Solid microalgae-containing composition for culturing fresh microalgae as well as preparation method and application of solid microalgae-containing composition

Abstract

The invention relates to the field of microalgae culture, in particular to a solid microalgae-containing composition for culturing fresh microalgae as well as a preparation method and application of the solid microalgae-containing composition. The composition containing the solid microalgae and used for culturing the fresh microalgae comprises live microalgae cells and food-grade gel. The viable microalgae cells are algae species with an appropriate pH value of 6 to 8.2 and / or algae species with an appropriate pH value of 8.3 to 13. The food grade gel is insoluble in the culture medium of microalgae and can support the growth of live microalgae cells. The composition containing the solid microalgae is aseptically packaged in the soft photobioreactor, and can be preserved for a long time. By utilizing the composition containing the solid microalgae disclosed by the invention, the sanitary fresh microalgae which can be directly eaten can be easily prepared by residents. According to the method, the sanitation problem of preparing the fresh microalgae by an existing liquid culture process is solved, and the tedious processes of harvesting algae cells, washing algae mud, cleaning and maintaining a culture device and the like in liquid culture can be avoided.

Description

Technical Field

[0001] The invention relates to the field of microalgae cultivation, and in particular to a composition containing solid microalgae for cultivating fresh-edible microalgae, and a preparation method and application thereof. Background Art

[0002] Microalgae are a type of single-cell oxygen-releasing photosynthetic microorganisms. There are six main types of microalgae approved as new food raw materials (new resource foods) in my country. Among them, Spirulina, Chlorella, and Haematococcus pluvialis have an annual output of about 10,000 tons, 2,000 tons, and 400 tons of dry products, respectively. Dunaliella salina, Nostoc sphaeroids Kütz, and Euglena have also been industrialized (Science China: Life Sciences, 2021, Vol. 51, No. 1: 26-39). At present, my country has become the world's largest producer of microalgae.

[0003] Edible microalgae have high application value. Microalgae cells are rich in proteins, amino acids, carbohydrates, vitamins, antibiotics, highly unsaturated fatty acids, polysaccharides, pigments and other high value-added biological substances. Taking Spirulina as an example, there are currently two species of Spirulina that can be cultivated on a large scale: Spirulina platensis and Spirulina maxima. Spirulina contains protein accounting for about 70% of its dry weight, contains many kinds of vitamins, trace elements, etc., and the content of β-carotene is 14 times that of ordinary carrots. At the same time, its cell wall lacks cellulose, which is conducive to human digestion and absorption. Therefore, Spirulina has been widely used in food, health care, medicine and other industries.

[0004] The product form of edible microalgae used in the food industry is mainly algae powder. Algae powder is made by harvesting large-scale cultured microalgae, spray drying it, and then pressing (adding auxiliary materials) it into algae tablets or encapsulating it. However, the content of some nutrients decreases during the high-temperature spray drying process (Chinese Food and Nutrition, 1995(1):22-23). ​​Fresh edible microalgae are not treated with high temperatures, so the temperature-sensitive components such as proteins, bioactive substances, and pigments in the algae cells are retained, and its active functionality is also better than that of algae powder.

[0005] Fresh microalgae are difficult to store. The literature (High Technology and Industrialization, 2016 (9): 80-86) reported the use of a fully enclosed photoreactor and automatic harvesting technology to produce fresh edible spirulina mud, which was then sold to users. This method of distributing fresh edible microalgae requires the cooperation of a cold chain, because the harvested algae mud is generally difficult to achieve commercial sterility and cannot be stored for a long time. The reason is that large-scale enclosed photoreactors themselves are difficult to sterilize at high temperatures and high pressures like fermentation tanks, and the culture medium and algae mud will be exposed to air during the algae cell harvesting process. Even if the inoculum during the culture is sterile, it is difficult to ensure the sterility of the harvested algae mud. To obtain sterile algae mud, it is necessary to sterilize various ingredients, use aseptic operations, sterilize reactors and other equipment, and also require clean workshops and aseptic packaging, which requires high production costs. Therefore, this kind of fresh algae mud has to rely on cold chain transportation to be sold, which brings difficulties to the promotion of fresh microalgae.

[0006] The document (Industrial Design, 2011 (3): 52-53) reports an "Eco-Fort" (home algae cultivation machine) for cultivating fresh edible spirulina at home, which can purify the air while producing fresh algae. After cultivating microalgae in a home algae cultivation machine, it is necessary to filter and harvest, and wash the algae mud with clean water to obtain fresh algae mud or algae pulp beverage that can be directly eaten. Therefore, for a device for cultivating fresh edible microalgae for home use, in addition to the need to set up a light source, it is also necessary to set up a cultivation chamber, a filter screen or filter cloth, a feed port, a water inlet pipe, a drain pipe, a delivery pump, a plurality of valves, etc., not only the cultivation device is complex in structure, cumbersome in operation, troublesome in cleaning and maintenance, and expensive. Another problem with the home algae cultivation machine is that since the cultivation device itself cannot be sterilized like a fermentation tank, and the feeding, discharging, harvesting, and cleaning processes of the cultivation device cannot avoid contact with the air, it is impossible to keep the cleanliness and sterility of each component and each operation step for a long time.

[0007] The root of the above-mentioned problems in cultivating fresh edible microalgae (directly edible without drying) is that the fresh edible algae mud for terminal consumption is obtained by liquid culture and harvesting, and the above-mentioned problems are difficult to overcome in the liquid culture mode. Summary of the invention

[0008] In order to fundamentally overcome these problems, the present invention provides a solid microalgae composition for culturing edible microalgae, and a preparation method and application thereof.

[0009] The composition containing solid microalgae for culturing edible microalgae comprises living microalgae cells and food-grade gel.

[0010] According to the composition containing solid microalgae of the present invention, the living microalgae cells are algae species suitable for pH 6-8.2, or algae species suitable for pH 8.3-13.

[0011] According to the composition containing solid microalgae of the present invention, the food-grade gel is insoluble in the culture medium of microalgae and can support the growth of living microalgae cells.

[0012] According to the composition containing solid microalgae of the present invention, as an option, the food-grade gel comprises one or more of gellan gum, agar, agarose, κ-carrageenan, λ-carrageenan, konjac gum, starch, psyllium gum, calcium alginate and gelatin.

[0013] According to the composition containing solid microalgae of the present invention, as an option, when the solid microalgae is an algae species suitable for pH 6-8.2, the food-grade gel is preferably calcium alginate, and / or, when the solid microalgae is an algae species suitable for pH 8.3-13, the food-grade gel is preferably λ-carrageenan.

[0014] According to the composition containing solid microalgae of the present invention, optionally, the composition further comprises a food preservative, a dehydration protectant and / or a gel enhancer.

[0015] According to the composition containing solid microalgae of the present invention, preferably, the composition is aseptically packaged in a soft photobioreactor. Further preferably, the soft photobioreactor is made of food-grade light-transmitting film material.

[0016] More preferably, the soft photobioreactor is sterile, and / or the soft photobioreactor can be disposable.

[0017] According to the composition containing solid microalgae of the present invention, the soft photobioreactor is provided with an air inlet, an exhaust port and / or a water inlet as required; wherein the air inlet is used to fill with protective gas, and when adding liquid culture medium for cultivation, air or other CO2-containing gas is introduced as required. 2 The exhaust port is used to exhaust the protective gas, and to exhaust air or other gases containing CO when adding liquid culture medium for cultivation. 2 The water inlet is used to add liquid culture medium or water when adding liquid culture medium for cultivation.

[0018] Further optionally, a sterilizing filter is provided at the air inlet, the exhaust port and / or the water inlet.

[0019] The present invention also provides a method for preparing a composition containing solid microalgae for culturing edible microalgae, comprising the following steps:

[0020] The freshly cultured and harvested microalgae mud is fully mixed with a solution of food-grade gel at a temperature above the gel sol temperature and below the tolerance temperature of algae cells, cooled and solidified, and then dehydrated to a desired moisture content to obtain a composition containing solid microalgae.

[0021] According to the preparation method of the present invention, specifically, the preparation method comprises the following steps:

[0022] 1) Preparing fresh algae mud: expanding the culture, harvesting, and pre-treating the microalgae cells to obtain fresh algae mud;

[0023] 2) preparing a gel solution: mixing food-grade gel with water, and heating to the sol temperature of the gel to dissolve the gel substance, thereby obtaining a gel solution;

[0024] 3) Alginate mixing: Cooling the gel solution to a temperature above its gelling temperature and below the tolerance temperature of algae cells, and fully mixing the fresh algae mud with the gel solution to obtain an algae mixed solution;

[0025] 4) Solidification and molding: forming the alginic gel mixture into a desired shape at a temperature above the gelling temperature of the gel, cooling the mixture to below the gelling temperature or to room temperature, and allowing the gel to solidify naturally to obtain a composition containing solid microalgae;

[0026] According to the preparation method of the present invention, preferably, the preparation method further comprises a dehydration step after solidification and molding in step 4), wherein the dehydration step comprises: dehydrating the composition containing solid microalgae to a desired moisture content to obtain a dehydrated composition containing solid microalgae.

[0027] According to the preparation method of the present invention, preferably, the preparation method further comprises the step of aseptically packaging the obtained (non-dehydrated or dehydrated) composition containing solid microalgae in a soft photobioreactor.

[0028] The present invention also provides use of any of the above compositions containing solid microalgae in culturing edible microalgae.

[0029] As a preferred embodiment, the application comprises the following steps: adding liquid culture medium into a soft photobioreactor encapsulating a composition containing solid microalgae (non-dehydrated or dehydrated), culturing to a desired time or a desired algal cell density under light and temperature conditions suitable for the algae species, and obtaining edible microalgae.

[0030] Furthermore, the application specifically includes the following steps:

[0031] 1) adding liquid culture medium from the water inlet of a soft photobioreactor encapsulating a composition containing solid microalgae (non-dehydrated or dehydrated);

[0032] 2) placing the soft photobioreactor added with the liquid culture medium in step 1) in a culture device, setting the light intensity and temperature required by the algae species; ventilating or not ventilating as required, wherein the ventilation includes introducing air or other materials containing CO2 from the air inlet. 2The gas is discharged from the exhaust port at the same time, air or other gas containing CO 2 of gas;

[0033] 3) After culturing to a desired time or a desired algae cell density, the soft photobioreactor is opened, and the solid alginic gel mixture in which the algae cells have proliferated after culturing is taken out to obtain edible microalgae.

[0034] The present application abandons the idea of ​​preparing edible microalgae by traditional liquid culture, and proposes a method for solid culture of edible microalgae: using edible gel to embed living (proliferable) microalgae cells, and aseptically encapsulating the solid microalgae-containing composition in a soft photobioreactor without or after dehydration as needed, and providing (selling) the composition to users (e.g., households). Users add liquid culture medium for algae species into the soft photobioreactor at home or other distributed occasions, and culture the algae by conventional methods, that is, using appropriate light, appropriate temperature, and supplementing or not supplementing CO as needed. 2 , so that the microalgae cells proliferate on the gel, and the proliferated algae cells are still attached to the edible gel. After the desired cell density or time is reached, the gel attached with the algae cells is taken out, and the algae cells and the gel can be eaten together with the gel by simply washing. The present invention eliminates the steps of cold chain transportation, algae cell harvesting, algae mud washing, etc. in the liquid culture method, and can greatly simplify the culture device for culturing fresh microalgae (that is, the culture device only needs to provide a light source and / or an aeration function, or even, the culture device is not needed and the culture is directly cultivated using sunlight).

[0035] Effects and advantages of the invention

[0036] The present invention aseptically encapsulates the composition containing solid microalgae in a soft photobioreactor, which can be stored for a long time. In the home or other distributed occasions, a cultivation device with a lighting, temperature control and gas supply system is provided. It only takes simple operation and a few days (4-7 days) to produce clean and hygienic fresh microalgae that can be directly eaten. The algae cell area yield is as high as 9.9g / (m 2 ·d). The present invention completely solves the hygienic problem of preparing fresh-eating microalgae by the existing liquid culture process, and can avoid the cumbersome processes of algae cell harvesting, algae mud washing, and culture device cleaning and maintenance in liquid culture.

[0037] Finally, 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 is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention is a sheet-shaped composition containing solid microalgae made of spirulina and λ-carrageenan, wherein (a) after solidification, (b) after dehydration, and (c) after packaging;

[0039] Figure 2 The present invention is a sheet-shaped composition containing solid microalgae made of chlorella, calcium alginate and kappa-carrageenan, wherein (a) is not dehydrated, and (b) is dehydrated;

[0040] Figure 3 The present invention is a sheet-shaped composition containing solid microalgae made of Nannochloropsis and agar, wherein (a) after solidification and (b) after dehydration;

[0041] Figure 4 The composition containing solid microalgae in the form of strips made of Chlorella and gellan gum in the embodiment of the present invention, wherein: (a) before dehydration, (b) after dehydration;

[0042] Figure 5 The granular composition containing solid microalgae made of spirulina and agarose in the embodiment of the present invention, wherein (a) before dehydration, (b) after dehydration;

[0043] Figure 6 The granular composition containing solid microalgae made of Nannochloropsis and calcium alginate in the embodiment of the present invention, wherein (a) before dehydration, (b) after dehydration;

[0044] Figure 7 The transparent soft photobioreactor (nitrogen filled storage) encapsulating a composition containing solid microalgae made of Chlorella, calcium alginate and κ-carrageenan in an embodiment of the present invention, wherein (left) is encapsulated directly without dehydration, and (right) is encapsulated after dehydration;

[0045] Figure 8 The transparent soft photobioreactor in the embodiment of the present invention is encapsulated with a sheet-shaped composition containing solid microalgae made of Spirulina and λ-carrageenan;

[0046] Fig. 9 The edible algae in sheets are cultured from the composition containing solid microalgae in sheets made of spirulina and λ-carrageenan in the embodiment of the present invention, wherein (a) before consumption, (b) to be consumed;

[0047] Fig.10 The present invention is a flow chart for preparing a composition containing solid microalgae for culturing edible microalgae. DETAILED DESCRIPTION

[0048] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0049] The present invention discloses a composition containing solid microalgae for culturing edible microalgae. The composition containing solid microalgae is aseptically encapsulated in a soft photobioreactor and consists of living microalgae cells and edible transparent or translucent gel (food-grade gel), wherein the living microalgae cells are uniformly dispersed inside and on the surface of the edible gel. After adding liquid culture medium into the soft photobioreactor, the gel does not dissolve in the culture medium of the microalgae and can support the growth of living microalgae cells, and the algae cells and the gel can be eaten together with simple cleaning.

[0050] The algae species may be algae species suitable for a neutral pH (pH 6-8.2), including but not limited to Chlorella (BG11 (+N) culture medium, pH adjusted to 7.1), Haematococcus pluvialis (SM (+N / -N) culture medium, wherein +N is used for growth and -N is used for induction, pH 6.8-7.1), and Nannochloropsis spp. (f / 2 culture medium, buffer may be added or pH may be adjusted to 7.6-7.8 using acid or alkali); the algae species may also be algae species suitable for an alkaline pH (pH 8.3-13), including but not limited to Spirulina (Zarrouk culture medium, pH 8.3).

[0051] The gel includes, but is not limited to, gellan gum (microorganism source), agar (marine plant source), agarose (marine plant source), κ-carrageenan (marine plant source), λ-carrageenan (marine plant source), konjac gum (terrestrial plant source), starch (terrestrial plant source, kudzu root starch, pea starch, mung bean starch, potato starch, sweet potato starch, corn starch, broad bean starch, rice starch, wheat starch), psyllium gum (i.e., psyllium polysaccharide, terrestrial plant source) and gelatin (animal source) formed by compounding one or more gelling substances; wherein, for algae species suitable for neutral pH (pH6-8.2), the gel also includes calcium alginate (marine plant source) and a gel formed by compounding thereof.

[0052] The gel, for algae species suitable for a neutral pH (pH 6-8.2), is preferably agar and calcium alginate gel, and the calcium alginate gel is formed by calcification of sodium alginate (ie, alginate).

[0053] The gel is preferably agarose and λ-carrageenan for algae species with an alkaline pH (pH 8.3-13).

[0054] In the composition containing solid microalgae, the dry weight content of algae cells is 0.02-2%, and the dry weight content of edible gel material is 1-20%;

[0055] The total colony count of the composition containing solid microalgae is preferably no more than 8.0×10 3 CFU / g, and the coliform group does not exceed 1 CFU / g. The colony count can ensure the hygienic safety of fresh edible microalgae obtained by users by adding the composition containing solid microalgae to the liquid culture medium for cultivation; the colony count can be achieved through conventional (existing food processing field) aseptic operation technology and workshop clean environment control.

[0056] Food preservatives may be selectively added to the edible gel in the composition containing solid microalgae according to the requirements of the shelf life and the characteristics of the algae species. The food preservatives include but are not limited to one or more of nisin, natamycin, ε-polylysine, sodium benzoate, etc.

[0057] Dehydration protective agents may be selectively added to the edible gel in the composition containing solid microalgae according to the requirements of the shelf life and the characteristics of the algae species. The dehydration protective agents include but are not limited to one or more of sucrose, glycerol, ascorbic acid, sodium isoVc, etc.

[0058] In order to further improve the gel properties, as an option but not limitation, a gel enhancer can be selectively added to the edible gel in the composition containing solid microalgae, including but not limited to one or more of sodium chloride, potassium chloride, etc. The gel enhancer can improve the gel strength and increase the elastic modulus.

[0059] The edible gel in the solid microalgae-containing composition may also be pre-added with components of the culture medium of the algae species.

[0060] The composition containing solid microalgae is in a solid shape that is convenient for harvesting, that is, a shape that can be harvested without complicated operations such as centrifugation and membrane filtration, including but not limited to flakes, strips, granules, etc.

[0061] The size of the composition containing solid microalgae is preferably: the thickness of the sheet is 0.1-0.6 cm, and the length and width are optional; the thickness of the strip is 0.1-0.6 cm, and the length is optional; the diameter of the granules is 0.1-0.6 cm.

[0062] The soft photobioreactor can be filled with nitrogen or evacuated to extend the storage period or shelf life of the composition containing solid microalgae.

[0063] The soft photobioreactor is made of a soft light-transmitting film material, and the soft light-transmitting film material includes but is not limited to a composite material of one or more of polyethylene, polyvinyl chloride, polypropylene, polyester, ethylene-vinyl acetate copolymer, polyurethane, polyethylene terephthalate, thermoplastic elastomer, polyimide, polyamide, etc.;

[0064] The soft light-transmitting film material is preferably a food-grade material.

[0065] The soft photobioreactor can be provided with an air inlet, an exhaust port and / or a water inlet; wherein the air inlet is used to fill with protective gas (nitrogen), and when liquid culture medium is added for cultivation, air or other CO2-containing gas can be introduced as needed. 2 Accordingly, the exhaust port is used to exhaust the protective gas (nitrogen), and, when adding liquid culture medium to culture, exhaust air or other gases containing CO 2 The water inlet is used to fill the liquid culture medium or water when adding liquid culture medium for cultivation; among them, for algae species with a suitable pH of neutral (pH6-8.2), air or other gas containing CO needs to be introduced when adding liquid culture medium for cultivation. 2 In this case, the soft photobioreactor needs to be provided with an air inlet and an exhaust port; for algae species suitable for alkaline pH (pH8.3-13), air or other liquid medium containing CO2 can be introduced when adding liquid culture medium for cultivation. 2 The gas may be supplied through the liquid culture medium (in this case, the soft photobioreactor needs to be provided with an air inlet and an exhaust port), or the liquid culture medium may be provided with sufficient carbon source at one time without ventilation. In this case, the soft photobioreactor does not need to be provided with an air inlet.

[0066] The air inlet, the exhaust port and / or the water inlet may be further provided with a sterilizing filter so as to better maintain a sterile environment in the soft photobioreactor.

[0067] The soft photobioreactor is preferably sterile, that is, it is in a sterile state before packaging.

[0068] The sterile soft photobioreactor is disposable.

[0069] The preparation method of the composition containing solid microalgae for culturing edible microalgae of the present invention comprises the following steps: fully mixing the algae mud of freshly cultured and harvested microalgae with the aqueous solution of edible gel material (hereinafter referred to as gel solution) at a temperature above the gel temperature and below the tolerance temperature of algae cells, cooling and solidifying to form a gel in a desired shape, not dehydrating or dehydrating to a desired moisture content as required, and further aseptically encapsulating the gel in a soft photobioreactor.

[0070] It should be noted that the gelation temperature of the gel solution is related to the concentration of the gelling substance. The general rule is: the higher the concentration of the gelling substance, the higher the gelling temperature. The gelling temperature can be adjusted by adjusting the concentration of the gelling substance to make it lower than the tolerance temperature of the algae cells. The temperature range between the two is the operating temperature range for mixing the microalgae mud and the gel solution, thereby ensuring that the mixing is completed before the gel solution solidifies and the vitality of the algae cells is maintained.

[0071] Preferably, the composition containing solid microalgae is prepared in a sterile environment, including but not limited to the raw materials, equipment, and operation room involved in the cultivation, harvesting, gel solution preparation, mixing of algae mud and gel solution (alginic acid mixing), solidification, dehydration, and packaging steps of fresh algae mud.

[0072] The specific steps of the preparation method include:

[0073] Step 1: Preparation of fresh algae mud. Microalgae cells are expanded, harvested, and pretreated (cleaned) to obtain fresh algae mud; conventional methods can be used, such as conventional expansion, conventional photobioreactor, conventional filtration or centrifugation, etc.

[0074] Preferably, in order to prolong the shelf life or shelf life of the composition containing solid microalgae and ensure hygienic safety, the preparation of the fresh algae mud adopts an aseptic culture process, that is, the conventional expansion, conventional photobioreactor, conventional filtration or centrifugation, etc. are operated under a sterile environment, using sterilized or sterilized water, sterilized nutrient salts, sterile air or other air containing CO 2 of gas.

[0075] Step 2: Preparation of gel solution: The edible gel material is mixed with water according to the required content, and heated to the sol temperature of the gel material to dissolve the gel material to obtain a gel solution.

[0076] Preferably, the gel solution is sterilized by conventional sterilization methods (eg, high temperature sterilization); or, the gel solution is directly heated to a sterilization temperature, such as 121°C.

[0077] Preferably, microalgae culture medium components are added to the gel solution, and the order of adding the microalgae culture medium components and the gel substance is not limited.

[0078] Step 3: Alginate mixing: The gel solution is cooled to a temperature above the gel temperature and below the tolerance temperature of the algae cells, and fresh algae mud is fully mixed with the gel solution according to the required dry weight content of algae cells to obtain an algae mixed solution.

[0079] Step 4: Solidification and molding. The alginic acid mixture is formed into a desired shape above its gel temperature, cooled to below its gel temperature or to room temperature, and the gel is naturally solidified to obtain a composition containing solid microalgae in a desired shape. The solidification and molding method can adopt conventional methods. For example, when the desired shape is preferably sheet, strip, or granule, the sheet can be formed by casting, brushing, scraping, etc., the strip can be formed by extrusion or cutting, and the granule can be formed by conventional granulation methods (such as drip weight, extrusion). The molding process can be batch operation or continuous operation.

[0080] Among them, it should be noted that for calcium alginate gel: the algae gel mixture obtained by mixing fresh algae mud with sodium alginate gel solution is dropped into or immersed in a Ca 2+ (e.g., CaCl 2 ) in an aqueous solution to form a calcium alginate gel. 2+ The concentration is 2-8 g / L and the calcification (ie, reaction) time is 5-9 minutes.

[0081] According to the preparation method of the present invention, preferably, the preparation method further comprises a dehydration step after solidification and forming in step 4, that is, step 5: dehydration. The composition containing solid microalgae is dehydrated to a desired moisture content to obtain a dehydrated composition containing solid microalgae. Dehydration can be carried out by conventional methods.

[0082] The dehydration step is preferably freeze drying, hot air drying or vacuum drying; it can be a batch operation or a continuous operation.

[0083] The freeze drying conditions are: pre-freezing at -60 to -70°C, drying at an absolute pressure of 20-30 Pa and -50°C for 4-8 hours. Conventional freeze drying equipment can be used.

[0084] The hot air drying condition is: drying with hot air at 35-45°C for 2-8 hours. Conventional hot air drying equipment can be used.

[0085] The vacuum drying conditions are: drying for 2-8 hours at a vacuum degree of 0.01-0.09 MPa and 35-45° C. Conventional vacuum drying equipment can be used.

[0086] Preferably, the dehydration step is performed in a sterile environment, that is, the operation room of the dehydration step is a sterile room (clean room), and the hot air is sterile air, for example, air that has been filtered and sterilized.

[0087] Step 6: Encapsulation. The composition containing solid microalgae (non-dehydrated or dehydrated) is aseptically encapsulated in a soft photobioreactor to obtain a composition containing solid microalgae encapsulated in a soft photobioreactor. Conventional methods and equipment can be used. Encapsulation can be performed in batch mode or continuously.

[0088] Preferably, the soft photobioreactor is sterilized before packaging, and conventional steam sterilization or irradiation sterilization can be used.

[0089] Preferably, the soft photobioreactor encapsulating the composition containing solid microalgae (non-dehydrated or dehydrated) is further filled with nitrogen, or vacuumed.

[0090] Step 7: Preservation: The composition containing solid microalgae (non-dehydrated or dehydrated) encapsulated in the soft photobioreactor is preserved according to conventional methods, such as but not limited to, in a warehouse, a business or a resident's home.

[0091] Preferably, the composition containing solid microalgae (non-dehydrated or dehydrated) encapsulated in the soft photobioreactor is stored at a low temperature of 1-5° C., and conventional equipment such as a household refrigerator can be used.

[0092] The preparation method of the composition containing solid microalgae (non-dehydrated or dehydrated) can add food preservatives to the gel solution of step 2 and / or the algae mixed solution of step 3 according to the requirements of the shelf life and the characteristics of the algae species, including but not limited to one or more of nisin, natamycin, ε-polylysine, sodium dehydroacetate and sodium benzoate, etc. Among them, the addition amount of nisin is in the range of 0.02-0.20g / L, the addition amount of natamycin is in the range of 0.002-0.02g / L, the addition amount of ε-polylysine is in the range of 0.01-0.10g / L, the addition amount of sodium dehydroacetate is in the range of 0.03-0.30g / L, and the addition amount of sodium benzoate is in the range of 0.05-0.50g / L.

[0093] The preparation method of the composition containing solid microalgae (non-dehydrated or dehydrated) can add dehydration protective agents to the gel solution of step 2 and / or the alginic gel mixture of step 3 according to the requirements of the shelf life and the characteristics of the algae species, including but not limited to one or more of sucrose, glycerol, ascorbic acid and sodium iso-Vc, etc. Among them, the addition amount of sucrose is in the range of 5-50g / L, the addition amount of glycerol is in the range of 10-100g / L, the addition amount of ascorbic acid is in the range of 0.05-0.5g / L, and the addition amount of sodium iso-Vc is in the range of 0.05-0.5g / L.

[0094] In order to further improve the gel properties of the composition containing solid microalgae (non-dehydrated or dehydrated), a gel enhancer may be added to the gel solution in step 2 and / or the alginic gel mixture in step 3, including but not limited to one or more of sodium chloride, potassium chloride, etc. The addition amount of sodium chloride is in the range of 0.1-2%, and the addition amount of potassium chloride is in the range of 0.1-2%.

[0095] The use of the composition containing solid microalgae for culturing edible microalgae of the present invention is preferably to add a liquid culture medium into a soft photobioreactor encapsulating the composition containing solid microalgae (non-dehydrated or dehydrated), and to culture to a desired time or desired algae cell density using a conventional microalgae culture method and culture device under suitable lighting and temperature conditions for the algae species, to obtain edible microalgae containing food-grade gel that can be directly eaten.

[0096] The specific steps include:

[0097] Cultivation and consumption. Liquid culture medium is added from the water inlet of the soft photobioreactor encapsulating the composition containing solid microalgae (non-dehydrated or dehydrated) (using conventional methods); the soft photobioreactor with liquid culture medium is placed in a culture device, and the light intensity and temperature required by the algae are set; air or other CO2-containing medium is introduced from the air inlet as needed. 2 The gas is discharged from the exhaust port at the same time, air or other gas containing CO 2 For algae species with a neutral pH (pH 6-8.2), air or other gases containing CO 2 For algae species with alkaline pH (pH8.3-13), air or other gases containing CO 2 The gas can also be ventilated without ventilation, but sufficient carbon source can be added to the liquid culture medium at one time; culture to the required time or required algae cell density, open (tear open, cut open) the soft photobioreactor, take out the cultured, algae cell-proliferated solid alginic gel mixture (i.e., fresh edible microalgae, including but not limited to flakes, strips, and granules), and eat it after simple cleaning (rinsing, rinsing), that is, the algae cells in the solid alginic gel mixture are eaten together with the gel material. Seasoning can be done as needed.

[0098] The liquid culture medium adopts a conventional culture medium formula of algae species, and is obtained by dissolving culture medium components (powder) with tap water or mineral water.

[0099] The culture device can be a conventional light incubator, a lighted shaker (including a rotary or rocking type), or other specially designed lighted and temperature controlled culture device, wherein air or other CO2-containing 2 The gas can be integrated into the culture device or set up separately.

[0100] Example 1

[0101] Composition containing solid microalgae in the form of sheets made of spirulina and λ-carrageenan

[0102] 1. Preparation of fresh algae mud. Cultivate Spirulina platensis in a conical flask. Add 200 mL of sterilized Zarrouk medium to a 500 mL conical flask and inoculate fresh Spirulina platensis. Initial OD 560 The value was 0.2, the bottle was sealed with a sealing film, and the flask containing the algae solution was placed in a shaking incubator at 35°C, 5000Lx, and 120r / min for cultivation. After 5 days of cultivation, the algae mud was filtered with a filter cloth and washed.

[0103] 2. Preparation of gel solution: Mix food-grade λ-carrageenan with deionized water at a concentration of 2%, heat to dissolve to obtain a gel solution, add 0.2% NaCl and 0.01 g / L natamycin, and sterilize at 121° C. for 20 min.

[0104] 3. Alginate mixing: Cool the sterilized gel solution to 42°C in a sterile environment, add the cleaned algae mud and mix well, the amount of fresh algae added is 2g (dry weight) / L, and obtain an algae mixed solution.

[0105] 4. Solidification and molding. Pour the mixed alginic acid mixture into a mold with a diameter of 10 cm, cast it into a liquid layer with a thickness of 0.3 cm, and naturally cool it down and solidify it under sterile room temperature conditions to obtain a sheet-like composition containing solid microalgae (such as Figure 1 (as shown in (a)).

[0106] 5. Dehydration. Place the sheet-like composition containing solid microalgae in a sterile drying oven in a clean area and dry it with hot air at 40°C for 4.5 hours to remove 76% of the water, thereby obtaining a sheet-like dehydrated composition containing solid microalgae (such as Figure 1 (as shown in (b)).

[0107] 6. Packaging. Place the dehydrated sheet-like composition containing solid microalgae in a 15×10 cm food-grade sterile soft photobioreactor, evacuate the chamber and seal it (e.g. Figure 1 (c)

[0108] 7. Preservation. The sheet-shaped dehydrated composition containing solid microalgae encapsulated in the soft photobioreactor is placed in a household refrigerator and stored at 4-5° C. in the dark for 6 months.

[0109] 8. Cultivation and consumption. After 6 months of storage, Zarrouk medium was added from the water inlet of the soft photobioreactor encapsulating the dehydrated solid microalgae-containing composition, and the mixture was placed in a rotary shaker with illumination, and the culture conditions were set at 35°C and 5000 lx (e.g. Figure 8 After 90 hours of cultivation, the soft photobioreactor was cut open and the solid alginic gel mixture (i.e., edible microalgae, such as Fig. 9After simple rinsing and slicing, add seasoning and you can eat it (as shown in (a) Fig. 9 As shown in (b)). According to calculations, the algae cell area yield can reach 9.9g / (m 2 ·d). After testing, the heavy metal content and microbial content are in line with relevant national standards.

[0110] Example 2

[0111] Composition containing solid microalgae in sheet form made of chlorella, calcium alginate and kappa-carrageenan

[0112] 1. Preparation of fresh algae mud. A glass bubbling column reactor (Φ60×600, mm) was used to culture Chlorella pyrenoidosa. The culture medium was BG11 culture medium. The actual volume of the reactor was 1 L. Air and CO 2 Mixed gas (CO 2 The content was 1.5%) and was introduced into the reactor through the aeration stone at the bottom of the reactor at a ventilation rate of 0.2 L min -1 The culture temperature was maintained at about 26°C. Light was provided by six parallel fluorescent lamps (40W), with three lamps spaced apart for the first two days (the light intensity on the reactor surface was about 60 μmol (m 2 s)), and from the third day on, all six lamps were turned on (the light intensity on the reactor surface was about 100 μmol / (m 2 s)). After culturing for 5 days, the algae mud was obtained by centrifugation and washed.

[0113] 2. Preparation of gel solution: Food-grade sodium alginate (2.0%) and κ-carrageenan (0.5%) were mixed with deionized water, heated to dissolve to obtain a gel solution, and 0.2% KCl and 0.05 g / L ε-polylysine were added, and sterilized at 121° C. for 20 min.

[0114] 3. Alginate mixing: Cool the sterilized gel solution to 42°C in a sterile environment, add the cleaned algae mud and mix well, the amount of fresh algae added is 2g (dry weight) / L, and obtain an algae mixed solution.

[0115] 4. Solidification and shaping. Pour the mixed alginic acid mixture into a mold with a length and width of 15 cm, and cast it into a liquid layer with a thickness of 0.25 cm. Cool it naturally and solidify it under sterile room temperature conditions. 2+ The solid microalgae-containing composition (such as Figure 2 Part of the mixture is directly packaged in step 6 without dehydration, and part of the mixture is dehydrated in step 5.

[0116] 5. Dehydration. The sheet-like composition containing solid microalgae is placed in a sterile vacuum drying oven in a clean room and vacuum dried for 2.5 hours at a vacuum degree of 0.08 MPa and 40° C. to remove 86% of the water, thereby obtaining a sheet-like dehydrated composition containing solid microalgae (such as Figure 2 (as shown in (b)).

[0117] 6. Packaging. Cut the undehydrated or dehydrated sheet-like composition containing solid microalgae into round shapes, place them in 15×10 cm food-grade sterile soft photobioreactors, fill them with nitrogen and seal them. Figure 7 (Left) Non-dehydrated or (Right) Dehydrated.

[0118] 7. Storage. The non-dehydrated or dehydrated sheet-shaped composition containing solid microalgae encapsulated in the soft photobioreactor is placed in a household refrigerator and stored at 4-5° C. in the dark for 3 months.

[0119] 8. Cultivation and consumption. After 3 months of storage, the BG11 culture medium was added from the water inlet of the soft photobioreactor encapsulating the non-dehydrated or dehydrated composition containing solid microalgae, and the reactor was placed in a rotary shaker with illumination. The culture conditions were set at 26°C and 2000 lx. Air and CO were introduced from the air inlet. 2 Mixed gas (CO 2 The content was 1.5%), the ventilation rate was 0.02L / min, and the exhaust gas was discharged from the exhaust port; after 5 days of cultivation, the soft photobioreactor was cut open, and the solid alginic gel mixture (i.e., edible microalgae) where the algae cells had proliferated was taken out, and after simple rinsing, it was sliced, seasoned, and eaten. After testing, the heavy metal content and microbial content of both were in line with the relevant national standards.

[0120] Example 3

[0121] Composition containing solid microalgae in sheet form made of Nannochloropsis and agar

[0122] 1. Preparation of fresh algae mud. Nannochloropsis oculata was cultured in a glass bubble column reactor (total volume 2.5 L) using f / 2 full nitrogen medium (NaNO 3 The volume of the reactor is 2.5L, and it consists of a glass tank, a gas distributor, a sampling tube, etc. The air is provided by a small air pump and enters the trachea after being sterilized by a 0.22μm air filter. 2 Mixed gas (CO 2The content of 1.0%) was dispersed into uniform fine bubbles by the gas distributor and entered the reactor at a ventilation rate of 0.8L / min. The temperature control part was achieved by connecting the built-in glass coil in the reactor to a constant temperature water bath, and the culture medium temperature was 25±1℃. The light was provided by fluorescent tubes (40W) arranged in parallel on both sides of the reactor, and the light intensity on the reactor surface was 150μmol / (m 2 s). After 6 days of cultivation, the algae mud was obtained by centrifugation and washed.

[0123] 2. Preparation of gel solution: Mix food grade agar (1.5%) with deionized water, heat to dissolve to obtain a gel solution, and sterilize at 121° C. for 20 min.

[0124] 3. Alginate mixing: Cool the sterilized gel solution to 36°C in a sterile environment, add the cleaned algae mud and mix well, the amount of fresh algae added is 3g (dry weight) / L, and obtain an algae mixed solution.

[0125] 4. Solidification and molding. Pour the mixed alginic acid mixture into a mold with a length of 15 cm and a width of 10 cm, cast into a liquid layer with a thickness of 0.3 cm, and naturally cool and solidify under sterile room temperature conditions to obtain a sheet-like composition containing solid microalgae (such as Figure 3 (as shown in (a)).

[0126] 5. Dehydration. The flaky solid algin mixture was placed in a -70°C refrigerator for pre-freezing for 2 hours, and then dried in a vacuum freeze dryer at an absolute pressure of 25 Pa and -50°C for 6 hours to remove 90% of the water, thereby obtaining a flaky dehydrated solid microalgae-containing composition (such as Figure 3 (as shown in (b)).

[0127] Example 4

[0128] Composition containing solid microalgae in the form of strips made of chlorella and gellan gum

[0129] 1. Preparation of fresh algae mud: Same as Example 2.

[0130] 2. Preparation of gel solution: Food grade gellan gum (3.0%) was mixed with deionized water, 0.3 g / L of ascorbic acid was added, and the mixture was heated to dissolve to obtain a gel solution, which was sterilized at 121° C. for 20 min.

[0131] 3. Alginate mixing: Cool the sterilized gel solution to 41°C in a sterile environment, add the cleaned algae mud and mix well, the amount of fresh algae added is 1.5g (dry weight) / L, and obtain an algae mixed solution.

[0132] 4. Solidification and shaping. Pour the mixed alginic acid mixture into the extruder tank, extrude it from the extruder head into a long strip with a diameter of about 0.5 cm, and drop it into sterile water at 28°C to solidify and shape, to obtain a strip-shaped composition containing solid microalgae (such as Figure 4 (as shown in (a)).

[0133] 5. Dehydration. Place the solid algin mixture in a sterile drying oven in a clean room and dry it with hot air at 40°C for 5 hours to remove 75% of the water to obtain a strip-shaped dehydrated solid microalgae-containing composition (such as Figure 4 (as shown in (b)).

[0134] Example 5

[0135] Granular composition containing solid microalgae made of spirulina and agarose

[0136] 1. Preparation of fresh algae mud: Same as Example 1.

[0137] 2. Preparation of gel solution: Food grade agarose (3.0%) was mixed with deionized water, heated to dissolve to obtain a gel solution, and sterilized at 121° C. for 20 min.

[0138] 3. Alginate mixing: The sterilized gel solution was cooled to 37°C in a sterile environment, and the cleaned algae mud was added and mixed. The amount of fresh algae added was 1.0 g (dry weight) / L to obtain an algae mixed solution.

[0139] 4. Solidification. Pour the mixed alginic acid mixture into the extruder tank, extrude it from the extruder head into granules with a diameter of about 0.5 cm, and drop it into sterile water at 26°C to solidify and form a granular composition containing solid microalgae (such as Figure 5 (as shown in (a)).

[0140] 5. Dehydration. The granular solid algin mixture is placed in a sterile drying oven in a clean room and dried with hot air at 40°C for 4 hours to remove 80% of the water to obtain a granular dehydrated solid microalgae-containing composition (such as Figure 5 (as shown in (b)).

[0141] Example 6

[0142] Granular composition containing solid microalgae made of Nannochloropsis and calcium alginate

[0143] 1. Preparation of fresh algae mud: Same as Example 3.

[0144] 2. Preparation of gel solution: Mix food-grade sodium alginate (3.0%) with deionized water, add 30 g / L sucrose, heat and dissolve to obtain a gel solution, and sterilize at 121° C. for 20 min.

[0145] 3. Alginate mixing: The sterilized gel solution was cooled to 42°C in a sterile environment, and the cleaned algae mud was added and mixed. The amount of fresh algae added was 2.5 g (dry weight) / L to obtain an algae mixed solution.

[0146] 4. Solidification and forming. Pour the mixed alginic acid mixture into the extruder tank, extrude it from the extruder head into particles with a diameter of about 0.4 cm, and drop it into the Ca 2+ The solidified composition was prepared by adding the solidified microalgae in a 4 g / L calcium chloride aqueous solution and then soaking for 7 min to obtain a granular composition containing solid microalgae (such as Figure 6 (as shown in (a)).

[0147] 5. Dehydration. The granular solid algin mixture is placed in a sterile vacuum drying oven in a clean room and vacuum dried for 2.5 hours at a vacuum degree of 0.09 MPa and 40° C. to remove 90% of the water to obtain a granular dehydrated solid microalgae-containing composition (such as Figure 6 (as shown in (b)).

[0148] Finally, 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 is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A composition containing solid microalgae for culturing edible microalgae, characterized in that: The composition includes living microalgae cells and food-grade gel.

2. The composition containing solid microalgae according to claim 1, characterized in that: The living microalgae cells are algae species suitable for pH 6-8.2, or algae species suitable for pH 8.3-13.

3. The composition containing solid microalgae according to claim 1, characterized in that: The food-grade gel does not dissolve in the culture medium of microalgae and can support the growth of living microalgae cells.

4. The composition containing solid microalgae according to claim 3, characterized in that: The food-grade gel comprises one or more of gellan gum, agar, agarose, kappa-carrageenan, lambda-carrageenan, konjac gum, starch, psyllium gum, calcium alginate and gelatin.

5. The composition containing solid microalgae according to claim 4, characterized in that: The solid microalgae is an algae species with a suitable pH of 6-8.2, and the food-grade gel is calcium alginate, and / or the solid microalgae is an algae species with a suitable pH of 8.3-13, and the food-grade gel is λ-carrageenan.

6. The composition containing solid microalgae according to any one of claims 1 to 5, characterized in that: The composition also includes a food preservative, a dehydration protectant and / or a gel enhancer.

7. The composition containing solid microalgae according to any one of claims 1 to 6, characterized in that: The composition is aseptically packaged in a soft photobioreactor.

8. The composition containing solid microalgae according to claim 7, characterized in that: The soft photobioreactor is made of food-grade light-transmitting film material.

9. The composition containing solid microalgae according to claim 7, characterized in that: The soft photobioreactor is sterile, and / or the soft photobioreactor is disposable.

10. The composition containing solid microalgae according to any one of claims 7 to 9, characterized in that: The soft photobioreactor is provided with an air inlet, an exhaust port and / or a water inlet as required; wherein the air inlet is used for charging protective gas, and, when liquid culture medium is added for cultivation, air or other gas containing CO2 is introduced as required; the exhaust port is used for discharging protective gas, and, when liquid culture medium is added for cultivation, air or other gas containing CO2 is discharged; the water inlet is used for charging liquid culture medium or water when liquid culture medium is added for cultivation.

11. The composition containing solid microalgae according to claim 10, characterized in that: The air inlet, the exhaust port and / or the water inlet are provided with a sterilizing filter.

12. A method for preparing a composition containing solid microalgae for culturing edible microalgae, comprising the following steps: The freshly cultured and harvested microalgae mud is fully mixed with a solution of food-grade gel at a temperature above the gel sol temperature and below the tolerance temperature of algae cells, cooled and solidified, and then dehydrated to a desired moisture content to obtain a composition containing solid microalgae.

13. The preparation method according to claim 12, characterized in that: The preparation method comprises the following steps: 1) Preparing fresh algae mud: expanding the culture, harvesting, and pre-treating the microalgae cells to obtain fresh algae mud; 2) preparing a gel solution: mixing food-grade gel with water, and heating to the sol temperature of the gel to dissolve the gel substance, thereby obtaining a gel solution; 3) Alginate mixing: Cooling the gel solution to a temperature above its gelling temperature and below the tolerance temperature of algae cells, and fully mixing the fresh algae mud with the gel solution to obtain an algae mixed solution; 4) Solidification and molding: the alginic gel mixture is formed into a desired shape above the gelling temperature of the gel, and then cooled to below the gelling temperature or to room temperature to allow the gel to solidify naturally, thereby obtaining a composition containing solid microalgae.

14. The preparation method according to claim 13, characterized in that: The preparation method further comprises a dehydration step after solidification and shaping in step 4), wherein the dehydration step comprises: dehydrating the composition containing solid microalgae to a desired moisture content to obtain a dehydrated composition containing solid microalgae.

15. The preparation method according to claim 12, 13 or 14, characterized in that: The preparation method further comprises the step of aseptically packaging the obtained composition containing solid microalgae in a soft photobioreactor.

16. Use of the composition containing solid microalgae according to any one of claims 1 to 11 in cultivating edible microalgae.

17. The use according to claim 16, characterized in that The following steps are involved: Liquid culture medium is added into a soft photobioreactor encapsulating a composition containing solid microalgae, and cultured under suitable illumination and temperature conditions for the algae species to a desired time or a desired algae cell density to obtain edible microalgae.

18. The use according to claim 17, characterized in that The following steps are involved: 1) adding liquid culture medium from the water inlet of the soft photobioreactor encapsulating the composition containing solid microalgae; 2) placing the soft photobioreactor added with the liquid culture medium in step 1) in a culture device, setting the light intensity and temperature required by the algae species; ventilating or not ventilating as needed, wherein the ventilation includes introducing air or other gas containing CO2 from the air inlet and exhausting air or other gas containing CO2 from the exhaust port; 3) After culturing to a desired time or a desired algae cell density, the soft photobioreactor is opened, and the solid alginic gel mixture in which the algae cells have proliferated after culturing is taken out to obtain edible microalgae.

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