Method for preparing high-quality krill meal from euphausia superba shelling byproducts

Abstract

The invention discloses a method for preparing high-quality euphausia superba powder by using euphausia superba shelling byproducts, which comprises the following steps: shelling euphausia superba cooked at low temperature, taking the euphausia superba shell byproducts, performing low-temperature vacuum drying until the moisture is below 15%, and crushing and sieving the obtained euphausia superba crisp substances to obtain the high-quality euphausia superba powder. According to the method disclosed by the invention, the euphausia superba unshelling byproducts are turned into wealth from waste, the high-quality euphausia superba meal which is superior to the traditional whole euphausia superba meal in key indexes is successfully prepared through precise process control, and a stable and excellent special raw material basis is provided for the high-end euphausia superba oil industry. According to experimental screening, the krill meal with the high astaxanthin content is obtained at the cooking temperature of 70 DEG C, the cooking time of 25 min and the vacuum drying temperature of 60 DEG C, the astaxanthin content reaches up to 4670.82 mu g / g oil and is far higher than that of krill meal prepared in the prior art, and breakthrough progress is achieved.

Description

Technical Field

[0001] This invention relates to the field of Antarctic krill processing technology, specifically to a method for preparing high-quality krill powder using Antarctic krill molting byproducts. Background Technology

[0002] Antarctic krill ( Euphausia superba As a key species in the Antarctic ecosystem, krill oil is hailed as "sea gold" due to its enormous biomass and unique nutritional composition. Its lipids are primarily phospholipid-type ω-3 polyunsaturated fatty acids, among which the bound eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exhibit superior bioavailability and physiological activity. Furthermore, the astaxanthin and vitamins naturally present in krill oil demonstrate significant effects in regulating blood lipids, antioxidation, and neuroprotection, making it a key focus of marine functional lipid research and development.

[0003] Antarctic krill are rich in endogenous enzymes such as lipase and protease, which are extremely active. To prevent rapid autolysis and spoilage and quality deterioration caused by enzymatic reactions after harvesting, they need to be immediately frozen or heat-processed to inactivate enzyme activity. Currently, the development and utilization of Antarctic krill heavily relies on onboard processing systems, forming a dual-track product flow mainly consisting of edible-grade "frozen deshelled krill meat" and raw material-grade "Antarctic krill powder." Among these, krill powder is not only a core link in realizing the high-value utilization of the entire krill and improving processing economics, but also a key intermediate connecting marine fishing and land-based deep processing. Its quality—especially oil content, oxidative stability, and retention rate of active ingredients—directly determines the extraction efficiency and overall quality of the final krill oil product.

[0004] However, current krill processing on board ships still faces a dual challenge: on the one hand, a large amount of shrimp shell byproducts generated during the krill meat production process lack targeted on-site processing technology, resulting in low-value disposal and low resource utilization; on the other hand, traditional shrimp powder processing, using whole shrimp as raw material, mainly involves processes such as steaming, drying, crushing, sieving, and packaging. Among these, steaming and drying are key steps, their core function being to inactivate endogenous enzymes through heat treatment to ensure subsequent stability, but side effects also arise: heat processing can trigger Maillard reactions and lipid oxidation, producing a cooked shrimp flavor and degrading heat-sensitive astaxanthin, which directly and negatively impacts the flavor, nutritional components, and color of Antarctic krill oil. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a method for preparing high-quality krill powder using byproducts of Antarctic krill molting. Using krill shells and other byproducts as raw materials, a combined low-temperature cooking and vacuum drying process is employed. This effectively inactivates endogenous enzymes while inhibiting lipid oxidation, Maillard reactions, and astaxanthin thermal degradation, thereby simultaneously improving the product's flavor, color, and stability. This method overcomes the challenges of flavor distortion, component loss, and uneven quality found in existing technologies, providing high-quality raw material support for the extraction of high-quality krill oil.

[0006] To achieve the above objectives, the present invention provides a method for preparing high-quality Antarctic krill powder, comprising the following steps: S1. Steam the Antarctic krill, then drain and cool it. S2. The steamed Antarctic krill obtained in step S1 is deshelled to separate Antarctic krill meat and by-products such as Antarctic krill shells. S3. Take the krill shells and other by-products from step S2 and dry them to obtain krill crisps. S4. Take the krill crisps from step S3, crush and sieve them to obtain Antarctic krill powder.

[0007] In one embodiment of the present invention, in step S1, the cooking temperature is 65~75 ℃ and the cooking time is 5~30 min; preferably, the cooking temperature and time are 75 ℃ and 20 min or 70 ℃ and 25 min.

[0008] In one embodiment of the present invention, in step S2, the dehulling process is carried out by centrifugal dehulling.

[0009] In one embodiment of the present invention, in step S2, the by-products such as krill shells include krill cephalothorax, krill caudal appendages, and krill shells other than cephalothorax and caudal appendages, such as abdominal shells.

[0010] In one embodiment of the present invention, in step S3, the drying is vacuum low-temperature drying, with a drying temperature of -20~65 ℃ and a vacuum degree of 10~10200 Pa, and the moisture content of the dried Antarctic krill should be below 15%; preferably, the drying temperature is 50~65 ℃ and the vacuum degree is 9800~10200 Pa.

[0011] In one embodiment of the present invention, in step S4, the pulverized Antarctic krill powder is sieved through a 400-600 mesh sieve.

[0012] The present invention also provides a high-quality Antarctic krill powder prepared according to the above method.

[0013] The present invention also provides an application of the above-mentioned krill powder in krill oil extraction.

[0014] Beneficial effects 1. This invention turns krill molting byproducts into valuable resources. Through precise process control, it successfully produces high-quality krill powder that surpasses traditional whole krill powder in key indicators, providing a stable and excellent raw material base for the high-end krill oil industry.

[0015] 2. This invention uses Antarctic krill shell by-products as raw materials to prepare krill powder. On the one hand, using Antarctic krill shell by-products as raw materials improves the utilization rate of krill raw materials. On the other hand, the head and shell of the shrimp are richer in a higher proportion of oil and astaxanthin than the shrimp meat, which helps to extract Antarctic krill oil with higher astaxanthin and phospholipid content in the subsequent process.

[0016] 3. This invention innovatively adopts a composite process system of low-temperature cooking combined with vacuum low-temperature drying. By precisely controlling the intensity of heat action, it effectively blocks the Maillard reaction pathway and the generation of volatile flavor substances, thereby significantly inhibiting the formation of characteristic flavors of cooked shrimp and preserving the fresh and lively flavor of Antarctic krill to the greatest extent.

[0017] 4. The integrated low-temperature cooking and vacuum low-temperature drying process constructed in this invention can effectively slow down the degradation of astaxanthin, resulting in a brighter natural orange-red color for the krill powder product, significantly improving the overall visual quality and product performance. Furthermore, experiments have shown that while lower cooking and drying temperatures help obtain krill oil and krill powder with better color, and the influence of temperature and time on the color of krill oil is relatively small below 75℃, the synergistic effect of cooking temperature, time, and drying temperature has a significant impact on the astaxanthin content. Through experimental screening, this invention obtained krill powder with a high astaxanthin content at a cooking temperature of 70℃, a cooking time of 25 min, and a vacuum drying temperature of 60℃, reaching an astaxanthin content as high as 4670.82 μg / g oil, far exceeding that of krill powder prepared by existing technologies, achieving a breakthrough.

[0018] 5. This invention achieves effective and controllable inactivation of key endogenous enzymes such as lipase and protease through a low-temperature cooking process, inhibiting adverse reactions such as lipid hydrolysis and protein hydrolysis at the source. This comprehensively ensures the quality stability and nutrient retention of krill powder during storage, extending the product's shelf life. This invention represents a leapfrog upgrade of shrimp shell by-products from "wasteful and low-value" to "functional raw materials," providing a crucial technological supplement to the Antarctic krill onboard processing system and possessing significant industrial application value and economic benefits. Attached Figure Description

[0019] Figure 1This study investigated the effect of boiling Antarctic krill at different temperatures on the activities of its protease (A) and lipase (B). Uncooked, 65, 70, 75, 80, 85, 90, and 100 represent Antarctic krill samples boiled at 65, 70, 75, 80, 85, 90, and 100 °C for 10 min, respectively. Different letters in the figure indicate significant differences between samples. p<0.05。

[0020] Figure 2 This study investigated the effects of different boiling times at 75 °C on the activities of Antarctic krill protease (A) and lipase (B). Uncooked, 5, 10, 15, 20, 25, 30 min, and control represent uncooked, boiled at 75 °C for 5, 10, 15, 20, 25, 30 min, and boiled at 100 °C for 5 min, respectively. Different letters in the figure indicate statistically significant differences between samples. p <0.05。

[0021] Figure 3 The visual colors of different Antarctic krill powder samples are shown. SSL1, SSL2, SSL3, SSL4 and DBL1 represent Antarctic krill powder samples obtained under the conditions of Example 1, Example 2, Example 3, Example 4 and Comparative Example 1, respectively.

[0022] Figure 4 The redness values ​​(a*) of different Antarctic krill powder samples are shown. SSL1, SSL2, SSL3, SSL4, and DBL1 represent the Antarctic krill powder samples obtained under the conditions of Example 1, Example 2, Example 3, Example 4, and Comparative Example 1, respectively. Different letters labeled in the figure indicate that the differences between samples are significant. p<0.05。

[0023] Figure 5 The redness values ​​(a*) of different Antarctic krill oil samples are shown. SSL1, SSL2, SSL3, SSL4, and DBL1 represent Antarctic krill oil samples extracted from Antarctic krill powder samples in Examples 1, 2, 3, 4, and Comparative Example 1, respectively. Different letters labeled in the figure indicate that the differences between samples are significant. p<0.05 .

[0024] Figure 6 The figure shows the astaxanthin content (ASTA) of different Antarctic krill oil samples. SSL1, SSL2, SSL3, SSL4, and DBL1 represent Antarctic krill oil samples extracted from Antarctic krill powder samples from Examples 1, 2, 3, 4, and Comparative Example 1, respectively. Different letters labeled in the figure indicate significant differences between samples. p<0.05 .

[0025] Figure 7 Electronic nose radar images of different Antarctic krill powder samples are shown. SSL1, SSL2, SSL3, SSL4, and DBL1 represent Antarctic krill powder samples processed under the conditions of Example 1, Example 2, Example 3, Example 4, and Comparative Example 1, respectively. Different letters labeled the data in the figure indicate that the differences between samples are significant. p<0.05 . Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0027] Source of raw materials Antarctic krill was purchased from Liaoning Fisheries Group Co., Ltd. (Dalian, China) and stored in a -20°C cold storage facility protected from light. Casein was purchased from Beijing Aladdin Biochemical Technology Co., Ltd. (Beijing, China). Isopropanol, trichloroacetic acid, p-nitrophenyllauric acid, Folin-Ciocalteu reagent, Tris-HCl buffer, and sodium carbonate were purchased from Beijing Baoxidi Co., Ltd. (Beijing, China). Unless otherwise specified, all other raw materials were commercially available.

[0028] Testing process 1. Lipase activity detection Weigh 50 g of krill sample and add it to pre-chilled 0.1 M, pH 8.0 Tris-HCl buffer at a ratio of 2:1 (g / mL). Homogenize in a high-speed homogenizer and let stand at 0 °C for 4 h. Centrifuge the homogenate at 10000 r / min for 30 min at 0 °C. The supernatant is the crude enzyme solution. Mix 0.1 mL of solution A with 1.5 mL of solution B at 40 °C and preheat for 4 min. Add 2 mL of crude enzyme solution and mix well. React at 40 °C for 20 min. Add 2 mL of ethanol and mix thoroughly. Terminate the reaction by placing the mixture in an ice bath. Measure the absorbance at 410 nm using a microplate reader. The higher the absorbance value, the stronger the enzyme activity.

[0029] Solution A (substrate): 3.33 mg / mL of p-nitrophenyllauric acid in isopropanol solution Solution B (buffer): 0.1 M Tris-HCl buffer solution with pH 8.0 containing 0.4% gum arabic. 2. Protease activity assay Weigh 50 g of krill sample and add pre-chilled 0.1 M, pH 8.0 Tris-HCl buffer at a ratio of 2:1 (g / mL). Homogenize in a high-speed homogenizer and let stand at 0 °C for 4 h. Centrifuge the homogenate at 10000 r / min for 30 min at 0 °C. The supernatant is the crude enzyme solution. Add 1 mL of crude enzyme solution and 2 mL of preheated 1% casein solution to each tube, incubate in a 37 °C water bath for 20 min, remove and immediately add 2 mL of trichloroacetic acid, shake quickly, let stand to precipitate residual protein, centrifuge (10000 r / min) for 15 min, and transfer the supernatant to another test tube. Add 1 mL of supernatant, 5 mL of sodium carbonate solution, and 1 mL of Folin reagent to each tube, shake well, incubate in a water bath for 20 min, and then measure the absorbance at 660 nm. The higher the absorbance value, the stronger the enzyme activity.

[0030] 3. Color detection The color of Antarctic krill powder and Antarctic krill oil was determined using a colorimeter combined with a three-point test method. Color was calibrated using three values: L*, a*, and b*, where L* represents the lightness (+) and darkness (+) of the color. ) degree, a* represents the red (+) green (+) degree of the color. The value b* represents the yellow (+) or blue (+) value of the color. )value.

[0031] 4. Sensory evaluation Sensory evaluation of Antarctic krill oil was conducted by a panel of 10 reviewers (5 women and 5 men, aged 20-30 years). A 1 g oil sample was placed in a 20 mL brown headspace vial, with numbers randomly assigned to the vial. The intensity of the cooked krill odor properties was assessed using a scale of 0-10, where 1 = 0 = imperceptible, 2 = slightly perceptible, 4 = perceptible, 6 = fairly perceptible, 8 = strongly perceptible, and 10 = very strongly perceptible. Reviewers were given a 1-minute break between testing different samples.

[0032] Example 1 A method for preparing high-quality Antarctic krill powder includes the following steps: S1. Steam the Antarctic krill (75 ℃, 20 min), then drain and cool. S2. Peel the cooked Antarctic krill to separate the cephalothorax portion of the Antarctic krill. S3. Take the krill cephalothorax cooked in step S2 and dry it at 65 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0033] Example 2 The difference between Example 2 and Example 1 is that in step S3, the drying temperature is 60 °C.

[0034] A method for preparing high-quality Antarctic krill powder includes the following steps: S1. Steam the Antarctic krill (75 ℃, 20 min), then drain and cool. S2. Peel the cooked Antarctic krill to separate the cephalothorax portion of the Antarctic krill. S3. Take the krill cephalothorax cooked in step S2 and dry it at 60 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0035] Example 3 The difference between Example 3 and Example 1 is that in step S1, the cooking temperature is 70 ℃ and the cooking time is 25 min.

[0036] A method for preparing high-quality Antarctic krill powder includes the following steps: S1. Steam the Antarctic krill (70 ℃, 25 min), then drain and cool. S2. Peel the cooked Antarctic krill to separate the cephalothorax portion of the Antarctic krill. S3. Take the krill cephalothorax cooked in step S2 and dry it at 65 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0037] Example 4 The difference between Example 4 and Example 3 is that in step S3, the drying temperature is 60 °C.

[0038] A method for preparing high-quality Antarctic krill powder includes the following steps: S1. Steam the Antarctic krill (70 ℃, 25 min), then drain and cool. S2. Peel the cooked Antarctic krill to separate the cephalothorax portion of the Antarctic krill. S3. Take the krill cephalothorax cooked in step S2 and dry it at 60 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0039] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in step S1, the cooking method is high-temperature cooking; and in step S3, the drying method is hot air drying.

[0040] S1. Steam the Antarctic krill (100 ℃, 5 min), then drain and cool. S2. Peel the cooked Antarctic krill to separate the cephalothorax portion of the Antarctic krill. S3. Take the krill head and thorax steamed product from step S2 and dry it with hot air at 80 ℃ for 2.2 h, then dry it with hot air at 55 ℃ for 0.5 h until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in step S2, the obtained product is the abdominal shell of Antarctic krill.

[0042] S1. Steam the Antarctic krill (75 ℃, 20 min), then drain and cool. S2. Peel the cooked Antarctic krill to separate the abdominal shell of the Antarctic krill. S3. Take the krill abdominal shell cooked product from step S2 and dry it at 65 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0043] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that in step S2, the obtained product is Antarctic krill muscle.

[0044] S1. Steam the Antarctic krill (75 ℃, 20 min), then drain and cool. S2. Peel the cooked Antarctic krill and separate the muscle part of the Antarctic krill. S3. Take the krill muscle cooked in step S2 and dry it at 65 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0045] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that in step S2, the product obtained is the tail foot of Antarctic krill.

[0046] S1. Steam the Antarctic krill (75 ℃, 20 min), then drain and cool. S2. Peel the cooked Antarctic krill and separate the tail and foot parts of the Antarctic krill. S3. Take the krill tail and foot cooked product from step S2 and dry it at 65 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S4. Take the krill crisps from step S3, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0047] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that step S2 is omitted.

[0048] S1. Steam the whole Antarctic krill (75 ℃, 20 min), then drain to obtain the steamed whole krill product. S2. Take the whole krill cooked product from step S1 and dry it at 65 ℃ and a vacuum of 10000 Pa until the moisture content is below 15% to obtain krill crisps. S3. Take the krill crisps from step S2, crush them, and sieve them (600 mesh) to obtain Antarctic krill powder.

[0049] As shown in Table 1, the oil content of krill powder prepared from different parts of Antarctic krill varies significantly. Among them, the oil content of the cephalothorax (Example 1), abdominal shell (Comparative Example 2), caudal foot (Comparative Example 4), and whole krill (Comparative Example 5) is significantly higher than that of the muscle (Comparative Example 3), indicating that by-products such as Antarctic krill shells are suitable raw materials for preparing krill powder for oil extraction.

[0050] Using Antarctic krill as raw material, after boiling at different temperatures for 10 minutes, the activities of protease and lipase in Antarctic krill were significantly reduced, and the decrease continued with increasing temperature. Figure 1 The activity of proteases decreased more slowly after 75 °C, while lipases tended to stabilize after 70 °C. Figure 2 Further evidence shows that extending the boiling time at 75 ℃ can also effectively inhibit the activity of both enzymes. The activity of protease after 15 min and lipase after 20 min is basically the same as that of the group boiled at 100 ℃ for 5 min.

[0051] Regarding product quality, the krill powder prepared in Examples 1-4 ( Figure 3 , Figure 4 ) and its extracted krill oil ( Figure 5The redness (a* value) of the sample was significantly higher than that of the control sample 1, indicating that the method of this invention can better preserve astaxanthin and give the product a better color. Astaxanthin content detection ( Figure 6 This further confirms that the astaxanthin content in the products of the examples is significantly higher, with Example 4 reaching 4670.82 μg / g oil, which is much higher than the 766.80 μg / g oil of Comparative Example 1.

[0052] Flavor analysis results showed that the krill powder prepared in Examples 1-4 had good flavor in electronic nose detection ( Figure 7 The sensor response values ​​for volatile substances such as sulfur and nitrogen oxides were significantly lower than those of Comparative Example 1, indicating that its content of volatile odor substances was lower. Correspondingly, the krill oil extracted from it also showed a lighter cooked shrimp flavor in sensory evaluation (Table 2), and its overall flavor quality was better.

[0053] Table 1. Oil content of krill meal

[0054] Note: SSL1, DBL2, DBL3, DBL4, and DBL5 represent Antarctic krill oil samples extracted from Antarctic krill powder samples from Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5, respectively.

[0055] Table 2. Sensory Evaluation Table of Cooked Shrimp Flavor of Krill Oil

[0056] Note: SSL1, SSL2, SSL3, SSL4, and DBL1 represent Antarctic krill oil samples extracted from Antarctic krill powder samples from Examples 1, 2, 3, 4, and Comparative Example 1, respectively.

[0057] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing high quality Euphausia superba powder, characterized by, The method comprises the following steps: S1, cooking Euphausia superba, then draining and cooling; S2, shelling the cooked Euphausia superba obtained in step S1 to separate Euphausia superba meat and Euphausia superba shell by-products; S3, drying the Euphausia superba shell by-products obtained in step S2 to obtain Euphausia superba crisp; S4, crushing and sieving the Euphausia superba crisp obtained in step S3 to obtain Euphausia superba powder.

2. The production method according to claim 1, characterized by, In step S1, the cooking temperature is 65-75℃, and the cooking time is 5-30 min.

3. The preparation method according to claim 1, characterized in that, In step S2, the shelling treatment adopts a centrifugal shelling method.

4. The method of claim 1, wherein, In step S2, the Euphausia superba shell by-products include at least one of Euphausia superba head and thorax, Euphausia superba tail and foot, and Euphausia superba abdominal shell.

5. The production method according to claim 1, characterized by, In step S3, the drying is vacuum low-temperature drying, the drying temperature is-20-65℃, the vacuum degree is 10-10200 Pa, and the moisture content of the dried Euphausia superba is below 15%.

6. The production method according to claim 1, characterized by, In step S1, the cooking temperature is 70℃, and the cooking time is 25 min; in step S3, the drying temperature is 60-65℃, and the vacuum degree is 9800-10200 Pa.

7. The preparation method according to claim 1, characterized in that, In step S4, the crushed Euphausia superba powder is sieved through a 400-600 mesh sieve.

8. High-quality Euphausia superba powder prepared by the preparation method in any one of claims 1-7.

9. Application of the high-quality Euphausia superba powder in claim 8 in Euphausia superba oil extraction.

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