High-stability nutrition-enriched algae oil cheese and preparation method thereof

Abstract

The invention discloses high-stability and nutrition-enriched algae oil cheese and a preparation method thereof, and belongs to the technical field of dairy product processing. Soybean protein isolate and konjac glucomannan are used as raw materials, an SPI-KGM grafted copolymer is prepared through a thermal induction self-assembly method, algae oil is taken and added into an SPI-KGM grafted copolymer solution, and the algae oil and the SPI-KGM grafted copolymer solution are mixed evenly to obtain the nanogel. According to the algal oil nanogel and the preparation method thereof, the algal oil nanogel technology is constructed through a thermal induction self-assembly method and a direct embedding method, the algal oil is embedded in the SPI-KGM grafted copolymer gel, the algal oil encapsulation efficiency of the algal oil nanogel is improved, meanwhile, the algal oil nanogel prepared through the method is smaller in particle size and closer to a spherical shape, and the stability and bioavailability of the algal oil are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of dairy product processing, and particularly relates to a high-stability and nutrient-fortified algal oil cheese and a preparation method thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention and does not necessarily be regarded as an admission or imply in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Algal oil is a natural oil extracted from microalgae (such as Schizochytrium Schizochytrium sp . and Crypthecodinium cohnii Crypthecodinium cohnii ) and has extremely high nutritional value and functionality. As a high-quality plant-based source of Omega-3, algal oil is rich in polyunsaturated fatty acids, among which the contents of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are particularly prominent (the proportion of DHA in some algal oils is as high as 30%-50%), and its molecular structure is stable and the bioavailability is high. Scientific research has confirmed that DHA / EPA in algal oil has significant physiological activities, including promoting cardiovascular and cerebrovascular health, enhancing cognitive function, regulating inflammatory responses, etc. Compared with traditional fish oil, algal oil not only avoids the risk of marine pollutants, but also has the characteristics of no fishy smell, strong antioxidant property, and being vegetarian-friendly, making it an ideal functional raw material in the fields of food, health products, medicine, etc. In the food industry, the application advantages of algal oil are significant. It can be added to dairy products, beverages, infant complementary foods, etc. to increase the Omega-3 content of products and meet the health needs of specific populations (such as pregnant women, children, vegetarians); as a substitute for fish oil or some vegetable oils, it can optimize the fatty acid ratio and develop healthy foods with low saturated fat and high unsaturated fat; it can also be better incorporated into the food system through technologies such as microencapsulation to extend the shelf life and maintain the stability of flavor and texture. In addition, the sustainable production characteristics of algal oil (such as low environmental load and not relying on fishery resources) also make it an important choice for the green food industry, meeting the dual trends of global health and environmental protection. With the growth of consumers' demand for functional foods, the application prospect of algal oil will be broader.

[0004] Although algal oil has significant advantages in nutrition and functionality (such as being rich in ω-3 polyunsaturated fatty acids such as DHA and EPA and antioxidant components), its wide application in the food industry still faces the following key limitations. First: The polyunsaturated fatty acids (PUFAs) in algal oil are extremely prone to oxidative degradation during processing and storage. In an acidic environment, high temperature, light, metal ions (such as Fe² + / Cu² +), singlet oxygen (¹O2) or free radicals, lipid peroxidation will be significantly accelerated, leading to nutritional loss, sensory deterioration and safety risks. Secondly, the high hydrophobicity of algal oil makes it difficult to disperse evenly in water-based food systems (such as beverages and dairy products), resulting in low intestinal absorption efficiency after oral administration and greatly reduced bioavailability. Therefore, the development of efficient and stable delivery systems (such as nanogels, microemulsions or Pickering emulsions) to protect algal oil from environmental stress and improve its solubility and targeted release performance has become a key research direction.

[0005] In recent years, the application of algae oil in nanogel systems has become a research hotspot in the fields of biomaterials, drug delivery and food science. Nanogels, as nanoscale hydrogel particles composed of a three-dimensional cross-linked polymer network, can efficiently encapsulate algae oil and significantly improve its stability and bioavailability. Through the encapsulation and protection of nanogels, algae oil can effectively resist the influence of environmental factors such as light, heat, and oxygen, while improving its dispersibility in the aqueous phase system. This technological breakthrough enables algae oil nanogels with excellent chemical stability to be widely used in the field of functional foods, such as beverages, soups, sauces, etc., thereby giving ordinary foods additional health benefits and promoting the innovation and development of functional foods.

[0006] Cheese, also known as cheese, is the concentrated essence of various milk sources, so it is known as the "gold" of dairy products. It contains nutrients such as fat, protein, carbohydrates, vitamin A, niacin, folic acid and biotin, and its calcium content is the highest among dairy products, which is easier to be absorbed by the human body. Daily consumption of cheese can maintain intestinal health, regulate intestinal flora, enhance the body's immunity and prevent tooth decay. In the production process of cheese, most of the lactose will be broken down, so cheese is also an ideal nutritious food for patients with lactose intolerance and diabetes.

[0007] At present, the application research of algae oil in cheese products is relatively limited, mainly restricted by the following two technical bottlenecks: First, algae oil as a seaweed extract has a distinct fishy smell, while cheese itself contains a milky smell. When algae oil is added, it will produce an unpleasant odor complex, which seriously damages the unique flavor characteristics and sensory quality of cheese; secondly, the existing algae oil microencapsulation technology generally has the problem of improper control of the encapsulation particle size. Excessive particle size will not only reduce the bioavailability of algae oil, but also lead to a large loss of core material (algae oil) during the encapsulation process, thereby affecting its compatibility in the cheese matrix, and ultimately manifested as the product is prone to phase separation, precipitation and other quality problems. In addition, the encapsulation efficiency of the current encapsulation technology is low, and it is difficult to simultaneously ensure the chemical stability of algae oil and the physical stability of the cheese system. Summary of the invention

[0008] To address the deficiencies of the prior art, the objective of the present invention is to provide a highly stable and nutrient - fortified algal oil cheese and its preparation method. The present invention constructs an algal oil nanogel technology through a thermal - induced self - assembly method and a direct encapsulation method, improving the stability and bioavailability of the algal oil dispersion.

[0009] To achieve the above objective, the technical solution of the present invention is as follows: In the first aspect, the present invention provides a method for preparing an algal oil nanogel, including: 1) Using soy protein isolate (SPI) and konjac glucomannan (KGM) as raw materials, preparing an SPI - KGM graft copolymer through a thermal - induced self - assembly method; 2) Taking algal oil and adding it to the SPI - KGM graft copolymer solution, mixing evenly to obtain an algal oil nanogel.

[0010] The present invention constructs an algal oil nanogel technology through a thermal - induced self - assembly method and a direct encapsulation method, encapsulating algal oil in the SPI - KGM graft copolymer gel. Compared with the prior art, the present invention significantly improves the encapsulation efficiency of algal oil by optimizing the intermolecular interaction of the graft copolymer. Moreover, the prepared algal oil nanogel has a smaller nanoscale particle size and a more regular spherical morphology, and its unique gel network structure also effectively enhances the oxidative stability of algal oil.

[0011] In some embodiments, in step 1), SPI and KGM are uniformly dispersed in water to obtain a mixed solution; the pH of the mixed solution is adjusted to 6.5 - 7.5, then freeze - dried and pulverized to obtain a powder. The powder is placed under the conditions of 75 - 85% relative humidity and 55 - 65 °C for reaction for 3 - 5 days to obtain a crude reaction product.

[0012] Preferably, in step 1), SPI and KGM are uniformly dispersed in deionized water in a certain proportion, and a homogeneous mixed solution is formed by magnetic stirring; subsequently, the pH of the mixed solution is adjusted to the weakly alkaline range of 6.5 - 7.5 using 0.1 M NaOH or HCl solution. The adjusted solution is subjected to freeze - drying treatment and mechanically pulverized to obtain a uniform composite powder. The powder is placed in a constant - temperature and constant - humidity chamber and reacted under the optimized conditions of 55 - 65 °C and 75 - 85% relative humidity for 3 - 5 days to finally obtain the crude reaction product.

[0013] The present invention realizes the controllable Maillard reaction between proteins and polysaccharides by subjecting the dried powder to a reaction under conditions of 75 - 85% relative humidity and 55 - 65 °C. Compared with the conventional aqueous solution reaction system, this reaction method in a dry environment has the following significant advantages: by precisely controlling the humidity conditions of the reaction system, the rate of the Maillard reaction can be effectively regulated; the reaction can proceed more completely; the particle size of the algal oil nano - gel emulsion can be significantly reduced; and the encapsulation rate of the algal oil can be significantly increased. This innovative method of controlling reaction conditions provides a new technical approach for the preparation of high - performance algal oil nano - gels.

[0014] In some embodiments, in step 1), a strong acid or weak acid is added to adjust the pH of the mixed solution, and hydrochloric acid is further preferably used.

[0015] In some embodiments, in step 1), the reaction product is added to water for dissolution and then centrifuged, and the supernatant is freeze - dried to obtain the SPI - KGM graft copolymer. The reaction product is dissolved twice to remove insoluble substances, improving the purity of the graft copolymer.

[0016] In some embodiments, in step 2), the SPI - KGM graft copolymer is dissolved in water, and algal oil is added to the SPI - KGM graft copolymer solution, and the mixture is stirred evenly at 50 - 60 °C to obtain the algal oil nano - gel.

[0017] In some embodiments, in step 1), the mass ratio of soy protein isolate to konjac glucomannan is (0.5 - 2.0):1.

[0018] In some embodiments, in step 2), the mass ratio of the SPI - KGM graft copolymer to algal oil is (2 - 5):1.

[0019] In some embodiments, in step 2), the crude reaction product is added to distilled water at a mass - to - volume ratio of 1:(8 - 11) (g / mL) for sufficient dissolution, and then centrifuged at a rotation speed of 3500 ± 200 r / min for 15 ± 3 min. The supernatant is collected and freeze - dried to obtain the SPI - KGM graft copolymer.

[0020] In some embodiments, in step 2), the reaction time between algal oil and the KGM - SPI graft copolymer is 20 - 50 min.

[0021] In some embodiments, in step 1), soy protein isolate and konjac glucomannan are dispersed in water and stirred and swollen at room temperature for 2 - 3 h.

[0022] In some embodiments, the molecular weight Mw of soy protein isolate is 170 - 270 Da, and the molecular weight Mw of konjac glucomannan is (2.5 - 3.7)×105 Da.

[0023] In a second aspect, the present invention provides an algal oil nano - gel, which is obtained by the above - mentioned method.

[0024] In a third aspect, the present invention provides an application of the algal oil nano - gel in the preparation of health foods or functional foods having the efficacy of regulating blood lipid, improving cognitive function, enhancing immunomodulatory activity and / or preventing and treating cardiovascular diseases.

[0025] In a fourth aspect, the present invention provides a high - stability and nutrient - fortified algal oil cheese, which comprises the above - mentioned algal oil nano - gel. This high - stability and nutrient - fortified algal oil cheese has no fishy smell of algal oil, can well protect the algal oil from oxidation, shows good sensory properties, and thus has great application potential in the stability protection of functional factors.

[0026] In a fifth aspect, the present invention provides a preparation method of a high - stability and nutrient - fortified algal oil cheese, comprising: Mix cheese, butter and water evenly, add the above - mentioned algal oil nano - gel, stir to obtain a blended mixture, and sterilize to obtain a high - stability and nutrient - fortified algal oil cheese.

[0027] The beneficial effects of the present invention are as follows: 1. The present invention innovatively uses SPI and KGM as composite matrices, and successfully constructs an SPI - KGM graft copolymer system through a thermal - induced self - assembly technique. This preparation method can make the grafting degree of the graft copolymer reach 45.68%, which is significantly better than the traditional preparation process. On this basis, by optimizing the direct embedding process parameters, efficient loading of algal oil is achieved, and the final prepared algal oil nano - gel has an encapsulation efficiency as high as 96.59% and shows excellent physicochemical stability.

[0028] 2. The algal oil nano - gel emulsion in the present invention is used as a functional additive in the fields of health products and foods, and shows significant advantages especially in cheese products. Due to its high encapsulation rate, stable physicochemical properties, small emulsion particle size and uniform spherical morphology, it can not only effectively improve the chemical stability of algal oil during processing and storage, but also cover up the fishy smell of algal oil, making the final product have better taste acceptance and broad market prospects.

[0029] 3. Compared with the technical solution of directly adding algal oil - embedded powder into cheese in the present invention, the algal oil - embedded powder has a larger particle size, which affects the uniformity of the product, and the loss rate of algal oil is relatively high during the embedding process. The final product is prone to precipitation and phase separation phenomena. These defects seriously restrict the stability and palatability of algal oil in the cheese system, and ultimately lead to quality problems such as loose texture and rough taste of the product.

[0030] 4. The highly stable and nutrient - fortified algal oil cheese prepared by the method of the present invention effectively masks the inherent fishy smell of algal oil through nano - gel technology, and the sensory quality of the product is excellent. The DHA and EPA contents in the algal oil nano - gel are relatively high, showing significant effects in regulating blood lipid metabolism and enhancing cognitive function. In addition, this nano - gel system has significant preventive and adjuvant therapeutic effects on various diseases related to the degradation of multiple body functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The schematic diagrams of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0032] Figure 1 It is the appearance morphology diagram of the algal oil - embedded composite particles in Example 1 of the present invention; Figure 2 It is the appearance morphology diagram of the algal oil - embedded composite particles in Comparative Example 1 of the present invention; Figure 3 It is the appearance morphology diagram of the algal oil - embedded composite particles in Comparative Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] Aiming at the problems existing in the existing algal oil embedding technology, such as low embedding rate, too large particle size, poor stability, especially the technical bottlenecks such as easy oxidation of algal oil after embedding, low bioavailability and large loss rate, the present invention innovatively proposes an algal oil nano - gel and its preparation method, and develops its application in cheese products.

[0034] In order to enable those skilled in the art to more clearly understand the technical solutions of the present invention, the following will specifically describe the technical solutions of the present invention in detail with reference to specific examples.

[0035] The raw materials and equipment used in the following examples are all obtained from ordinary commercial sources. Among them, soy protein isolate SPI is food - grade, with a purity ≥ 90% and a molecular weight Mw = 245.682 Da; konjac glucomannan KGM is food - grade, with a purity ≥ 98% and a molecular weight Mw = 3.07×10 5 Da.

[0036] Example 1 An algal oil nano - gel, and its preparation method is as follows: Accurately weigh 3.0 g of SPI and KGM (accurate to 0.01 g), mix them evenly and dissolve them in 100 mL of distilled water to prepare a mixed solution containing 3% (w / v) SPI and 3% (w / v) KGM. The mixed solution was continuously stirred magnetically for 4 h at room temperature (25±2°C) to ensure sufficient swelling. The pH value of the mixed solution was accurately adjusted to 7.0 using 2.0 mol / L hydrochloric acid solution. The adjusted solution was transferred to a freeze dryer, pre-frozen at -50°C for 4 h, and then freeze-dried for 24 h under 0.1 mbar vacuum conditions. The freeze-dried product was ground in a mortar and sieved through a 120-mesh (pore size 125 μm) standard sieve. The sieved powder was placed in a constant temperature and humidity chamber (temperature 60±1°C, relative humidity 79±1%) for 4 days. The reaction product was taken and added with distilled water at a ratio of 1:10 (w / v) to dissolve, and the supernatant was collected after centrifugation at 3500 r / min for 15 min. The supernatant was freeze-dried again, and the obtained SPI-KGM graft copolymer was placed in a desiccator and stored in the dark for later use.

[0037] 5.0 g of SPI-KGM graft copolymer was completely dissolved in 20 mL of distilled water to prepare a homogeneous solution with a concentration of 1 mg / mL. 1.0 g of algae oil was slowly added to 20 mL of the above SPI-KGM graft copolymer solution, and magnetic stirring was performed at a speed of 500 r / min for 30 min at a constant temperature of 55±1°C to ensure that the two phases were fully mixed and emulsified, and finally a stable aqueous dispersion system algae oil nanogel was formed through physical embedding.

[0038] Example 2 An algae oil nanogel, the preparation method of which is as follows: 1.5 g SPI and 3.0 g KGM were accurately weighed and placed in a beaker, and 100 mL distilled water was added and mixed evenly. The sample was stirred continuously for 3 h at room temperature to fully swell the sample, and finally a mixed solution with a mass concentration of SPI and KGM of 1.5% and 3% (w / v), respectively, was obtained. The pH value of the mixed solution was adjusted to 6.5 with 2 mol / L hydrochloric acid solution, and then transferred to a freeze dryer for freeze drying for 24 h. The freeze-dried product was ground and passed through a 120-mesh sieve to obtain a uniform powder. The above powder was placed in a constant temperature and humidity chamber (temperature 55°C, relative humidity 75%) for a grafting reaction for 5 days. After the reaction was completed, the copolymer was dissolved in distilled water at a ratio of 1:9 (w / v) and stirred thoroughly until completely dissolved. Subsequently, the mixture was centrifuged at 3500 r / min for 15 min, and the supernatant was collected for freeze drying to finally obtain the SPI-KGM graft copolymer. All products were placed in a desiccator for storage.

[0039] 4.0 g of the SPI-KGM graft copolymer was completely dissolved in 20 mL of distilled water to prepare a homogeneous solution with a concentration of 1 mg / mL. Subsequently, 1.0 g of algal oil was added to this solution, and it was treated with magnetic stirring (rotation speed 500 r / min) for 20 min under the condition of constant temperature at 50 °C to fully mix the algal oil and the SPI-KGM graft copolymer, and finally a stable aqueous dispersion system of algal oil nanogel was formed.

[0040] Example 3 An algal oil nanogel, and its preparation method is as follows: Accurately weigh 4.5 g of SPI and 3.0 g of KGM, mix them evenly and dissolve in 100 mL of distilled water. Stir continuously at room temperature for 5 h to fully swell it, and a mixed solution with mass fractions of SPI and KGM being 4.5% and 3% (w / v) respectively is prepared. After adjusting the pH to 7.5 with 2 mol / L hydrochloric acid solution, the mixed solution is placed in a freeze dryer and freeze-dried for 24 h. The freeze-dried product is ground and sieved through a 120-mesh sieve to obtain a uniform powder. The sieved powder is placed in a constant temperature and humidity box (temperature 65 °C, relative humidity 85%) and reacted for 3 days. After the reaction is completed, the obtained copolymer is added to distilled water according to the ratio of 1:11 (w / v) and fully dissolved, and centrifuged at 3500 r / min for 15 min to remove insoluble substances. The supernatant is collected and freeze-dried to obtain the SPI-KGM graft copolymer, which is placed in a desiccator and stored at 4 °C for standby.

[0041] 6.0 g of the SPI-KGM graft copolymer was completely dissolved in 20 mL of deionized water to prepare a mother liquor with a concentration of 300 mg / mL. 1.0 g of algal oil raw material was added to the above solution, and under the condition of constant temperature water bath at 60 ± 0.5 °C, magnetic stirring was carried out at a rotation speed of 800 r / min for 40 min to fully homogenize the system. Finally, a water-dispersible algal oil nanogel was prepared by the direct embedding method.

[0042] Example 4 A highly stable and nutrient-enriched algal oil cheese, and its preparation method is as follows: Weigh each component by mass percentage: 52% water, 30% cheese, 10% butter, 1.5% granulated sugar, 5.0% of the algal oil nanogel prepared in Example 1, 1.5% compound thickener. Add the raw materials in the above order to the milk melting pot in turn, and stir fully until a uniform mixed solution is formed. After sealing the prepared solution, it is kept warm and sterilized at 90 °C for 9 min, and after the sterilization is completed, it is transferred to the cheese storage tank for temporary storage. The temperature of the storage tank is maintained at 85 °C and stirring is kept, and hot filling is carried out at 80 °C. After filling, it is quickly cooled with condensed water, and after cooling to a suitable temperature, it is sheared and formed. Pack according to the product specification requirements, and the finished product is put into storage to obtain the highly stable and nutrient-enriched algal oil cheese.

[0043] Example 5 A highly stable and nutrient - fortified algal oil cheese, the difference in the preparation method from Example 4 is: using the algal oil nanogel in Example 2.

[0044] Example 6 A highly stable and nutrient - fortified algal oil cheese, the difference in the preparation method from Example 4 is: using the algal oil nanogel in Example 3.

[0045] Comparative Example 1 An algal oil nanogel, the preparation method is as follows: Accurately weigh 3.0 g of SPI and KGM each, after fully mixing, dissolve them in 100 mL of distilled water. After using a pH meter to adjust the pH of the mixed solution to 7.0, add 1.0 g of algal oil. Place the above - mentioned mixed system on a magnetic stirrer and stir at a constant speed for 30 min to make it fully mixed evenly, obtaining an algal oil nanogel solution. Finally, perform freeze - drying treatment on the obtained solution to obtain a powdered sample of algal oil nanogel.

[0046] Comparative Example 2 An algal oil nanogel, the preparation method is as follows: Dissolve whey protein concentrate (WPC) powder in distilled water, stir magnetically at room temperature for 2 h to make it fully dissolve, then place it in a 4 °C refrigerator and let it stand overnight to ensure complete hydration, finally obtaining a WPC solution with a concentration of 1.0 mg / mL. Subsequently, add pullulan (PUL) to the WPC solution to a final concentration of 0.8 mg / mL. After it is completely dissolved, heat the mixed solution in an 80 °C constant - temperature water bath for 20 min to promote the formation of the WPC / PUL complex. Finally, cool the sample to room temperature for standby.

[0047] Accurately weigh an appropriate amount of algal oil and dissolve it in absolute ethanol, stir magnetically for 1 h at room temperature in the dark to prepare an algal oil ethanol solution with a concentration of 30 μg / mL. Subsequently, mix the algal oil ethanol solution and the WPC / PUL complex solution with different PUL concentrations in a ratio of 1:2 (v / v), and continuously stir magnetically at room temperature in the dark for 5 h until the solution color reaches a stable state. After mixing is completed, use a vacuum rotary evaporator (25 °C, 100 r / min) to remove ethanol to obtain a WPC / PUL / algal oil nano - dispersion. Finally, centrifuge the dispersion at 3000 r / min for 10 min to remove the un - encapsulated free algal oil, and the algal oil nanogel is obtained.

[0048] Test Example Systematic performance characterizations were carried out on the algal oil nanogels prepared in Examples 1-3 and Comparative Examples 1-2, including indicators such as grafting rate, encapsulation rate, particle size distribution, microscopic morphology, storage stability, and bioaccessibility.

[0049] The specific detection methods are as follows: (1) The grafting rate and encapsulation rate were determined by ultraviolet spectrophotometry; (2) A Zetasizer Nano-ZS laser particle size analyzer was used to determine the particle size distribution and Zeta potential of the algal oil nanogel; (3) The microscopic morphology and dispersion state of the algal oil nanogel were observed by transmission electron microscopy (TEM); (4) Its bioaccessibility was evaluated by in vitro simulated digestion combined with cell uptake experiments; (5) For the stability test, with the algal oil retention rate as the index, after storing the sample in the dark at 4 °C for 30 days, the retention rate of the active ingredient was determined by ultraviolet spectrophotometry to evaluate the long-term stability of the preparation.

[0050] The detection results are shown in Table 1. It can be seen from Table 1 that compared with Comparative Examples 1-2, the algal oil nanogels prepared in Examples 1-3 were prepared by the thermal-induced self-assembly method and the direct embedding method, with a high encapsulation rate and more stable physicochemical properties. The nanogel has a smaller particle size and a uniform distribution, the morphology is closer to a regular sphere, has high bioaccessibility, and effectively eliminates the characteristic odor of algal oil.

[0051] Table 1 Parameters of the algal oil nanogel inclusion in Examples and Comparative Examples

[0052] From the above analysis, it can be seen that the present invention has successfully prepared a high-stability and nutrient-enriched algal oil cheese product. The innovation of this product is mainly reflected in the following aspects: First, a graft copolymer with a grafting degree of 45.68% was prepared by the thermal-induced self-assembly technique; second, based on this copolymer, an algal oil nanogel emulsion system with excellent physicochemical stability was constructed by the direct embedding method. This emulsion system has the following significant advantages: (1) high encapsulation efficiency, which can effectively protect the active ingredients of algal oil; (2) the nanoparticles have a small particle size and a uniform distribution; (3) the particle morphology tends to be a regular sphere, which is beneficial to improving the physical stability of the system. These characteristics together ensure the stable existence of algal oil in the cheese matrix, thus achieving the purpose of product nutrient enrichment.

[0053] The prepared high-stability and nutrient-enriched algal oil cheese has no fishy smell of algal oil, shows good sensory properties, the DHA and EPA contents of the algal oil nanogel are relatively high, and it shows significant effects in regulating blood lipid metabolism and enhancing cognitive function. In addition, this nanogel system has a significant preventive and adjuvant therapeutic effect on various diseases related to the degradation of body functions.

[0054] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of algal oil nanogel, characterized in that, Comprising: 1) Using soy protein isolate and konjac glucomannan as raw materials, preparing SPI-KGM graft copolymer by thermal-induced self-assembly method; 2) Adding algal oil into the SPI-KGM graft copolymer solution, mixing evenly to obtain algal oil nanogel.

2. The preparation method of the algal oil nano-gel according to claim 1, characterized in that, In step 1), soy protein isolate and konjac glucomannan are evenly dispersed in water to obtain a mixed solution; adjusting the pH of the mixed solution to 6.5 - 7.5, then performing freeze-drying and pulverizing to obtain a powder, and reacting the powder under the conditions of 75 - 85% relative humidity and 55 - 65 °C for 3 - 5 d to obtain a crude reaction product; Preferably, adding strong acid or weak acid to adjust the pH of the mixed solution, and more preferably hydrochloric acid.

3. The preparation method of the algal oil nano-gel as claimed in claim 1, wherein, In step 1), the reaction product is added to water for dissolution and then centrifuged, and the supernatant is taken for freeze-drying to obtain SPI-KGM graft copolymer.

4. The preparation method of the algal oil nanogel according to claim 1, wherein, In step 2), the SPI-KGM graft copolymer is dissolved in water, algal oil is added to the SPI-KGM graft copolymer solution, and stirred and mixed evenly at 50 - 60 °C to obtain algal oil nanogel.

5. The preparation method of the algal oil nanogel according to claim 1, characterized in that, In step 1), the mass ratio of soy protein isolate to konjac glucomannan is (0.5 - 2.0):1; Or, in step 2), the mass ratio of SPI-KGM graft copolymer to algal oil is (2 - 6):

1.

6. The preparation method of the algal oil nano-gel according to claim 1, wherein In step 2), the crude reaction product is added to distilled water according to a mass-volume ratio of 1:(8 - 11) for complete dissolution, centrifuged, and the supernatant is taken for freeze-drying to obtain SPI-KGM graft copolymer; Or, in step 2), the reaction time of algal oil and SPI-KGM graft copolymer is 20 - 50 min.

7. An algal oil nanogel, characterized in that, Prepared by the preparation method described in any one of claims 1 - 6.

8. Use of the algal oil nanogel described in claim 7 in the preparation of a health food or functional food having the efficacy of regulating blood lipid, improving cognitive function, enhancing immune regulation activity and / or preventing and treating cardiovascular diseases.

9. A high-stability and nutrition-fortified algal oil cheese, characterized in that, Comprising the algal oil nanogel described in claim 7.

10. A method for preparing the highly stable and nutrient - fortified algal oil cheese according to claim 9, characterized in that, Comprising: Mixing cheese, butter and water evenly, adding the algal oil nanogel described in claim 7, and stirring to obtain a blended mixture, Sterilizing to obtain algal oil nutrient-fortified cheese.

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