Preparation method of whitening carrageenan

Abstract

The invention discloses a preparation method of whitening carrageenan. Fully soaking the crude rubber in a 10% ethanol solution; adding 30% H2O2 at 40 DEG C, continuously stirring, and controlling the reaction pH value to be unchanged; and after 120 minutes, washing the reactant with water until the reactant is neutral, detecting whether residues exist or not by using H2O2 test paper, and if no H2O2 residues exist, drying, crushing and collecting a sample. Compared with an existing refined carrageenan treatment process, the method has the advantages that long-time strong alkali soaking treatment is avoided, the production efficiency and the product yield are improved, meanwhile, operation is easy, the environment is not polluted, the waste liquid recovery and treatment cost is reduced, and the economic benefits of enterprises are improved. The prepared whitening carrageenan can be compounded with polysaccharides such as gelatin and xanthan gum, the appearance quality of the product is improved, and the application range of the whitening carrageenan in the field of food is widened.

Description

Technical Field

[0001] The invention relates to the field of carrageenan, and in particular to a preparation method of whitening carrageenan. Background Art

[0002] Carrageenan is a seaweed polysaccharide extracted from the cell wall of red algae. Due to its excellent gelling, stability and compounding properties, it is widely used in food, medicine, chemical industry and other fields. Industrially produced carrageenan has two types: refined carrageenan and crude carrageenan. At present, the production process of refined carrageenan by domestic enterprises requires the red algae to be soaked in alkali solution, rinsed multiple times, heated to gel, filtered, cooled to gel, squeezed and dehydrated, dried and crushed, and other steps (Cai Ying, Hu Zhang, Li Sidong, et al. A method for extracting carrageenan from sand vegetables: China, CN110713553B[P]. 2021-12-10). The obtained carrageenan powder has high whiteness and high gel strength, but there are problems such as many processing links, low yield, large amount of alkali and water consumption, large amount of industrial wastewater, and high production cost. The production process of crude carrageenan is relatively simple. The product is obtained by directly soaking the red algae in alkali solution, rinsing, drying and cutting. It takes a short time, has a high yield, high utilization rate and low cost. However, since the preparation process does not go through the steps of boiling gel, filtering, and purification, the crude carrageenan powder has lower whiteness and lower gel strength than the refined carrageenan. Therefore, it is mostly used in products with low whiteness requirements, and the product has low added value. Considering that the higher the whiteness of carrageenan on the market, the higher the gel strength, the higher the added value of its products and the wider the application range (Hong Qinglin, Xiao Anfeng, Weng Huifen, et al. A method for decolorizing carrageenan assisted by enzyme: China, CN107540757B[P]. 2021-03-16; Lin Kuncheng, He Dianguo, Han Ahuo, et al. A method for extracting carrageenan: China, CN103570843B[P]. 2014-10-29). If a decolorization process that can effectively improve the whiteness of crude carrageenan can be found, its application value and potential can be improved. Summary of the invention

[0003] In view of the above problems, the present invention uses commercially available crude carrageenan as raw material, decolorizes the crude carrageenan with a green environmentally friendly reagent H2O2, and obtains the optimal whitened carrageenan to meet the needs of actual production and processing, and improve the utilization value and added value of the crude carrageenan.

[0004] To achieve the above object, the present invention provides a method for preparing whitening carrageenan, characterized in that it comprises the following steps:

[0005] S1. Soak the crude glue in 10% ethanol solution;

[0006] S2. At 40°C, 30% H2O2 was added to the reaction mass and stirred continuously, and the reaction pH was controlled to remain unchanged;

[0007] After reacting for 120 minutes, wash the reactants with water until neutral, and use an H2O2 test paper to detect whether there is any residue. If there is no H2O2 residue, dry, crush, and collect the sample; otherwise, repeat the water washing until there is no residue.

[0008] Furthermore, in the step S1, the dosage ratio of the crude gum to the 10% ethanol solution is 50 g: 1250 ml.

[0009] Furthermore, in the step S2, the dosage ratio of the crude gum to 30% H2O2 is 50 g: 12 ml.

[0010] Furthermore, in the step S2, keeping the reaction pH constant means controlling the pH to be 4 - 10.

[0011] Furthermore, in the step S2, keeping the reaction pH constant means controlling the pH to be 6.

[0012] The preparation method of the whitened carrageenan in the embodiment of the present invention can avoid the long - time strong alkali soaking treatment compared with the existing refined carrageenan treatment process, improve the production efficiency and product yield. At the same time, after the H2O2 decolorization treatment, the sample can be collected by drying and crushing, with simple operation. And the small amount of H2O2 waste liquid produced only decomposes into water and oxygen after decomposition, without polluting the environment, reducing the waste liquid recovery and treatment cost, and being beneficial to improving the economic benefits of the enterprise.

[0013] Compared with the crude gum, the whiteness of the whitened carrageenan obtained by this method has increased by 48%, the gel strength has increased by 47%, and the gel transmittance has increased by 192% (ethanol concentration 10%, reaction temperature 40 °C, reaction pH 6, H2O2 addition amount 12 mL, reaction time 120 min). This is beneficial for compounding and using with polysaccharides such as gelatin and xanthan gum, improving the appearance quality of the product, and broadening its application in the food field. Description of the Drawings

[0014] Figure 1 It is a diagram showing the influence of ethanol concentration on the quality of the whitened carrageenan in Example 1 of the present invention.

[0015] Figure 2 It is a diagram showing the influence of reaction temperature on the quality of the whitened carrageenan in Example 2 of the present invention.

[0016] Figure 3 It is a diagram showing the influence of reaction pH on the quality of the whitened carrageenan in Example 3 of the present invention.

[0017] Figure 4 It is a diagram showing the influence of H2O2 addition amount on the quality of the whitened carrageenan in Example 4 of the present invention.

[0018] Figure 5 It is a diagram showing the influence of reaction time on the quality of the whitened carrageenan in Example 5 of the present invention.

[0019] Figure 6 It is a comparison chart of Example 6 of the present invention with commercially available crude glue and refined glue powder.

[0020] Figure 7 It is a comparison chart of Example 6 of the present invention with commercially available crude glue and refined glue gel plates. Detailed implementation manners

[0021] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described by referring to the drawings below are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention. For those technical or conditions not specified in the embodiments, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0022] The test materials used in the present invention are all ordinary commercially available products and can be purchased in the market. For example, crude glue and refined glue can be purchased from Green New (Fujian) Food Co., Ltd., and analytical pure 30% H2O2 and absolute ethanol can be purchased from Sinopharm Chemical Reagent Co., Ltd.

[0023] The measurement methods of the whiteness, gel strength, relative strength, yield and gel transmittance of carrageenan in the following examples are as follows:

[0024] Measurement of carrageenan whiteness: Dry, crush and sieve (80 mesh) different carrageenan samples respectively. Take an appropriate amount of carrageenan powder and put it into a sample press, and use an ADCI-WSI whiteness colorimeter to measure the blue light whiteness of different samples. (The relative humidity of the measurement environment is less than 85%; if the measurement duration exceeds 1 h, the whiteness meter needs to be recalibrated once).

[0025] Measurement of carrageenan gel strength and calculation of relative strength: Prepare a 1.5% (W / V) carrageenan solution (containing 0.2% KCl). After heating it in a boiling water bath until it is completely dissolved, pour the glue solution into a petri dish with a diameter of 90 mm, cool and solidify it at room temperature, cover it with a plastic wrap, and place it at 20 °C for 15 h. Place the petri dish to be measured on the left tray of a tray balance, fix the plunger with a cross-sectional area of 1 cm 2 just in contact with the gel surface, place a beaker on the right tray of the balance, and slowly pour distilled water evenly. When the gel surface breaks, immediately stop pouring water, and record the weight of the beaker and distilled water at this time, which is the gel strength of carrageenan. After measuring the gel strength of the whitened carrageenan and the crude glue respectively, calculate the relative strength according to the following formula:

[0026]

[0027] In the formula:

[0028] GS1 is the gel strength of the whitened carrageenan (g·cm -2 );

[0029] GS2 is the gel strength of the crude gum (g·cm -2 ).

[0030] Determination of the yield: Place the moisture rapid detector horizontally, weigh 3.00 g of the whitened carrageenan and the crude gum respectively, and evenly place them on the sample tray. The measurement temperature is 105 °C, the ambient temperature is 5 - 40 °C, and the ambient relative humidity is 15% - 80%. After the determination, directly read the dry weight percentage of different samples, denoted as ω. The sample yield is calculated according to the following formula:

[0031]

[0032] In the formula:

[0033] ω1 and ω2 are the dry weight percentages (%) of the whitened carrageenan and the crude gum respectively;

[0034] m1 is the mass (g) of the whitened carrageenan obtained from each 50 g of the crude gum after treatment with H2O2.

[0035] Determination of the transmittance of the carrageenan gel: Prepare a 1.5% potassium carrageenan solution (0.2% KCl), place it at room temperature for 12 h, use distilled water as the reference, and measure the transmittance (%) of the carrageenan gel at a wavelength of 700 nm using a UV-visible spectrophotometer.

[0036] Example 1:

[0037] Add anhydrous ethanol to water, stir and mix evenly to prepare 1250 mL of ethanol solutions with concentrations of 0, 10%, 20%, 30%, and 40% respectively;

[0038] Place 5 portions of the crude gum (50 g / portion) into the prepared ethanol solutions respectively, soak them thoroughly, and seal; place the reaction materials to be on a magnetic stirrer, add 12 mL of analytical pure 30% H2O2 to the reactants uniformly, continuously stir and react. The reaction conditions are 40 °C, pH = 6, and 120 min. After the reaction is completed, drain the reactants, wash them with water until neutral, and use an H2O2 test paper to detect whether there is H2O2 residue. If there is no residue, dry, crush, and collect the samples; otherwise, repeat the water washing until there is no residue.

[0039] Detect the whiteness, relative strength, and yield of the collected samples. The results are as Figure 1As shown, after testing, the whiteness and relative strength of the whitened carrageenan decreased with the increase of ethanol concentration, while the yield increased with the increase of ethanol concentration. With whiteness as the main investigation index, relative strength and yield as secondary indicators, the optimal ethanol concentration was selected as 10%.

[0040] Example 2

[0041] Place 5 portions of crude glue (50g / portion) in 1250ml of prepared 10% ethanol solution and soak them fully, then seal them; place the materials to be reacted on magnetic stirrers, add 12mL of analytical pure 30% H2O2 to the reactants, control the reaction temperatures to 25, 30, 35, 40, and 45°C, respectively, stir the reaction continuously, and the reaction conditions are pH=6, 120min. After the reaction is completed, drain the reactants, wash with water until neutral, and use H2O2 test paper to detect whether there is H2O2 residue. If there is no residue, dry, crush, and collect the sample; otherwise, wash with water repeatedly until there is no residue.

[0042] The collected samples were tested for whiteness, relative strength and yield. The results are as follows: Figure 2 As shown, after testing, as the reaction temperature increases from 25°C to 45°C, the whiteness, yield and relative strength of the whitened carrageenan increase, decrease and decrease respectively. Especially when the reaction temperature rises to 45°C, more and more colloid is lost into the reaction system, and water washing makes it impossible to recover it, and the final yield drops sharply. Therefore, the optimal reaction temperature is selected as 40°C.

[0043] Example 3

[0044] Place 4 portions of crude glue (50g / portion) in 1250ml of prepared 10% ethanol solution and soak them fully, then seal them; place the materials to be reacted on magnetic stirrers, add 12mL of analytical pure 30% H2O2 to the reactants, control the reaction pH to 4, 6, 8, and 10, respectively, stir the reaction continuously, and the reaction conditions are 40°C and 120min. After the reaction is completed, drain the reactants, wash with water until neutral, and use H2O2 test paper to detect whether there is H2O2 residue. If there is no residue, dry, crush, and collect the sample; otherwise, wash with water repeatedly until there is no residue.

[0045] The collected samples were tested for whiteness, relative strength and yield. The results are as follows: Figure 3 As shown in the figure, the whiteness and gel strength of the whitened carrageenan increased compared with the crude carrageenan in the pH range of 4-10. Among them, the whiteness of the whitened carrageenan was the highest at pH 10, which was not significantly different from that at pH 6, but the relative strength decreased, so the optimal pH was selected as 6.

[0046] Example 4

[0047] Five portions of crude gum (50 g per portion) were respectively placed in 1250 mL of the prepared 10% ethanol solution and soaked thoroughly, then sealed; the materials to be reacted were respectively placed on a magnetic stirrer, and 0, 4, 8, 12, 16 mL of analytical pure 30% H2O2 were respectively added to the reactants, and the reaction was continuously stirred. The reaction conditions were 40 °C, pH = 6, and 120 min. After the reaction was completed, the reactants were drained, washed with water until neutral, and a H2O2 test paper was used to detect whether there was H2O2 residue. If there was no residue, it was dried, pulverized, and the sample was collected; otherwise, the washing with water was repeated until there was no residue.

[0048] The whiteness, relative strength and yield of the collected samples were detected, and the results were as Figure 4 shown. After detection, when the addition amount increased from 0 to 12 mL, the whiteness and relative strength of the whitened carrageenan were positively correlated; when the H2O2 addition amount was further increased to 16 mL, the relative strength decreased significantly. Therefore, the optimal H2O2 addition amount was selected as 12 mL.

[0049] Example 5

[0050] Five portions of crude gum (50 g per portion) were respectively placed in 1250 mL of the prepared 10% ethanol solution and soaked thoroughly, then sealed; the materials to be reacted were respectively placed on a magnetic stirrer, and 12 mL of analytical pure 30% H2O2 were added to the reactants. The reaction conditions were 40 °C, pH = 6, and the reaction times were 60, 90, 120, 150, 180 min respectively. After the reaction was completed, the reactants were drained, washed with water until neutral, and a H2O2 test paper was used to detect whether there was H2O2 residue. If there was no residue, it was dried, pulverized, and the sample was collected; otherwise, the washing with water was repeated until there was no residue.

[0051] The whiteness, relative strength and yield of the collected samples were detected, and the results were as Figure 5 shown. After detection, in the range of reaction time from 60 to 120 min, the whiteness and relative strength of the whitened carrageenan both increased significantly; between 120 and 180 min of reaction time, the whiteness did not increase significantly, while the yield continued to decrease. Therefore, the optimal reaction time was selected as 120 min.

[0052] Example 6

[0053] 50 g of crude gum was placed in 1250 mL of the prepared 10% ethanol solution and soaked thoroughly, then sealed; the material to be reacted was placed on a magnetic stirrer, and 12 mL of analytical pure 30% H2O2 was added to the reaction system, and it was continuously stirred. The reaction conditions were 40 °C, pH = 6, and 120 min. After the reaction was completed, the reactants were drained, washed with water until neutral, and a H2O2 test paper was used to detect whether there was H2O2 residue. If there was no residue, it was dried, pulverized, and the sample was collected; otherwise, the washing with water was repeated until there was no residue.

[0054] The powder of the sample obtained in this example is compared with commercially available crude glue and refined glue as follows Figure 6 As shown, the gel plate of the sample obtained in this example is compared with commercially available crude glue and refined glue as follows Figure 7 As shown. The whiteness, gel strength and gel transmittance of the sample obtained in this example, commercially available crude glue and commercially available refined glue are detected respectively. The results are shown in Table 1. After detection, the whiteness, gel strength and gel transmittance of the whitened carrageenan obtained by this method are 64.46%, 720.87 g / cm 2 , 21.23% respectively. Compared with the crude glue, they are increased by 48%, 47% and 192% respectively.

[0055] Table 1 Physical and chemical indexes of the whitened carrageenan obtained in Example 6 and commercially available crude glue and refined glue

[0056]

[0057]

[0058] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principle and purpose of the present invention.

Claims

1. A preparation method of whitening carrageenan, characterized in that, The steps include: S1. Soak the crude glue in 10% ethanol solution; S2. At 40°C, 30% H2O2 was added to the reaction mass and stirred continuously, and the reaction pH was controlled to remain unchanged; S3. After 120 minutes of reaction, the reactants were washed with water until neutral, and H2O2 test paper was used to check whether there was any residue. If there was no H2O2 residue, the samples were dried, crushed, and collected; otherwise, the samples were washed repeatedly until no residue was left.

2. The preparation method of the whitening carrageenan according to claim 1, wherein, In the step S1, the usage ratio of the crude rubber and the 10% ethanol solution is 50 g:1250 ml.

3. The preparation method of the whitening carrageenan according to claim 1, wherein, In the step S2, the usage ratio of the crude rubber and 30% H2O2 is 50g:12ml.

4. The preparation method of the whitening carrageenan according to claim 1, characterized in that In the step S2, the reaction pH is controlled to be constant while the pH is controlled to be 4-10.

5. The preparation method of the whitening carrageenan according to claim 4, wherein, In the step S2, the reaction pH is controlled to be 6 instead of being changed.

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