Microcapsule powder capable of covering oil smell of euphausia superba and preparation method of microcapsule powder

Abstract

The invention discloses microcapsule powder for covering the oil smell of euphausia superba oil and a preparation method of the microcapsule powder, and belongs to the field of euphausia superba oil processing. The microcapsule powder is composed of 50-75% of OSA starch, 10-30% of euphausia superba oil, 3-20% of sodium alginate, 1-10% of succinic acid and 0.5-5% of calcium hydrophosphate, during preparation, the OSA starch is gelatinized and then sheared and homogenized with the euphausia superba oil to obtain a miniemulsion, the succinic acid, the sodium alginate and the calcium hydrophosphate are prepared into a mixed solution, the mixed solution is mixed with the miniemulsion in proportion, and spray drying is performed to obtain a finished product. An OSA starch-sodium alginate double-wall material system is adopted, a compact cross-linked layer is formed through pH response, peculiar smell substances such as trimethylamine can be completely masked, the astaxanthin retention rate is up to 95.14%, the embedding rate reaches 89.48%, krill oil oxidation is effectively inhibited, krill oil is converted into powder, the stability and the sensory property are improved, application of krill oil in the food field is widened, the technology is simple, and the method is suitable for industrial production. The method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of Antarctic krill oil processing, and more particularly to a microcapsule for masking the odor of Antarctic krill oil and its preparation method. Background Technology

[0002] Antarctic krill oil is a refined functional oil extracted from Antarctic krill. It is rich in phospholipids, DHA, EPA, astaxanthin, and vitamin E, among other active ingredients. It demonstrates significant efficacy in reducing inflammation, preventing and treating cardiovascular disease, combating diabetes, improving cognitive function, maintaining skin health, aiding weight loss, and regulating gut health. Its unsaturated fatty acids exist in phospholipid form, which, compared to triglyceride and ethyl ester forms, not only has higher bioavailability but can also cross the blood-brain barrier smoothly, making it a highly efficient way to supplement DHA for the brain.

[0003] However, the industrial application of Antarctic krill oil has long been limited by multiple core technological challenges. Unlike traditional refined oils, the production process often simplifies refining techniques to maximize the retention of functional active ingredients such as phospholipid polyunsaturated fatty acids and astaxanthin. This results in the product being prone to residual impurities such as proteins, amino acids, and metal ions. Simultaneously, phospholipid polyunsaturated fatty acids and astaxanthin are extremely sensitive to transition metal ions, heat, oxygen, and free radicals, making Antarctic krill oil oxidatively unstable. During extraction and post-processing, it is prone to oxidation reactions, generating volatile compounds such as amines, aldehydes, and ketones—these substances are the main source of its unpleasant odor, severely restricting its widespread application in the food industry. Furthermore, the double bonds of ω-3 polyunsaturated fatty acids in krill oil are easily oxidized, producing harmful substances such as aldehydes and ketones under light and high-temperature conditions. Its active ingredients are also sensitive to pH; in the acidic environment of the stomach (pH 1-3), phospholipid molecules are easily hydrolyzed and broken, leading to a significant decrease in the retention rate of active ingredients within a short period. Moreover, under traditional processing methods, krill oil has poor compatibility with the carrier, and free oil is prone to precipitation when preparing encapsulated products, which not only wastes raw materials but also seriously affects the quality of the final product.

[0004] To address the aforementioned issues, related research on encapsulation technology has been conducted in relevant fields. For example, patent application CN121369694 A discloses a method for preparing liposomes encapsulating Antarctic krill oil. This method uses octenyl succinate starch ester, sodium alginate, and pea protein as composite wall materials, combined with rapeseed oil phospholipids or soybean phospholipids and phytosterols to prepare liposomes. The synergistic effect between the materials improves the stability and absorption efficiency of krill oil. However, this technology still has significant shortcomings: First, the liposome preparation process requires multiple shearing, homogenization, and microfluidic treatments. The two homogenization operations at 45°C significantly increase the oxidation risk of krill oil, while also leading to a substantial increase in production energy consumption and time costs. Second, the high proportion of aqueous phase in the liposomes results in an actual krill oil loading of only 0.60% in the system, and the AKO content in the dry liposome system is only 1.83%, far lower than the level of conventional Antarctic krill oil, which is also the reason for its less pronounced fishy smell. Third, the thermodynamic stability of liquid liposomes is poor, and problems such as fusion, core material leakage, and oxidative deterioration are prone to occur during long-term storage, which is not conducive to the diversified application of krill oil in the food industry.

[0005] In contrast, microencapsulation technology has garnered widespread attention in the industry due to its advantages such as ease of transportation and storage, excellent stability, and significant economic benefits. This technology can construct a physical barrier through the wall material, effectively isolating pro-oxidative factors such as oxygen and metal ions, thus enhancing the oxidative stability of lipids and blocking and masking unpleasant odor substances. Furthermore, it can transform the active ingredients of high-viscosity liquid krill oil into an easily processed powder form, significantly extending the shelf life of the raw material and effectively overcoming the limitations of industrial application of Antarctic krill oil. Summary of the Invention

[0006] Technical issues Industrially produced Antarctic krill oil contains residual impurities, making it prone to oxidation, which produces unpleasant odors, and it is easily hydrolyzed in gastric acid. Traditional encapsulation methods often result in the precipitation of free oil, and existing liposome encapsulation technologies suffer from high oxidation risk, high energy consumption and costs, low loading capacity, and poor stability. Therefore, there is an urgent need for a more efficient encapsulation technology with low oxidation risk, no unpleasant odor, and higher loading capacity.

[0007] Technical content To address the issues of insufficient odor masking and inadequate stability of Antarctic krill oil, and to broaden its applications in the food industry, this invention prepares a microcapsule powder that can effectively mask its odor and achieve efficient encapsulation. This invention uses a compound of OSA starch (with excellent surface activity and emulsifying properties, and is safe and available in a stable supply) and sodium alginate (with excellent cross-linking properties, biocompatibility, and pH responsiveness, and the ability to control the release of volatile substances) as the encapsulation carrier. Combined with formula optimization, this achieves efficient encapsulation of krill oil, further expanding its food application scenarios.

[0008] The present invention adopts the following technical solution: A microcapsule powder for masking the odor of Antarctic krill oil, the microcapsule powder being composed of the following components by mass fraction: 50-75% OSA starch, 10-30% Antarctic krill oil, 3-20% sodium alginate, 1-10% succinic acid, and 0.5-5% dicalcium phosphate.

[0009] Furthermore, the microcapsule powder is composed of the following components in mass fractions: 55-70% OSA starch, 15-25% Antarctic krill oil, 4-15% sodium alginate, 2-8% succinic acid, and 1-5% dicalcium phosphate.

[0010] Preferably, the microcapsule powder is composed of the following components by mass fraction: 55-60% OSA starch, 15-20% Antarctic krill oil, 10-15% sodium alginate, 5-8% succinic acid, and 2-4% dicalcium phosphate.

[0011] Furthermore, the content of trimethylamine, n-hexanal, and 3-methylhexanal in the microcapsule powder is 0 mg / kg, the content of (E,E)-2,4-heptadienal is less than 0.01 mg / kg, the content of (E,E)3,5-octadien-2-one is less than 0.5 mg / kg, and the content of 2-n-propylfuran is less than 0.2 mg / kg.

[0012] A method for preparing microcapsule powder that masks the odor of Antarctic krill oil, the method comprising the following steps: Step 1: Disperse OSA starch in water, gelatinize, and stir to obtain a gelatinized product; Step 2: Add Antarctic krill oil to the gelatinized material from Step 1, and then cut to obtain a crude emulsion of Antarctic krill oil. Step 3: Homogenize the crude emulsion obtained in Step 2 using a homogenizer to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve succinic acid in water, adjust the pH to alkaline using ammonium hydroxide, then add sodium alginate and stir until fully dissolved. Add calcium hydrogen phosphate to the dissolved sodium alginate solution to obtain a sodium alginate mixed solution. Step 5: Mix the Antarctic krill oil emulsion obtained in Step 3 with the sodium alginate mixed solution obtained in Step 4 to obtain the spray drying feed solution; Step 6: Spray dry the feed liquid obtained in Step 5 to obtain Antarctic krill oil microcapsule powder.

[0013] Furthermore, the gelatinization conditions in step 1 are heating at 85~95°C for 30~35 minutes.

[0014] Furthermore, the stirring time in step 1 is 12-15 hours.

[0015] Furthermore, in step 2, the concentration of OSA starch in the crude emulsion is 10-20 wt%.

[0016] Furthermore, in step 2, the concentration of Antarctic krill oil in the crude emulsion is 3-10 wt%.

[0017] Furthermore, in step 2, the shearing speed is 9000~10000 rpm, and the time is 2~3 min.

[0018] Furthermore, in step 3, the homogenization pressure is 40~50 MPa, the number of times is 3~5, and the temperature is 15~18°C.

[0019] Furthermore, in step 4, the concentration of succinic acid in the sodium alginate mixed solution is 0.5~2wt%.

[0020] Furthermore, in step 4, the concentration of sodium alginate in the sodium alginate mixed solution is 1~5wt%.

[0021] Furthermore, in step 4, the concentration of dicalcium phosphate in the sodium alginate mixed solution is 0.25~1wt%.

[0022] Furthermore, in step 4, ammonium hydroxide is used to adjust the pH of succinic acid to 8-8.5.

[0023] Furthermore, in step 5, the Antarctic krill oil emulsion and sodium alginate are mixed at a mass ratio of 1:0.5~1.5.

[0024] Furthermore, in step 6, the inlet air temperature for spray drying is 120~140°C, and the feed rate is 400~600mL / h.

[0025] Beneficial effects 1. Effectively masks unpleasant odors and eliminates flavor shortcomings: This invention uses a compound system of OSA starch and sodium alginate double-wall material, combined with the synergistic effect of succinic acid and calcium hydrogen phosphate, to effectively mask the main volatile odor-causing substances in Antarctic krill oil, such as trimethylamine, n-hexanal, and 3-methylhexanal. At the same time, it reduces the content of characteristic off-odor substances such as (E,E)-2,4-heptadienal, (E,E)-3,5-octadien-2-one, and 2-n-propylfuran, solving the problems of fishy and rancid flavors in krill oil and significantly improving its sensory performance.

[0026] 2. Inhibits oxidative degradation and enhances component stability: During the spray drying process, the dual-wall material system triggers a pH response due to temperature rise. After the calcium hydrogen phosphate dissolves, it forms a dense cross-linked layer with sodium alginate on the surface of the emulsion droplets, constructing a physical barrier. This not only isolates oxygen, metal ions, and other pro-oxidizing factors, but also inhibits further oxidation of krill oil during the spray drying thermal processing, preventing the formation of new undesirable flavor substances. At the same time, it effectively protects astaxanthin in krill oil, increasing the astaxanthin retention rate to a maximum of 95.14%, which is far superior to the single OSA starch encapsulation effect, solving the problem of easy degradation of active ingredients in krill oil.

[0027] 3. Achieve efficient encapsulation and reduce raw material loss: The optimized formula and process achieve efficient encapsulation of krill oil, with an encapsulation rate of up to 89.48% and a microcapsule yield maintained at a high level of over 90%. Compared with other compound wall material systems such as xanthan gum and chitosan, it significantly reduces the free precipitation of krill oil and raw material loss during the production process, and increases the krill oil loading per unit mass of microcapsules, balancing encapsulation effect and production economy. Attached Figure Description

[0028] Figure 1 The electronic nose signal response diagrams for Examples 1-4, Comparative Examples 1-2, and krill oil crude oil are shown; wherein a is a comparison diagram of the electronic nose signal response of the microcapsule powder of Examples 1-4, the microcapsule powder of Comparative Examples 1-2, and the krill oil crude oil, and b is a comparison diagram of the electronic nose signal response of Examples 1-4 and Comparative Examples 1-2.

[0029] Figure 2 Examples 1-4 and Comparative Examples 1-2 are shown in the electronic nose radar distribution diagrams; where a is a comparison diagram of the electronic nose radar distribution of Examples 1-4 and Comparative Examples 1-2, and b is a comparison diagram of the electronic nose radar distribution of Examples 1-4.

[0030] Figure 3 The electronic nose PCA diagrams are for Examples 1-4, Comparative Examples 1-2, and krill oil crude oil; where a is a comparison diagram of the electronic nose PCA of the microcapsule powder of Examples, the microcapsule powder of Comparative Examples, and krill oil crude oil, and b is a comparison diagram of the electronic nose PCA of Examples 1-4 and Comparative Example 1. Detailed Implementation

[0031] The following describes preferred embodiments of the present invention. It should be understood that these embodiments are for better explanation of the present invention and are not intended to limit the present invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0032] In the examples and comparative examples, the mass concentrations of OSA starch and Antarctic krill oil were calculated relative to the mass of the crude emulsion; the mass concentrations of succinic acid, sodium alginate, dicalcium phosphate, xanthan gum, and chitosan were calculated relative to their respective polysaccharide solutions.

[0033] Example 1 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain the gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve 0.5 wt% succinic acid (0.5 g) in water, adjust the pH to 8.5 using ammonium hydroxide, then add 1 wt% sodium alginate (1 g) and stir for 2 h to ensure complete dissolution. Add 0.25 wt% dicalcium phosphate (0.25 g) to the dissolved sodium alginate solution to obtain a sodium alginate mixed solution. Step 5: After thoroughly mixing the Antarctic krill oil emulsion obtained in Step 3 with the sodium alginate mixed solution obtained in Step 4 at a mass ratio of 1:1, the spray drying feed solution is obtained. Step 6: Spray dry the feed liquid obtained in Step 5 with an inlet air temperature of 120°C and a feed rate of 500 mL / h to obtain Antarctic krill oil microcapsule powder.

[0034] Example 2 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain the gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve 1 wt% succinic acid (1 g) in water, adjust the pH to 8.5 using ammonium hydroxide, then add 2 wt% sodium alginate (2 g) and stir for 2 h to ensure complete dissolution. Add 0.5 wt% dicalcium phosphate (0.5 g) to the dissolved sodium alginate solution to obtain a sodium alginate mixed solution. Step 5: After thoroughly mixing the Antarctic krill oil emulsion obtained in Step 3 with the sodium alginate mixed solution obtained in Step 4 at a mass ratio of 1:1, the spray drying feed solution is obtained. Step 6: Spray dry the feed liquid obtained in Step 5 with an inlet air temperature of 120°C and a feed rate of 500 mL / h to obtain Antarctic krill oil microcapsule powder.

[0035] Example 3 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain the gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve 1.5 wt% succinic acid (1.5 g) in water, adjust the pH to 8.5 using ammonium hydroxide, then add 3 wt% sodium alginate (3 g) and stir for 2 h to ensure complete dissolution. Add 0.75 wt% dicalcium phosphate (0.75 g) to the dissolved sodium alginate solution to obtain a sodium alginate mixed solution. Step 5: After thoroughly mixing the Antarctic krill oil emulsion obtained in Step 3 with the sodium alginate mixed solution obtained in Step 4 at a mass ratio of 1:1, the spray drying feed solution is obtained. Step 6: Spray dry the feed liquid obtained in Step 5 with an inlet air temperature of 120°C and a feed rate of 500 mL / h to obtain Antarctic krill oil microcapsule powder.

[0036] Example 4 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain the gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve 2 wt% succinic acid (2 g) in water, adjust the pH to 8.5 using ammonium hydroxide, then add 4 wt% sodium alginate (4 g) and stir for 2 h to fully dissolve it. Add 1 wt% calcium hydrogen phosphate (1 g) to the dissolved sodium alginate solution to obtain a sodium alginate mixed solution. Step 5: After thoroughly mixing the Antarctic krill oil emulsion obtained in Step 3 with the sodium alginate mixed solution obtained in Step 4 at a mass ratio of 1:1, the spray drying feed solution is obtained. Step 6: Spray dry the feed liquid obtained in Step 5 with an inlet air temperature of 120°C and a feed rate of 500 mL / h to obtain Antarctic krill oil microcapsule powder.

[0037] Comparative Example 1 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Spray dry the fine emulsion obtained in Step 3 at an inlet air temperature of 120℃ and a feed rate of 500mL / h to obtain Antarctic krill oil microcapsule powder.

[0038] Comparative Example 2 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve 1 wt% (1 g) xanthan gum in water and stir for 2 h to ensure complete dissolution, thus obtaining a xanthan gum solution; Step 5: After thoroughly mixing the Antarctic krill oil emulsion obtained in Step 3 with the xanthan gum mixture obtained in Step 4 at a mass ratio of 1:1, the feed solution for spray drying is obtained. Step 6: Spray dry the feed liquid obtained in Step 5 with an inlet air temperature of 120°C and a feed rate of 500 mL / h to obtain Antarctic krill oil microcapsule powder.

[0039] Comparative Example 3 Step 1: Disperse 15 wt% OSA starch (15 g) in water, gelatinize at 90°C for 30 min, and stir at room temperature for 12 h to obtain the gelatinized product; Step 2: Add 5 wt% Antarctic krill oil (5 g) to the gelatinized material from Step 1, and shear at 10,000 rpm for 2 min to obtain a crude emulsion of Antarctic krill oil. Step 3: The crude emulsion obtained in Step 2 is homogenized using a homogenizer at a pressure of 45 MPa for 4 times and a cooling water temperature of 15°C to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve 1%wt chitosan (1 g) in 1%wt acetic acid solution and stir for 2 h to ensure complete dissolution, thus obtaining a chitosan solution; Step 5: After thoroughly mixing the Antarctic krill oil emulsion obtained in Step 3 with the chitosan solution obtained in Step 4 at a mass ratio of 1:1, the mixture is sheared at 10,000 rpm for 2 min, homogenized 4 times at 45 MPa, and the condensate temperature is 15℃ to obtain the feed liquid for spray drying. Step 6: Spray dry the feed liquid obtained in Step 5 with an inlet air temperature of 120℃ and a feed rate of 500 mL / h to obtain Antarctic krill oil microcapsule powder.

[0040] Result detection 1. Determination of encapsulation rate and yield of Antarctic krill oil Determination of total oil content in microcapsules: Add approximately 1 g of microcapsule powder (M) to a 50 mL centrifuge tube, add 40 mL of 100 mM sodium citrate solution (or deionized water), shake gently and evenly to dissolve completely, then divide the liquid into two 50 mL centrifuge tubes, add 10 mL of n-hexane to each tube, mix vigorously, then add 10 mL of isopropanol and mix well. Centrifuge at 4000 r for 5 min, take the upper organic phase and rotary evaporate it in a constant weight (m0) rotary evaporator until all organic solution has evaporated, then place it in a 55℃ oven until constant weight (m1).

[0041]

[0042] Determination of surface oil content of microcapsules: First, weigh approximately 1 g of the microcapsule product, denoted as M, and extract with 15 ml of n-hexane for about 2 min. Then, centrifuge at 4000 r for 5 min, collect the supernatant, filter, and further extract the powder with 10 mL of n-hexane. After centrifugation and filtration, collect the two filtrates, add 10 mL of isopropanol and 5 mL of deionized water, mix thoroughly, and centrifuge at 4000 r for 5 min. Transfer the upper organic phase to a constant weight (m0) rotary evaporator flask and evaporate until all organic solution has evaporated. Place in a 55℃ oven until constant weight (m1). The formulas for calculating surface oil, encapsulation efficiency, and loading capacity are as follows:

[0043]

[0044]

[0045] The encapsulation efficiency results are shown in Table 1. Compared with Comparative Example 1, the surface oil content in Examples 1-4 showed a trend of first increasing and then decreasing, while the encapsulation efficiency showed a trend of first decreasing and then increasing. There was no significant difference in yield among the examples. This indicates that under low concentration conditions, the addition of sodium alginate negatively affects the Antarctic krill oil OSA starch emulsion, leading to an increase in surface oil and a decrease in encapsulation efficiency. When the concentration exceeds 2%, the effect of sodium alginate on the Antarctic krill oil OSA starch emulsion continues to decrease, with the highest encapsulation efficiency reaching 89.48%. The encapsulation efficiency of Comparative Example 2 was significantly higher than that of other examples and comparative examples, but the yield was significantly lower. This indicates that the OSA starch and xanthan gum compound system can effectively encapsulate some krill oil, but the loss of krill oil during the production process is relatively high. In addition, the yield of Comparative Example 3 was much lower than that of Comparative Examples 1-4, indicating that the loading of Antarctic krill oil microcapsules per unit mass is low, which will cause a large loss of krill oil during the production of krill oil microcapsules.

[0046] Table 1

[0047] 2. Detection of Astaxanthin Retention Rate in Antarctic Krill Oil Microcapsules Weigh approximately 2 g of spray-dried Antarctic krill oil emulsion and approximately 1 g of Antarctic krill oil microcapsules. Dissolve the microcapsules in 5 mL of 100 mM sodium citrate solution. Then, add 10 mL of ethyl acetate to each of the two systems and vortex in the dark for 10 min. Centrifuge the solutions at 5000 r / min for 10 min, collect the supernatant, and read the absorbance at 480 nm using a spectrophotometer. Calculate the astaxanthin concentration using formula (1):

[0048]

[0049] In the formula, A = absorbance; V = supernatant volume; P = sample weight; A (1%，1 cm) =2150 (specific absorbance of astaxanthin in ethyl acetate); AST M =Astaxanthin concentration in microcapsules after spray drying; ASE =Astaxanthin concentration in pre-emulsion before spray drying.

[0050] The results of the astaxanthin retention rate determination are shown in Table 2. Compared with Comparative Example 1, except for the significantly reduced astaxanthin retention rate in Example 1, the astaxanthin retention rates in Examples 1 to 4 were all significantly higher than those in Comparative Example 1. This indicates that sodium alginate can effectively form a relatively dense shell around the OSA starch Antarctic krill oil emulsion under high concentration conditions, thereby preventing the astaxanthin in Antarctic krill oil from being degraded during the hot spray drying process.

[0051] Table 2

[0052] Note:" "Indicates no testing was conducted" 3. Electronic nose detection using Antarctic krill oil microcapsules The effects of different spray-drying temperatures and core-to-wall material ratios on the odor differences of krill oil microcapsules were analyzed using a Heracles II rapid gas chromatography-electronic nose. 0.12 g of krill oil sample was accurately weighed according to the total oil content of different microcapsules and placed in a 20 mL headspace vial, sealed with a metal screw cap, and analyzed in parallel. The assay was performed three times. Detection conditions: chromatographic columns were a non-polar DB-5 column (10 m ~ 0.18 mm) and a low / medium polar DB1701 column (10 m ~ 0.18 mm). Extraction temperature was 25°C for 1200 s; injection port temperature was 250°C with an injection volume of 2000 µL; trapping temperature was 50°C; injection port temperature and FID detector temperature were 250°C and 260°C, respectively. The temperature program was as follows: initial column temperature 50°C, increased to 80°C at 1°C / min, then increased to 120°C at 3°C / min, held for 21 s, and finally increased to 250°C at 1.5°C / min, held for 60 s. The flavor compounds were analyzed using Alphasoft V12.44, the data processing software integrated into the rapid gas chromatography electronic nose.

[0053] Signal response intensity diagram as shown Figure 1 As shown, principal component analysis was performed using Alphasoft V12.44, and the resulting radar plot and PCA plot are shown below. Figure 2 and Figure 3 As shown. By Figure 1 a and Figure 3 It can be seen that, compared with unencapsulated krill oil, the microcapsules obtained by spray drying can initially and significantly mask the unpleasant flavor of krill oil. For example... Figure 1 b、 Figure 2 a and Figure 3 As shown in a and b, the signal response intensity and radar response of Comparative Examples 1-2 were significantly higher than those of Examples 1-4, and there were significant differences between different groups. Therefore, compared with other wall materials, the OSA starch / sodium alginate bilayer wall material can significantly reduce the unpleasant flavor of krill oil. Figure 2 b and Figure 3 As shown in b, with the increase of sodium alginate concentration, the radar intensity of undesirable flavors of Antarctic krill oil microcapsules decreased significantly, and the PCA plot showed that there were significant differences among the groups of Example 1, Example 2-3, and Example 4, which preliminarily indicates that the undesirable flavor masking effect of krill oil is best when the sodium alginate concentration is 4%.

[0054] 4. Gas chromatography-mass spectrometry of Antarctic krill oil microcapsules Headspace solid-phase microextraction (HS-SPME) conditions: Accurately calculate the total oil content of different microcapsules and weigh 0.3 g of krill oil sample into a 20 mL headspace vial. Add 5 μL of internal standard cyclohexanone (concentration 1 μg / μL), quickly cap and seal, and maintain the sample at 60°C for 10 min. Add 75 μm DVB / CAR / PDMS and 1 cm extraction head to the sample vial using HS-SPME, and extract at 60°C for 30 min. Remove the extraction head and insert it into the inlet of the gas chromatography-mass spectrometry (GC-MS) instrument, with a resolution time of 10 min.

[0055] GC conditions: Capillary column: J&W VF-WAXms (30 m × 0.25 mm × 0.25 μm); Carrier gas: He, flow rate: 1.8 mL / min, splitless; Temperature program: Initial column temperature: 40°C, hold for 1 min, increase to 50°C at 2°C / min, then increase to 120°C at 2.5°C / min, then increase to 240°C at 6°C / min, hold for 4 min; Detector temperature: 250°C.

[0056] MS conditions: EI ionization source, electron energy 70 eV, scan quality range 33~550 m / z. Table 3

[0057] Note:" "Indicates no results were detected."

[0058] The gas chromatography-mass spectrometry (GC-MS) results are shown in Table 3. 37 volatile substances were detected in Antarctic krill oil, including 9 esters, 8 ketones, 4 amines, 2 aldehydes, 4 pyrazines, 2 alcohols, 2 furans, and 6 other substances. Comparative Example 1, Example 1, and Example 2 each detected 15 volatile substances, including 5 esters, 2 ketones, 4 aldehydes, 1 alcohol, 1 furan, and 2 other substances. Example 3 detected 14 volatile substances, including 5 esters, 2 ketones, 3 aldehydes, 1 alcohol, 1 furan, and 2 other substances. Example 4 detected 12 volatile substances, including 5 esters, 2 ketones, 2 aldehydes, 1 alcohol, 1 furan, and 1 other substance.

[0059] Esters are derived from the further synthesis of free fatty acids and alcohols in krill oil. Gas chromatography-mass spectrometry (GC-MS) results show that the crude oil contains extremely high levels of esters, which is related to the gradient heating during GC-MS analysis. Ethyl oleate and ethyl trans-oleate exhibit a rancid, fatty odor. Compared to Comparative Example 1, the ester content in Examples 1 and 2 was slightly increased, while the ester content in Examples 3 and 4 was significantly decreased. This indicates that sodium alginate at low concentrations negatively impacts the encapsulation effect of Antarctic krill oil, damaging the outer layer of the microcapsule powder. However, at high concentrations, a dense protective film can form on the outside of the microcapsule powder, ensuring the microcapsules remain stable even under heating conditions.

[0060] Aldehydes are produced through the oxidation of unsaturated fatty acids or the degradation of amino acids, and they have a crucial impact on the overall flavor. Antarctic krill oil contains two aldehydes: (E,E)-2,4-heptadienal and benzaldehyde, which exhibit fishy, ​​rancid, and bitter almond odors. The synergistic effect of these two aldehydes further degrades the flavor of the krill oil. The comparative example and Examples 1-4 completely masked the unpleasant flavor of benzaldehyde. With increasing sodium alginate concentration, Examples 1-4 showed a significantly improved masking effect on the odor of (E,E)-2,4-heptadienal, reducing its content by approximately 74%-95%. Furthermore, during the spray-drying process, Antarctic krill oil undergoes oxidation under thermal processing, producing new aldehydes: n-hexanal, nonanal, and 3-methylhexanal. Compared with Comparative Example 1, in Examples 1-4, when the sodium alginate concentration was 4%, further oxidation of Antarctic krill oil could be effectively avoided, resulting in a reduction of the contents of hexanal and 3-methylhexanal to 0 mg / kg, and a reduction of nonanal content by approximately 33%.

[0061] Ketones mainly originate from the degradation of unsaturated fatty acids and have a significant impact on the overall flavor of Antarctic krill oil. The comparative and example samples effectively masked most of the volatile ketones within the Antarctic krill oil, except for 3,5-octadien-2-one and (E,E)3,5-octadien-2-one. A dynamic conversion exists between these two; the former mainly contributes to grassy and astringent flavors with a higher threshold, while the latter possesses a strong fishy and oxidized oil flavor with a lower threshold. Examples 1-4, compared to Comparative Example 1, showed relatively better flavor masking effects for both 3,5-octadien-2-one and (E,E)3,5-octadien-2-one, reducing their content by approximately 24-40% and 44-56%, respectively. Example 1 showed the lowest content of both, because the microcapsule powder under these conditions underwent further oxidation, converting the ketones into aldehydes or carboxylic acids.

[0062] Heterocyclic compounds are typically produced through Maillard reactions or amino acid degradation, processes that contribute to the overall flavor. The flavors of the four pyrazines and one furan in crude krill oil can be effectively masked by Antarctic krill oil microcapsule powder. 2-n-propylfuran exhibits a metallic, fishy odor, and its content in Examples 1-4 was reduced by approximately 76% compared to Comparative Example 1.

[0063] Amines are the main components of Antarctic krill oil, with trimethylamine being particularly prominent. Comparative Example 1 and Examples 1-4 all effectively masked the unpleasant flavor of amines. Dimethyl sulfide exhibits a spoiled seafood odor, which was also masked by the Antarctic krill oil microcapsule powder in Comparative Example 1-4. 2-Ethylpyrrole exhibits a beany odor, and its content is sharply higher than that of crude oil. This is related to the further oxidation during the spray drying of the krill oil. In Example 4, the 2-ethylpyrrole content was comparable to that of crude oil, while the 2-ethylpyrrole content in Examples 1-3 was lower than that in Example 4. This is related to the further chain reaction of 2-ethylpyrrole.

[0064] In summary, both Comparative Example 1 and Example 4 can initially mask undesirable flavors in krill oil. However, the wall material of Comparative Example 1 is relatively thin, resulting in poor masking of some aldehydes, ketones, and heterocyclic compounds. Furthermore, it promotes oxidation of Antarctic krill oil during spray drying, generating new aldehydes. Among Examples 1-4, Example 4 shows the best masking effect on undesirable flavors in Antarctic krill oil and effectively prevents further oxidation.

[0065] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformations or equivalent substitutions fall within the scope of protection of the present invention.

Claims

1. A microcapsule powder for masking the odor of Antarctic krill oil, characterized in that, The microcapsule powder is composed of the following components by mass fraction: 50-75% OSA starch, 10-30% Antarctic krill oil, 3-20% sodium alginate, 1-10% succinic acid, and 0.5-5% dicalcium phosphate.

2. The microcapsule powder according to claim 1, characterized in that, The microcapsule powder is composed of the following components by mass fraction: 55-70% OSA starch, 15-25% Antarctic krill oil, 4-15% sodium alginate, 2-8% succinic acid, and 1-5% dicalcium phosphate.

3. The microcapsule powder according to claim 1, characterized in that, The microcapsule powder is composed of the following components by mass fraction: 55-60% OSA starch, 15-20% Antarctic krill oil, 10-15% sodium alginate, 5-8% succinic acid, and 2-4% dicalcium phosphate.

4. The microcapsule powder according to any one of claims 1 to 3, characterized in that, The microcapsule powder contains 0 mg / kg of trimethylamine, n-hexanal, and 3-methylhexanal, less than 0.01 mg / kg of (E,E)-2,4-heptadienal, less than 0.5 mg / kg of (E,E)3,5-octadien-2-one, and less than 0.2 mg / kg of 2-n-propylfuran.

5. A method for preparing the microcapsule powder according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: Step 1: Disperse OSA starch in water, gelatinize, and stir to obtain a gelatinized product; Step 2: Add Antarctic krill oil to the gelatinized material from Step 1, and then cut to obtain a crude emulsion of Antarctic krill oil. Step 3: Homogenize the crude emulsion obtained in Step 2 using a homogenizer to obtain a fine emulsion of Antarctic krill oil. Step 4: Dissolve succinic acid in water, adjust the pH to alkaline using ammonium hydroxide, then add sodium alginate and stir until fully dissolved. Add calcium hydrogen phosphate to the dissolved sodium alginate solution to obtain a sodium alginate mixed solution. Step 5: Mix the Antarctic krill oil emulsion obtained in Step 3 with the sodium alginate mixed solution obtained in Step 4 to obtain the spray drying feed solution; Step 6: Spray dry the feed liquid obtained in Step 5 to obtain Antarctic krill oil microcapsule powder.

6. The preparation method according to claim 5, characterized in that, In step 1, the gelatinization conditions are heating at 85-95°C for 30-35 minutes and stirring for 12-15 hours.

7. The preparation method according to claim 5, characterized in that, In step 2, the shearing speed is 9000~10000 rpm, and the time is 2~3 min.

8. The preparation method according to claim 5, characterized in that, In step 3, the homogenization pressure is 40-50 MPa, the number of times is 3-5, and the temperature is 15-18°C.

9. The preparation method according to claim 5, characterized in that, In step 4, ammonium hydroxide is used to adjust the pH of succinic acid to 8-8.

5.

10. The preparation method according to claim 5, characterized in that, In step 6, the inlet air temperature for spray drying is 120~140°C, and the feed rate is 400~600 mL / h.

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