potatoes provides an important raw material basis for the industrialization of anthocyanins.

Purple sweet potato originated in Japan and was introduced into my country in the 1980s. The content of anthocyanins in purple sweet potato is relatively high, up to 60mg/100g fresh potato. The natural food coloring produced by purple sweet potato is safe, non-toxic, non-odor, bright in color, and has certain nutritional and pharmacological effects. It has great application potential in food, beverage, cosmetics, and medicine. my country has made great progress in the extraction of pigments from purple sweet potatoes, and the extraction technology has become increasingly mature. In addition, purple sweet potatoes have high yields and wide adaptability. Therefore, compared with grape skins and black rice, the extraction of anthocyanins from purple sweet potatoes has more raw materials It has the advantages of easy source, high pigment yield, and low extraction cost; in addition, its acylation group makes it less sensitive to light, heat, air, etc. than ordinary anthocyanins, and its properties are more stable.

The main components of purple sweet potato anthocyanins are derivatives of acylated cyanidin and paeoniflorin. The main active group of anthocyanin antioxidant activity is the phenolic hydroxyl group in the molecule. There are multiple phenolic groups in the structure of purple sweet potato anthocyanins Hydroxyl, its acyl component is also an aromatic acid containing phenolic hydroxyl, they are all hydroxyl donors, but also a free radical scavenger. Existing experiments have proved that paeoniflorin isolated from purple sweet potato has antioxidant activity equivalent to that of butylated hydroxyanisole (HBA), and the antioxidant capacity of pigments extracted from purple sweet potato pulp and peel can be compared with BHA and BHT. comparable to. A large number of in vitro experiments on antioxidant activity showed that purple sweet potato anthocyanins exhibited considerable reducing power in the model, the ability to scavenge hydroxyl radicals, resist Fe ²⁺ -induced peroxidation of lecithin liposomes and inhibit the formation of lecithin liposomes by H ₂ O ₂ The ability to induce hemolysis of red blood cells.

Through searching, it is found that macroporous adsorption resin technology is the main method for purifying natural pigments at present. After being treated with macroporous resin adsorption technology, it can effectively remove a large amount of moisture-absorbing components such as sugars, inorganic salts, and mucilage in the pigment extract, which is beneficial to enhance the stability and solubility of the product, and at the same time make the pigment components highly enriched and Improve pigment quality. Nevertheless, the purified anthocyanins are only more than ten percent, and the color value is not ideal.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a preparation method for secondary purification of purple sweet potato anthocyanins by using cation exchange resins, which can realize industrialized further purification and preparation of refined purple sweet potato anthocyanins.

Technical scheme of the present invention is:

A preparation method for secondary purification of purple sweet potato anthocyanins by cation exchange resin, the steps of the preparation method are:

(1). Preparation of raw materials: Dissolve the primary refined product of purple sweet potato anthocyanin in water, filter to obtain a clear clear liquid, dilute the clear liquid so that the absorbance value (527nm) of the clear liquid is 10-100, and adjust the pH value to 3～3.5;

(2). Adsorption: The supernatant is loaded into the sample, and the purple sweet potato anthocyanin is slowly adsorbed on the cation exchange resin column at a temperature of 5-50°C and a flow rate of 0.5-3BV/h;

(3). Impurity removal: After the adsorption is completed, the unadsorbed residual liquid is eluted with distilled water with a pH of 2.5 to 3.5 at 2 to 5 BV/h until the effluent is colorless;

(4). Elution: use the eluent to desorb with the constant flow pump to control the flow rate, and elute the purple sweet potato anthocyanin adsorbed on the cation exchange resin at a temperature of 5-50°C and a flow rate of 0.5-2BV/h. Collect the elution mixture;

(5). Recovering the eluent: recovering ethanol from the eluent mixture by vacuum distillation;

(6). Impurity removal again: put the ethanol-removed eluent mixture on the AB-8 macroporous adsorption resin, distilled water to elute the hydrochloric acid in the mixture, and use the eluent to elute the purple sweet potato anthocyanin on the macroporous adsorption resin , collecting the elution mixture;

(7). Recovering the eluent: recovering the eluent from the above-mentioned eluent mixture by vacuum distillation;

(8). Freeze-drying: Freeze-dry the elution mixture from which part of the eluent is removed until the eluent is exhausted, and then the purple sweet potato anthocyanin product can be obtained.

Moreover, the purple sweet potato anthocyanin dissolved in water is filtered by a centrifugal filtration method or a plate and frame filtration method, and a constant flow pump is used to control the flow rate.

Moreover, the cation exchange resin column is: polar macroporous cation exchange resin D061, polar macroporous cation exchange resin D072, polar cation exchange resin 002×7, polar cation exchange resin 001×7×7 or polar Cation exchange resin 001×4.

Moreover, the eluent in step (4) is a 50% ethanol solution containing 2% hydrochloric acid.

Moreover, the eluent in step (6) is an aqueous ethanol solution with a concentration of 40-95% (V/V).

Advantage and positive effect of the present invention are:

1. The preparation process of the present invention is relatively simple, the chemical properties of the product are stable, and the cost of large-scale production is low. The cation exchange resin technology is successfully used in the secondary refining of purple sweet potato anthocyanins, and it is a purple sweet potato anthocyanin product with relatively high purity and color value The large-scale industrialized refined production provides the possibility for the further development and wide application of the obtained active product.

2. The color value of the purple sweet potato anthocyanin product obtained by the present invention is increased by more than 2 times on the original basis, which solves the long-standing problems of low color value and poor stability of natural pigments. In addition, we measured the total polyphenols and total flavonoids content of this product, and found that the total polyphenols and total flavonoids content of the product has increased compared with the original, and the advancement is very obvious.

3. The present invention can also measure the antioxidant capacity of the obtained purple sweet potato anthocyanins. Experiments have proved that the obtained purple sweet potato anthocyanins have strong antioxidant properties, have a positive effect on protecting liver function and reducing serum transaminases, have a strong inhibitory effect on oncogenes, and are also effective on cardiovascular diseases such as hypertension. Good preventative effect.

Detailed ways

The present invention will be further described in detail below through the specific examples, the following examples are only descriptive, not restrictive, and cannot limit the protection scope of the present invention with this.

The cation exchange resins adopted in the present invention are respectively: polar macroporous cation exchange resin D061, polar macroporous cation exchange resin D072, polar cation exchange resin 002 × 7, polar cation exchange resin 001 × 7 × 7 and Polar cation exchange resin 001×4. The present invention is described only by taking polar macroporous cation exchange resin D061 as an example, and the working modes of other cation exchange resins are basically the same as D061.

A preparation method for secondary purification of purple sweet potato anthocyanins by cation exchange resin, the steps of the preparation method are:

(1). Raw material preparation: The raw material used in the present invention is a primary refined product of purple sweet potato anthocyanins. Dissolve the primary refined product in water and filter to remove insoluble matter. The filtration method can be filtered by centrifugal filtration or plate-and-frame filtration. After filtration, a clear clear liquid can be obtained. Dilute the clear liquid properly to make the clear liquid The absorbance value (527nm) is 10-100, and the pH value is adjusted to 3-3.5;

The treated polar macroporous cation exchange resin D061 resin was wet-packed in distilled water, the glass column was 1.7×42cm, the height of the resin column was 38cm, and the volume of the resin was about 250ml.

(2). Adsorption: Load the supernatant liquid as a sample, and slowly adsorb purple sweet potato anthocyanins on a cation exchange resin column at a temperature of 20°C and a flow rate of 1.0 column volume per hour (BV/h). Use a constant flow pump to control the flow rate; when the absorbance value in the effluent reaches 1/10 of the absorbance value of the sample, it is considered that the breakthrough point of adsorption has been reached, and the sample injection is stopped, and the sample volume is 1000ml;

(3). Impurity removal: After the adsorption is completed, the unadsorbed residual liquid is eluted with 2.0 BV/h of distilled water with a pH of 3 until the effluent is colorless;

(4). Elution: use the eluent to desorb with the constant flow pump to control the flow rate, and elute the purple sweet potato anthocyanin adsorbed on the cation exchange resin at a temperature of 20°C and a flow rate of 0.5BV/h, and collect the The mixed solution was eluted, and the eluent was a 50% ethanol solution containing 2% hydrochloric acid.

(5). Recovering the eluent: recovering ethanol from the eluent mixture by vacuum distillation;

(6). Impurity removal again: AB-8 macroporous adsorption resin is applied to the ethanol-removed eluent mixed solution, and the hydrochloric acid in the distilled water elutes the mixed solution, and the eluent (ethanol-water solution, whose concentration is 40～95%) (V/V)) elute the purple sweet potato anthocyanins on the macroporous adsorption resin, and collect the elution mixture;

(7). Recovery of the eluent: the eluent mixture is recovered by vacuum distillation;

(8). Freeze-drying: freeze-dry the elution mixture from which part of the eluent has been removed until the eluent is exhausted, and then the purple sweet potato anthocyanin product can be obtained.

In the present invention, the content of purple sweet potato anthocyanins prepared by cation exchange resin D061 can be expressed by the result determined by the color value method, and the specific determination method and result calculation are carried out according to the following steps:

After refining, the purple sweet potato pigment is subjected to vacuum freeze-drying for 24 hours to obtain the purple sweet potato pigment dry powder. Accurately weigh 1.000g of the primary refined and secondary refined pigment products respectively, dissolve them in a citric acid-disodium hydrogen phosphate buffer solution with pH=3.0, set the volume in a 100mL volumetric flask, filter out the insoluble matter, and take 1mL of the pigment The solution was diluted to an appropriate multiple, the absorbance value was measured at a wavelength of 527nm, and the color value was calculated according to formula 1.

${\mathrm{E.}}_{1\mathrm{cm}}^{1\%}=\frac{A\×B}{W}$ Formula 1

in:

A: Absorbance value

B: dilution factor

W: pigment quality

Measure product color price according to formula 1 experimental method:

A refined product ${\mathrm{E.}}_{1\mathrm{cm}}^{1\%}=62.4;$ Secondary Refined Products ${\mathrm{E.}}_{1\mathrm{cm}}^{1\%}=136.8.$

The color price of secondary refined products is 2.19 times higher than that of primary refined products.

Claims (5)

1. the preparation method of a cation exchange resin secondarily purified anthocyanins pigment from purple sweet potato, it is characterized in that: preparation method's step is:

(1). feedstock production: a purified product of anthocyanins pigment from purple sweet potato is soluble in water, filter and to obtain clarifying clear liquid, diluting the absorbance (527nm) that this clear liquid makes this clear liquid is 10～100, regulating the pH value is 3～3.5;

(2). absorption: with sample on the clear liquid, be that 5～50 ℃, flow velocity are under 0.5～3BV/h condition, slowly on cation exchange resin column, carry out the absorption of anthocyanins pigment from purple sweet potato in temperature;

(3). removal of impurities: after absorption finishes, being the raffinate that 2.5～3.5 distilled water wash-out does not adsorb with the pH of 2～5BV/h, is colourless to effluent liquid;

(4). wash-out: using constant flow pump control flow velocity to carry out desorb with elutriant, is that wash-out is adsorbed on anthocyanins pigment from purple sweet potato on the Zeo-karb under 0.5～2BV/h condition at 5～50 ℃ of temperature, flow velocity, collects this wash-out mixed solution;

(5). reclaim elutriant: adopt the underpressure distillation mode to reclaim ethanol this wash-out mixed solution;

(6). removal of impurities again: will remove AB-8 macroporous adsorbent resin on the alcoholic acid wash-out mixed solution, the hydrochloric acid in the distilled water wash-out mixed solution with the anthocyanins pigment from purple sweet potato on the elutriant wash-out macroporous adsorbent resin, is collected this wash-out mixed solution;

(7). reclaim elutriant: adopt the underpressure distillation mode to reclaim elutriant above-mentioned wash-out mixed solution;

(8). lyophilize: the wash-out mixed solution lyophilize that will remove the part elutriant to elutriant totally, can obtain the anthocyanins pigment from purple sweet potato product.

2. the preparation method of cation exchange resin secondarily purified anthocyanins pigment from purple sweet potato according to claim 1, it is characterized in that: it is to adopt centrifugal filtration process or Plate Filtration method to filter that water-soluble anthocyanins pigment from purple sweet potato is filtered, and uses constant flow pump control flow velocity.

3. the preparation method of cation exchange resin secondarily purified anthocyanins pigment from purple sweet potato according to claim 1, it is characterized in that: described cation exchange resin column is: polar macroporous Zeo-karb D061, polar macroporous Zeo-karb D072, polarity Zeo-karb 002 * 7, polarity Zeo-karb 001 * 7 * 7 or polarity Zeo-karb 001 * 4.

4. the preparation method of cation exchange resin secondarily purified anthocyanins pigment from purple sweet potato according to claim 1, it is characterized in that: the elutriant in step (4) is 50% ethanolic soln that contains 2% hydrochloric acid.

5. the preparation method of cation exchange resin secondarily purified anthocyanins pigment from purple sweet potato according to claim 1, it is characterized in that: the elutriant in step (6) is an aqueous ethanolic solution, its concentration is 40～95% (V/V).