Extraction method of konjac glucomannan

Abstract

The invention discloses an extraction method of konjac glucomannan, which comprises the following steps: cutting konjac into blocks, and soaking the blocks in an activated carbon solution for decoloration and deodorization treatment; soaking the blocky konjak in water at 45-55 DEG C; crushing the soaked blocky konjak, and soaking the crushed blocky konjak in an ethanol solution containing nano silicon oxide; performing ultrasonic stirring for 20 to 30 minutes; adding an alcohol solvent, carrying out alcohol precipitation under the assistance of ultrasonic waves, and carrying out centrifugal separation to obtain a precipitate; washing the precipitate with a 80% ethanol solution, and adding an ester modifier; and drying and grinding to obtain the konjac glucomannan. According to the method, diced konjak is subjected to decoloration and deodorization treatment through an activated carbon solution, crushed konjak is subjected to ultrasonic stirring in an ethanol solution containing nano silicon oxide, surface polishing of the crushed konjak powder can be achieved through nano silicon oxide particles, konjak blocks are subjected to hot water soaking treatment, and then the konjak blocks are subjected to ultrasonic stirring; meanwhile, subsequent ester modification is matched; finally, the konjac glucomannan with high transparency and low viscosity is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of konjac gum extraction, and in particular to a method for extracting konjac gum. Background Art

[0002] Konjac gum is a natural food extracted from the root of konjac. It has the characteristics of low calories, high fiber, fat-free and cholesterol-free. It has been widely used in food and food additives.

[0003] When konjac gum is used as an additive, it is required to have properties such as low viscosity and high transparency so as not to affect the color and taste of other foods. The extraction and preparation methods of konjac gum in the prior art cannot meet the requirements of high transparency and low viscosity when konjac gum is used as an additive.

[0004] The existing patent CN104725525A discloses a method for preparing konjac gum, comprising subjecting konjac slices to color protection treatment, homogenizing to form a colloidal substance, shearing under different rotation speed conditions, and adding water and 50% ethanol at different stages; then adding mannitol and extracting under ultrasonic action; washing with ethanol after extraction, drying to form powder, and obtaining konjac powder; dispersing the konjac powder into an ethanol solution and a potassium chloride mixed solution, and subjecting the mixture to microwave and ultrasonic treatment to obtain konjac gum; the preparation method can reduce the content of alkaloids and sulfur dioxide in konjac gum, but because the color protection treatment process is added, highly transparent konjac gum cannot be obtained.

[0005] Therefore, it is necessary to find a new extraction process to prepare konjac gum with high transparency and low viscosity. Summary of the invention

[0006] The purpose of the present invention is to provide a method for extracting konjac gum; the konjac gum prepared by the method of the present application has high transparency and low viscosity.

[0007] In order to achieve the above purpose, this application adopts the following technical solutions:

[0008] A method for extracting konjac gum, comprising:

[0009] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization;

[0010] S2: Soaking the konjac block in water at 45-55°C;

[0011] S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide; and ultrasonically stirring it for 20-30 minutes;

[0012] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and obtaining a precipitate by centrifugation;

[0013] S5: washing the precipitate with 80% ethanol solution, adding an ester modifier, and drying and grinding to obtain konjac gum.

[0014] Furthermore, the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.04-0.05:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0015] Furthermore, the soaking time in step S2 is greater than or equal to 2 hours.

[0016] Furthermore, in step S3, the particle size of the nano silicon oxide is less than or equal to 200 nm.

[0017] Furthermore, the mass fraction of the nano silicon oxide in the ethanol solution is 0.5-1.5wt%.

[0018] Furthermore, the mass fraction of ethanol in the ethanol solution in step S3 is 30-40wt%.

[0019] Furthermore, the alcohol solvent in step S4 is ethanol with a mass concentration of 70%.

[0020] Furthermore, in step S4, the ultrasonic power during alcohol precipitation is 300W-400W.

[0021] Furthermore, the ester modifier is octenyl succinic anhydride.

[0022] Beneficial effects of the present invention:

[0023] The present application carries out decolorization and deodorization process to the konjac of cutting by activated carbon solution, can remove the pigment in konjac in advance, ensure the transparency of konjac glucomannan extracted; The present application carries out ultrasonic stirring in the ethanol solution comprising nano silicon oxide for the konjac after crushing, can realize the surface polishing of konjac powder after crushing by nano silicon oxide particles, effectively removes the impurities such as the pigment on the surface of konjac powder, makes the impurities such as pigment fully dissolved in the ethanol solution, further improves the transparency of konjac glucomannan. The present application soaks enough time in the warm water of temperature height room temperature, can soften the organizational structure in konjac block, can also remove starch impurities etc. simultaneously, is convenient to the carrying out of subsequent processing technology, improves the output of konjac glucomannan. DETAILED DESCRIPTION

[0024] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of protection of the present invention. Unless otherwise specified, the experimental materials, reagents, instruments, etc. used in the examples of this application are all commercially available; unless otherwise specified, all technical means in the examples of the present invention are conventional means well known to those skilled in the art.

[0025] The present application provides a method for extracting konjac gum, comprising:

[0026] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization;

[0027] The mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.04-0.05:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0028] In the present application, the konjac blocks are soaked in an activated carbon solution for 30 minutes to allow the activated carbon to fully adsorb the pigment in the konjac blocks, and then the activated carbon and the konjac blocks are separated; since the particle sizes of the two are quite different, they can be separated by filters with different mesh sizes. This step can be repeated 5-6 times for the decolorization and deodorization process to ensure that the activated carbon can fully decolorize and deodorize the konjac blocks.

[0029] The activated carbon has a large specific surface area and can absorb the pigment on the surface of the konjac block, ensuring that the subsequently prepared konjac gum has no pigment deposition, so as to improve the transparency of the finally prepared konjac gum.

[0030] S2: Soaking the konjac block in water at 45-55°C;

[0031] The soaking time is greater than or equal to 2 hours. Soaking enough time in warm water at a high temperature and room temperature can soften the organizational structure in the konjac block, and can also remove starch impurities, etc., which is convenient for the subsequent processing technology and improves the output of konjac gum.

[0032] S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide; and ultrasonically stirring it for 20-30 minutes;

[0033] In this step, the mass fraction of ethanol in the ethanol solution is 30-40wt%, the particle size of nano silicon oxide is less than or equal to 200nm, and the mass fraction of nano silicon oxide in the ethanol solution is 0.5-1.5wt%.

[0034] The crushed konjac is ultrasonically stirred in an ethanol solution containing nano-silicon oxide. The surface of the crushed konjac flour can be polished by the nano-silicon oxide particles, and impurities such as pigments on the surface of the konjac flour can be effectively removed, so that the impurities such as pigments are fully dissolved in the ethanol solution, and the transparency of konjac gum is further improved.

[0035] The particle size of the crushed konjac flour is much larger than that of the nano-silicon oxide particles, and the polished konjac flour and the nano-silicon oxide can be separated by using filter screens with different apertures.

[0036] In the present application, the nano silicon oxide has a certain hardness. During the ultrasonic stirring process, the nano silicon oxide continuously rubs the surface of the konjac flour, so that the browning part, the impurity part, and the pigment on the surface can be removed under the friction force, and at the same time, it is dissolved in the ethanol solution. Through this step, the transparency of the konjac gum can be further improved.

[0037] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and obtaining a precipitate by centrifugation;

[0038] The alcohol solvent is 70% ethanol by mass concentration. The ultrasonic power is 300W-400W during alcohol precipitation. 70% ethanol can effectively precipitate the sugar components. The alcohol precipitation process can fully and effectively separate the macromolecules or sugar components, so that konjac gum can be fully precipitated, which helps to increase the yield of konjac gum.

[0039] S5: washing the precipitate with 80% ethanol solution, adding an ester modifier, and drying and grinding to obtain konjac gum.

[0040] The specific ester modifier is octenyl succinic anhydride. Octenyl succinic anhydride can esterify konjac gum and help reduce the viscosity of konjac gum.

[0041] The present application uses an activated carbon solution to decolorize and deodorize cut konjac, which can remove the pigment in the konjac in advance and ensure the transparency of the extracted konjac gum; the present application conducts ultrasonic stirring in an ethanol solution containing nano-silicon oxide on the crushed konjac, and the surface of the crushed konjac flour can be polished by nano-silicon oxide particles, effectively removing impurities such as pigments on the surface of the konjac flour, allowing the pigments and other impurities to be fully dissolved in the ethanol solution, further improving the transparency of the konjac gum.

[0042] The present application soaks enough time in warm water of high temperature room temperature, can soften the organizational structure in the konjac block, can also remove starch impurities etc., is convenient for the subsequent processing technology, improves the output of konjac glucomannan. At the same time, cooperate with subsequent ester modification, can reduce the viscosity of konjac glucomannan; Konjac glucomannan prepared by the present application method has high transparency and low viscosity.

[0043] Example 1

[0044] A method for extracting konjac gum provided in this embodiment comprises:

[0045] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; wherein the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.04:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0046] S2: Soaking the konjac block in water at 45-55° C. for 2 hours or longer.

[0047] S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide, and ultrasonically stirring it for 20-30 minutes; wherein the mass fraction of ethanol in the ethanol solution is 30wt%, and the particle size of the nano-silicon oxide is less than or equal to 200nm. The mass fraction of the nano-silicon oxide in the ethanol solution is 0.5wt%.

[0048] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and centrifuging to obtain a precipitate; wherein the alcohol solvent is ethanol with a mass concentration of 70%; and the ultrasonic power during the alcohol precipitation is 300W-400W.

[0049] S5: washing the precipitate with an 80% ethanol solution, adding octenyl succinic anhydride; drying and grinding to obtain konjac gum; octenyl succinic anhydride can esterify the konjac gum, which helps to reduce the viscosity of the konjac gum.

[0050] The transparency of the konjac gum solution was measured by a spectrophotometer, and the viscosity of the konjac gum was measured by a rotational viscometer. The results are shown in Table 1.

[0051] Example 2

[0052] A method for extracting konjac gum provided in this embodiment comprises:

[0053] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; wherein the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.05:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0054] S2: Soaking the konjac block in water at 45-55° C. for 2 hours or longer.

[0055] S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide, and stirring it with ultrasound for 20-30 minutes; wherein the mass fraction of ethanol in the ethanol solution is 40wt%, and the particle size of the nano-silicon oxide is less than or equal to 200nm. The mass fraction of the nano-silicon oxide in the ethanol solution is 1.5wt%.

[0056] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and centrifuging to obtain a precipitate; wherein the alcohol solvent is ethanol with a mass concentration of 70%; and the ultrasonic power during the alcohol precipitation is 300W-400W.

[0057] S5: washing the precipitate with an 80% ethanol solution, adding octenyl succinic anhydride; drying and grinding to obtain konjac gum; octenyl succinic anhydride can esterify the konjac gum, which helps to reduce the viscosity of the konjac gum.

[0058] The transparency of the konjac gum solution was measured by a spectrophotometer, and the viscosity of the konjac gum was measured by a rotational viscometer. The results are shown in Table 1.

[0059] Example 3

[0060] A method for extracting konjac gum provided in this embodiment comprises:

[0061] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; wherein the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.045:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0062] S2: Soaking the konjac block in water at 45-55° C. for 2 hours or longer.

[0063] S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide, and ultrasonically stirring it for 20-30 minutes; wherein the mass fraction of ethanol in the ethanol solution is 35wt%, and the particle size of the nano-silicon oxide is less than or equal to 200nm. The mass fraction of the nano-silicon oxide in the ethanol solution is 1wt%.

[0064] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and centrifuging to obtain a precipitate; wherein the alcohol solvent is ethanol with a mass concentration of 70%; and the ultrasonic power during the alcohol precipitation is 300W-400W.

[0065] S5: washing the precipitate with an 80% ethanol solution, adding octenyl succinic anhydride; drying and grinding to obtain konjac gum; octenyl succinic anhydride can esterify the konjac gum, which helps to reduce the viscosity of the konjac gum.

[0066] The transparency of the konjac gum solution was measured by a spectrophotometer, and the viscosity of the konjac gum was measured by a rotational viscometer. The results are shown in Table 1.

[0067] Comparative Example 1

[0068] A method for extracting konjac gum provided in this embodiment comprises:

[0069] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; wherein the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.045:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0070] S2: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide, and stirring it with ultrasound for 20-30 minutes; wherein the mass fraction of ethanol in the ethanol solution is 35wt%, the particle size of the nano-silicon oxide is less than or equal to 200nm, and the mass fraction of the nano-silicon oxide in the ethanol solution is 1wt%.

[0071] S3: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and centrifuging to obtain a precipitate; wherein the alcohol solvent is ethanol with a mass concentration of 70%; and the ultrasonic power during alcohol precipitation is 300W-400W.

[0072] S4: washing the precipitate with an 80% ethanol solution, adding octenyl succinic anhydride; drying and grinding to obtain konjac gum; octenyl succinic anhydride can esterify the konjac gum, which helps to reduce the viscosity of the konjac gum.

[0073] The transparency of the konjac gum solution was measured by a spectrophotometer, and the viscosity of the konjac gum was measured by a rotational viscometer. The results are shown in Table 1.

[0074] Comparative Example 2

[0075] A method for extracting konjac gum provided in this embodiment comprises:

[0076] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; wherein the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.045:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0077] S2: Soaking the konjac block in water at 45-55° C. for 2 hours or longer.

[0078] S3: crushing the soaked konjac block, and soaking it in an ethanol solution; ultrasonic stirring for 20-30 minutes; wherein the mass fraction of ethanol in the ethanol solution is 35wt%.

[0079] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and centrifuging to obtain a precipitate; wherein the alcohol solvent is ethanol with a mass concentration of 70%; and the ultrasonic power during the alcohol precipitation is 300W-400W.

[0080] S5: washing the precipitate with an 80% ethanol solution, adding octenyl succinic anhydride; drying and grinding to obtain konjac gum; octenyl succinic anhydride can esterify the konjac gum, which helps to reduce the viscosity of the konjac gum.

[0081] The transparency of the konjac gum solution was measured by a spectrophotometer, and the viscosity of the konjac gum was measured by a rotational viscometer. The results are shown in Table 1.

[0082] Comparative Example 3

[0083] A method for extracting konjac gum provided in this embodiment comprises:

[0084] S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; wherein the mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.045:1; and the soaking time of the konjac pieces in the activated carbon solution is 30 minutes.

[0085] S2: Soaking the konjac block in water at 45-55° C. for 2 hours or longer.

[0086] S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide, and ultrasonically stirring it for 20-30 minutes; wherein the mass fraction of ethanol in the ethanol solution is 35wt%, and the particle size of the nano-silicon oxide is less than or equal to 200nm. The mass fraction of the nano-silicon oxide in the ethanol solution is 1wt%.

[0087] S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and centrifuging to obtain a precipitate; wherein the alcohol solvent is ethanol with a mass concentration of 70%; and the ultrasonic power during the alcohol precipitation is 300W-400W.

[0088] S5: washing the precipitate with 80% ethanol solution, drying and grinding to obtain konjac gum.

[0089] The transparency of the konjac gum solution was measured by a spectrophotometer, and the viscosity of the konjac gum was measured by a rotational viscometer. The results are shown in Table 1.

[0090] Table 1 Comparison of transparency and viscosity of konjac gum prepared in each embodiment and comparative example

[0091]

[0092] It can be seen that: in Comparative Example 1, hot water immersion treatment is not carried out, and the viscosity of the konjac glucomannan prepared therefrom is greater than the viscosity of the konjac glucomannan in Examples 1 to 3 of the present application, and the transparency of the konjac glucomannan is also less than the transparency of the konjac glucomannan in Examples 1 to 3 of the present application. It is shown that the hot water immersion process can affect the transparency and viscosity of the konjac glucomannan at the same time.

[0093] Comparative Example 2 lacks polishing process, and the transparency of the konjac glucomannan prepared therefrom is less than the transparency of the konjac glucomannan in Examples 1 to 3 of the present application, and the viscosity is also slightly improved compared with Examples 1 to 3 of the present application, indicating that the polishing process of nano silicon oxide affects the transparency and viscosity of konjac glucomannan at the same time.

[0094] In Comparative Example 3, no esterification modification was performed, and the viscosity of the prepared konjac glucomannan was greater than that of the konjac glucomannan in Examples 1 to 3 of the present application, and the transparency was not much different from that in Examples 1 to 3. This indicates that the ester modification of the present application can reduce the viscosity of konjac glucomannan.

[0095] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for extracting konjac gum, characterized in that, include: S1: Cut the konjac into pieces and soak them in an activated carbon solution for decolorization and deodorization; S2: Soaking the konjac block in water at 45-55°C; S3: crushing the soaked konjac block, soaking it in an ethanol solution containing nano-silicon oxide; and ultrasonically stirring it for 20-30 minutes; S4: adding an alcohol solvent, performing alcohol precipitation under the assistance of ultrasound, and obtaining a precipitate by centrifugation; S5: washing the precipitate with 80% ethanol solution, adding an ester modifier, and drying and grinding to obtain konjac gum.

2. A method for extracting konjac gum according to claim 1, characterized in that, The mass ratio of activated carbon to konjac pieces in the activated carbon solution is 0.04-0.05:1; and the konjac pieces are immersed in the activated carbon solution for 30 minutes.

3. A method for extracting konjac gum according to claim 1, characterized in that, The soaking time in step S2 is greater than or equal to 2 hours.

4. A method for extracting konjac gum according to claim 1, characterized in that, In step S3, the particle size of the nano silicon oxide is less than or equal to 200 nm.

5. A method for extracting konjac gum according to claim 4, characterized in that, The mass fraction of the nano silicon oxide in the ethanol solution is 0.5-1.5wt%.

6. A method for extracting konjac gum according to claim 1, characterized in that, The mass fraction of ethanol in the ethanol solution in step S3 is 30-40wt%.

7. A method for extracting konjac gum according to claim 1, characterized in that, The alcohol solvent in step S4 is ethanol with a mass concentration of 70%.

8. A method for extracting konjac gum according to claim 7, characterized in that, The ultrasonic power during alcohol precipitation in step S4 is 300W-400W.

9. A method for extracting konjac gum according to claim 1, characterized in that, The ester modifier is octenyl succinic anhydride.

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