METHOD FOR EXTRACTING USEFUL SUBSTANCES FROM SHRIMP SHELLS

Abstract

Disclosed is a method for extracting useful substances from shrimp shells. The method comprises: crushing the shrimp shells, mixing the crushed shrimp shells and water, then heating same to 28° C.-35° C., adjusting the pH value to 6.8-7.5, preferably 6.8-7, then adding an alkaline protease and mixing same, heating same to 42° C.-48° C., performing constant-temperature enzymolysis for 50-70 min, and performing sieving to obtain an enzymatic hydrolysate and solid residues; performing centrifugal separation treatment on the enzymatic hydrolysate to obtain a shrimp protein deposit containing astaxanthin; mixing the shrimp protein deposit and water, performing heating while stirring, adjusting the pH value to 6.8-7.0, performing heating to 58° C.-60° C., adding vegetable oil, and performing emulsification for 50-70 min under stirring to obtain an emulsion; and performing centrifugation on the emulsion, and performing delamination to obtain astaxanthin-containing oil in an upper layer, water in a middle layer, and a shrimp protein in a lower layer. The method of the present invention uses waste biomass obtained after shrimps processed as a raw material, and can simultaneously extract several high-value substances, thereby not only improving the utilization rate of the raw material, but also shortening the production cycle; and no organic solvent is added, such that the method is clean, green and environmentally friendly.

Claims

1.-10. (canceled)

11. A method for extracting useful substances from shrimp shells, comprising the following steps: S1, crushing the shrimp shells to obtain fragments; S2, mixing the fragments obtained in S1 with water at a mass ratio of (1-2):(1-2) to obtain a mixture; S3, heating the mixture obtained in S2 to 28-35° C., then adjusting the pH value to 6.8-7.5, adding an alkaline protease, mixing, heating to 42-48° C., performing constant-temperature enzymolysis, and sieving to obtain enzymatic hydrolysate and solid residues, wherein the mass ratio of the alkaline protease to the mixture is 1:(800-1200), and continuous stirring at a rate of 45-60 r/min is required during the enzymolysis; S4, performing centrifugal separation on the enzymatic hydrolysate obtained in S3 to obtain an astaxanthin-containing shrimp protein deposit; S5, mixing the astaxanthin-containing shrimp protein deposit obtained in S4 with vegetable oil, heating to 57-60° C. while stirring, adding water, and emulsifying for 50-70 min under stirring to obtain an emulsion, wherein the mass ratio of the water to the shrimp protein deposit is (1.2-1.8):1, and the temperature difference between the mixture of shrimp protein deposit and vegetable oil and the added water is not more than 1° C.; and S6, centrifuging the emulsion in S5, and delaminating to obtain astaxanthin-containing oil in an upper layer, water in a middle layer, and a shrimp protein in a lower layer.

12. The method according to claim 11, wherein in S1, the fragments have a size of 4-9 cm2.

13. The method according to claim 11, wherein in S3, the sieving is performed through an 80-mesh vibrating screen.

14. The method according to claim 11, wherein in S3, the constant-temperature enzymolysis time is 50-90 min.

15. The method according to claim 14, wherein in S3, the constant-temperature enzymolysis time is 50-70 min.

16. The method according to claim 11, wherein in S4, during the centrifugal separation, the centrifugal rate is 4000-5000 r/min, and the centrifugal time is 10-14 min.

17. The method according to claim 11 wherein in S5, the pH value is adjusted with glacial acetic acid or hydrochloric acid.

18. The method according to claim 11, wherein in S5, the temperature difference between the mixture of shrimp protein deposit and vegetable oil and the added water is not more than 0.5° C.

19. The method according to claim 11, wherein in S6, during the centrifuging, the centrifuging rate is 5500-6500 r/min, and the centrifuging time is 10-14 min.

20. The method according to claim 11, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3a and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3a with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

21. The method according to claim 12, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

22. The method according to claim 13, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

23. The method according to claim 14, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

24. The method according to claim 15, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

25. The method according to claim 16, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

26. The method according to claim 17, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

27. The method according to claim 18, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

28. The method according to claim 19, further comprising steps of extracting useful substances from the solid residues obtained in S3, comprising: S3A, decolorizing the solid residues, then mixing the decolorized solid residues with water at a mass ratio of 1:(1.2-1.8), then adjusting the pH value to 2.5-3.5 with citric acid, controlling the temperature to 50-60° C., stirring for 8-10 h at a speed of 45-55 r/min, and performing solid-liquid separation to obtain calcium-containing liquid and decalcified solid residues; S3B, concentrating the calcium-containing liquid obtained in S3A and performing spray drying to obtain calcium citrate powder; mixing the decalcified solid residues obtained in S3A with water at a mass ratio of (1-2):(1-2), adding NaOH, adjusting the pH value to 13-14, then heating to 42-48° C., stirring at a constant temperature for 10-12 h, and performing solid-liquid separation to obtain solid substances; and S3C, milling the solid substances obtained in S3B into a colloidal solution with a colloid mill, then mixing the colloidal solution with water at a mass ratio of 1:(1.5-2.5), adjusting the pH value to 3.0-3.2, heating to 45-55° C., stirring at a constant temperature for 6-10 h, performing solid-liquid separation, concentrating and spray-drying the liquid components obtained by the solid-liquid separation to obtain water-soluble chitosan, and drying and milling the solid components obtained by the solid-liquid separation to obtain water-insoluble chitosan.

29. The method according to claim 20, wherein in S3A, during the decolorizing, the solid residues and water are mixed at a mass ratio of 1:(1.2-1.8), heated to 42-48° C., then added with hydrogen peroxide, and stirred for 2-4 h, and solid-liquid separation is performed to obtain decolorized solid residues.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] Example 1: A method for extracting astaxanthin and shrimp protein from crayfish shells by a biological enzyme method included the following steps:

Step 1, crayfish shells (including heads and tails) were pretreated, and 100 kg of frozen crayfish shells were minced into 20-50 mm fragments with a meat mincer.
Step 2, the crayfish shell fragments and water at a ratio of 1:1 were put into a reaction tank and heated to 30-40° C. with a pH value of 7.0, and 1000:1 biological alkaline enzyme powder (manufacturer: Nanning Pangbo Biological Engineering Co., Ltd., specification 200u) was added, followed by stirring at a constant temperature of 45° C. and a speed of 45-60 r/min, and digestion for 60 min, thus obtaining 100 kg of enzymatic hydrolysate.
Step 3, the 100 kg of enzymatic hydrolysate obtained was centrifuged to obtain 17.4 kg of astaxanthin-rich shrimp protein pulp.
Step 4, the 17.4 kg of astaxanthin-rich shrimp protein pulp was placed in a digestion tank, 7 kg of vegetable oil was added, the pulp was heated to 58° C., 58.5° C. pure water was added at a mass ratio of 6:4, stirring was performed for 60 min, then centrifugation was performed to obtain 12.6 kg of solid shrimp protein in the lower layer and 550 g of astaxanthin oil containing 6.1 wt % astaxanthin in the upper layer, and defatting and drying were performed to obtain 33550 mg of 99 wt % high-purity astaxanthin.

[0031] Optionally, after the enzymolysis, the solid residues obtained were placed in a digestion tank for decolorization, hydrogen peroxide was added at a ratio of 1000 g:13 ml, followed by stirring for 3 h. After the decolorization was completed, the solution was placed in the digestion tank for decalcification. The pH value was adjusted to 3.0-3.2 with citric acid, followed by stirring at a constant temperature to 50° C., digestion for 10 h, and solid-liquid separation, thus obtaining calcium-containing liquid and decalcified solid residues.

[0032] Solid filtration: centrifugal drying was performed on the calcium-containing liquid to obtain calcium citrate, the decalcified solid residues were placed in the digestion tank for deacetylation, the pH value was adjusted to 13.5 with NaOH, the decalcified solid residues were digested for 12 h, solids were filtered (the filtrate was recycled), the deacetylated solids weremilled by a colloid mill, the obtained colloidal solution was placed in the digestion tank for dissolution, the pH value was adjusted to 3.0 with glacial acetic acid, the solids weredissolved for 8 h, finally the pH value was adjusted to 6.8 with NaOH, filtration was performed again, the obtained liquid was concentrated, the concentrate was dried to obtain 27000 mg of water-soluble chitosan, and the obtained solids were dried and milled to obtain 34000 mg of water-insoluble chitosan.

[0033] Example 2: A method for extracting astaxanthin and shrimp protein from sea shrimp shells by a biological enzyme method included the following steps:

Step 1, frozen sea shrimp shells (including heads and tails) were minced into 20-50 mm fragments.
Step 2, the minced shrimp shell fragments and water at a ratio of 1:1 were put into a reaction tank and heated to 30° C. to 40° C., with a pH value of 6.8-7.0. 1000:1 biological alkaline enzyme powder was added, followed by stirring at a constant temperature of 45° C. and a speed of 50 r/min, and digestion for 90 min, thus obtaining 100 kg of enzymatic hydrolysate.
Step 3, the 100 kg of enzymatic hydrolysate obtained was centrifuged to obtain 16.5 kg of astaxanthin-rich shrimp protein pulp.
Step 4, the 16.5 kg of astaxanthin-rich shrimp protein pulp was placed in a digestion tank, 7 kg of vegetable oil was added, the pulp was stirred and heated to 55° C., 56° C. pure water was added at a mass ratio of 6:4, stirring was performed at a constant temperature for 60 min, and centrifugation was performed to obtain 9.7 kg of solid shrimp protein in the lower layer and 420 g of dark red astaxanthin oil liquid, and defatting and drying were performed to obtain 25620 mg of 99 wt % astaxanthin.

[0034] Optionally, after the enzymolysis, the solid residues obtained were placed in a digestion tank for decolorization, hydrogen peroxide was added at a ratio of 1000 g:13 mL, followed by stirring for 3 h. After the decolorization was completed, the solution was placed in the digestion tank for decalcification. The pH value was adjusted to 3.0-3.2 with citric acid, followed by stirring at a constant temperature to 50° C., digestion for 10 h, and solid-liquid separation, thus obtaining calcium-containing liquid and decalcified solid residues.

[0035] Solid filtration: centrifugal drying was performed on the calcium-containing liquid to obtain calcium citrate, the decalcified solid residues were placed in the digestion tank for deacetylation, the pH value was adjusted to 13.5 with NaOH, the decalcified solid residues were digested for 12 h, solids were filtered (the filtrate was recycled), the deacetylated solids were milled by a colloid mill, the obtained colloidal solution was placed in the digestion tank for dissolution, the pH value was adjusted to 3.0 with glacial acetic acid, the solids were dissolved for 8 h, finally the pH value was adjusted to 6.8 with NaOH, filtration was performed again, the obtained liquid was concentrated, the concentrate was dried to obtain 20150 mg of water-soluble chitosan, and the obtained solids were dried and milled to obtain 18460 mg of water-insoluble chitosan.

[0036] The applicant repeated Examples 1 and 2 and only changed the temperature when pure water was added in step 4. When the difference between the initial temperature of the pure water and the temperature of the mixture of shrimp protein pulp and oil was more than 1° C., saponification will occur. As a result, it was difficult to separate astaxanthin.

[0037] Specifically, in order to further confirm the importance of controlling the temperature difference within 1° C. in step 4, a further relevant case was provided as follows: Example 1 was repeated, except that: in step 4, pure water at T° C. was added (the mass ratio of water to shrimp protein deposit was 6:4), and emulsification was performed for 60 min under stirring to obtain an emulsion; then the emulsion was centrifuged and delaminated to obtain astaxanthin oil in the upper layer, water in the middle layer and shrimp protein in the bottom layer. The above experiment was repeated using the same batch of astaxanthin-containing shrimp protein deposit as a raw material and the temperature T of the added water as a variable. The situations of the astaxanthin-containing oil that can be finally separated were shown in Table 1.

TABLE-US-00001 TABLE 1 Situations of astaxanthin-containing oil that can be separated by adding T° C. pure water Constant temperature 58° C. in digestion tank T/° C. 48 49 50 51 52 53 54 Mass of 88 120 200 245 271 355 385 astax- anthin oil/g T/° C. 55 56 57 58 59 60 61 Mass of 445 480 520 554 540 520 460 astax- anthin oil/g T/° C. 62 63 64 65 66 67 68 Mass of 445 395 350 320 265 187 130 astax- anthin oil/g

[0038] The above tests proved that during the purification and emulsification, the temperature difference between the oil phase and the added water had a great impact on the separation of astaxanthin; when water was added to the oil phase, the greater the temperature difference between oil and water was, the lower the quality of the astaxanthin-containing oil obtained was, and the worse the purification effect was; only when the temperature difference between oil and water was within 1° C., the emulsification, separation and purification effects were the best. The main reason was that the emulsification was incomplete and even serious saponification occurred due to the influence of temperature, which affected the separation of the astaxanthin-containing oil and resulted in poor separation of astaxanthin. It can be seen that this application can avoid the saponification phenomenon and achieve a good separation effect by controlling the temperature difference between oil and water within 1° C.

[0039] It can be seen that the practices of separating astaxanthin and shrimp protein from the shrimp protein deposit by using vegetable oil and water and controlling the temperature difference between oil and water can effectively solve the problem of deep extraction of shrimp protein and astaxanthin from the enzymatic hydrolysate, and have obvious advantages compared with the existing technologies such as oil extraction.

[0040] The above examples are only to illustrate the technical concept and technical features of the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent modification based on the essence of the present invention should fall within the protection scope of the present invention.