A method for extracting white chitin from shrimp shells

Abstract

The present invention relates to the technical field of comprehensive utilization of product processing waste, and particularly to a method for extracting white chitin from shrimp shells. The method of the present invention comprises the following steps: Step 1, soaking the shrimp shells in an organic acid solution and filtering to obtain solid A; Step 2, mixing and stirring solid A with an alkali solution and sodium dodecyl sulfate, and filtering to obtain solid B; Step 3, soaking solid B in an organic acid solution and filtering to obtain solid C; Step 4, mixing and stirring solid C with an alkali solution and sodium dodecyl sulfate, and filtering to obtain white chitin. The present invention uses an organic acid to replace hydrochloric acid to remove calcium carbonate, and does not use oxidants such as potassium permanganate, hydrogen peroxide, and sodium bisulfite for shrimp shell decolorization, and finally obtains white chitin, and the shrimp shells are relatively intact. The waste liquid generated in each step can be recycled, which is green and environmentally friendly, can make full use of shrimp shells, and is beneficial to environmental protection and resource conservation.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of product processing waste, and particularly relates to a method for extracting white chitin from shrimp shells. Background Art

[0002] Chitin is a type of high polymer of N-acetylglucosamine widely present in crustaceans, insects, and fungi. Chitin has wide application values in the fields of medicine, food, industry, etc. For example, in the pharmaceutical industry, it can be used to manufacture artificial skin and biodegradable and absorbable surgical sutures that can accelerate wound healing. In the food industry, it can be used as a food additive and preservative. In textile printing and dyeing, it can be used to manufacture various adhesives. In environmental protection, it can be used as a flocculant for treating industrial sewage and urban domestic sewage. Chitin has stable properties and is insoluble in water, dilute acids, dilute alkalis, and general organic solvents. In living organisms, it is often covalently bonded to proteins and mixed with inorganic salts, pigments, etc. To extract chitin from shrimp shells, generally hydrochloric acid is used to remove calcium carbonate, sodium hydroxide is used to remove proteins, and potassium permanganate, hydrogen peroxide, and sodium bisulfite are used for decolorization. However, long-term contact with hydrochloric acid will cause certain damage to the molecular structure of chitin and result in the cleavage of glycosidic bonds. Decolorization under strong oxidant conditions will also cause the cleavage of glycosidic bonds, and both will reduce the extraction rate of chitin. Currently, potassium permanganate, hydrogen peroxide, and hydrochloric acid are strictly regulated drugs, which to a certain extent affect the extraction of chitin. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for extracting white chitin from shrimp shells to solve the problems of non-white chitin and low extraction rate in the existing methods for extracting chitin from shrimp shells.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention, a method for extracting white chitin from shrimp shells, includes the following steps:

[0006] Step 1, soaking the shrimp shells in an organic acid solution, and filtering to obtain solid A;

[0007] Step 2, mixing and stirring the solid A with an alkali solution and sodium dodecyl sulfate, and filtering to obtain solid B;

[0008] Step 3, soaking the solid B in an organic acid solution, and filtering to obtain solid C;

[0009] Step 4, mixing and stirring the solid C with an alkali solution and sodium dodecyl sulfate, and filtering to obtain white chitin.

[0010] Another technical solution of the present invention, a chitin prepared by using the above method.

[0011] The third technical solution of the present invention is the application of the above chitin in the preparation of medicines, foods or the industrial field.

[0012] The present invention discloses the following technical effects:

[0013] Aiming at the problems of non-white chitin and low extraction rate in the existing method for extracting chitin from shrimp shells, the present invention provides a method for simply extracting white chitin. The present invention uses organic acids to replace hydrochloric acid to remove calcium carbonate, and does not use oxidants such as potassium permanganate, hydrogen peroxide, and sodium bisulfite for decolorizing shrimp shells. Finally, white chitin is obtained, and the shrimp shells are relatively intact. The waste liquid generated in each step can be recycled and reused, which is green and environmentally friendly, can make full use of shrimp shells, and is beneficial to environmental protection and resource conservation.

[0014] The method of the present invention is simple to operate, the process is controllable, and it is easy to scale up production. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a photograph of the chitin prepared in Example 1 of the present invention, Comparative Example 1, and Comparative Example 4.

[0017] Figure 2 It is a photograph of the fresh shrimp shells used in Example 1 of the present invention.

[0018] Figure 3 It is a photograph of the chitin prepared in Example 1 of the present invention. Detailed Embodiments

[0019] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and implementation schemes of the present invention.

[0020] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0021] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0022] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the description of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of this invention are obvious to those skilled in the art. The description of this invention and the examples are merely exemplary.

[0023] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0024] The "%" and "‰" mentioned in this invention, unless otherwise specified, both represent mass percentage and mass per thousand.

[0025] In the first aspect of this invention, a method for extracting white chitin from shrimp shells is provided, comprising the following steps:

[0026] Step 1: Soak the shrimp shells in an organic acid solution, and filter to obtain solid A;

[0027] Step 2: Mix and stir solid A with an alkali solution and sodium dodecyl sulfate, and filter to obtain solid B;

[0028] Step 3: Soak solid B in an organic acid solution, and filter to obtain solid C;

[0029] Step 4: Mix and stir solid C with an alkali solution and sodium dodecyl sulfate, and filter to obtain white chitin.

[0030] In a preferred embodiment of this invention, in Step 1, the organic acid solution is an aqueous citric acid solution with a mass concentration of 2 - 4%; the mass-to-volume ratio of the shrimp shells to the organic acid solution is 4 g:10 - 16 mL.

[0031] In a preferred embodiment of this invention, in Step 1, the soaking temperature is room temperature and the time is 24 hours. During the soaking process in Step 1, stir for 30 minutes every 6 hours.

[0032] In a preferred embodiment of the present invention, in step 2, the alkaline solution is an aqueous NaOH solution with a mass concentration of 2-6%; the mass-to-volume ratio of the shrimp shells to the alkaline solution in step 2 is 4 g:10-16 mL.

[0033] In a preferred embodiment of the present invention, in step 2, the temperature of the stirring treatment is 60-70 °C and the time is 6-7 hours; in the preparation process of solid B in step 2, the mass concentration of sodium dodecyl sulfate in the reaction system is 0.5-2‰ (that is, the mass concentration of sodium dodecyl sulfate in the mixed reaction system of solid A and the alkaline solution is 0.5-2‰).

[0034] In a preferred embodiment of the present invention, in step 3, the organic acid solution is an aqueous citric acid solution with a mass concentration of 2-4%; the temperature of the soaking is at room temperature and the time is 12-20 hours. In step 3, during the soaking process, stir for 30 minutes every 4 hours. The mass-to-volume ratio of the shrimp shells to the organic acid solution in step 3 is 4 g:10-16 mL.

[0035] In steps 1 and 3 of the present invention, if the concentration of citric acid is too high, it will degrade chitin. If the concentration of citric acid is too low, the decalcification is incomplete and it takes a longer time. Therefore, the present invention preferably limits the concentration of the organic acid (citric acid) to the above parameters.

[0036] The present invention also tried to replace acetic acid with other organic acids such as acetic acid, formic acid, malic acid, etc. to prepare chitin. The results showed that the prepared chitin was mixed with red color and white chitin could not be obtained because the acidity was low.

[0037] In steps 1 and 3, if the temperature and time of soaking are lower than the above-mentioned parameters, they are not suitable (for example, if the temperature is too high and the time is too long, chitin will degrade resulting in a low yield; if the temperature is too low and the soaking time is too short, the decalcification is insufficient).

[0038] In a preferred embodiment of the present invention, in step 4, the alkaline solution is an aqueous NaOH solution with a mass concentration of 2-6%; in the preparation process of the white chitin in step 4, the mass concentration of sodium dodecyl sulfate in the reaction system is 0.5-2‰ (that is, the mass concentration of sodium dodecyl sulfate in the mixed reaction system of solid C and the alkaline solution is 0.5-2‰).

[0039] In steps 2 and 4, if the concentration of the alkaline solution is too high, it is corrosive and unsafe. If the concentration of the alkaline solution is too low, it will affect the protein hydrolysis. Therefore, the present invention preferably limits the concentration of the alkaline solution to the above parameters.

[0040] Other alkaline solutions commonly used in the art, such as potassium hydroxide, are also applicable to the present invention.

[0041] In a preferred embodiment of the present invention, in step 4, the temperature of the stirring treatment is 60-70 °C and the time is 6-7 hours. The mass-volume ratio of the shrimp shells to the alkali solution in step 4 is 4 g: 10-16 mL.

[0042] In steps 2 and 4, if the temperature of the stirring treatment is too high, it is unsafe and energy-consuming, and if it is too low, the protein removal effect is not good; if the time of the stirring treatment is too long, the efficiency is low, and if it is too short, the protein removal effect is not good. Therefore, the present invention preferably limits the temperature and time of the stirring treatment to the above parameter ranges.

[0043] Sodium dodecyl sulfate in steps 2 and 4 acts as a surfactant and can play various roles such as washing, wetting, penetration, and dispersion. If the concentration of sodium dodecyl sulfate is too high, a large amount of foam will be generated, increasing the cleaning difficulty; if the concentration is too low, the decolorization effect is not good.

[0044] In a preferred embodiment of the present invention, in steps 1 to 4, after filtration, it further includes the steps of washing to neutrality and filtering again.

[0045] The present invention does not particularly limit the stirring speed in steps 1 to 4, and a commonly used stirring speed in the art such as 100 r / min can be adopted.

[0046] The second aspect of the present invention provides a chitin prepared by using the above method.

[0047] The third aspect of the present invention provides the application of the above chitin in the preparation of medicines, foods or the industrial field.

[0048] In the present invention, the chitin extraction rate = mass of chitin ÷ mass of fresh shrimp shells × 100%.

[0049] The following further illustrates the present invention through examples.

[0050] Example 1

[0051] Step 1, 40 grams of fresh shrimp shells (as shown in the physical photo), add 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours, rotation speed 100 r / min, filter, rinse to neutrality, filter. Figure 2 Step 2, add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in step 1, add 1.5‰ of sodium dodecyl sulfate (that is, the mass concentration of sodium dodecyl sulfate in the mixed system of the solid obtained by filtration in step 1 and the NaOH aqueous solution is 1.5‰), at 60 °C, rotation speed 100 r / min, stir for 6 hours, filter, wash to neutrality, filter.

[0052]

[0053] ​Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtration in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0054] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and dry to obtain white chitin with a chitin extraction rate of 6.5%.

[0055] The physical picture of the chitin prepared in this example is as Figure 3 shown, and it can be seen from Figure 3 that the chitin prepared in this example is white.

[0056] Example 2

[0057] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0058] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 1, add 1.0‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and then filter again.

[0059] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtration in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0060] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 1.0‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and dry to obtain white chitin with a chitin extraction rate of 6.8%. (That is, the only difference from Example 1 is that the concentration of sodium dodecyl sulfate in Steps 2 and 4 is 1.0‰, and the other steps and parameters are the same as those in Example 1)

[0061] Example 3

[0062] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0063] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 1, add 2.0‰ of sodium dodecyl sulfate, stir at 60 °C with a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and then filter again.

[0064] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtration in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours with a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0065] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 2.0‰ of sodium dodecyl sulfate, stir at 60 °C with a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, dry to obtain white chitin, and the chitin extraction rate is 6.6%. (That is, the difference from Example 1 is only that the concentration of sodium dodecyl sulfate in Steps 2 and 4 is 2.0‰, and the other steps and parameters are the same as those in Example 1)

[0066] Example 4

[0067] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours with a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0068] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 1, add 1.5‰ of sodium dodecyl sulfate, stir at 70 °C with a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and then filter again.

[0069] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtration in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours with a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0070] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 1.5‰ of sodium dodecyl sulfate, stir at 70 °C with a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, dry to obtain white chitin, and the chitin extraction rate is 6.7%. (That is, the difference from Example 1 is only that the stirring temperature in Steps 2 and 4 is 70 °C, and the other steps and parameters are the same as those in Example 1)

[0071] Example 5

[0072] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0073] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 1, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and then filter again.

[0074] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtering in Step 2, soak at room temperature for 20 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0075] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 3, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and dry to obtain white chitin with a chitin extraction rate of 6.2%. (That is, the only difference from Example 1 is that the soaking time in Step 3 is 20 hours, and the other steps and parameters are the same as those in Example 1)

[0076] Example 6

[0077] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0078] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 1, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 7 hours, filter, wash until neutral, and then filter again.

[0079] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtering in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and then filter again.

[0080] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 3, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 7 hours, filter, wash until neutral, and dry to obtain white chitin with a chitin extraction rate of 6.4%. (That is, the only difference from Example 1 is that the stirring time in Steps 2 and 4 is 7 hours, and the other steps and parameters are the same as those in Example 1)

[0081] Comparative Example 1

[0082] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter again.

[0083] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 1, add 1.5‰ of NaCl, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and filter again.

[0084] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtering in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter again.

[0085] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 3, add 1.5‰ of NaCl, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and obtain chitin with a red impurity. (That is, the difference from Example 1 is only that sodium dodecyl sulfate in Steps 2 and 4 is replaced by NaCl, and the other steps and parameters are the same as those in Example 1)

[0086] Comparative Example 2

[0087] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% acetic acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter again.

[0088] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtering in Step 1, add 1.5‰ of sodium dodecyl sulfate, stir at 60 °C at a rotation speed of 100 r / min for 6 hours, filter, wash until neutral, and filter again.

[0089] Step 3: Add 100 mL of 3% acetic acid aqueous solution to the solid obtained by filtering in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter again.

[0090] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C and a rotation speed of 100 r / min for 6 hours, filter, and wash until neutral to obtain chitin mixed with red. (That is, the difference from Example 1 is only that the citric acid aqueous solution in Steps 1 and 3 is replaced with acetic acid aqueous solution, and the other steps and parameters are the same as those in Example 1).

[0091] Comparative Example 3

[0092] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter.

[0093] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 1, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C and a rotation speed of 100 r / min for 6 hours, filter, and wash until neutral, and filter.

[0094] Step 3: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 2, add 1.5‰ sodium dodecyl sulfate, stir at 60 °C and a rotation speed of 100 r / min for 6 hours, filter, and wash until neutral to obtain chitin mixed with red. (That is, the difference from Example 1 is only that the step of treating with citric acid aqueous solution in Step 3 is omitted, and the other steps and parameters are the same as those in Example 1).

[0095] Comparative Example 4

[0096] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter.

[0097] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 1, add 1.5‰ sodium dodecyl sulfate, stir at room temperature and a rotation speed of 100 r / min for 6 hours, filter, and wash until neutral, and filter.

[0098] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtration in Step 2, soak at room temperature for 12 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter.

[0099] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 1.5‰ sodium dodecyl sulfate, stir at a rotation speed of 100 r / min at room temperature for 6 hours, filter, and wash until neutral to obtain chitin with a red tint. (That is, the difference from Example 1 is only that the stirring temperature in Steps 2 and 4 is room temperature, and the other steps and parameters are the same as those in Example 1).

[0100] Comparative Example 5

[0101] Step 1: Add 40 g of fresh shrimp shells to 130 mL of 3% citric acid aqueous solution, soak at room temperature for 24 hours, stir for 30 minutes every 6 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter.

[0102] Step 2: Add 130 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 1, add 1.5‰ sodium dodecyl sulfate, stir at a rotation speed of 100 r / min at 60°C for 6 hours, filter, and wash until neutral, and filter.

[0103] Step 3: Add 100 mL of 3% citric acid aqueous solution to the solid obtained by filtration in Step 2, soak at room temperature for 6 hours, stir for 30 minutes every 4 hours at a rotation speed of 100 r / min, filter, rinse until neutral, and filter.

[0104] Step 4: Add 100 mL of 4% NaOH aqueous solution to the solid obtained by filtration in Step 3, add 1.5‰ sodium dodecyl sulfate, stir at a rotation speed of 100 r / min at 60°C for 6 hours, filter, and wash until neutral to obtain chitin with a red tint. (That is, the difference from Example 1 is only that the soaking time at room temperature in Step 3 is 6 hours, and the other steps and parameters are the same as those in Example 1).

[0105] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for extracting white chitin from shrimp shells, characterized in that, It includes the following steps: Step 1: Soak the shrimp shells in an organic acid solution, and filter to obtain solid A; Step 2: Mix and stir solid A with an alkali solution and sodium dodecyl sulfate, and filter to obtain solid B; Step 3: Soak solid B in an organic acid solution, and filter to obtain solid C; Step 4: Mix and stir solid C with an alkali solution and sodium dodecyl sulfate, and filter to obtain white chitin; In Step 1, the organic acid solution is an aqueous citric acid solution with a mass concentration of 2-4%; the mass-to-volume ratio of the shrimp shells to the organic acid solution is 4g:10-16mL; In Step 1, the soaking temperature is room temperature and the time is 24 hours; In Step 2, the alkali solution is an aqueous NaOH solution with a mass concentration of 2-6%; the mass-to-volume ratio of the shrimp shells to the alkali solution in Step 2 is 4g:10-16mL; In Step 2, the stirring temperature is 60-70°C and the time is 6-7 hours; during the preparation of solid B in Step 2, the mass concentration of sodium dodecyl sulfate in the reaction system is 0.5-2‰; In Step 3, the organic acid solution is an aqueous citric acid solution with a mass concentration of 2-4%; the soaking temperature is room temperature and the time is 12-20 hours; In Step 4, the alkali solution is an aqueous NaOH solution with a mass concentration of 2-6%; during the preparation of the white chitin in Step 4, the mass concentration of sodium dodecyl sulfate in the reaction system is 0.5-2‰; In Step 4, the stirring temperature is 60-70°C and the time is 6-7 hours.

2. Chitin prepared by the method according to claim 1.

3. Use of the chitin according to claim 2 in the preparation of pharmaceuticals, food or the industrial field.

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