New technology for removing fishy smell and moisture of natural pigment cuttlefish ink

Abstract

The invention discloses a novel process for removing fishy smell and moisture of natural pigment cuttlefish ink, which comprises the following steps of: performing enzymolysis and fishy smell removal by using double enzymes, and converting fishy smell substances into odorless components in situ through the synergistic effect of protease and trimethylamine oxidase; ultrasonic-assisted three-stage membrane separation is combined with a magnetic nanoparticle self-cleaning system, so that efficient and continuous separation is realized; sodium alginate-calcium ions are subjected to crosslinking concentration, a bionic microcapsule barrier is constructed, and the pigment stability and moisture resistance are synchronously improved; and pre-cooling step vacuum freeze-drying is carried out, and a melanin structure is protected through a temperature control program. The obtained cuttlefish ink product is relatively low in content of residual trimethylamine, relatively high in melanin retention rate, relatively weak in 450nm absorbance attenuation and relatively small in moisture content fluctuation in a 30-day humid and hot environment. The invention solves the problems of incomplete deodorization, easy degradation of pigment, serious membrane pollution and the like in the traditional process, and has high efficiency and environmental protection property.

Description

Technical Field

[0001] The invention relates to the technical field of cuttlefish ink processing, in particular to a new process for removing fishy smell and moisture from natural pigment cuttlefish ink. Background Art

[0002] Natural cuttlefish ink, as a high-value bio-pigment, is widely used in food, cosmetics, and functional materials. However, its industrialization faces three major technical bottlenecks: 1. Incomplete removal of fishy odor: Although traditional processes (acid treatment, activated carbon adsorption) can partially remove fishy substances such as trimethylamine, they lead to loss of natural flavor and chemical residues, and cannot solve the problem of continuous release of small molecule amines; 2. Poor pigment stability: Cuttlefish melanin is susceptible to oxidation, thermal degradation and moisture migration during processing. Conventional drying processes (spray drying, oven drying) accelerate pigment fading, and the absorbance at 450nm often decays by more than 5%; 3. Imbalance between energy consumption and efficiency: Existing membrane separation technology suffers from severe membrane fouling when processing high-viscosity cuttlefish juice. Frequent shutdowns for cleaning reduce production capacity (flux attenuation > 50% / 2h), while the linear temperature rise program of the freeze-drying process exacerbates the destruction of micro-nanostructures by ice crystals.

[0003] Although some studies have attempted to combine enzymatic hydrolysis and membrane separation, there is a technical gap: Enzyme treatment only focuses on protein hydrolysis and ignores the in situ transformation of fishy molecules; the membrane system lacks an online anti-pollution mechanism and cannot operate continuously; color protection and moisture-proof measures are separated (such as the single addition of antioxidants), making it difficult to take into account long-term stability. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] Therefore, in order to solve the above technical problems, the present invention provides the following technical solution: a new process for removing fishy smell and moisture from natural pigment cuttlefish ink, comprising the following steps: S1: Dual enzyme combined enzymatic deodorization; Heat fresh cuttlefish ink to 48-52°C, stir at 200±20 rpm, add 0.4-0.6% by mass of protease, adjust the pH to 7.8-8.2, and react for 1.8-2.2 hours; After the reaction, adjust the pH to 4.3-4.7 and let it stand for 25-35 minutes to remove the precipitate; Add 0.2-0.4% by weight of sucrase and 0.08-0.12% by weight of trimethylamine oxidase to the supernatant, adjust the pH to 4.8-5.2, and react at 48-52°C for 1.3-1.7 hours to form an enzymatic hydrolyzate. S2: ultrasound-assisted three-stage membrane separation; The enzymatic hydrolysate enters the nano-ceramic membrane system with the assistance of ultrasound and proceeds in sequence: Microfiltration: membrane pore size 0.18~0.22μm, pressure 0.12~0.18MPa; Ultrafiltration: molecular weight cut-off 8~12kDa, pressure 0.25~0.35MPa; Nanofiltration: molecular weight cut-off 250~350Da, pressure 0.45~0.55MPa; S3: sodium alginate-calcium ion cross-linking concentration; After membrane separation, 0.25-0.35% by mass of sodium alginate is added to the concentrate, ultrasonically dispersed, and 0.4-0.6 mol / L calcium chloride solution is added dropwise to a final concentration of 0.08-0.12% to form sodium alginate-calcium ion cross-linked microcapsules; Concentrate to 8-12% of the original volume using vacuum membrane distillation; S4: pre-cooled step vacuum freeze-drying; Precool to ≤-80℃ and hold for 1.5~2.5 hours; Primary drying: vacuum degree ≤10Pa, plate temperature rises from -40℃ to -30℃, maintains for 10~14 hours, then rises to -20℃ and maintains for 10~14 hours; Secondary drying: the plate temperature is raised to 23-27°C for 7-9 hours until the moisture content is ≤3%.

[0006] As a preferred embodiment of the new process for removing fishy smell and moisture from cuttlefish ink, the present invention provides a novel process for removing fishy smell and moisture from cuttlefish ink, wherein: the protease is Alcalase®, with an enzyme activity of ≥2.4 U / g; the sucrase is an invertase, with an enzyme activity of ≥250 U / g; and the trimethylamine oxidase has an enzyme activity of ≥500 U / g.

[0007] As a preferred solution of the new process for removing fishy smell and moisture from natural pigment cuttlefish ink described in the present invention, the nano-ceramic membrane system is integrated and electromagnetic coil array. The system applies a steady-state magnetic field of 0.4-0.6T for 4-6 minutes every 25-35 minutes of operation to drive the nanoparticles to move in a directional manner in the membrane pores and degrade pollutants.

[0008] As a preferred solution of the new process for removing fishy smell and moisture from natural pigment cuttlefish ink described in the present invention, in step S3, 0.04-0.06% by mass of kojic acid is added to the concentrate and stirred for 8-12 minutes.

[0009] As a preferred solution of the new process for removing fishy smell and moisture from natural pigment cuttlefish ink described in the present invention, the membrane material of the vacuum membrane distillation is a polytetrafluoroethylene-polyethersulfone composite membrane with a contact angle of ≥120°.

[0010] As a preferred embodiment of the new process for removing fishy smell and moisture from natural pigment cuttlefish ink described in the present invention, in step S4, in the primary drying stage, the plate temperature is first gradually increased from -40°C to -30°C within 10 to 14 hours, and then the temperature is increased from -30°C to -20°C within 10 to 14 hours.

[0011] As a preferred embodiment of the novel process for removing fishy smell and moisture from cuttlefish ink, a natural pigment, described in the present invention, the final product produced by the process is a powder having a particle size of 0.3-5.5 μm and a powder fineness of 0.3-5.5 μm. After being stored at 25° C. and a relative humidity of 75% for 30 days, the moisture content of the powder does not fluctuate by more than 1.5%.

[0012] As a preferred solution of the new process for removing fishy smell and moisture from the natural pigment cuttlefish ink described in the present invention, the final product prepared by the process has a cuttlefish melanin retention rate of ≥97% and an absorbance attenuation of ≤0.6% at 450nm.

[0013] As a preferred solution of the new process for removing fishy smell and moisture from natural pigment cuttlefish ink described in the present invention, ultrasonic assistance and membrane separation are carried out simultaneously, and the ultrasonic energy density is 15-25W / L.

[0014] A natural pigment cuttlefish ink product, characterized in that it is prepared by the process described in any one of claims 1 to 9, has a residual trimethylamine content of ≤0.01 mg / kg, and is coated with a sodium alginate-calcium ion cross-linked microcapsule layer.

[0015] The present invention, through the close coupling of four major technical modules: enzymatic conversion, intelligent membrane separation, bionic microcapsule color protection and moisture resistance, and step-controlled temperature freeze-drying, not only solves the multiple technical difficulties of fishy smell removal, color protection, moisture resistance, and continuous production in traditional processes, but also achieves a comprehensive improvement in performance indicators. The specific beneficial effects are as follows: 1. The present invention innovatively introduces trimethylamine oxidase, which catalyzes the fishy substance trimethylamine into odorless trimethylamine oxide in situ during the enzymatic hydrolysis stage, replacing the traditional methods of passive interception or adsorption. It has a significant deodorizing effect while retaining the natural flavor components in cuttlefish ink to the greatest extent.

[0016] 2. The present invention adopts an intelligent self-cleaning membrane system with ultrasound-assisted coupling of magnetic protease nanoparticles. Driven by a directional magnetic field, it continuously degrades membrane pore pollutants without the need for frequent shutdown for cleaning, meeting the needs of industrial continuous production and significantly improving processing efficiency and equipment utilization.

[0017] 3. The present invention constructs sodium alginate-calcium ion cross-linked microcapsules after membrane concentration and introduces tyrosinase inhibitors such as kojic acid to form a dynamic moisture barrier and chemical antioxidant dual protection, effectively preventing oxidative fading and deliquescence agglomeration.

[0018] 4. The present invention adopts a pre-cooling combined with a step-by-step temperature rise freeze-drying procedure to precisely control ice crystal growth and sublimation dynamics to avoid mechanical damage to melanin particles and ensure the activity and dispersion performance of downstream applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them: Figure 1 This is a workflow diagram of embodiment 1 of the present invention. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0023] Example 1 Reference Figure 1 , which is the first embodiment of the present invention, provides a new process for removing fishy smell and moisture from natural pigment cuttlefish ink, and the specific steps are as follows: S1: enzymatic hydrolysis stage; 500 kg of fresh cuttlefish ink was stirred at 50°C and 200 rpm, and 0.5% Alcalase® (pH 8.0, 2 hours) was added. The pH was adjusted to 4.5 and the mixture was allowed to stand for 30 minutes. The supernatant was collected, and 0.3% invertase and 0.1% trimethylamine oxidase (pH 5.0, 50°C, 1.5 hours) were added. After the reaction, the pH was adjusted to 7.0.

[0024] S2: membrane separation and magnetic self-cleaning; The enzymatic hydrolysate was introduced into the membrane separation system with the assistance of ultrasound (20W / L): Microfiltration (0.2 μm, 0.15 MPa) → ultrafiltration (10 kDa, 0.3 MPa) → nanofiltration (300 Da, 0.5 MPa); A 0.5T magnetic field (lasting 5 minutes) is triggered every 30 minutes. The system contains 0.01% magnetic iron oxide core-coated protease nanoparticles for online self-cleaning.

[0025] S3: microcapsule cross-linking and vacuum membrane steaming; 0.3% sodium alginate was added to the concentrate, and 0.5M calcium chloride was added dropwise to a final concentration of 0.1% to form sodium alginate-calcium ion cross-linked microcapsules; the solution was then concentrated to 10% of its original volume using vacuum membrane distillation (cold side 40°C / hot side 60°C, 0.08 MPa).

[0026] S4: step-by-step freeze-drying; Precooling: -80℃, 2h; Primary drying: -40℃→-30℃, 12h (vacuum degree ≤ 10Pa); Secondary drying: 25℃, 8h.

[0027] The product properties finally obtained in this embodiment are as follows: Trimethylamine residue ≤ 0.008 mg / kg; Membrane flux attenuation rate (8h) ≤ 8%; Melanin retention rate 98.2% (450nm ΔA (absorbance) = 0.4%); Moisture resistance (30 days, 25℃ / 75% RH) moisture content change +1.2%; Powder particle size: 0.4~5.0μm.

[0028] Example 2 This is the second embodiment of the present invention. This embodiment differs from the first embodiment in that in step S1, only 0.3% invertase is added, and trimethylamine oxidase is not added. Other steps and parameters are the same as those in embodiment 1.

[0029] The comparison data of the finished product obtained in this embodiment and Example 1 are as follows:

[0030] It can be seen from this that when trimethylamine oxidase is not added, the fishy substances cannot be converted in situ, and it is difficult to completely remove the fishy smell by relying solely on membrane separation (NF retention rate 85%).

[0031] Example 3 This is the third embodiment of the present invention. This embodiment differs from the first embodiment in that: in step S2 of the first embodiment, the nanoparticles of the magnetic iron oxide core-coated protease and the magnetic field are removed, and only 20W / L ultrasonic assistance is retained; after the membrane is contaminated, 0.1M NaOH is shut down and circulated alkaline washing is performed for 30 minutes.

[0032] The comparison data of the process data of this embodiment and embodiment 1 are as follows:

[0033] As can be seen, after removing the magnetic self-cleaning system and adopting the traditional ultrasonic plus downtime alkaline cleaning solution, the membrane flux decay rate reached as high as 62% within 2 hours, requiring frequent downtime for cleaning to maintain performance. The processing capacity decreased by 36% over 8 hours, and residual cleaning agent posed additional safety risks. Compared with Example 1, magnetic self-cleaning not only ensured the long-term stable operation of the membrane system, but also significantly improved processing efficiency and production safety.

[0034] Example 4 This is the fourth embodiment of the present invention. This embodiment differs from the first embodiment in that: in step S3 of the first embodiment, sodium alginate and calcium chloride are not added, and vacuum membrane distillation and concentration are directly performed; and 0.05% kojic acid is additionally added before freeze-drying.

[0035] The comparison data of the finished product obtained in this embodiment and Example 1 are as follows:

[0036] This indicates that without cross-linking the sodium alginate-calcium ion microcapsules, melanin oxidation is exacerbated, the retention rate drops to 83.5%, and the moisture absorption rate soars to +8.9% within 30 days, leading to powder agglomeration. This demonstrates that microcapsule cross-linking not only provides antioxidant protection but also effectively inhibits moisture absorption and maintains powder dispersion, making it an essential technical solution for improving product stability and storage.

[0037] Example 5 This is the fifth embodiment of the present invention. This embodiment differs from the first embodiment in that the primary drying stage in step S4 of the first embodiment is changed to a linear temperature increase from -40°C to -20°C / 24h (the total duration is the same as that of the first embodiment), and the other steps remain unchanged.

[0038] The performance of the final product is compared with that of Example 1:

[0039] As can be seen, after switching the freeze-drying process to a linear temperature ramp, melanin retention dropped to 89.7%, large particles (>10μm) appeared in the powder, and rehydration time was extended from 30s to over 5min, severely compromising the integrity of the microcapsule structure. This result clearly demonstrates that the stepped temperature ramp strategy, through multi-stage temperature control, helps form a dense microcapsule structure, maximizing the protection of the active ingredient and improving the solubility of the powder.

[0040] The data comparison of the above examples 1 to 5 is shown in the following table:

[0041] Note: All example data are based on 50 kg batch pilot results. The detection methods include: trimethylamine residue (GC-MS method, GB5009.208-2016), melanin retention rate (HPLC-UV method, JChromatogrB2020), and membrane flux (GB / T32360-2015).

[0042] Compared with the comparative example, Example 1 achieves significant improvement through the following key technical features: The deodorization efficiency of TMAO enzyme in situ conversion was increased by 99.8% (Comparative Example 2); The magnetic self-cleaning system reduces cleaning time by 83% and increases production capacity by 36% (Compared with Example 3); The sodium alginate-calcium ion microcapsules cooperated with the step-by-step freeze-drying process, and the melanin retention rate in cuttlefish juice was increased by 15.5% (comparing Example 4 with Example 5).

[0043] The above data fully demonstrates the significant progress of the various technical features of the present invention in solving industry pain points and meets the requirements of patent law for creativity.

[0044] The steps in Example 1 form an integrated whole. Comparative examples lacking any of these steps exhibit significant performance degradation: increased residual fishy odor, severe membrane fouling, increased pigment oxidation, or significant freeze-drying damage. The four-pronged technology not only individually plays a key role but also synergistically achieves comprehensive optimization of squid ink in terms of fishy removal, color preservation, moisture resistance, and efficient production, demonstrating significant non-obviousness and industrial application value.

[0045] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A new process for removing fishy smell and moisture from natural pigment cuttlefish ink, characterized by: The following steps are involved: S1: Dual enzyme combined enzymatic deodorization; Heat fresh cuttlefish ink to 48-52°C, stir, add 0.4-0.6% by mass of protease, adjust the pH to 7.8-8.2, and react for 1.8-2.2 hours; After the reaction, the pH was adjusted to 4.3-4.7 and the mixture was allowed to stand to remove the precipitate; Add 0.2-0.4% by weight of sucrase and 0.08-0.12% by weight of trimethylamine oxidase to the supernatant, adjust the pH to 4.8-5.2, and react at 48-52°C for 1.3-1.7 hours to form an enzymatic hydrolyzate. S2: ultrasound-assisted three-stage membrane separation; The enzymatic hydrolysate enters the nano-ceramic membrane system with the assistance of ultrasound and proceeds in sequence: Microfiltration: membrane pore size 0.18~0.22μm, pressure 0.12~0.18MPa; Ultrafiltration: molecular weight cut-off 8~12kDa, pressure 0.25~0.35MPa; Nanofiltration: molecular weight cut-off 250~350Da, pressure 0.45~0.55MPa; S3: sodium alginate-calcium ion cross-linking concentration; After membrane separation, 0.25-0.35% by mass of sodium alginate is added to the concentrate, ultrasonically dispersed, and 0.4-0.6 mol / L calcium chloride solution is added dropwise to a final concentration of 0.08-0.12% to form sodium alginate-calcium ion cross-linked microcapsules; Concentrate to 8-12% of the original volume using vacuum membrane distillation; S4: pre-cooled step vacuum freeze-drying; Precool to ≤-80℃ and hold for 1.5~2.5 hours; Primary drying: vacuum degree ≤10Pa, plate temperature rises from -40℃ to -30℃, maintains for 10~14 hours, then rises to -20℃ and maintains for 10~14 hours; Secondary drying: the plate temperature is raised to 23-27°C for 7-9 hours until the moisture content is ≤3%.

2. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 1, characterized in that: The protease is Alcalase®, with an enzyme activity of ≥2.4 U / g; the sucrase is an invertase, with an enzyme activity of ≥250 U / g; and the trimethylamine oxidase has an enzyme activity of ≥500 U / g.

3. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 2, characterized in that: The nano-ceramic membrane system integrates nanoparticles of protease coated with magnetic iron oxide cores and an electromagnetic coil array. The system applies a steady-state magnetic field of 0.4-0.6T for 4-6 minutes every 25-35 minutes of operation to drive the nanoparticles to move in a directional manner within the membrane pores and degrade pollutants.

4. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 3, characterized in that: In step S3, 0.04-0.06% by mass of kojic acid is added to the concentrated solution and stirred for 8-12 minutes.

5. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 4, characterized in that: The membrane material of vacuum membrane distillation is polytetrafluoroethylene-polyethersulfone composite membrane with a contact angle of ≥120°.

6. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 5, characterized in that: In step S4, during the primary drying stage, the board temperature is first gradually increased from -40°C to -30°C over 10 to 14 hours, and then from -30°C to -20°C over another 10 to 14 hours.

7. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 6, characterized in that: The final product obtained by this process is a powder with a particle size of 0.3-5.5μm and a powder fineness of 0.3~5.5μm. After being stored in an environment of 25℃ and relative humidity of 75% for 30 days, its moisture content fluctuates by no more than 1.5%.

8. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 7, characterized in that: The final product prepared by the process has a cuttlefish melanin retention rate of ≥97% and a 450nm absorbance attenuation of ≤0.6%.

9. The novel process for removing fishy smell and moisture from natural pigment cuttlefish ink according to claim 8, characterized in that: Ultrasonic assistance and membrane separation are carried out simultaneously, and the ultrasonic energy density is 15-25W / L.

10. A natural pigment cuttlefish ink product, characterized by: The microcapsule is prepared by the process according to any one of claims 1 to 9, has a residual trimethylamine content of ≤0.01 mg / kg, and is coated with a sodium alginate-calcium ion cross-linked microcapsule layer.

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