Microalgae composite sugar powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of food processing, in particular to microalgae composite sugar powder as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a sweetening agent, a wall material, microalgae powder and water, and shearing to obtain primary slurry; carrying out homogenization treatment on the primary slurry to obtain secondary slurry; and carrying out spray drying on the secondary slurry to obtain the microalgae composite sugar powder. According to the technical path, an algae-sugar integrated interface is constructed, the inherent problems of sensory defects, poor physical properties, chemical instability and the like of microalgae can be synchronously solved, and an ideal burdening solution is provided for efficient application of microalgae components in public daily food such as baking, beverages, candies and the like.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a microalgae complex sugar powder, its preparation method, and its application. Background Technology

[0002] Microalgae are a type of photosynthetic microorganism, rich in various nutrients such as protein, polysaccharides, and unsaturated fatty acids. my country has approved eight types of microalgae, including Spirulina, Dunaliella salina, Haematococcus pluvialis, Chlorella vulgaris, Euglena scoparia, Nostoc commune, Micrococcus pseudomicrophylla, and Chlamydomonas reinhardtii, as new food ingredients, laying the foundation for their application in the food industry. Furthermore, microalgae products such as Spirulina, Chlorella vulgaris, and DHA algal oil, rich in protein, polyunsaturated fatty acids, phycocyanin, and natural pigments, have been included in the "GB 28300 Standard for the Use of Food Additives" and the "Catalogue of Nutritional Fortifiers for Infant and Toddler Complementary Foods," and can be used in the fields of nutritional supplements or functional foods.

[0003] However, the direct application of microalgae powder in mass-market, high-demand everyday foods (such as cakes, bread, and beverages) remains limited, mainly because: Sensory defects: Microalgae powder usually has a distinct algae smell and bitter taste, and its pigments such as chlorophyll are unstable under light and heat conditions, and are prone to fading or browning, which seriously affects the flavor and appearance of the end product and results in low consumer acceptance.

[0004] Poor processing adaptability: Microalgae powder has a small particle size (D90=5~25 µm), multiple hydroxyl groups on the surface, and a high fiber content, resulting in poor solubility and dispersibility, and it is prone to clumping. Direct addition can damage the texture of food (e.g., it can hinder the formation of gluten network, making baked goods hard and not fluffy). In addition, the hydrophilicity of microalgae powder and the hygroscopicity of sugar work together to make it extremely easy to absorb moisture and clump when dry-mixed with powdered sugar, forming hard lumps that cannot be dispersed, affecting the user experience.

[0005] Stability issues: The natural pigments (such as chlorophyll and astaxanthin) and lipids in microalgae are sensitive to light, heat and oxygen. They are prone to oxidative degradation during processing and storage, which can lead to product fading, flavor deterioration and loss of commercial value.

[0006] Currently, the main forms of sugar-containing products based on microalgae on the market include directly mixed compressed candies, solid beverages, and algal cell extracts. Their core processing technologies can be summarized into three categories: "direct dry mixing," "microencapsulation secondary blending," and "cell wall breaking extraction-recrystallization." Among these, products primarily in dry-mixed powder or compressed form, such as "spirulina compressed candies," typically use mechanical mixing to physically blend algal powder or algal cell extracts with sucrose (or brown sugar) at room temperature to achieve a uniform appearance. This type of mixing method has weak interfacial bonding, easily leading to problems such as algal sugar separation, moisture absorption and clumping, oxidation of active ingredients, and color fading in the finished product. Existing solutions utilize technologies such as spray drying to encapsulate algal oil using whey protein and maltodextrin as wall materials, preparing algal oil DHA microcapsule powder with a surface oil content ≤0.5% and a particle size of 20~80 µm, which is then dry-mixed with sugar particles. While this method improves the stability of algal oil to some extent, its raw material is microalgal oil rather than whole-component algal powder, failing to fully utilize the water-soluble nutrients in the algae. Furthermore, this mixed structure remains a surface-attached type, and the microcapsule wall material is easily damaged under mechanical action, leading to problems such as core material oxidation, product clumping, and discoloration. A novel preparation approach is urgently needed to achieve microalgal powder and sugar matrix embedding or chemical bonding at the microscale. On the other hand, the "cell wall breaking extraction-recrystallization" process focuses on separating and purifying polysaccharides after cell wall breaking, and then recrystallizing them after degradation to produce trehalose for use as a sweetener in food. This process alters the natural component form of microalgae and does not represent the direct utilization of the entire microalgal composition.

[0007] Therefore, how to overcome the limitations of existing technologies and provide a method for preparing microalgae composite sugar powder based on co-processing has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a microalgae compound sugar powder, its preparation method and application, overcoming the defects of microalgae powder being prone to moisture absorption and clumping, slow water dispersibility and easy oxidation and fading of active ingredients when used directly or dry mixed with sugar, and obtaining a new type of compound ingredient with uniform structure, stable performance and can be directly applied to various foods.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing microalgae complex sugar powder, comprising the following steps: Sweetener, wall material, microalgae powder and water are mixed and sheared to obtain primary slurry; The primary slurry is homogenized to obtain the secondary slurry; The secondary slurry was spray-dried to obtain microalgae complex sugar powder.

[0010] Optionally, the microalgae powder includes one or more of Spirulina platensis, Spirulina macrophylla, Nostoc commune, Chlorella pyrenoidosa, Euglena, Dunaliella salina, Haematococcus pluvialis, and Chlamydomonas reinhardtii; the particle size of the microalgae powder is ≤100 mesh.

[0011] Optionally, the sweetener includes fine granulated sugar, fine erythritol, or fine xylitol; The wall material includes gum arabic or porous starch.

[0012] Optionally, the mass ratio of the microalgae powder, wall material, and sweetener is 0.5~1.2:2~3:5.5~7; and the solid content of the sweetener and wall material in water is 40~50%.

[0013] Optionally, the mixing temperature is 50~60℃; the shearing speed is 10000~12000 r / min, and the time is 5~10 min.

[0014] Optionally, the homogenization pressure is 40~60MPa, the temperature is <60℃, and the homogenization process is repeated 2~3 times.

[0015] Optionally, the inlet air temperature of the spray dryer is 160~180℃, the outlet air temperature is 75~85℃, the atomization pressure is 12~18MPa, and the negative pressure is -190~-200Pa.

[0016] Optionally, the particle size of the microalgae complex sugar powder is ≤80 mesh.

[0017] The present invention also provides microalgae complex sugar powder prepared by the above preparation method.

[0018] The present invention also provides the application of the above-mentioned microalgae complex sugar powder in food processing.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing microalgae composite sugar powder based on a co-processing technology. The method first mixes microalgae powder, sweetener, and wall material in water to form a homogeneous slurry; then, the slurry is subjected to high-pressure homogenization to obtain a highly stable emulsified dispersion system; finally, it is spray-dried to obtain a novel microalgae composite sugar powder with uniform structure and stable performance. This technical approach constructs an integrated algae-sugar interface, simultaneously solving the inherent problems of microalgae such as sensory defects, undesirable physical properties, and chemical instability, providing an ideal ingredient solution for the efficient application of microalgae components in everyday foods such as baking, beverages, and confectionery. Attached Figure Description

[0020] Figure 1 Comparison of the appearance of ordinary microalgae powder and microalgae sugar powder of Example 1; Figure 2The image shows a comparison of the appearance of baked goods made from microalgae sugar powder and ordinary microalgae powder, as shown in Example 1. Figure 3 This is a comparison of the appearance of tofu made with microalgae sugar powder and ordinary microalgae powder in Example 1. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.

[0027] This invention provides a method for preparing microalgae complex sugar powder, comprising the following steps: Sweetener, wall material, microalgae powder and water are mixed and sheared to obtain primary slurry; The primary slurry is homogenized to obtain the secondary slurry; The secondary slurry was spray-dried to obtain microalgae complex sugar powder.

[0028] Understandably, existing technologies for sugar-containing products based on microalgae employ a physical blending structure of "encapsulation followed by mixing" or direct mixing. The microcapsule particles and sugar particles are independent, bound only by van der Waals forces, resulting in a clear interface. This structure is prone to separation under mechanical force or humidity, leading to microcapsule breakage, core material oxidation, and product hygroscopic clumping. In contrast, this invention employs a "co-processing integrated encapsulation" structure. Microalgae powder, sweetener, and wall material are homogenized under high pressure in a liquid phase to achieve uniform mixing at the micron / submicron level, followed by instantaneous co-curing via spray drying, forming a "matrix-dispersed phase" structure. Continuous phase (matrix): A continuous, dense solid matrix composed of recrystallized sweeteners and wall materials.

[0029] Dispersed phase: Microalgal cells and their cell fragments are uniformly embedded and encapsulated in this continuous phase matrix.

[0030] This structure physically isolates the active ingredients of microalgae from the sweetener-wall material matrix, significantly reducing their contact area with oxygen, moisture, and light, thus fundamentally solving the problems of oxidation, moisture absorption, and fading. Simultaneously, the sweetener particles themselves are partially coated with the wall material, reducing their hygroscopicity. Therefore, this invention prepares a novel composite with uniform composition and stable structure, rather than a simple mixture.

[0031] In this invention, the microalgae powder is derived from microalgae that has been approved by the state as a new food ingredient. The microalgae powder is a uniform powder that passes through a 100-mesh sieve. It is green in color, has the unique umami flavor of algae, and has no off-odor. Furthermore, the selected algae strains should have excellent antioxidant properties to ensure that the final product has a stable color during processing.

[0032] In some embodiments of the present invention, the microalgae powder includes, but is not limited to, Spirulina platensis (… Spirulina platensis Spirulina macrophylla ( ) Spirulina maxima ), Nostoc commune ( Nostoc sphaeroides Chlorella proteoglycans () Chlorella pyrenoidesa Euglena ( Euglena gracilis Dunaliella salina (), Dunaliella salina Haematococcus pluvialis ( Haematococcus pluvialis ) and Chlamydomonas reinhardtii ( Chlamydomonas reinhardtii One or more of the following: the microalgae powder has a particle size ≤100 mesh.

[0033] In this invention, the microalgae powder is the core ingredient, providing abundant protein, vitamins, minerals, dietary fiber, antioxidants (such as phycocyanin, astaxanthin, and beta-carotene), and Omega-3 unsaturated fatty acids (such as DHA). It is the source of the entire product's nutritional value. The natural pigments such as chlorophyll and phycocyanin in the microalgae give the product a unique green or blue-green color, partially replacing artificial colorings. Although the algal odor is a drawback, its unique "umami" flavor, enhanced by this process, can improve the overall flavor profile of the food.

[0034] In this invention, the sweetener includes fine granulated sugar, fine erythritol, or fine xylitol; In this invention, the sweetener is a sugar, which serves as a matrix component, sweetener, and excipient, forming the main body of the composite sugar powder particles. During spray drying, the dissolved sugar recrystallizes and, together with the wall material, constructs a matrix encapsulating microalgae, thus shaping the product's structure and morphology. Its most basic function is to provide sweetness, allowing the product to be directly used as a sweetener in food. The addition of sugar also reduces the relative proportion of microalgae and wall material in the slurry, lowering the overall viscosity and making the slurry easier to pump and atomize, ensuring the smooth operation of the spray drying process.

[0035] In this invention, the wall material comprises gum arabic or porous starch.

[0036] In some embodiments of the present invention, the porous starch is commercially available food-grade microporous starch, purchased from Zhucheng Xingmao Corn Development Co., Ltd.

[0037] In this invention, the wall materials serve to encapsulate, adsorb, and protect the microalgae particles. Gum arabic forms a continuous, dense film on the surface of the microalgae particles, completely encapsulating them and achieving physical isolation from the external environment. This barrier effectively prevents oxidation, fading, and flavor deterioration, and significantly masks the algal odor and bitterness of the microalgae themselves. Porous starch, primarily through its large specific surface area and pore structure, adsorbs and fixes the microalgae powder, achieving uniform dispersion and isolation at the microscale, effectively blocking oxygen and preventing clumping. It also masks undesirable flavors and improves the product's dispersibility. Both wall materials ensure a uniform, stable, high-quality slurry, ultimately forming a powder with good flowability and stable structure, improving the stability, solubility, and flavor acceptability of the microalgae sugar powder.

[0038] The present invention involves dissolving sweeteners and wall materials sequentially in pure water at 50-60°C, stirring continuously until completely dissolved, preparing a mixed aqueous solution with a solid content of 40-50%, adding microalgae powder while maintaining the temperature, and shearing at high speed to obtain a uniformly mixed primary slurry.

[0039] In this invention, the mass ratio of the microalgae powder, wall material, and sweetener is 0.5~1.2:2~3:5.5~7; the solid content of the sweetener and wall material in water is 40~50%.

[0040] In this invention, the mixing temperature is 50~60℃; the shearing speed is 10000~12000r / min, and the time is 5~10min.

[0041] The present invention involves pumping primary slurry into a high-pressure homogenizer after impurity removal through a 60-mesh vibrating screen for homogenization to obtain a highly stable emulsified dispersion system. The material temperature is controlled at <60 ℃ throughout the homogenization process using an ice-water jacket and plate heat exchanger. The discharged material immediately enters a buffer tank and is pressurized with nitrogen at 0.2 bar to prevent oxidation.

[0042] In this invention, the homogenization pressure is 40~60MPa, the temperature is <60℃, and the homogenization process is repeated 2~3 times.

[0043] The present invention involves feeding the homogenized slurry into a pressure spray tower within 30 minutes, controlling the inlet air temperature to be 160~180℃, the outlet air temperature to be 75~85℃, the atomization pressure to be 12~18MPa, and the negative pressure inside the tower to be -190~-200Pa.

[0044] The microalgae composite sugar powder of this invention is spray-dried and immediately fed into a vibrating fluidized bed, cooled with dehumidifying air at 20-30°C for 2-5 minutes to ensure the discharge temperature is <30°C. It is then passed through an 80-mesh sieve, with less than 3% of the residue remaining, yielding the finished microalgae composite sugar powder. The cooled powder is then fed into a packaging machine under nitrogen protection, with the aluminum foil bag filled with nitrogen to ensure residual oxygen is <2%, and then sealed and boxed.

[0045] In this invention, the particle size of the microalgae composite sugar powder is ≤80 mesh.

[0046] The preparation method of this invention improves the processing performance of microalgae powder: (1) It fundamentally solved the problem of moisture absorption and clumping and the separation of trehalose. This invention utilizes a co-processing technique combining solution-based shearing, high-pressure homogenization, and spray drying to achieve a uniform distribution of microalgae, sweeteners, and wall materials at the micron / submicron level in the liquid phase. After instantaneous drying, these components form dense, homogeneous spherical composite particles. This structure reduces the product's specific surface area and surface energy, effectively suppressing moisture adsorption and the tendency for clumping.

[0047] (2) Increased the water solubility and dispersibility of algae powder This invention utilizes a high-pressure homogenization process to thoroughly break down microalgae cell clusters, allowing them to fully interact with the wall material and form a highly stable dispersion system. After spray drying, the resulting product has uniform particles and a smooth surface, can be rapidly wetted and settled in cold water, and can completely dissolve and disperse within 60 seconds without stirring, with no visible particle sedimentation, fully meeting the application requirements of high-end instant beverages (such as cold-dissolved milk tea).

[0048] (3) Significantly improved the oxidative stability and color stability of algae powder. In this invention, gum arabic or porous starch is combined with a homogenization process to form an effective protective barrier around microalgal cells and cell debris. The subsequent spray drying process rapidly solidifies this structure, minimizing oxidative losses during processing.

[0049] (4) It effectively masks the unpleasant flavor of microalgae. The co-processing technology described in this invention achieves efficient encapsulation of microalgae components. The dense protective layer formed by spray drying effectively encapsulates volatiles with an algal odor inside the particles. Thus, when prepared and tasted, the pure sweetness of sugar and the neutral flavor of the wall material are released first, greatly masking and weakening the algal odor and bitterness, leaving only a faint algal freshness, thereby improving sensory acceptance.

[0050] The present invention also provides microalgae complex sugar powder prepared by the above preparation method.

[0051] The microalgae complex sugar powder has the following characteristics: Sensory characteristics: Uniform powder, color close to that of the raw material microalgae, particle size >100 mesh; pure sweetness, very low algae smell, and slightly algae umami flavor.

[0052] Physical properties: Good fluidity, does not absorb moisture and clump; excellent cold solubility, can be quickly dispersed and dissolved in room temperature water or milk.

[0053] Stability: After 7 days of accelerated testing at 60℃, chlorophyll retention rate >85% and peroxide value increase <1.0 meq / kg.

[0054] The present invention also provides the application of the above-mentioned microalgae complex sugar powder in food processing.

[0055] The microalgae compound sugar powder described in this invention can be used as a novel healthy ingredient and is widely applied in the processing of various popular foods. Specific application examples include, but are not limited to: Surface decoration: This product can be directly sprinkled on the surface of baked goods (such as cakes and cookies) or beverages (a layer of cocoa butter or coconut oil needs to be sprayed on first to fix it) to add color and flavor.

[0056] Steamed or boiled foods (such as steamed buns and noodles): Based on the original recipe, replace 5-12% of the flour with this product, reduce the total water content of the recipe by 2-4%, and appropriately extend the steaming time by 3-5 minutes to produce a healthy staple food with a slightly green color and a special flavor.

[0057] For baked goods (cakes, bread, cookies, etc.): Replace 3-8% of the low-gluten or high-gluten flour with this product in the original recipe, and simultaneously reduce the total sugar content by 10-17%. Also, add 0.4-0.8% (based on total flour) of vital gluten to compensate for the decrease in gluten strength caused by gluten dilution. Add the algae powder during the "powder premixing" stage, sifting it together with the low-gluten flour and vital gluten powder beforehand and refrigerating it. Pre-emulsify the egg yolk mixture with the fat before adding the powders. During baking, lower the top heat temperature by 5°C while keeping the bottom heat temperature unchanged, and extend the baking time by 4-8 minutes to ensure the product is fully cooked while highlighting the algae aroma and sweet flavor.

[0058] Yogurt products: After standardizing the ingredients for yogurt, add this product during the sugar dissolving stage to replace 10-20% of the added sucrose. Homogenize at 800-1200 r / min for 6-15 minutes, and keep subsequent fermentation and other processes unchanged to produce green yogurt rich in microalgae nutrients.

[0059] For fillings (such as lotus seed paste): Add this product at the final stage of the filling cooking process (when the material temperature is ≤70℃), replacing 15-50% of the added sugar. Quickly stir until evenly mixed, then remove from heat. This product has good dispersibility and will not discolor significantly due to prolonged heating.

[0060] Beverages and Ice Cream: Replace 20-40% of added sugars in various beverages (such as lattes, milk tea, and soy milk) and ice cream. When used in smoothies or ice cream, an additional 0.1% xanthan gum or 0.8-1.3% inulin can be added to maintain system stability and melt resistance.

[0061] Starch-based dessert toppings (such as tapioca pearls and taro balls): During the production process, replacing 2-5% of the added starch with this product can give the toppings a unique color and flavor.

[0062] Understandably, adding the microalgae complex sugar powder of this invention to food can achieve natural nutritional fortification, developing functional foods with health claims. Simultaneously, it provides stable and uniform natural green flavor, and its inherent sweetness can directly replace part of the sugar in the formula, simplifying the ingredient list. The umami flavor of microalgae can also blend well with the flavors of dairy products, grains, etc., enhancing the layering and richness of the flavor. Furthermore, this microalgae complex sugar powder can quickly and evenly integrate into batter, milk, beverages, and other systems. Due to its excellent dispersibility and encapsulation properties, it does not damage the gluten network or protein gel structure like ordinary microalgae powder, better maintaining the ideal texture of baked goods (fluffy and soft) and dairy products (smooth and delicate).

[0063] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0064] Example 1 (1) Dissolve 2.5 kg of gum arabic and 6.5 kg of fine sugar in pure water at 50°C, and stir continuously until completely dissolved to prepare a mixed aqueous solution with a solid content of 43%. Keep the temperature, add 1 kg of Chlorella microalgae powder, and disperse at high speed (10000 r / min) for 8 minutes to obtain a uniformly mixed slurry. (2) After removing impurities by passing the slurry through a 60-mesh vibrating screen, pump it into a high-pressure homogenizer and homogenize it three times under a pressure of 50 MPa to obtain a highly stable emulsified dispersion system. The material temperature is controlled at 50°C by using an ice water jacket and plate heat exchanger throughout the homogenization process. The material is immediately discharged into a buffer tank and pressurized with nitrogen at 0.2 bar to prevent oxidation. (3) The homogenized slurry is fed into a pressure spray tower within 30 minutes. The inlet air temperature is controlled at 170 ℃, the outlet air temperature at 80 ℃, the atomization pressure at 15 MPa, and the negative pressure inside the tower is maintained at −190 Pa. The powder at the bottom of the tower immediately enters the vibrating fluidized bed and is cooled with dehumidifying air at 25 ℃ for 4 minutes to make the outlet temperature <30 ℃. The powder is passed through an 80-mesh sieve, and the residue on the sieve is <3%, to obtain the finished microalgae composite sugar powder.

[0065] Example 2 The only difference from Example 1 is that gum arabic is replaced with porous starch; the rest of the steps are the same as in Example 1.

[0066] Example 3 The only difference from Example 1 is that fine sugar is replaced with fine erythritol, and the other steps are the same as in Example 1.

[0067] Test Example 1 Quality comparison between the microalgae sugar powder prepared in this invention and ordinary microalgae powder: Table 1. Quality comparison between the microalgae sugar powder prepared in this invention and ordinary microalgae powder.

[0068] Figure 1 The image shows a comparison of the appearance of ordinary microalgae powder (left) and microalgae sugar powder of Example 1 (right). It can be seen that the microalgae sugar powder of Example 1 is a spherical composite particle with a dense structure and uniform composition. This structure can reduce the specific surface area and surface energy of the product, thereby effectively inhibiting the tendency of water adsorption and moisture absorption and agglomeration.

[0069] Test Example 2 Comparison of cakes made with regular microalgae powder and this microalgae sugar powder: Weigh the ingredients as shown in Table 2. Sift the algae powder, low-gluten flour, and wheat gluten together by weight and refrigerate beforehand. Emulsify the milk, oil, and salt, then add the egg yolks and mix well. Pour in the premixed powder and mix in a Z-shape until no dry powder remains. Beat the chilled egg whites and lemon juice at medium speed until foamy, then add the granulated sugar in three batches, beating until stiff peaks form. Take 1 / 3 of the meringue and gently fold it into the egg yolk mixture, then pour it back into the remaining meringue and fold gently to form a fluffy batter. Pour the batter into the mold until it is about 70% full, tap the mold to remove large air bubbles, and bake in a preheated oven at 150°C for 30 minutes, then increase the temperature to 160°C and bake for another 15 minutes, or until golden brown and a toothpick inserted leaves no wet residue. Immediately after removing from the oven, invert the mold and let it cool completely before unmolding.

[0070] Figure 2 Table 3 shows a comparison of the appearance of baked goods made from the microalgae sugar powder prepared in Example 1 of this invention and ordinary microalgae powder. Table 3 also compares the quality of cakes made from ordinary microalgae powder and this microalgae sugar powder. Figure 2 As shown in Table 3, compared with ordinary microalgae powder cakes, the baked products prepared using the microalgae sugar powder of the present invention have higher nutritional content, lower calories, a uniform and natural algae green color, a delicate and soft texture, and almost no air pockets, which can better maintain the fluffiness of baked goods.

[0071] Table 2. Ingredient composition of cakes made from ordinary microalgae powder and this microalgae sugar powder

[0072] Table 3. Quality Comparison of Cakes Made with Ordinary Microalgae Powder and This Microalgae Sugar Powder

[0073] Test Example 3 Comparison of tofu pudding made with regular microalgae powder and this microalgae sugar powder: Tofu pudding is made according to the following process: soaking soybeans → blanching → grinding → filtering → boiling → adding microalgae powder (this step is omitted for regular tofu pudding) → coagulation and settling → finished product packaging. First, inspect and remove any attached impurities, shriveled or broken soybeans. Soak the selected soybeans in clean water for 9 hours. Then, soak the soybeans in warm water for 30 minutes to remove some of the odor and fishy smell. Grind the softened soybeans with 9 times their weight of water using a high-speed blender to prepare raw soy milk. First, filter the raw soy milk through a 120-mesh nylon filter to remove soybean residue. Then, filter the raw soy milk a second time and collect the filtrate. To prepare the filtrate, take 0.75% of the soybean weight of microalgae powder, disperse it in 10 mL of warm water, and add it to the boiling filtrate while rapidly stirring to ensure even mixing. After boiling, reduce the heat to low and maintain a simmer for 2-3 minutes, then let it cool. Take 0.25% glucono-δ-lactone by weight of soybeans, dissolve it in 20 mL of warm water, quickly pour the cooled soy milk (about 80°C) into the container holding the glucono-δ-lactone solution, stir quickly and evenly, and let it stand for 15 minutes to solidify.

[0074] Figure 3 Table 4 compares the appearance of tofu pudding made with microalgae powder prepared in Example 1 of this invention with that made with ordinary microalgae powder. The textural analysis of tofu pudding made with microalgae powder in Example 1 is also compared with that made with ordinary tofu pudding. Figure 3 As shown in Table 4, the tofu pudding prepared with added microalgae compound sugar powder is green, uniform and natural, and the microalgae sugar powder tofu pudding has better elasticity and chewiness.

[0075] Table 4. Comparison of textural analysis between microalgae-based sugar powdered tofu pudding and regular tofu pudding

[0076] In summary, adding the microalgae compound sugar powder of this invention to various foods has the following significant advantages compared to adding ordinary microalgae powder: ① Improve the sensory quality of food Flavor: This product has very low algae fishy and bitter taste, retaining only the fresh taste of algae, thus avoiding the destruction of food flavor caused by directly adding microalgae powder.

[0077] Color: It can give food a natural, uniform, and stable green color, and because the active ingredients are protected, they are not easy to fade or brown during processing and storage, making the product more attractive.

[0078] Texture: Its excellent solubility and dispersibility allow it to quickly integrate into food systems without producing a rough or grainy texture. Unlike ordinary microalgae powder, it does not damage the gluten network or protein gel structure, thus resulting in a smooth texture in dairy products.

[0079] ② Enrich the variety of food products This product, as a "ready-to-use" compound ingredient, can directly replace part of the sugar and flour, saving food manufacturers the tedious process and technical difficulties of processing and compounding microalgae powder, thus lowering the application threshold.

[0080] This makes it simple and easy to develop green and healthy foods rich in microalgae nutrients (such as green bread, green yogurt, green ice cream, etc.).

[0081] This invention solves many technical bottlenecks in the application of microalgae through a unique preparation method, transforming it from a difficult-to-process raw material into an ideal food ingredient that is easy to use, has stable performance, and is rich in functions. Its addition can comprehensively improve the overall quality of food.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a microalgal composite sugar powder, characterized by, The method comprises the following steps: mixing a sweetener, a wall material, a microalgae powder and water, shearing to obtain a first slurry; homogenizing the first slurry to obtain a second slurry; spray drying the second slurry to obtain a microalgae composite sugar powder.

2. The production method according to claim 1, characterized by, The microalgae powder comprises one or more of Arthrospira platensis, Arthrospira maxima, Synechococcus globosus, Chlorella pyrenoidosa, Euglena gracilis, Dunaliella salina, Haematococcus pluvialis and Chlamydomonas reinhardtii; and the particle size of the microalgae powder is ≤100 mesh.

3. The production method according to claim 1, characterized by, The sweetener comprises fine granular erythritol or fine granular xylitol.

4. The method of claim 1, wherein, The wall material comprises gum arabic or porous starch. The mass ratio of the microalgae powder, the wall material and the sweetener is 0.5-1.2:2-3:5.5-7; and the solid content of the sweetener and the wall material in water is 40-50%.

5. The preparation method according to claim 1, characterized in that, The temperature of the mixing is 50-60℃; the shearing speed is 10000-12000 r / min, and the shearing time is 5-10 min.

6. The method of claim 1, wherein, The homogenization pressure is 40-60 MPa, and the temperature is <60℃; and the homogenization frequency is 2-3 times.

7. The preparation method according to claim 1, characterized in that, The inlet air temperature of the spray drying is 160-180℃, the outlet air temperature is 75-85℃, the atomization pressure is 12-18 MPa, and the negative pressure is -190--200 Pa.

8. The method of claim 1, wherein, The particle size of the microalgae composite sugar powder is ≤80 mesh.

9. The microalgae composite sugar powder prepared by the preparation method of any one of claims 1-8.

10. The microalgae composite sugar powder of claim 9 for use in food processing.

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