Characterisation of a casein-/whey protein concentrate-Antarctic krill oil emulsion system and improvement of its storage stability.

AIMS: To develop Antarctic krill oil emulsions with casein and whey protein concentrate (WPC) and study their physicochemical properties and storage stability. METHODS: Emulsions were prepared by homogenisation and ultrasonication. The properties of the emulsions were investigated via ultraviolet ray spectroscopy, dynamic light scattering, confocal laser scanning microscope, sodium dodecyl sulphate-polyacrylamide gel electrophoresis, Fourier transform infra-red spectrometer, and fluorescence spectrum. Shelf life was predicted by the Arrhenius model. RESULTS: Casein- and WPC-krill oil emulsions were well formed; the mean particle diameters were less than 128.19 ± 0.64 nm and 158 ± 1.56 nm, the polymer dispersity indices were less than 0.26 ± 0.01 and 0.27 ± 0.01, and the zeta potential were around -46.88 ± 5.02 mV and -33.51 ± 2.68 mV, respectively. Shelf life was predicted to be 32.67 ± 1.55 days and 29.62 ± 0.65 days (40 °C), 27.69 ± 1.15 days and 23.58 ± 0.14 days (50 °C), 24.02 ± 0.15 days and 20.1 ± 0.08 days (60 °C). CONCLUSION: The prepared krill oil emulsions have great potential to become a new krill oil supplement.

Krill oil supplementation for knee pain: a systematic review and meta-analysis with trial sequential analysis of randomized controlled trials.

INTRODUCTION: Knee pain is a major cause of disability worldwide, particularly among the elderly. Current treatments, including nonsteroidal anti-inflammatory drugs and analgesics, often lead to adverse effects. Krill oil is being explored as a potential alternative, however its efficacy in managing knee symptoms remains unclear. METHODS: MEDLINE, Embase, and Cochrane databases were searched until May 2024 for studies comparing krill oil and placebo in knee pain patients. Endpoints included knee pain, stiffness, physical function, and lipid profiles (HDL-C, LDL-C, triglycerides, and total cholesterol). A restricted maximum likelihood random-effects model with standardized mean differences (SMD) and 95% confidence intervals (CI) was used. A trial sequential analysis was conducted to evaluate further research implications. RESULTS: We included five trials with 700 patients using krill oil for knee pain. Results showed no significant difference between krill oil and placebo for knee pain, knee stiffness, and lipid profiles. However, krill oil demonstrated a significant small effect in improving knee physical function (SMD -0.24, 95% CI [-0.41; -0.08], I2 = 0%).Trial sequential analysis provided certainty that krill oil enhances knee physical function compared to placebo and indicated no improvement in knee pain, but the findings for knee stiffness need to be confirmed by further research. CONCLUSION: This study found that krill oil supplementation did not significantly improve knee pain, stiffness, or lipid profile, although it may help knee physical function. Based on these findings, krill oil supplementation is not yet justified for knee pain.

Advances in encapsulation systems of Antarctic krill oil: From extraction to encapsulation, and future direction.

Antarctic krill oil (AKO) is highly sought after by consumers and the food industry due to its richness in a variety of nutrients and physiological activities. However, current extraction methods are not sufficient to better extract AKO and its nutrients, and AKO is susceptible to lipid oxidation during processing and storage, leading to nutrient loss and the formation of off-flavors and toxic compounds. The development of various extraction methods and encapsulation systems for AKO to improve oil yield, nutritional value, antioxidant capacity, and bioavailability has become a research hotspot. This review summarizes the research progress of AKO from extraction to encapsulation system construction. The AKO extraction mechanism, technical parameters, oil yield and composition of solvent extraction, aqueous enzymatic extraction, supercritical/subcritical extraction, and three-liquid-phase salting-out extraction system are described in detail. The principles, choice of emulsifier/wall materials, preparation methods, advantages and disadvantages of four common encapsulation systems for AKO, namely micro/nanoemulsions, microcapsules, liposomes and nanostructured lipid carriers, are summarized. These four encapsulation systems are characterized by high encapsulation efficiency, low production cost, high bioavailability and high antioxidant capacity. Depending on the unique advantages and conditions of different encapsulation methods, as well as consumer demand for health and nutrition, different products can be developed. However, existing AKO encapsulation systems lack relevant studies on digestive absorption and targeted release, and the single product category of commercially available products limits consumer choice. In conjunction with clinical studies of AKO encapsulation systems, the development of encapsulation systems for special populations should be a future research direction.

Does krill oil enhancing the new bone formation in orthopedically expanded median palatal suture in rat model? A micro-CT and immunohistochemical analysis.

BACKGROUND: The purpose of this study was to assess the effects of systemically given krill oil (KO) on the development of new bone formation in the sutura palatina media following rapid maxillary expansion (RME). METHODS: 28 4-5 week-old male Wistar albino rats were randomly divided into 4 groups: Control (C), Only Expansion (OE) (no supplement but undergoing expansion and retention), KE (supplemented during both the expansion and retention phases), Krill Oil Nursery Group (KN) (supplemented during the 40-day nursery phase as well as during the expansion and retention phases). A 5-day RME was followed by a 12-day retention period. All rats were euthanized simultaneously. Micro-computerized tomography (Micro-CT), hemotoxylen-eosin (H&E) staining, and immunohistochemical analysis were conducted. Kruskal-Wallis and Dunn tests with Bonferonni corrrection were applied (p < 0.05). RESULTS: Expansion and KO supplementation did not cause a statistically significant change in bone mineral density (BMD), bone volume fraction (BV/TV), spesific bone surface (BS/BV) and trabecular thickness (Tb.Th). While the expansion prosedure increased the trabecular seperation (Tb.Sp), KO supplemantation mitigated this effect. The KE group exhibited a statistically significantly increase in trabecular number (Tb.N) compared to the OE group. Although receptor activator of nuclear factor-kappa-Β ligand (RANKL)/osteoprotegerin (OPG) ratios did not show significant differences between groups, the KE and OE groups demonstrated the lowest and highest value, respectively. KE showed a reduced amount of tartrate-resistant acid phosphatase (TRAP) compared to the OE. CONCLUSION: KO positively affected the architecture of the new bone formed in the mid-palatal suture. In this rat model of RME, results support the idea that administering of KO during the expansion period or beginning before the RME procedure may reduce relapse and enhance bone formation within the mid-palatal suture.

Impact of Antarctic krill oil supplementation on skeletal muscle injury recovery after resistance exercise.

BACKGROUND: Antarctic krill oil (KO) is a natural source of n-3 polyunsaturated fatty acids (n-3 PUFAs), and is rich in phospholipids, Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA), astaxanthin, flavonoids, vitamins, trace elements, and other bioactive substances. KO has been confirmed to have anti-inflammatory and immunomodulatory effects. n-3 PUFAs also have been purported to improve the recovery of muscular performance. Moreover, the phospholipids present in KO can enhance n-3 PUFA bioavailability because of its higher absorption rate in plasma compared to fish oil. Astaxanthin, found in Antarctic KO, is a red carotenoid and powerful antioxidant that inhibits oxidative stress after intense exercise. Hence, we examined the effect of KO supplementation on the recovery of exercise by measuring muscular performance, oxidant/antioxidant and anti-inflammatory activity, and the markers of muscle damage following a rigorous bout of resistance exercise. METHODS: 30 college-aged resistance-trained males (20.4 ± 0.92 years, 74.09 ± 7.23 kg, 180.13 ± 4.72 cm) were randomly supplemented with 3 g/d KO or placebo (PL) for 3 days and continued to consume after resistance exercise for 3 days until the experiment finished. Before supplementation, pre-exercise performance assessments of knee isokinetic strength, 20 m sprint, hexagon test, and blood serum creatine kinase (CK), lactate dehydrogenase (LDH), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-2 (IL-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were completed. Then after 3 days of supplementation, participants completed a bout of muscle-damaging exercise, and subsequently, they performed and repeated the exercise performance assessments and blood-related indicators tests immediately (0 h), as well as at 6, 24, 48, and 72 h post-muscle-damaging exercise. RESULTS: Compared to the PL group, the serum CK of KO group was significantly lower at 24 h and 48 h post-exercise; the hexagon test time of the KO group was significantly lower than that of the PL group at 6 h and 24 h post-exercise; the KO group's isokinetic muscle strength showed different degrees of recovery than that of the PL group at 24 h and 48 h, and even over-recovery at 72 h post-exercise; the SOD level of the KO group was significantly higher than that of the PL group at 0, 6, and 24 h after exercise; the T-AOC level of the KO group was significantly higher than that of the PL group at 0, 6, and 72 h after exercise; the MDA level of the KO group was significantly lower than that of the PL group at 6 h; and there was no significant difference in serum IL-2, IL-6, and TNF-α between the two groups. CONCLUSION: Our results demonstrated that 3 g/d KO supplementation and continued supplementation after exercise can alleviate exercise-induced muscle damage (EIMD) and promote post-exercise recovery.

Krill Oil's Protective Benefits against Ultraviolet B-Induced Skin Photoaging in Hairless Mice and In Vitro Experiments.

Krill oil (KO) shows promise as a natural marine-derived ingredient for improving skin health. This study investigated its antioxidant, anti-inflammatory, anti-wrinkle, and moisturizing effects on skin cells and UVB-induced skin photoaging in hairless mice. In vitro assays on HDF, HaCaT, and B16/F10 cells, as well as in vivo experiments on 60 hairless mice were conducted. A cell viability assay, diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity test, elastase inhibition assay, procollagen content test, MMP-1 inhibition test, and hyaluronan production assay were used to experiment on in vitro cell models. Mice received oral KO administration (100, 200, or 400 mg/kg) once a day for 15 weeks and UVB radiation three times a week. L-Ascorbic acid (L-AA) was orally administered at 100 mg/kg once daily for 15 weeks, starting from the initial ultraviolet B (UVB) exposures. L-AA administration followed each UVB session (0.18 J/cm2) after one hour. In vitro, KO significantly countered UVB-induced oxidative stress, reduced wrinkles, and prevented skin water loss by enhancing collagen and hyaluronic synthesis. In vivo, all KO dosages showed dose-dependent inhibition of oxidative stress-induced inflammatory photoaging-related skin changes. Skin mRNA expressions for hyaluronan synthesis and collagen synthesis genes also increased dose-dependently after KO treatment. Histopathological analysis confirmed that krill oil (KO) ameliorated the damage caused by UVB-irradiated skin tissues. The results imply that KO could potentially act as a positive measure in diminishing UVB-triggered skin photoaging and address various skin issues like wrinkles and moisturization when taken as a dietary supplement.

Two-Step Enzymolysis of Antarctic Krill for Simultaneous Preparation of Value-Added Oil and Enzymolysate.

Antarctic krill is a crucial marine resource containing plenty of high-valued nutrients. However, krill oil as a single product has been developed by the current solvent extraction with high cost. From the perspective of comprehensive utilization of Antarctic krill, this study proposed a novel two-step enzymolysis-assisted extraction in attempt to produce value-added oil and enzymolysate simultaneously. After two-step chitinase/protease hydrolysis, the lipid yield increased from 2.09% to 4.18%, reaching 112% of Soxhlet extraction. The method greatly improved the yields of main components while reducing the impurity content without further refining. After optimization, the oil contained 246.05 mg/g of phospholipid, 80.96 mg/g of free eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and 0.82 mg/g of astaxanthin. The by-product enzymolysate was abundant in water-soluble proteins (34.35 mg/g), oligopeptides (13.92 mg/g), amino acids (34.24 mg/g), and carbohydrates (5.79 mg/g), which was a good source of functional nutrients. In addition, both oil and enzymolysate showed high antioxidant capacity. This novel method could simultaneously provide oil and enzymolysate amounting for 58.61% of dried krill.

Antarctic Krill Oil from Euphausia superba Ameliorates Carrageenan-Induced Thrombosis in a Mouse Model.

FJH-KO obtained from Antarctic krill, especially Euphausia superba, has been reported to contain high amounts of omega-3 polyunsaturated fatty acids (n-3 PUFA) and to exhibit anticancer and anti-inflammatory properties. However, its antithrombotic effects have not yet been reported. This study aimed to investigate the antithrombotic effects of FJH-KO in carrageenan-induced thrombosis mouse models and human endothelial cells. Thrombosis was induced by carrageenan injection, whereas the mice received FJH-KO pretreatment. FJH-KO attenuated carrageenan-induced thrombus formation in mouse tissue vessels and prolonged tail bleeding. The inhibitory effect of FJH-KO was associated with decreased plasma levels of thromboxane B2, P-selectin, endothelin-1, ß-thromboglobulin, platelet factor 4, serotonin, TNF-α, IL-1ß, and IL-6. Meanwhile, FJH-KO induced plasma levels of prostacyclin I2 and plasminogen. In vitro, FJH-KO decreased the adhesion of THP-1 monocytes to human endothelial cells stimulated by TNF-α via eNOS activation and NO production. Furthermore, FJH-KO inhibited the expression of TNF-α-induced adhesion molecules such as ICAM-1 and VCAM-1 by suppressing the NF-κB signaling pathway. Taken together, our study demonstrates that FJH-KO protects against carrageenan-induced thrombosis by regulating endothelial cell activation and has potential as an antithrombotic agent.

Dietary soybean lecithin promoted growth performance and feeding in juvenile Chinese perch (Siniperca chuatsi) could be by optimizing glucolipid metabolism.

To explore the potential benefits of dietary phospholipids (PLs) in fish glucose metabolism and to promote feed culture of Chinese perch (Siniperca chuatsi), we set up six diets to feed Chinese perch (initial mean body weight 37.01 ± 0.20 g) for 86 days, including: Control diet (CT), 1% (SL1), 2% (SL2), 3% (SL3), 4% (SL4) soybean lecithin (SL) and 2% (KO2) krill oil (KO) supplemental diets (in triplicate, 20 fish each). Our study found that the SL2 significantly improved the weight gain rate and special growth rate, but the KO2 did not. In addition, the SL2 diet significantly improved feed intake, which is consistent with the mRNA levels of appetite-related genes (npy, agrp, leptin A). Additionally, in the CT and SL-added groups, leptin A expression levels were nearly synchronized with serum glucose levels. Besides, the SL2 significantly upregulated expression levels of glut2, gk, cs, fas and downregulated g6pase in the liver, suggesting that it may enhance glucose uptake, aerobic oxidation, and conversion to fatty acids. The SL2 also maintained the hepatic crude lipid content unchanged compared to the CT, possibly by significantly down-regulating the mRNA level of hepatic lipase gene (hl), and by elevating serum low-density lipoprotein (LDL) level and intraperitoneal fat ratio in significance. Moreover, the serum high-density lipoprotein levels were significantly increased by PL supplementation, and the SL2 further significantly increased serum total cholesterol and LDL levels, suggesting that dietary PLs promote lipid absorption and transport. Furthermore, dietary SL at 1% level could enhance non-specific immune capacity, with serum total protein level being markedly higher than that in the CT group. In conclusion, it is speculated that the promotion of glucose utilization and appetite by 2% dietary SL could be linked. We suggest a 1.91% supplementation of SL in the diet for the best growth performance in juvenile Chinese perch.

Omega-3 phospholipids and obesity-associated NAFLD: Potential mechanisms and therapeutic perspectives.

Prevalence of non-alcoholic fatty liver disease (NAFLD) increases in line with obesity and type 2 diabetes, and there is no approved drug therapy. Polyunsaturated fatty acids of n-3 series (omega-3) are known for their hypolipidaemic and anti-inflammatory effects. Existing clinical trials suggest varying effectiveness of triacylglycerol- or ethyl ester-bound omega-3 in the treatment of NAFLD, without affecting advanced stages such as non-alcoholic steatohepatitis. Preclinical studies suggest that the lipid class used to supplement omega-3 may determine the extent and nature of their effects on metabolism. Phospholipids of marine origin represent an alternative source of omega-3. The aim of this review is to summarise the available evidence on the use of omega-3 phospholipids, primarily in obesity-related NAFLD, and to outline perspectives of their use in the prevention/treatment of NAFLD. A PubMed literature search was conducted in May 2021. In total, 1088 articles were identified, but based on selection criteria, 38 original papers were included in the review. Selected articles describing the potential mechanisms of action of omega-3 phospholipids have also been included. Preclinical evidence clearly indicates that omega-3 phospholipids have strong antisteatotic effects in the liver, which are stronger compared to omega-3 administered as triacylglycerols. Multiple mechanisms are likely involved in the overall antisteatotic effects, involving not only the liver but also adipose tissue and the gut. Robust preclinical evidence for strong antisteatotic effects of omega-3 phospholipids in the liver should be confirmed in clinical trials. Further research is needed on the possible effects of omega-3 phospholipids on advanced NAFLD.

Krill Oil Inhibits Cholesterol Synthesis and Stimulated Cholesterol Excretion in Hypercholesterolemic Rats.

The present study aimed to investigate the antihypercholesterolemic effects of krill oil supplementation in high-cholesterol diet-induced hypercholesterolemic rats, and the mechanisms underlying these effects. Rats were divided into five groups: normal control, control (high-cholesterol diet), krill oil 100 mg/kg b.w. (high-cholesterol diet with Krill oil 100 mg/kg b.w.), and krill oil 200 mg/kg b.w. (high-cholesterol diet with Krill oil 200 mg/kg b.w.). After 12 weeks, the rats were sacrificed to observe the effects of krill oil on cholesterol synthesis and excretion. We found that krill oil supplementation suppressed total triglycerides, total cholesterol, and LDL-cholesterol levels, as well as HMG-CoA reductase activity. It stimulated AMPK phosphorylation, LDL receptor and ACAT2 expression in the liver, and the fecal output of cholesterol. Furthermore, it decreased the levels of P-selectin, sVCAM-1, and NO, as well as aortic wall thickness, demonstrating its role in the prevention of atherosclerosis. Thus, we suggest that krill oil supplementation can reduce LDL-cholesterol levels in the blood during hypercholesterolemia by stimulating the uptake of LDL-cholesterol into tissue and cholesterol excretion, as well as inhibition of cholesterol synthesis.

Antioxidative Effect of Chlorella Pyrenoidosa Protein Hydrolysates and Their Application in Krill Oil-in-Water Emulsions.

Chlorella pyrenoidosa is an excellent source of protein, and in this research, we assessed the antioxidant and emulsifying effects of Chlorella protein hydrolysate (CPH) using neutral proteases and alkaline proteases, as well as the properties of CPH-derived krill oil-in-water (O/W) emulsions. The CPHs exhibited the ability to scavenge several kinds of free radicals, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), O2-, hydroxyl, and ABTS. Additionally, the CPHs (5 mg/mL) scavenged approximately 100% of the DPPH and ABTS. The CPHs showed similar emulsifying activities to Tween 20 and excellent foaming activities (max FS 74%), which helped to stabilize the krill oil-in-water emulsion. Less than 10 mg/mL CPHs was able to form fresh krill oil-in-water emulsions; moreover, the CPHs (5 mg/mL) in a krill O/W emulsion were homogenous, opaque, and stable for at least 30 days. Based on their inhibitory effects on the peroxide value (POV) and thiobarbituric acid reactive substances (TRABS), the CPHs were found to be able to inhibit lipid oxidation in both emulsifying systems and krill O/W emulsions. Thus, the CPHs could improve superoxide dismutase (SOD) activities by 5- or 10-fold and decrease the high reactive oxygen species (ROS) level caused by the addition of H2O2 in vitro. In conclusion, health-promoting CPHs could be applied in krill oil-in-water emulsions as both emulsifiers and antioxidants, which could help to improve the oxidative and physical stability of emulsions.

Diet restriction alone improves glucose tolerance and insulin sensitivity than its coadministration with krill or fish oil in a rabbit model of castration-induced obesity.

This study investigated the effect of 50% diet restriction and its coadministration with krill oil (KO) or fish oil (FO) on glucose tolerance and insulin sensitivity in a rabbit model of obesity. Castrated male rabbits were 50% restricted fed and supplemented with KO or FO (600 mg omega-3 polyunsaturated fatty acids/daily) for 2 months. Simultaneously, two control groups were used: castrated, full-diet-fed and castrated, 50% restricted fed rabbits without additives restricted group (RG). The energy-restricted diet decreased final body weight in castrated male rabbits and improved most insulin sensitivity and ß-cell function indexes. Combining the same diet and KO or FO, further reduced fasting blood glucose levels. However, this feed regime significantly accelerated insulin secretion and reduced gene expression of insulin receptor substrate-1, pyruvate kinase and 3-hydroxy-3-methylglutaryl-CoA synthase 2. This was manifested by reduced dynamic insulin sensitivity, assessment homoeostasis-ß-cell function indices and increased glucose elimination rate to levels comparable to or above the obese animals. Aspartate and alanine aminotransferases enzyme activities were raised more than those in the obese group. Surprisingly, KO and FO administration downregulated acetyl-coenzyme A oxidase and carnitine palmitoyltransferase 2 messenger RNA gene expression compared to the RG. In conclusion, we can assume that a better effect on insulin sensitivity and glucose tolerance was observed in the diet restriction alone than in the coadministration of KO or FO when animals are exposed to highly obesity predisposing factors. These effects could be at least in part ascribed to the modified gene expression levels of some critical enzymes and factors involved in liver glucose metabolism and ß-oxidation.

Administration of krill oil extends lifespan of fish Nothobranchius guentheri via enhancement of antioxidant system and suppression of NF-κB pathway.

Krill oil (KO) extracted from Antarctic krill (Euphausia superba) mainly comprises phospholipids and triglycerides. KO has been shown to prolong the median lifespan of the nematode Caenorhabditis elegans, but to shorten the lifespan of long-lived F1 mice; therefore, it remains controversial over the life-extending property of KO. In this study, we clearly demonstrated that dietary intake of KO extended both the mean and maximum lifespans of aged male Nothobranchius guentheri (p < 0.05), reduced the accumulation of lipofuscin (LF) (p < 0.05) in the gills and senescence-associated ß-galactosidase (SA-ß-Gal) (p < 0.05) in the caudal fins, and lowered the levels of protein oxidation (p < 0.05), lipid peroxidation (p < 0.01), and reactive oxygen species (ROS) (p < 0.01) in the muscles and livers, indicating that KO possesses rejuvenation and anti-aging activity. We also showed that KO enhanced the activities of antioxidant enzymes catalase (CAT) (p < 0.05), superoxide dismutase (SOD) (p < 0.05), and glutathione peroxidase (GPX) (p < 0.05) in aged male N. guentheri. In addition, KO administration effectively reversed histological lesions including inflammatory cell infiltration and structural collapse in the muscles and livers of aged N. guentheri and suppressed the nuclear factor kappa-B (NF-κB) signaling pathway (p < 0.05), a master regulator of inflammation. Altogether, our study indicates that KO has anti-aging and rejuvenation property. It also suggests that KO exerts its anti-aging and rejuvenation effects via enhancement of the antioxidant system and suppression of the NF-κB signaling pathway.

Characterization of Molecular Species and Anti-Inflammatory Activity of Purified Phospholipids from Antarctic Krill Oil.

The phospholipids (PLs) from Antarctic krill oil were purified (>97.2%) using adsorption column chromatography. Forty-nine PL molecular species were characterized by ultrahigh-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). Most of molecular species contained eicosapentaenoic acid (EPA, 20:5), docosahexaenoic acid (DHA, 22:6), docosapentaenoic acid (DPA, 22:5), and arachidonic acid (AA, 20:4). Notably, a special species PC (20:5/22:6) (1298.17 nmol/g) and many ether PLs were detected. The Antarctic krill PL liposome (IC50 = 0.108 mg/mL) showed better anti-inflammatory activity than crude Antarctic krill oil (IC50 = 0.446 mg/mL). It could block NF-κB signaling pathway via suppression of IκB-α degradation and p65 activation and dose-dependently reduce the cellular content of inflammatory mediators including nitric oxide (NO), reactive oxygen species (ROS), and inflammatory cytokines in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. In addition, it can suppress carrageenan-induced mouse paw swelling. Results from the present study could provide a reference for better evaluation of nutritional and medicinal values of Antarctic krill oil.

Advances in Technologies for Highly Active Omega-3 Fatty Acids from Krill Oil: Clinical Applications.

Euphausia superba, commonly known as krill, is a small marine crustacean from the Antarctic Ocean that plays an important role in the marine ecosystem, serving as feed for most fish. It is a known source of highly bioavailable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid). In preclinical studies, krill oil showed metabolic, anti-inflammatory, neuroprotective and chemo preventive effects, while in clinical trials it showed significant metabolic, vascular and ergogenic actions. Solvent extraction is the most conventional method to obtain krill oil. However, different solvents must be used to extract all lipids from krill because of the diversity of the polarities of the lipid compounds in the biomass. This review aims to provide an overview of the chemical composition, bioavailability and bioaccessibility of krill oil, as well as the mechanisms of action, classic and non-conventional extraction techniques, health benefits and current applications of this marine crustacean.

Characterization of Astaxanthin Nanoemulsions Produced by Intense Fluid Shear through a Self-Throttling Nanometer Range Annular Orifice Valve-Based High-Pressure Homogenizer.

Stable, oil-in-water nanoemulsions containing astaxanthin (AsX) were produced by intense fluid shear forces resulting from pumping a coarse reagent emulsion through a self-throttling annular gap valve at 300 MPa. Compared to crude emulsions prepared by conventional homogenization, a size reduction of over two orders of magnitude was observed for AsX-encapsulated oil droplets following just one pass through the annular valve. In krill oil formulations, the mean hydrodynamic diameter of lipid particles was reduced to 60 nm after only two passes through the valve and reached a minimal size of 24 nm after eight passes. Repeated processing of samples through the valve progressively decreased lipid particle size, with an inflection in the rate of particle size reduction generally observed after 2-4 passes. Krill- and argan oil-based nanoemulsions were produced using an Ultra Shear Technology™ (UST™) approach and characterized in terms of their small particle size, low polydispersity, and stability.

Preparation and Characterization of Microemulsions Based on Antarctic Krill Oil.

Antarctic krill oil is high in nutritional value and has biological functions like anti-inflammation and hypolipidemic effects. But it has and unpleasant smell, and unsaturated fatty acids are prone to oxidative deterioration. Its high viscosity and low solubility in water make it difficult for processing. Microemulsion can be a new promising route for development of krill oil product. We determined a formula of krill oil-in-water microemulsion with krill oil: isopropyl myristate = 1:3 as oil phase, Tween 80:Span 80 = 8:2 as surfactant, ethanol as co-surfactant and the mass ratio of surfactant to co-surfactant of 3:1. After screening the formula, we researched several characteristics of the prepared oil-in-water microemulsion, including electrical conductivity, microstructure by transmission electron microscope and cryogenic transmission electron microscope, droplet size analysis, rheological properties, thermal behavior by differential scanning calorimeter and stability against pH, salinity, and storage time.

A Green Enzymatic Extraction Optimization and Oxidative Stability of Krill Oil from Euphausia Superba.

Krill oil enriched with polyunsaturated fatty acids is in the form of phospholipid. However, its application as a dietary supplement is limited, because of its rapid deterioration. Thus, this study aims to investigate the oxidative stability of krill oil extracted from Euphausia superba. Under optimal conditions (enzyme concentration 0.16%, enzymolysis time 2.9 h, and enzymolysis temperature of 45 °C) designed by response surface methodology, the extraction yield of krill oil is 86.02%. Five assays, including peroxide value (POV), thiobarbituric acid-reactive substances (TBARS), pH value, and turbidity were used to determine the oxidative stability of krill oil nanoliposomes during storage. Carboxymethyl chitosan (CMCS) nanoliposomes showed a significant reduction in POV and TBARS values, a prevention of pH value decrease and turbidity increase. This study indicated that CMCS nanoliposome can effectively improve the oxidative stability of krill oil during storage. Furthermore, the release profile in vitro illustrated that the controlled release of krill oil carried out by CMCS nanoliposomes is feasible.

Krill Oil Attenuates Cognitive Impairment by the Regulation of Oxidative Stress and Neuronal Apoptosis in an Amyloid ß-Induced Alzheimer's Disease Mouse Model.

In the present study, we investigated the cognitive improvement effects and its mechanisms of krill oil (KO) in Aß25-35-induced Alzheimer's disease (AD) mouse model. The Aß25-35-injected AD mouse showed memory and cognitive impairment in the behavior tests. However, the administration of KO improved novel object recognition ability and passive avoidance ability compared with Aß25-35-injected control mice in behavior tests. In addition, KO-administered mice showed shorter latency to find the hidden platform in a Morris water maze test, indicating that KO improved learning and memory abilities. To evaluate the cognitive improvement mechanisms of KO, we measured the oxidative stress-related biomarkers and apoptosis-related protein expressions in the brain. The administration of KO inhibited oxidative stress-related biomarkers such as reactive oxygen species, malondialdehyde, and nitric oxide compared with AD control mice induced by Aß25-35. In addition, KO-administered mice showed down-regulation of Bax/Bcl-2 ratio in the brain. Therefore, this study indicated that KO-administered mice improved cognitive function against Aß25-35 by attenuations of neuronal oxidative stress and neuronal apoptosis. It suggests that KO might be a potential agent for prevention and treatment of AD.