Amounts Of Astaxanthin Research Articles

Pioneering Astaxanthin-Tumor Cell Membrane Nanoparticles for Innovative Targeted Drug Delivery on Melanoma.

Recently, the use of the tumor or its secretions as drug carriers has gradually become popular, with the advantages of high biocompatibility and enhanced drug delivery to specific cells. Melanoma is the most malignant tumor of all skin cancers; it is the most metastatic and, therefore, the most difficult to treat. The main purpose of this study is to develop nanovesicles with tumor cell membrane secretion properties to encapsulate target substances to enhance the therapeutic effect of cancer. Astaxanthin was selected as an anticancer drug due to our previous research finding that astaxanthin has extremely high antioxidant, anti-ultraviolet damage, and anti-tumor properties. The manufacturing method of the astaxanthin nanovesicle carrier is to mix melanoma cells and astaxanthin in an appropriate ratio and then remove the genetic material and inflammatory factors of cancer cells by extrusion. In terms of results, after the co-culture of astaxanthin nanovesicles and melanoma cancer cells, it was confirmed that the ability of astaxanthin nanovesicles to inhibit the growth and metastasis of melanoma cancer cells was significantly better than the same amount of astaxanthin alone, and it had no effect on normal Human cells are also effective. There was no apparent harm on normal cells, indicating the ability of the vesicles to be selectively transported. Our findings illustrated the potential of astaxanthin nanovesicles as an anticancer drug.

Effect of feeding astaxanthin with different E/Z‐isomer ratios on astaxanthin accumulation in Pacific white shrimp Litopenaeus vannamei

AbstractAstaxanthin is traditionally utilized in crustacean aquaculture to enhance the characteristic pink‐red color of these species. It has been reported that the bioavailability and body accumulation efficiency of astaxanthin differ based on its E/Z‐isomer species, and these trends vary widely among animal species. This study investigated the influences of feeding astaxanthin having different E/Z‐isomer proportions on astaxanthin accumulation in Pacific white shrimp Litopenaeus vannamei. Z‐Isomer‐rich astaxanthin was prepared from the synthetic (all‐E)‐astaxanthin standard by thermal treatment, and the prepared all‐E‐isomer‐rich astaxanthin pellets (E‐AST‐P; total Z‐isomer proportion = 4.7%) and Z‐isomer‐rich astaxanthin pellets (Z‐AST‐P; total Z‐isomer proportion of astaxanthin = 81.8%) were fed to L. vannamei for 8 weeks. The feeding of Z‐AST‐P significantly improved the body astaxanthin concentration compared to those fed the control pellets without adding astaxanthin isomers and E‐AST‐P; the astaxanthin concentrations after the 8‐week treatments of the control pellets, E‐AST‐P, and Z‐AST‐P were 7.3 ± 0.5, 6.2 ± 1.8, and 12.3 ± 1.3 µg g–1, respectively. This result suggested that astaxanthin Z‐isomers have higher bioavailability and/or body accumulation efficiency than (all‐E)‐astaxanthin in L. vannamei.Practical Applications: The bioavailability of astaxanthin is generally very low, which is a critical issue for its use in crustacean aquaculture. In this study, we found that feeding a pellet rich in astaxanthin Z‐isomers showed a greater accumulation efficiency of astaxanthin in the whole body of L. vannamei than that fed a pellet rich in the all‐E‐isomer. Thus, the use of Z‐isomer‐rich astaxanthin feeds would contribute to improving the quality of crustacean and reducing the feed costs (i.e., reduction of the use amount of astaxanthin).

Improving astaxanthin production in Escherichia coli by co-utilizing CrtZ enzymes with different substrate preference

BackgroundThe bifunctional enzyme β-carotene hydroxylase (CrtZ) catalyzes the hydroxylation of carotenoid β-ionone rings at the 3, 3’ position regardless of the presence of keto group at 4, 4’ position, which is an important step in the synthesis of astaxanthin. The level and substrate preference of CrtZ may have great effect on the amount of astaxanthin and the accumulation of intermediates.ResultsIn this study, the substrate preference of PCcrtZ from Paracoccus sp. PC1 and PAcrtZ from Pantoea Agglomerans were certified and were combined utilization for increase astaxanthin production. Firstly, PCcrtZ from Paracoccus sp. PC1 and PAcrtZ from P. Agglomerans were expressed in platform strains CAR032 (β-carotene producing strain) and Can004 (canthaxanthin producing strain) separately to identify their substrate preference for carotenoids with keto groups at 4,4’ position or not. The results showed that PCcrtZ led to a lower zeaxanthin yield in CAR032 compared to that of PAcrtZ. On the contrary, higher astaxanthin production was obtained in Can004 by PCcrtZ than that of PAcrtZ. This demonstrated that PCCrtZ has higher canthaxanthin to astaxanthin conversion ability than PACrtZ, while PACrtZ prefer using β-carotene as substrate. Finally, Ast010, which has two copies of PAcrtZ and one copy of PCcrtZ produced 1.82 g/L of astaxanthin after 70 h of fed-batch fermentation.ConclusionsCombined utilization of crtZ genes, which have β-carotene and canthaxanthin substrate preference respectively, can greatly enhance the production of astaxanthin and increase the ratio of astaxanthin among total carotenoids.

Dietary astaxanthin modulated the performance, gastrointestinal histology, and antioxidant and immune responses and enhanced the resistance of Litopenaeus vannamei against Vibrio harveyi infection

Astaxanthin (AX) is one of the commonly used feed supplements to enhance the growth performance and provide antioxidant and immune functions of several aquatic animals. In the current study, juveniles of white-leg shrimp (Litopenaeus vannamei) with mean initial weight of 0.340 ± 0.041 g were fed with diets supplemented with 0 (control), 25, 50, 100, and 200 mg/kg feed for 8 weeks. At the end of the feeding trial, shrimps were exposed to Vibrio harveyi, and their mortality rates were observed for additional 10 days. The growth indices in the AX-fed groups were significantly (P < 0.05) higher than what were observed in shrimps in the control group. Dietary AX stimulated the final weight, weight gain, and specific growth rate and optimum growth levels were achieved at 100–200 mg AX/kg feed. Furthermore, the AX-enriched diets significantly enhanced feed intake more than the control diet, and the amount of AX had no effects on feed conversion ratios. In comparison to the control group, the AX-fed animals had significantly (P < 0.05) higher villi length, villi width, and absorption area and their optimum values were observed at 100–200 mg AX/kg feed treatments. Moreover, the intestinal morphometry especially villi and its crypt, both internal and external tunica muscularis, and submucosal tissues did not show any inflammatory and/or degenerative changes in AX-fed shrimp. Furthermore, the dietary AX at escalating levels linearly and quadratically enhanced (P < 0.05) the activities of serum superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and increased levels of total antioxidant capacity and reduced glutathione. In addition, malondialdehyde levels decreased significantly in AX-fed animals, and the highest levels were observed in the control group (without AX). The expression levels of cMn-SOD, CAT, and GPx genes were significantly upregulated in the hepatopancreas of L. vannamei fed with AX-enriched diets (especially in the 200-mg/kg feed treatment) as compared with the control diet. The immunity indices of the AX treatments (hematocyte count, total protein, lysozyme, phagocytic activity, and phenoloxidase) of L. vannamei were linearly (P < 0.05) and quadratically (P < 0.05) increased. This study revealed the antibacterial activity of AX against V. harveyi abundance. After the bacterial challenge, feeding L. vannamei with dietary AX significantly increased (P < 0.05) the relative percentage of survival, especially in the treatment of 200-mg/kg diet (82.7%). The findings of the current study demonstrate that dietary AX (100–200 mg/kg feed) was effective in enhancing the growth, antioxidant status, immune response, and increasing the resistance of L. vannamei against V. harveyi infection.

Astaxanthin from Crustaceans and Their Byproducts: A Bioactive Metabolite Candidate for Therapeutic Application.

In recent years, the food, pharma, and cosmetic industries have shown considerable interest in bioactive molecules of marine origin that show high potential for application as nutraceuticals and therapeutic agents. Astaxanthin, a lipid-soluble and orange-reddish-colored carotenoid pigment, is one of the most investigated pigments. Natural astaxanthin is mainly produced from microalgae, and it shows much stronger antioxidant properties than its synthetic counterpart. This paper aims to summarize and discuss the important aspects and recent findings associated with the possible use of crustacean byproducts as a source of astaxanthin. In the last five years of research on the crustaceans and their byproducts as a source of natural astaxanthin, there are many new findings regarding the astaxanthin content in different species and new green extraction protocols for its extraction. However, there is a lack of information on the amounts of astaxanthin currently obtained from the byproducts as well as on the cost-effectiveness of the astaxanthin production from the byproducts. Improvement in these areas would most certainly contribute to the reduction of waste and reuse in the crustacean processing industry. Successful exploitation of byproducts for recovery of this valuable compound would have both environmental and social benefits. Finally, astaxanthin’s strong biological activity and prominent health benefits have been discussed in the paper.

Optimization of ultrasonic-assisted extraction of astaxanthin from green tiger (Penaeus semisulcatus) shrimp shell

This study was aimed at optimizing the astaxanthin extraction efficiency from shrimp shell (green tiger, Penaeus semisulcatus). Astaxanthin was extracted using selected nonpolar/polar solvents (petroleum ether, n-hexane, ethanol, acetone) individually and in ternary mixtures of petroleum ether, acetone, and water in ratios of 15:50:35, 50:45:5, and 15:75:10 for different times (2,4 and 6 h). The results showed that solvents with higher polarity were more suitable for the extraction of astaxanthin, and increasing the extraction time from 2 to 6 h improved the extraction yield. The conditions of extraction of astaxanthin with the desirable solvent were then optimized with the ultrasonic method using the Box-Behnken design [variables included: extraction temperature (25 to 45 °C), extraction time (5 to 15 min), and ultrasound amplitude (20 to 100%)]. Optimal extraction conditions were determined as the ultrasonic amplitude of 23.6%, extraction time of 13.9 min, and extraction temperature of 26.3 °C. Under this optimum condition, the amount of astaxanthin, ferric reducing antioxidant power, and free radical scavenging capacity of the extract were obtained as 51.5%, 1705 μmol of Fe2+/g, and 73.9%, respectively. Extraction and analysis of the extract at the optimum point were used to validate the results.

An accurate, rapid, and sensitive method for simultaneous determination of four typical heterocyclic amines in roasted pork patties: Application in the study of inhibitory effects of astaxanthin.

Heterocyclic aromatic amines, as a group of mutagenic and carcinogenic compounds, have gained worldwide concern. In this study, an accurate, rapid, and sensitive confirmation and quantification method of four major heterocyclic aromatic amines in roasted pork was developed based on Q-Orbitrap along with Quick, Easy, Cheap, Effective, Rugged, and Safe extraction. The limit of detections and limit of quantitations were found to be 0.2-1.2 μg/kg and 0.6-3.5μg/kg, respectively, revealing the high sensitivity of this method. Obtained results showed recoveries ranging from 78.1 to 97.4%, depending on the different heterocyclic aromatic amines and spiked levels. Precision was in the range of 2.6-4.5% for four heterocyclic aromatic amines at different levels. In addition, the developed method had been applied to investigate the inhibitory effects of astaxanthin on the above-mentioned heterocyclic aromatic amines in roasted pork. The amount of astaxanthin with the best inhibitory effects was 7.5mg (0.0375%), which led to significant reduction in heterocyclic aromatic amines levels over 50%.

Оценка эффективности методов регулирования окраски белоногой креветки Penaeus vannamei ваквакультуре

During steps of technology adjustment of cultivation whiteleg shrimp Penaeus vannamei juvenile to commercial size in recirculating aquaculture system influence of feed composition and containers color on shrimp coloring was studied. Three experiments were carried out in which we used three types of feeds (compound feed for shrimps Gemma Diamond (France); compound feeds for bottom fish and crustaceans Tetra Min Granules and Tetra Wafer Mix (Germany); containers in blue and black, as well as with a black bottom and blue walls. Tetra’s feeds contain astaxanthin-rich brine shrimp artemia. At the end of the experiment all shrimps were photographed. The color indexes of shrimps were estimated in the CIELab color space in Adobe Photoshop program. The experiments have shown that the use of black containers and feeds with a high content of astaxanthin in the whiteleg shrimp P. vannamei cultivation permits one to get the darkest coloring of individuals. The color tone and, in part, the intensity of the shrimp coloring depended on the amount of astaxanthin in the feed. The brightness characteristics of the coloring largely depended on the color of the bottom and walls of the containers. In black containers, the shrimp had a darker color than in blue containers or containers with black bottom and blue walls.

Astaxanthin accumulation in Haematococcus pluvialis cells induced by nitrogen deficiency and high light intensity

It was established that nitrogen deficiency initiated at the resting phase of Haematococcus pluvialis (H. pluvialis) is not an effective stress factor in combination with high light intensity to induce the accumulation of astaxanthin in algae cells. The amounts of astaxanthin in H. pluvialis cells in the absence of nitrogen were lower compared to those when complete Rudic medium was used, regardless of the light intensity. This fact indicates the need for a certain amount of nitrogen in the medium for the functioning of the astaxanthin synthesis system. In addition, the low yield of astaxanthin in the experimental variants cultivated on incomplete Rudic medium is associated with the insufficient amount of nitrogen for its biosynthesis and also with a decrease in the expression level of the PSY gene encoding a key enzyme of the carotenoid biosynthesis chain – phytoene synthase.

Astaxanthin biosynthesis in transgenic Dunaliella salina (Chlorophyceae) enhanced tolerance to high irradiation stress

Astaxanthin is a highly valuable derivative of β-carotene, as well as an important raw material for pharmacy and healthy industries. Dunaliella salina is a halotolerant green alga that contains manifold nutriments and possesses a remarkable ability to adapt environment. The alga is also able to effectively accumulate β-carotene up to 10% of its dry weight. However, D. salina is lack of the enzymes for astaxanthin synthesis so that the accumulated β-carotene cannot be converted to astaxanthin in the alga. The designed experiment was that the exogenous key enzyme genes for astaxanthin synthesis, β-carotene ketolase and β-carotene hydroxylase cloned from Haematococcus pluvialis (Chlorophyceae), were co-transformed into D. salina by bombardment deliver system. The observation of laser scanning confocal microscope and analysis of PCR amplification confirmed the efficient expression of the transformed genes. Compared with the wild type strain, the transformants showed stronger high irradiation adaptability with higher cell survival rate, light saturation point, maximum relative electron transport rate and lower ROS level. The results of biochemical analysis indicated that the activities of antioxidant enzymes showed no significant difference between the two groups. At the transcriptional level, four carotenogenic genes (PSY, PDS, ZDS, LCYB) expressed 2~4 fold higher in the transformants than in the wild type. The tested transformants treated under high irradiation intensity were able to synthesize astaxanthin and the amount of astaxanthin was 5.56 μg/g dry weight measured by HPLC. This study may provide fundamental data for metabolic engineering to synthesize astaxanthin in D. salina.

Antioxidant in a model biomembrane – astaxanthin and its esters mixed with DPPC in Langmuir films

Amphiphilic properties of astaxanthin molecule and its esters make it possible to include it in self-organized structures based on lipid membrane components. Astaxanthin and its mono- and diesters were isolated from the extract of the microalgae Haematococcus Pluvialis, purified by column chromatography, and identified by thin-layer chromatography. The absence of impurities in astaxanthin and its esters was confirmed by means of high performance liquid chromatography method with detection in the ultraviolet-visible region and mass spectrometric detection. The model systems of the cell membrane lipid bilayer — Langmuir films of mixtures of DPPC with astaxanthin and its mono- and diesters, were formed at the air-water interface and studied by a complex of methods. It was found that an increase in the amount of astaxanthin, as well as the addition of its esters to the Langmuir films of DPPC, leads to an increase of values of area per molecule at the surface pressure isotherm uprise and decrease of Langmuir film collapse pressure. The addition of astaxanthin mono- and diesters prevents the phase transition in the DPPC monolayer more strongly than unesterified astaxanthin.

Interaction Effects of Salinity, High Light Intensity and Acetate on Growth and Pigment Production on Scenedesmus obliquus

The aim of the present study was to examine the effects of salinity, high light intensity, and their interactions with acetate on the growth and changes taking place in the pigment, protein, and carbohydrate contents of Scenedesmus obliquus. Algal growth was inhibited by 300 mM NaCl, high light intensity, and their combination. Adding acetate to the culture medium considerably increased the fresh weight S. obliquus, even in cultures under stresses. The amounts of chlorophylls and total carotenoids decreased by stresses and acetate; however, addition of acetate to the cultures under stresses improved the reducing effect of stresses. Among carotenoids, the amount of astaxanthin, as a secondary carotenoid, increased, while the amount of β-carotene and lutein, as primary carotenoids, decreased under salinity and light stresses. The effects of acetate addition on two types of carotenoids under stress conditions were diverse. By adding acetate under stress condition, the amount of astaxanthin decreased; while the amount of β-carotene and lutein considerably increased. Stresses caused a decrease in protein and carbohydrate contents. Application of acetate alone stimulated biosynthesis of protein and carbohydrate in S. obliquus. Moreover, acetate improved the effects of stresses on reduction of protein and carbohydrate contents. The obtained results revealed that application of acetate was the most effective factor to enhance the biomass and astaxanthin production.

The effect of astaxanthin on resistance of juvenile prawns Macrobrachium nipponense (Decapoda: Palaemonidae) to physical and chemical stress.

In recent years, the use of new scientific techniques has effectively improved aquaculture production processes. Astaxanthin has various properties in aquaculture and its antioxidant benefits have been closely related to stress resistance; besides, it is an essential factor for growth in many crustaceans and fish. The objective of this study was to evaluate the resistance of prawn (Macrobrachium nipponense) fed diets containing different amounts of astaxanthin (AX) to the shock and stress of different physicochemical environments. A 70-day trial was conducted to evaluate the effect of supplementation of a source of astaxanthin (Carophyll Pink, 10% astaxanthin, w/w, Hoffman-La Roche, Switzerland) at various levels in the diet of M. nipponense juveniles. Four dry diets were prepared: AX0 without astaxanthin, AX50 with 50 mg/kg, AX100 with 100 mg/kg, and AX150 with 150 mg/kg astaxanthin. The feeding trial was conducted in a recirculation water system consisting of 12 fiberglass tanks (1000L) used for holding prawns. Three replicate aquaria were initially stocked with 36 org/m2 per tank. During the trial, prawns were maintained on a 12:12-h light:dark photoperiod with an ordinary incandescent lamp, and the water quality parameters were maintained as follows: water temperature, 25-26°C; salinity, 1 g/L; pH, 8.5-8.8; dissolved oxygen, 6.0-6.5 mg/L; and ammonia-nitrogen, 0.05 mg/L. Incorporation of AX, production output, and physiological condition were recorded after 10 weeks of feeding. At the end of the growing period, the prawns were exposed to thermal shock (0°C), ammonia (0.75 mg/L), and reduced oxygen (0.5 mg/L). The time to lethargy and the time to complete death of the prawns were recorded. The results showed that control prawns had the shortest time to lethargy and death compared with prawns subjected to the other treatments. The results of this study have shown that the amount of muscle tissue and gill carotenoids in prawn fed with an AX150 diet showed greater reduction than those exposed to other treatments. It is possible that higher levels of astaxanthin in the body under oxygen reduction stress can be beneficial for prawns. These results suggest that male prawns showed lethargy earlier than females, and the percentage of carotenoid reduction in muscle and gill tissues was higher in males.

Characterization of oil including astaxanthin extracted from krill (Euphausia superba) using supercritical carbon dioxide and organic solvent as comparative method

Krill oil including astaxanthin was extracted using supercritical CO2 and hexane. The effects of different parameters such as pressure (15 to 25MPa), temperature (35 to 45 °C), and extraction time, were investigated. The flow rate of CO2 (22 gmin−1) was constant for the entire extraction period of 2.5 h. The maximum oil yield was found at higher extraction temperature and pressure. The oil obtained by SC-CO2 extraction contained a high percentage of polyunsaturated fatty acids, especially EPA and DHA. The acidity and peroxide value of krill oil obtained by SC-CO2 extraction were lower than that of the oil obtained by hexane. The SC-CO2 extracted oil showed more stability than the oil obtained by hexane extraction. The amount of astaxanthin in krill oil was determined by HPLC and compared at different extraction conditions. The maximum yield of astaxanthin was found in krill oil extracted at 25 MPa and 45 °C.

Correlation between astaxanthin amount and a* value in fresh Atlantic salmon ( Salmo salar) muscle during different irradiation doses

The amount of astaxanthin and a* value changes in fresh Atlantic salmon light and dark muscle during cold storage was studied for different e-beam doses (0, 1, 1.5, 2 and 3 kGy). Astaxanthin (mg/kg muscle) and a* value decreased with increasing irradiation dose for both fresh light and dark muscle. The level of irradiation dose gave high correlation between a* value and amount of astaxanthin. The reason for the change in colour or decrease in a* value of Atlantic salmon during irradiation could be due to the destruction of astaxanthin. The amount of astaxanthin and a* value of 1 kGy treated salmon fillets were not significantly different ( p > 0.05) from that of the control but significantly different ( p < 0.05) from other irradiation treatments. The colour ( a* value) of salmon muscle was related to the content of astaxanthin, which decreased as irradiation increased. The amount of astaxanthin in light muscle was three to five times greater than dark muscle. This study demonstrated that irradiating salmon fillets at 1 kGy, can be successfully used and leads to no significant change in colour and amount of astaxanthin.

Calanusoil as a natural source for flesh pigmentation in Atlantic salmon (Salmo salarL.)

The present study was to understand how efficiently the astaxanthin in Calanus oil is utilized for flesh colouration in Atlantic salmon (Salmo salar). Postsmolts of the fish (309 g) were held at 7.9 °C and they were fed diets containing 20 or 60 mg astaxanthin per kilogram feed derived from a synthetic source or from Calanus oil for 181 days. Besides growth and feed intake assessments, at day 81 and 181, fish flesh were subjected to colour analysis and astaxanthin determination. Growth and feed performance did not vary between the groups. There were significant differences in the amount of astaxanthin in muscle between almost all groups both at day 81 (P < 0.05) and at day 181 (P < 0.001). However, a notable similarity between fish receiving 20 mg astaxanthin from the synthetic source and those receiving 60 mg astaxanthin from Calanus oil (P > 0.05) at day 181 indicated that comparable amounts were deposited only with the greater level of the natural source. Tristimuli colorimeter a* values support the analytical results at day 181. Although Calanus oil did serve as a natural dietary pigment source for farmed salmon, its inclusion level should provide more than 60 mg astaxanthin per kilogram feed to achieve colouration preferred by the market.

Digestibility and muscle retention of astaxanthin in Atlantic salmon, Salmo salar, fed diets with the red yeast Phaffia rhodozyma in comparison with synthetic formulated astaxanthin

To elucidate whether astaxanthin plasma concentration, deposition and retention in the muscle (% of ingested dose) and apparent digestibility coefficients (ADC) were influenced by astaxanthin source, triplicate groups of size-graded (initial average weight of 0.69 kg) Atlantic salmon ( Salmo salar), individually labelled with PIT-tags were fed two different experimental diets (6 tanks, each containing 20 fish) for 86 days. Two experimental extruded feeds (7.3 mm) were supplemented with approximately 40 mg astaxanthin from the red yeast Phaffia rhodozyma (Ecotone™) or Lucantin ® Pink (LP), respectively. Technical tests applying light microscopy (LM) compared to scanning electron microscopy (SEM) were used to obtain information on visible structural changes of the P. rhodozyma cells during feed processing and digestion. The fish increased its weight by 74% irrespective of dietary treatment. The specific growth rate was 0.64% day − 1 for the experiment, corresponding to a thermal growth coefficient of 2.15. The feed conversion ratios ranged from 0.96 to 0.98. The final total carotenoid concentration of the muscle was significantly higher ( P < 0.05) in salmon fed the diet supplemented with P. rhodozyma (2.56 mg kg − 1 ) compared to salmon fed the diet supplemented with LP (1.96 mg kg − 1 ). The total concentrations of the astaxanthin metabolite idoxanthin were similar in the two treatments, but the composition of the 3′,4′- cis and 3′,4′- trans glycolic isomers was significantly ( P < 0.05) affected by treatment (idoxanthin 3′,4′- cis-to 3′,4′- trans glycolic isomer ratio 0.3 to 1.20 for salmon fed the diets supplemented with P. rhodozyma and LP, respectively). The highest retention of dietary astaxanthin was found in the muscle of salmon fed the diet supplemented with P. rhodozyma cells (6.3%), and it was 86% higher than for salmon fed the synthetic control astaxanthin. This was reflected by the astaxanthin ADC which was about 64 to 68% in salmon fed the diet supplemented with P. rhodozyma and 38 to 42% in the salmon fed the synthetic control ( P < 0.05). Plasma and muscle carotenoid concentrations correlated poorly ( R 2 = 0.0007), and indicated that plasma concentration of carotenoids is a relatively weak indicator of muscle concentration for salmon fed diets with similar concentrations of astaxanthin. Microscopy tests revealed that the identification of P. rhodozyma cells in complex matrices was more reliable when LM was used compared to SEM. The extruded feed supplemented with Ecotone™ contained isolated P. rhodozyma cells and was free of cell clusters. Some empty cells could be detected. Semi-quantitative analysis by LM revealed that the number of cells was 2.3- to 4.6-fold higher in faeces samples than in the feed. In the faeces various amounts of astaxanthin were observed in the cells. The majority of cells with little or no astaxanthin showed clearly visible lesions or ruptures in the cell wall. It is concluded that Ecotone™ represents a more effective astaxanthin source for pigmentation of Atlantic salmon muscle than LP, but microscopic analysis revealed a potential for further improvement.

Quality parameters of the flesh of Atlantic salmon ( Salmo salar) as affected by dietary fat content and full-fat soybean meal as a partial substitute for fish meal in the diet

Atlantic salmon fed for 9.5 months, diets containing medium (MF, 32%) or high (HF; 39%) fat levels with fish meal (FM) or 10% of the FM protein replaced by full-fat soybean meal (FFSM) protein were analyzed by sensory profiling. No significant differences were observed in sensory characteristics. Fish fed HF diets had more total carcass lipid, larger abdominal and myoseptal fat deposits as determined by chemical analyses, visual evaluation, and computerized X-ray tomography. CIE-1976 redness and yellowness ( a ∗, b ∗ ) were higher in salmon fed HF diets, suggesting that intestinal astaxanthin absorption was facilitated by higher dietary fat content. No significant effects of dietary protein source on the amount of astaxanthin in the muscle, visual color score, proximate composition, fat deposition or sensory characteristics were observed. FFSM may partly replace FM in diets for salmonids without compromising the sensory quality.

Plasma carotenoid concentration indicates the availability of dietary astaxanthin for Atlantic salmon, Salmo salar

Atlantic salmon with an initial weight of 1.1 kg were fed three extruded diets with different amounts of astaxanthin (5, 51 and 61 mg kg −1) in an experiment lasting for 26 weeks. Availability of astaxanthin was assessed after collection of blood plasma from 2 × 10 fish per pen (three pens per diet; two groups of fish per pen, previously unpigmented and pigmented prior to the start of the experiment). The salmon weighed 2–2.5 kg at the time of blood sampling. Correlations were made between mean values for plasma carotenoid concentration and dietary astaxanthin concentration, flesh carotenoid concentration at 24 weeks of feeding, and the amount of carotenoids (mg) retained in flesh per kg body weight increase. There were no differences observed in plasma astaxanthin concentration between salmon which were pigmented or unpigmented prior to the study. The correlation between plasma astaxanthin concentration and dietary astaxanthin concentration was r = 0.90. Plasma astaxanthin concentration and mg astaxanthin retained in flesh per kg body weight increase were also highly correlated ( r = 0.92), as was the correlation between plasma astaxanthin concentration and flesh carotenoid level ( r = 0.95). Plasma astaxanthin concentrations ranged from 0.5 to 5 μg ml −1.

Astaxanthin deposition in the flesh of Atlantic Salmon, Salmo salar L., in relation to dietary astaxanthin concentration and feeding period

Atlantic salmon, Salmo salar L., were fed nine experimental diets containing from 0 to 200 mg astaxanthin per kg−1 for six time periods, ranging from 3 to 21 months, in sea cages at Matre Aquaculture Research Station, Matredal, Norway. The sampled fish had an initial mean weight of 115 g and reached a weight of 3.2 kg at the termination of the experiment. Every third month, 10 fish from each dose and time group were sampled and the astaxanthin concentration in the flesh determined. The amount of astaxanthin in the flesh ranged from 0.7 to 8.9 mg kg−1 at the termination of the experiment. This paper discusses deposition of astaxanthin in the flesh of Atlantic salmon in relation to dietary carotenoid levels in the 0–200 mg kg−1 range and feeding times of 3–21 months. Under the conditions of this experiment, no significant effect on astaxanthin deposition rate could be achieved by increasing the astaxanthin level above 60 mg kg dry feed−1. Atlantic salmon should be fed astaxanthin-supplemented diets during the whole seawater stage in order to obtain maximal astaxanthin level in the flesh.