Preparation method of colorless amorphophallus bulbifer alkaline gel
By adding amino acids such as L-tyrosine, L-glutamic acid, and L-aspartic acid to bulbil konjac flour, chelating metal ions and regulating pH value, the problem of color change of bulbil konjac under alkaline conditions was solved, and a safe and stable colorless konjac gel was prepared, which is suitable for products such as konjac tofu.
Patent Information
- Application Number
- CN202511849584.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-01-27
AI Technical Summary
When konjac bulbils form red or reddish-brown complexes with metal ions under alkaline conditions, they cause discoloration of konjac gel products. Existing technologies using oxidants and chemical additives involve complicated processes and the risk of chemical residues, which violate food safety standards.
A colorless konjac bulbil alkaline gel was prepared by mixing amino acids such as L-tyrosine, L-glutamic acid, and L-aspartic acid with konjac bulbil flour, chelating metal ions, and adjusting pH to form stable complexes, thereby blocking the reaction between flavonoids and metal ions.
The color difference of colorless bulb yellow konjac alkaline gel is less than 2, the inhibition rate is greater than 90%, the water holding capacity is greater than 95%, and the compressive strength is greater than 50 kPa, which meets food safety standards and does not affect the gel strength.
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Figure CN121400570A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing colorless bulb yellow konjac alkaline gel, belonging to the field of food preparation technology. Background Technology
[0002] Due to its strong disease resistance, bulbiferous konjac (Amorphophallus bulbifer) has gradually become an important raw material to replace traditional white konjac and flower konjac. However, its bulbs contain high levels of flavonoids, which, under alkaline conditions, complex with metal ions (such as aluminum and iron) to form red or reddish-brown complexes, causing discoloration of gel products such as konjac tofu and seriously affecting its commercial value.
[0003] While existing technologies that use oxidants (such as hydrogen peroxide) to induce color change followed by fading are effective, they require complex chemical auxiliaries (such as EDTA and calcium alginate) and multiple processing steps, resulting in cumbersome processes and the risk of chemical residues. In particular, according to my country's current national food safety standard GB 2760-2024, the aforementioned chemical reagents (such as EDTA and hydrogen peroxide) are not permitted for use in the processing of konjac gel products, further limiting the application of this technology in compliant production.
[0004] Amino acids are natural substances with metal ion chelating ability and pH buffering properties, but their application in inhibiting discoloration of konjac gel has not been reported. Summary of the Invention
[0005] This invention provides a method for preparing colorless bulbil yellow konjac alkaline gel, comprising the following steps: Mix the amino acids with konjac bead powder, add water to make a suspension, stir to dissolve, add an alkaline coagulant, heat to 60-80℃ and keep warm for 10-30 minutes to form a gel.
[0006] The aforementioned bulbil konjac flour is obtained by washing, deactivating enzymes, drying, and pulverizing bulbil konjac tubers.
[0007] In some embodiments, the amino acids include L-glutamic acid and L-tyrosine, and the amount of L-glutamic acid and L-tyrosine added is 0.5%-2% and 0.1%-1.5% of the weight of konjac flour, respectively.
[0008] In the preferred embodiment, the amino acids include L-glutamic acid and L-tyrosine, and the amount of L-glutamic acid and L-tyrosine added is 0.8%-1.2% and 0.5%-1.0% of the weight of konjac flour, respectively.
[0009] In some embodiments, the amino acid further includes L-aspartic acid, and the amount of L-aspartic acid added is 2%-5% of the mass of konjac flour.
[0010] In some embodiments, the amino acid further includes L-aspartic acid, and the amount of L-aspartic acid added is 3%-4% of the mass of konjac flour.
[0011] In some embodiments, the amino acids are L-glutamic acid, L-tyrosine, and L-aspartic acid, and the amounts of L-glutamic acid, L-tyrosine, and L-aspartic acid added are 1%, 0.5%, and 3% of the mass of the konjac bead flour, respectively.
[0012] In some embodiments, the amount of mixed amino acids added is: less than 0.5% will result in insufficient inhibitory effect, and more than 5% may affect gel texture, that is, the total amount of mixed amino acids should be controlled to ≤5%.
[0013] In some embodiments, konjac flour containing mixed amino acids is mixed with water at a mass ratio of 1:20-50 to form a suspension. Mixing uniformity: High-speed stirring (1000-2000 rpm, 5-10 minutes) is used to ensure that arginine and konjac flour are in full contact.
[0014] In some embodiments, the mixture of amino acids and konjac bead powder can be mixed, water can be added to adjust the pH to 5.5-6.5, and then microwave-assisted treatment can be performed, wherein the microwave conditions are 300-400W and the treatment time is 2-5 minutes.
[0015] In some embodiments, the alkaline coagulant is calcium carbonate or calcium hydroxide, and the amount used is 1%-5% of the mass of konjac flour.
[0016] The present invention also provides a colorless bulbil yellow konjac alkaline gel prepared by the method described above. The colorless bulbil yellow konjac alkaline gel has a color difference of less than 2, more preferably less than 1, and more preferably less than 0.5; a color change inhibition rate of more than 90%, more preferably more than 95%; a water holding capacity of more than 95%, more preferably more than 98%; and a compressive strength of more than 50 kPa, more preferably more than 60 kPa.
[0017] Metal ion chelation: L-tyrosine, L-glutamic acid, and L-aspartic acid bind with free metal ions (such as Fe) in konjac through their amino and carboxyl groups. 3+ Al 3+ It forms a stable complex, blocking the reaction between flavonoids and metal ions.
[0018] pH buffering effect: The basic properties of L-tyrosine, L-glutamic acid, and L-aspartic acid can stabilize the pH value of the system and reduce the promoting effect of alkaline conditions on color change.
[0019] The technical solution of this application has the following beneficial effects: 1. Natural and safe: Amino acids are food-grade additives with no risk of chemical residues, meeting the requirements of the food industry. 2. Simplified process: The process omits multiple steps such as oxidation-induced color change and fading, and achieves color change inhibition directly through a one-step mixing process. 3. High efficiency and stability: L-tyrosine, L-glutamic acid and L-aspartic acid have dual functions of chelation and pH regulation, and have a significant effect on inhibiting color change (color difference value ΔE≤2, further preferably ΔE≤1, further preferably ΔE≤0.5). 4. Strong compatibility: It is suitable for various alkaline gel products (such as konjac tofu and konjac noodles) without affecting gel strength and water retention.
[0020] For the first time, L-tyrosine was used to inhibit the discoloration of alkaline gels in Amorphophallus bulbifera, achieving highly efficient inhibition through a dual mechanism of chelating metal ions and pH regulation.
[0021] The primary component is L-aspartic acid, with L-glutamic acid as a secondary component and L-tyrosine as a minor component. Synergistic optimization of mixing methods (high-speed stirring) and gel preparation conditions (temperature, pH) was conducted. Attached Figure Description
[0022] Figure 1 The image shows the browning inhibition effect of Example 1, where A is the treated sample and B is the untreated powder.
[0023] Figure 2 The image shows the browning inhibition effect of Example 2, where A is the treated sample and B is the untreated powder.
[0024] Figure 3 The image shows the browning inhibition effect of Example 3, where A is the treated sample and B is the untreated powder. Detailed Implementation
[0025] Example 1 Processing method: A ternary complex system of 0.5% L-tyrosine + 1.0% glutamic acid + 3.0% aspartic acid was mixed with water and konjac flour, and then microwave-assisted treatment was carried out with sodium bicarbonate (300W, intermittent treatment for 5 min).
[0026] The above ingredients include 0.6g of L-tyrosine, 1.2g of L-glutamic acid, 3.6g of L-aspartic acid, 120g of konjac bead flour, 2500g of water, and 1.5g of sodium bicarbonate.
[0027] Experimental results: ΔE=0.5, browning inhibition rate reached a maximum of 96.8% (measured by spectrophotometry of flavonoid-metal complex absorbance). L-tyrosine inactivates polyphenol oxidase by chelating copper ions, L-glutamate enhances the water-holding capacity of the system and reduces the efficiency of enzymatic reaction, forming a triple inhibition mechanism with L-aspartic acid. The effect is shown in the figure below. Figure 1 As shown, A is the processed sample, and B is the unprocessed refined powder.
[0028] Gel properties: The water-holding capacity of the color-protected bulbil konjac flour gel is 96.5%, and the compressive strength is 565 gf / cm. 2 Normal bulbil konjac flour gel has a water-holding capacity of ≥90% and a compressive strength of 485 gf / cm. 2 The konjac gel treated with amino acid combination color protection did not decrease in water retention or compressive strength; in fact, it showed a slight improvement. This demonstrates that the gel treated with this patent does not affect the normal use of konjac powder. This solution simplifies the process and improves safety by replacing chemical additives with natural amino acids, exhibiting significant innovation and industrialization potential.
[0029] Method for testing compressive strength: The "SMSTAXTPLUSC" texture analyzer was used with the "SMSP / 25P" probe. The measurement was performed at room temperature. Each treatment group was measured in parallel three times.
[0030] Example 2 Processing method: A binary complex system of 0.5% L-tyrosine + 1.0% glutamic acid was used. Water was added and mixed with konjac bead flour. Sodium bicarbonate was added and microwave-assisted treatment was carried out (300W, intermittent treatment for 5 minutes).
[0031] The above ingredients include 0.6g of L-tyrosine, 1.2g of L-glutamic acid, 120g of konjac bead flour, 2500g of water, and 1.5g of sodium bicarbonate.
[0032] Experimental results: ΔE=1.2, with a maximum browning inhibition rate of 81.7% (measured by spectrophotometry of the absorbance of the flavonoid-metal complex). L-tyrosine enhanced the stability of L-glutamate and synergistically blocked the formation of the enzyme-substrate complex. Simultaneously, the pH buffering effect of L-tyrosine prolonged the effective action time of L-glutamate. See the effect diagram below. Figure 2 As shown, A is the processed sample, and B is the unprocessed refined powder.
[0033] Gel properties: The water-holding capacity of the color-protected konjac flour gel was 93.7%, and the compressive strength was 520 gf / cm. 2 .
[0034] Example 3 Processing method: A 0.5% L-tyrosine system was used, which was mixed with water and konjac bead flour, and then microwave-assisted treatment was carried out with sodium bicarbonate (300W, intermittent treatment for 5 min).
[0035] The above ingredients include 0.6g of L-tyrosine, 120g of konjac bead flour, 2500g of water, and 1.5g of sodium bicarbonate.
[0036] Experimental results: ΔE=3.2, with a maximum browning inhibition rate of 32.4%. A single amino acid competitively binds to the active site of polyphenol oxidase via its thiol group; however, due to its single site of action and susceptibility to oxidative inactivation, the inhibitory effect is limited. See the effect diagram below. Figure 3 As shown, A is the processed sample, and B is the unprocessed refined powder.
[0037] Gel properties: The water-holding capacity of the color-protected bulbil konjac flour gel is 92.5%, and the compressive strength is 517 gf / cm. 2 .
[0038] Example 4 Processing method: Take 120g of konjac bead powder, add 2g of L-histidine, 0.8g of L-proline and 4g of L-glutamine, mix and add 3.5L of water to make a suspension emulsion. After stirring to dissolve, add 2.0g of sodium bicarbonate and keep warm at 65℃ for 25 minutes to form a gel.
[0039] ΔE=2.1, browning inhibition rate 67.7%. The water-holding capacity of the color-protected konjac flour gel was 90.1%, and the compressive strength was 511 gf / cm². 2 .
[0040] Example 5 Processing method: Take 120g of konjac bead powder, add 0.3g of L-cysteine and 2g of glycine, mix and add 3.5L of water to make a suspension emulsion, stir to dissolve and then add 4g of calcium hydroxide, keep warm at 70℃ for 25 minutes to form a gel.
[0041] ΔE=3.8, browning inhibition rate 41.5%. Sulfur-containing amino acids showed weak browning inhibition, resulting in weak gel strength and poor water retention in the sample. The water retention of the gel from bulbil-konjac flour after color-protecting treatment was 88.4%, and the compressive strength was 487 gf / cm². 2 .
[0042] Example 6 Processing method: Take 120g of konjac bead powder, add 0.8g of L-tyrosine, 0.5g of tryptophan and 0.1g of ascorbic acid, mix and add 3.5L of water to make a suspension emulsion. After stirring to dissolve, add 4g of sodium bicarbonate and keep warm at 70℃ for 25 minutes to form a gel.
[0043] ΔE=1.5, browning inhibition rate 81.5%. The water-holding capacity of the color-protected konjac flour gel was 89.3%, and the compressive strength was 532 gf / cm². 2 Phenolic amino acids and antioxidants have a synergistic effect in color protection.
[0044] Example 7 Processing method: Take 500g of konjac bead powder, add 5g of L-tyrosine, 10g of L-glutamic acid and 10g of L-aspartic acid, mix and add 10.5L of water to make a suspension emulsion. After stirring to dissolve, add 15g of sodium bicarbonate and keep warm at 65℃ for 25 minutes to form a gel.
[0045] Experimental results: The browning inhibition rate reached as high as 95.4%.
[0046] Gel properties: The water-holding capacity of the color-protected konjac flour gel was 94.6%, and the compressive strength was 553 gf / cm. 2 .
[0047] Example 8 Processing method: Take 500g of konjac bead powder, add 10g of L-glutamic acid, mix and add 10.5L of water to make a suspension emulsion. After stirring to dissolve, add 15g of sodium bicarbonate and keep warm at 40℃ for 45 minutes to form a gel.
[0048] Experimental results: ΔE=2.9, browning inhibition rate 55.4%.
[0049] Example 9 Processing method: Take 500g of konjac bead powder, add 5g of L-tyrosine and 10g of L-aspartic acid, mix and add 10.5L of water to make a suspension emulsion. After stirring to dissolve, add 15g of sodium bicarbonate and keep warm at 65℃ for 25 minutes to form a gel.
[0050] ΔE=0.9, browning inhibition rate 86.2%.
[0051] Example 10 Processing method: Take 100g of konjac bulb powder, add 0.05g of disodium EDTA and 1g of L-tyrosine, mix and add 1.5L of water to make a suspension, stir to dissolve and then add 2g of sodium bicarbonate, keep warm at 65℃ for 25 minutes to form a gel.
[0052] ΔE=0.9, browning inhibition rate 86.2%. Integrated metal ions block enzymatic browning.
Claims
1. A method for preparing colorless bulbil yellow konjac alkaline gel, characterized in that, Includes the following steps: Mix the amino acids with konjac bead powder, add water to make a suspension, stir to dissolve, add an alkaline coagulant, heat to 60-80℃ and keep warm for 10-30 minutes to form a gel.
2. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 1, characterized in that, The aforementioned bulbil konjac flour is obtained by washing, deactivating enzymes, drying, and pulverizing bulbil konjac tubers.
3. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 1, characterized in that, The amino acids include L-glutamic acid and L-tyrosine, with the addition amounts of L-glutamic acid and L-tyrosine being 0.5%-2% and 0.1%-1.5% of the weight of the konjac flour, respectively.
4. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 3, characterized in that, The amino acids include L-glutamic acid and L-tyrosine, and the amount of L-glutamic acid and L-tyrosine added is 0.8%-1.2% and 0.5%-1.0% of the weight of konjac flour, respectively.
5. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 4, characterized in that, The amino acids also include L-aspartic acid, and the amount of L-aspartic acid added is 2%-5% of the mass of konjac flour.
6. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 5, characterized in that, The amino acids also include L-aspartic acid, and the amount of L-aspartic acid added is 3%-4% of the mass of konjac flour.
7. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 1, characterized in that, Konjac flour containing mixed amino acids is mixed with water at a mass ratio of 1:20-50 to form a suspension.
8. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 1, characterized in that, Another method for preparing colorless bulbil konjac alkaline gel is to mix mixed amino acids with bulbil konjac flour, add water to adjust the mixture, add alkali, adjust the pH to 5.5-6.5, and then perform microwave-assisted treatment. The microwave conditions are 300-400W, and the treatment time is 2-5 minutes.
9. The method for preparing colorless bulbil yellow konjac alkaline gel according to claim 1, characterized in that, The alkaline coagulant is potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, or calcium hydroxide, and the amount used is 1%-5% of the mass of konjac flour.
10. A colorless bulbil yellow konjac alkaline gel, characterized in that, The colorless bulbil yellow konjac alkaline gel prepared by the method according to any one of claims 1-9 has a color difference of less than 2; a color change inhibition rate of greater than 90%; a water holding capacity of greater than 95%; and a compressive strength of greater than 50 kPa.