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Context. Bright stellar positions are now known with an uncertainty below 1 mas thanks to Gaia DR2. Between 2019–2020, the Galactic plane will be the background of Jupiter. The dense stellar background will lead to an increase in the number of occultations, while the Gaia DR2 catalogue will reduce the prediction uncertainties for the shadow path. Aims. We observed a stellar occultation by the Galilean moon Europa (J2) and propose a campaign for observing stellar occultations for all Galilean moons. Methods. During a predicted period of time, we measured the light flux of the occulted star and the object to determine the time when the flux dropped with respect to one or more reference stars, and the time that it rose again for each observational station. The chords obtained from these observations allowed us to determine apparent sizes, oblatness, and positions with kilometre accuracy. Results. We present results obtained from the first stellar occultation by the Galilean moon Europa observed on 2017 March 31. The apparent fitted ellipse presents an equivalent radius of 1561.2 ± 3.6 km and oblatenesses 0.0010 ± 0.0028. A very precise Europa position was determined with an uncertainty of 0.8 mas. We also present prospects for a campaign to observe the future events that will occur between 2019 and 2021 for all Galilean moons. Conclusions. Stellar occultation is a suitable technique for obtaining physical parameters and highly accurate positions of bright satellites close to their primary. A number of successful events can render the 3D shapes of the Galilean moons with high accuracy. We encourage the observational community (amateurs included) to observe the future predicted events. [ABSTRACT FROM AUTHOR]

The technique of mutual approximations accurately gives the central instant of the maximum apparent approximation of two moving natural satellites in the plane of the sky. This can be used in ephemeris fitting to infer the relative positions of satellites with high precision. Only mutual phenomena – occultations and eclipses – can achieve better results. However, mutual phenomena only occur every six years in the case of Jupiter. Mutual approximations do not have this restriction and can be observed at any time in the year as long as the satellites are visible. In this work, we present 104 central instants determined from the observations of 66 mutual approximations between the Galilean moons carried out at different sites in Brazil and France during the period 2016–2018. For 28 events, we have at least two independent observations. All telescopes were equipped with a narrow-band filter centred at 889 nm with a width of 15 nm to eliminate the scattered light from Jupiter. The telescope apertures ranged between 25 and 120 cm. For comparison, the precision of the positions obtained with classical CCD astrometry is about 100 mas, for mutual phenomena it can be 10 mas or less, and the average internal precision obtained with mutual approximations is 11.3 mas. This new type of simple, yet accurate, observations can significantly improve the orbits and ephemeris of Galilean satellites and thus it can be very useful for the planning of future space missions to the Jovian system. [ABSTRACT FROM AUTHOR]

ABSTRACT Nowadays, there is increasing interest in natural antioxidants from food by-products. Astaxanthin is a potent antioxidant and one of the major carotenoids in crustaceans and salmonids. An ultra-high pressure liquid chromatographic method was developed and validated for the determination of astaxanthin in shrimp by-products, and its migration from new packaging materials to food simulants was also studied. The method uses an UPLC® BEH guard-column (2.1 × 5 mm, 1.7 µm particle size) and an UPLC® BEH analytical column (2.1 × 50 mm, 1.7 µm particle size). Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) acetonitrile-methanol (containing 0.05 m ammonium acetate)-dichloromethane (75:20:5, v/v/v) and (B) ultrapure water. This method was evaluated with respect to validation parameters such as linearity, precision, limit of detection, limit of quantification and recovery. Low-density polyethylene films were prepared with different amounts of the lipid fraction of fermented shrimp waste by extrusion, and migration was evaluated into food simulants (isooctane and ethanol 95%, v/v). Migration was not detected under the tested conditions. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work the proximal analysis, physicochemical characterization, fatty acid profile and astaxanthin content of pigmented oil obtained by fermentation shrimp heads are presented. Lipids are the major components in the oil (95%). The saponification number is 178.62 mg KOH/g, iodine value 139.8 cg iodine/g, and the peroxide value was not detected. Density and viscosity were 0.92 mg/ml and 64 centipoises, respectively. The highest contents of fatty acids were linoleic (C18:2n6), oleic (C18:1n9) and palmitic (C16:0). Eicosapentaenoic acid (C20:5n3, EPA) and docosahexaenoic acid (C22:6n3, DHA) account for 9% of the total. The content of astaxanthin was 2.72 mg/g dry weight. The pigmented oil is a dietary source of nutrients with high value such as astaxanthin. [ABSTRACT FROM AUTHOR]

Whole white corn was ground, and lime, water and xanthan gum (XG, 0.5% w/w), carboxymethylcellulose (CMC, 0.5% w/w), guar gum (GG, 0.5% w/w) or a gums mix (XG, 0.25% w/w; CMC, 0.15% w/w; GG, 0.10% w/w) were added. Blends were extruded, dried and ground to obtain nixtamalized corn flour (ENCF), and they were used to make tortillas. The particle size distribution, particle size index, water absorption capacity (WAC) and water absorption index (WAI) were determined in flour; moisture content and viscoelastic characteristics (G′, G′′, tan δ) were determined in corn masa; tortillas were made, and texture (cutting force and rollability) and sensory evaluation were carried out. ENCF with XG and gums mix had the highest WAC, and tortillas were softer (33%) than tortillas from ENCF without gums. Corn masa viscoelasticity (tan δ) correlated negatively with tortilla firmness (r = − 0.84). Corn tortillas made with XG and gums mix had acceptable organoleptic characteristics. PRACTICAL APPLICATION The extrusion process allows the using of the whole corn to make tortillas and reduce processing costs and the contaminant effluents (cooking liquor). The addition of a mix of gums during extrusion makes the corn masa retain more water and modify its rheological properties, improving masa handling characteristics and tortilla textural quality. The evaluation of masa viscoelasticity with the dynamic method makes it possible to differentiate corn masas and to select the best treatments. [ABSTRACT FROM AUTHOR]

A simple and specific analytical method was developed and tested for the determination of sulforaphane in broccoli by-products. The method includes the optimization of the conversion of glucoraphanin to sulforaphane, followed by purification of extracts using solid-phase extraction and high-performance liquid chromatography (HPLC) analysis. The response surface methodology was used to find optimum conditions for the preparation and purification procedure. Chromatographic conditions for reversed-phase HPLC with UV photodiode array detection were as follows: column, Exil ODS C18, 25 × 0.46 cm, 5 μm; column temperature, 36°C; mobile phase, a 30 : 70 (v/v) mixture of acetonitrile:water; flow rate, 0.6 mL/min. The detection wavelength was UV 202 nm. Under these conditions, excellent linearity was obtained ( r2 = 1), and the overall recovery was 97.5 and 98.1% for fresh florets and lyophilized florets, respectively. The precision results showed that the relative standard deviation of the repeatability for florets fresh and lyophilized was 3.0 and 4.0%, respectively. Sulforaphane contents were determined in the edible portion of fresh broccoli, and broccoli crop remains. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents a high performance liquid chromatography (HPLC) method for the determination of riboflavin and free aromatic amino acids. To determine riboflavin, the method includes an acid hydrolysis (HCl 0.1 N) followed by an enzymatic digestion and a protein precipitation with trichloroacetic acid. An analytical column, Chrom SEP SS C18 5 µm (4.6 mm × 150 mm) was used with an isocratic flow using a mobile phase consisting of 5 mM ammonium acetate-methanol (72:28, vv-1), at a flow rate of 1.0 mL min-1 to 28°C. The method showed adequate linearity, repeatability, reproducibility, accuracy, and limits of detection. The method was used to quantify the cited analytes in three different forms of hydrolysate obtained from fermented shrimp remnants. [ABSTRACT FROM AUTHOR]

In the present study, a simple and rapid reversed-phase HPLC method for the determination of astaxanthin in shrimp waste hydrolysate has been developed and validated. The analytical procedure involves the direct extraction of astaxanthin from the lipid fraction with methanol. The analytical column, SS Exil ODS, was operated at 25C. The mobile phase consisted of a mixture of water:methanol:dichloromethane:acetonitrile (4.5:28:22:45.5 v/v/v/v) at a flow rate of 1.0 mL/min. Detection and identification were performed using a photodiode array detector ( λdetection = 476 nm). The proposed HPLC method showed adequate linearity, repeatability and accuracy. Copyright © 2006 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study presents an HPLC method for the quantification of sterols in edible seaweeds. Sterols were identified by HPLC/mass spectrometry (HPLC-MS) in positive APCI mode. The samples were saponified by refluxing with 1 m ethanolic KOH, and the non-saponifiable fraction was extracted with hexane. Sterols were quantified by HPLC with UV detection (HPLC-UV), on a 15 × 0.4 cm Kromasil 100 C18 5 µm column (mobile phase 30:70 v/v methanol:acetonitrile; flow rate 1.2 mL/min; column temperature 30°C; detection wavelength 205 nm). Method repeatability for fucosterol was good (coefficient of variation 2.4%). Sterol contents were determined in canned or dried brown seaweeds ( Himanthalia elongata, Undaria pinnatifida, Laminaria ochroleuca) and red seaweeds ( Palmaria sp., Porphyra sp.). The predominant sterol was fucosterol in brown seaweeds (83-97% of total sterol content; 662-2320 µg/g dry weight), and desmosterol in red seaweeds (87-93% of total sterol content; 187-337 µg/g dry weight). Copyright © 2004 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A high-performance liquid chromatographic (HPLC) method is described for determination of the ratio of β- d-mannuronic acid to α- l-guluronic acid (M/G ratio) in dietary fibre of edible seaweeds. Total dietary fibre (TDF) content was determined gravimetrically. The TDF fraction was hydrolysed with 12 m and 1 m H2SO4, then neutralized with AG 4 × 4 resin. The uronic acids were separated in a Tracer Extrasil SAX 5 µm column (25 cm × 4 mm) at 35°C, with 2 m m KH2PO4 containing 5% methanol as mobile phase at a flow rate of 1.5 mL/min. The detection wavelength was UV 210 nm. The chromatographic identifications of β- d-mannuronic acid and α- l-guluronic acid were confirmed by liquid chromatography-mass spectrometry (LC-MS). The method precision was 1.4% for β- d-mannuronic acid and 3.5% for α- l-guluronic acid. The method was used to determine M/G ratio in canned seaweeds ( Saccorhiza polyschides and Himanthalia elongata) and in dried seaweeds ( H. elongata, Laminaria ochroleuca, Undaria pinnatifida, Palmaria sp. and Porphyra sp.). Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Chitosan (CAS n. 9012-76-4) is a natural polysaccharide obtained by the partial deacetylation of chitin. It is a linear polymer of b (1-4) 2-acetamido-2-deoxy-D-glucose and 2-amino-2-deoxy-D-glucose in different proportions. Chitin is the most abundant polysaccharide after cellulose and the main source is the shells of crustaceans. It has been demonstrated that some important properties are directly related to the antimicrobial activity of chitosan. Some of these properties are the molecular weight (Mw), the degree of polymerisation (DP) and the degree of deacetylation (DD). In this work several analytical techniques (FTIR (Fourier-transform Infrared Spectroscopy), NMR (Nuclear Magnetic Resonance Spectroscopy) and SEM (Scanning Electron Microscopy)) were attempted to characterize two different samples obtained from shrimp waste. It can be concluded that sample 1 should be more suitable to be added as an active agent to a film. [ABSTRACT FROM AUTHOR]

The possibility of using the lipid fraction from fermented shrimp waste as a source of natural a-tocopherol to produce packaging with antioxidant properties was evaluated. A fast reverse-phase ultra-performance liquid chromatographic (RP-UPLC) method coupled with a diode array detector was developed to determine α-tocopherol in the lipid fraction of shrimp waste. The α-tocopherol level found using acetonitrile as extraction solvent was 50.5 mg/100 g sample, indicating. [ABSTRACT FROM AUTHOR]

Electrospinning can be used to prepare membranes with characteristics for biomedical application. In this work, the electrospinning conditions for the fabrication of membranes based on polymers extracted from natural sources such as chitosan and collagen were optimized (injection flow, injection volume, distance from the collector to the neddle, needle size and voltage). Specifically, four formulations were prepared with pure chitosan and mixtures of collagen (purified or hydrolyzed) and agarose. The optimal electrospinning conditions were an injection flow rate of 0.1 ml/h, a 16 G needle, an injection volume of 5 ml, a distance of 8 cm between the needle and the collector, and a voltage of 20 kV. Agarose addition resulted in greater elongation at break and maximum stress, and greater elasticity was observed in the mixture with hydrolyzed collagen. Fiber formation was observed in the structure prepared from chitosan and hydrolyzed collagen. The water holding capacity was greatest in the pure chitosan membranes and the addition of other polymers reduced this property by their interaction. The contributions of this research are as follows:•The electrospinning conditions were the same for the fabrication of membranes from pure chitosan and chitosan mixed with natural polymers.•The mechanical and biological properties of the membranes were improved by the addition of hydrolyzed collagen and agarose.•The addition of hydrolyzed collagen promoted the formation of fibers and porous membranes., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2025 The Authors. Published by Elsevier B.V.)

A new, simple, and reproducible isocratic high-performance liquid chromatography (HPLC) method has been developed for the determination of free and total tyrosine and tryptophan in a protein concentrate. To determine total amino acids, the method involves alkaline hydrolysis of the proteins with sodium hydroxide at 120 degrees C for 4h in the absence of air. Best results were achieved with a SS Exil ODS column 5microm (25cmx0.46cm i.d.), with an eluent of methanol: 40mM sodium acetate buffer (adjusted to pH 4.5 with acetic acid; 20:80, v/v), a flow rate of 0.80mL/min at 26 degrees C, and with programmable fluorescence detection. Under optimum conditions excellent linearity was obtained, and the overall recovery was 90.5, and 95.9% for total tryptophan and tyrosine, respectively. The precision results showed that the relative standard deviation of the repeatability and reproducibility were < or =4.78 and < or =4.65, respectively. This method was used to quantify the cited analytes in the protein concentrate obtained during the lactic acid fermentation of shrimp waste.

This work presents a high-performance liquid chromatography (HPLC) method for the quantitation of glucosamine in chitin. The method includes an acid hydrolysis of chitin. The chromatographic separation is achieved using a Hypersil ODS 5-microm column (250 x 4.6 mm) at 38 degrees C, with precolumn derivatization with 9-fluorenylmethyl-chloroformate and UV detection (lambda = 264 nm). The mobile phase is a mixture of mobile phase A [30 mM ammonium phosphate (pH 6.5) in 15:85 methanol-water (v/v)], mobile phase B [15:85 methanol-water (v/v)], and mobile phase C [90:10 acetonitrile-water (v/v)], with a flow rate of 1.2 mL/min. The HPLC method proposed showed adequate repeatability (relative standard deviation, 5.8%), accuracy (92.7% recovery), and sensitivity, with a detection limit of 2 microg/mL. The method is successfully applied to the quantitation of glucosamine for the determination of the purity of chitin from shrimp waste.

This study presents an HPLC method for the simultaneous quantification of retinol, alpha-tocopherol, and cholesterol in shrimp waste hydrolysate lipid fraction. The method includes microscale saponification and extraction with n-hexane. Liposoluble vitamins and cholesterol were quantified by HPLC with UV detection (HPLC-UV), on a 25 cm x 0.46 cm SS Exil ODS 5 microm column, mobile phase 68:28:4 (v/v/v) methanol:acetonitrile:water; flow rate 1.4 ml/min; column temperature 36 degrees C. The detection was operated using two channels of a diode-array spectrophotometer, 325 nm for retinol and 208 nm for alpha-tocopherol and cholesterol. With these conditions, the overall recovery was 95.7, 100.8, and 98.0% for retinol, alpha-tocopherol, and cholesterol, respectively. The method precision (relative standard deviation) was 1.83% for retinol, 2.32% for alpha-tocopherol, and 1.98% for cholesterol. This method was used to quantify the cited analytes in the hydrolysate obtained during lactic acid fermentation of shrimp waste. This hydrolysate may be a valuable supplement of nutrients in fish production.

This work presents an HPLC method for the quantification of free amino acids in lyophilized protein fraction from shrimp waste hydrolysate which is obtained by acid lactic fermentation and analyzed using pre-column derivatization with 9-fluorenylmethyl-chloroformate. The amino acids were separated in a Hypersil ODS 5 microm column (250 mm x 4.6 mm) at 38 degrees C. The mobile phase was a mixture of phase A: 30 mM ammonium phosphate (pH 6.5) in 15:85 (v/v) methanol/water; phase B: 15:85 (v/v) methanol/water; and phase C: 90:10 (v/v) acetonitrile/water, with flow rate 1.2 ml/min. Fluorescence detection was used at an excitation wavelength of 270 nm and an emission wavelength of 316 nm. Method precisions for the different amino acids were between 4.4 and 7.1% (relative standard deviation, RSD); detection limits were between 23 and 72 ng/ml; and the recoveries were between 89.0 and 95.0%. The amino acid present at the highest concentration was tyrosine.

A high-performance liquid chromatography method for the microscale determination of alpha- and gamma-tocopherol in leaves, flowers and fresh beans from Moringa oleifera is reported. The method includes microscale saponification and extraction with n-hexane. Optimized conditions for reversed-phase HPLC with UV detection were as follows: column, 25 cm x 0.46 cm, Exil ODS 5-microm; column temperature, 25 degrees C; mobile phase, a 20:80 (v/v) mixture of methanol:acetonitrile; flow rate, 1.0 ml/min. With these conditions, method precision (relative standard deviation) was 5.6% for alpha-tocopherol and 4.9% for gamma-tocopherol. We used this method to measure alpha- and gamma-tocopherol in samples from M. oleifera as part of nutritional studies in edible plants cultivated in the Northwest México.

This study presents a high-performance liquid chromatography (HPLC) method for simultaneous determination of thiamine and riboflavin and the results of its application to a number of edible seaweeds that are sampled in dried form (Himanthalia elongata, Laminaria ochroleuca, Undaria pinnatifida, Palmaria sp., and Porphyra sp.) or as canned food (H. elongata and Saccorhiza polyschides). Samples are prepared by acid and enzymatic hydrolysis. Optimized conditions for reversed-phase HPLC with fluorescence detection are as follow: column, Kromasil 100 C18; column temperature, 35 degrees C; mobile phase, a 72:28 (v/v) mixture of 0.005 M ammonium acetate (pH 6.7)-methanol; and flow rate, 1.35 mL/min. With these conditions, recovery is 95.52% for thiamine and 90.08% for riboflavin, and the method precision (relative standard deviation) is 2.66% for thiamine and 2.21% for riboflavin. On a dry weight basis, thiamine contents range from 0.14 microg/g in dried H. elongata to 2.02 microg/g in dried Porphyra and riboflavin contents from 0.31 microg/g in canned H. elongata to 6.15 microg/g in dried Porphyra.

A high-performance liquid chromatographic (HPLC) method for the microscale determination of alpha-tocopherol in macroalgae is reported. The method includes microscale saponification and extraction with n-hexane. The presence of alpha-tocopherol in macroalgae samples was confirmed by HPLC-MS. Alpha-tocopherol levels as determined in samples by HPLC with UV and fluorescence detection did not differ significantly; however, fluorescence detection has a higher sensitivity (detection limit 10.4 ng/ml, vs. 104 ng/ml with UV detection), as well as good precision (relative standard deviation 1.81%) and recovery (94.3%). Fluorescence detection is also faster. We used this method to determine the alpha-tocopherol contents of four commercial macroalgae products from northwest Spain as part of nutritional studies in dehydrated Himanthalia elongata and Laminaria ochroleuca, and also in canned Himanthalia elongata and Saccorhiza polychides.