TVB-N was analyzed according to Zhuang et al. (2019) (link) with minor modification. Briefly, 25 ml cooled ultrapure water was added to 2.5 g prawn muscle. After homogenization (F6/10, FLUKO, Germany) for 30 s on ice, the mixture was shaken on a shaker (ZWY-100H, Zhicheng, China) at 100 r/min for 30 min, then centrifuged at 3500 g for 3 min (CF16RXⅡ, HITACHI, Japan). Five-milliliter of the resulting supernatant was well mixed with 5 ml MgO (Yuanye, China) suspension (10 g/l), and then the mixture was to distill completely through Kjeldahl Apparatus (KDY-9820, China). Meanwhile, 10 ml boric acid (Biorigin, China) solution (20 g/l) was used to absorb the distillate. After that, the boric acid solution was titrated with standard sulfuric acid solution (Haianhongmeng, China) to pH of 4.65. TVB-N value was determined and expressed as mg N/100 g flesh, according to the consumption of sulfuric acid. For each treatment, three replications were performed.
Cf16rxii
Manufactured by Hitachi
Sourced in Japan
The CF16RXII is a compact multipurpose centrifuge designed for a wide range of laboratory applications. It features a maximum speed of 16,000 rpm and a maximum relative centrifugal force of 21,380 x g. The centrifuge can accommodate sample volumes up to 250 mL and is compatible with a variety of rotor types.
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Lab products found in correlation
Uv 726, by Shimadzu (3 mentions)
Bradford method, by Solarbio (1 mentions)
Milli q integral water purification system, by Merck Group (1 mentions)
Vhx 5000, by Keyence (1 mentions)
T10 basic ultra turrax, by IKA Group (1 mentions)
Acetic acid, by Beijing Chemical Works (1 mentions)
Multiskan mk3 microplate reader, by Thermo Fisher Scientific (1 mentions)
S 4800 scanning electron microscope, by Hitachi (1 mentions)
Nadph, by Roche (1 mentions)
Personal 11, by TAITEC (1 mentions)
Vc 96n, by TAITEC (1 mentions)
15 protocols using cf16rxii
1
Determination of TVB-N in Prawn Muscle
2
Enzyme Activity Determination in Processed Juices
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The extraction solution consisted of a 0.2 mol/L phosphate buffer (pH = 6.5) containing 4% (w/v) polyvinylpolypyrrolidone (PVPP). The composite juice and extraction mixture (8 g: 4 ml, m/v) were shaken uniformly and centrifuged at 6155 g for 15 min at 4°C (CF16RXⅡ, Hitachi). The supernatant was used to determine PPO and POD activity.
For the PPO assay, 1 ml supernatant was added to 2 ml of 0.2 mol/L phosphate buffer (pH = 6.5) containing 0.5 mol/L catechol. The absorbance was measured at 420 nm for 1 min (scanning interval was 0.1 s) using a UV‐visible spectrophotometer (UV‐1800, Uniko instrument co., Ltd). The analysis was carried out in triplicate.
For the POD assay, 1 ml supernatant was added to 0.2 ml of 1.5% hydrogen peroxide (v/v) and 2.2 ml of 0.2 mol/L phosphate buffer (pH = 6.5) containing 1% guaiacol (v/v). The absorbance was measured at 475 nm (scanning interval was 0.1 s) for 1 min using a UV‐visible spectrophotometer (UV‐1800, Uniko instrument co., Ltd). The analysis was carried out in triplicate.
The residual activity for both PPO and POD enzymes was calculated according to: where A is the activity of the UHPH‐treated juice and A0 is the activity of the untreated juice.
For the PPO assay, 1 ml supernatant was added to 2 ml of 0.2 mol/L phosphate buffer (pH = 6.5) containing 0.5 mol/L catechol. The absorbance was measured at 420 nm for 1 min (scanning interval was 0.1 s) using a UV‐visible spectrophotometer (UV‐1800, Uniko instrument co., Ltd). The analysis was carried out in triplicate.
For the POD assay, 1 ml supernatant was added to 0.2 ml of 1.5% hydrogen peroxide (v/v) and 2.2 ml of 0.2 mol/L phosphate buffer (pH = 6.5) containing 1% guaiacol (v/v). The absorbance was measured at 475 nm (scanning interval was 0.1 s) for 1 min using a UV‐visible spectrophotometer (UV‐1800, Uniko instrument co., Ltd). The analysis was carried out in triplicate.
The residual activity for both PPO and POD enzymes was calculated according to: where A is the activity of the UHPH‐treated juice and A0 is the activity of the untreated juice.
3
Antioxidant Capacity Determination by DPPH
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Refer to the method of Miller et al. (1995 (link)) and modify it slightly. Ten milliliter of juice was centrifuged at 6155 g for 10 min at 4°C (CF16RXⅡ, Hitachi) to get the extract. The extract (100 μl) was mixed with 4 ml methanolic determined by stable radical method (DPPH) solution (0.14 mmol/L). The samples were kept in the dark for 45 min at room temperature before measurement of the decrease in the absorption at 517 nm. Determinations were performed using a spectrophotometer (UV‐726, Shimadzu). Trolox solutions within the range of 100–1000 μmol/L were used for calibration. A new Trolox calibration curve was made for each assay. The results were expressed as Trolox equivalents (TE) where one TE equals the net protection produced by one mmol Trolox. The standard curve can be found in Appendix S1 .
4
Determination of Total Phenols in Juice
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Ten milliliters of juice was centrifuged at 6155 g for 10 min at 4°C (CF16RXⅡ, Hitachi). The supernatant was collected and diluted 8‐fold with distilled water for further analysis.
The total phenols were determined using the Folin–Ciocalteu method described by Cao et al. (2011 (link)) with some modifications. An amount of 0.4 ml diluent was mixed with 2 ml Folin–Ciocalteu reagent (previously diluted 10‐fold with distilled water) and 1.8 ml sodium carbonate solution (7.50%), set for 1 h in the dark at room temperature, and then the mixture was immediately measured at 765 nm using a spectrophotometer (UV‐726, Shimadzu). Results were expressed as µg of gallic acid equivalent (GAE) per milliliter juice (µg GAE/ml). The standard curve can be found in AppendixS1 .
The total phenols were determined using the Folin–Ciocalteu method described by Cao et al. (2011 (link)) with some modifications. An amount of 0.4 ml diluent was mixed with 2 ml Folin–Ciocalteu reagent (previously diluted 10‐fold with distilled water) and 1.8 ml sodium carbonate solution (7.50%), set for 1 h in the dark at room temperature, and then the mixture was immediately measured at 765 nm using a spectrophotometer (UV‐726, Shimadzu). Results were expressed as µg of gallic acid equivalent (GAE) per milliliter juice (µg GAE/ml). The standard curve can be found in Appendix
5
Juice Suspension Stability Analysis
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Suspension stability was performed after centrifuging 30 ml juice samples at 1520 g for 10 min at 4°C (CF16RXⅡ, Hitachi). The absorbance was measured before and after centrifugation at a wavelength of 660 nm using a spectrophotometer (UV‐726, Shimadzu), set A0 and A, and the A/A0 ratio was used to characterize suspension stability.
6
Determination of Prawn Muscle Salt-Soluble Protein
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The determination of salt-soluble protein was based on Wu et al. (2014) (link) with minor modification. One-gram prawn muscle was added with 15 ml cooled ultrapure water and then homogenized (F6/10, FLUKO, Germany) for 30 s on ice. The homogenate was extracted at 4 °C for 20 min and centrifuged at 10,000 g using a centrifuge at 4 °C for 20 min (CF16RXII, HITACHI, Japan). Supernatant was removed, and precipitate was added with 15 ml Tris-maleate buffer (0.6 M NaCl-20 mM Tris-maleate, pH 7.0) and then homogenized for 30 s. Then, the homogenate was kept at 4 °C for 60 min to extract salt-soluble protein and centrifuged at 10,000 g at 4 °C for 20 min. The obtained supernatant was diluted to 25 ml (0.6 M NaCl-20 mM Tris-maleate, pH 7.0), which was myofibrillar protein solution for quantitative determination. Salt-soluble protein content was determined using a kit according to the Bradford method (Solarbio, China). For each treatment, three replications were performed.
7
Assessing Nanoparticle Suspension Stability
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A centrifuge was used to test the suspension of CS–TPP nanoparticles (Hitachi CF16RXII). The specimens were placed in centrifuge tubes and centrifuged for 2 h at 6,000 revolutions per minute. Following that, the suspension was monitored for sedimentation. If no sedimentation occurs, the suspension has particles with a size range of nanometers.
8
Magnetic Manipulation of Titanium Nanosheets
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Aqueous dispersions of unilamellar TiNSs were centrifuged using a Hitachi model CF16RXII centrifuge and a Hitachi model T15A41 rotor. Redispersion of TiNSs was carried out using a HiPep laboratories model PepSyzer II shaker. Magnetic orientation of TiNSs was carried out using a JASTEC model JMTD-10T100 superconducting magnet with a vertical bore of 100 mm. Ion conductivity was measured by using a Horiba model DS-71E conductivity meter. Zeta potentials were measured by using a Malvern model Zetasizer Nano ZSP zeta potential analyser. Polarized optical microscopy was performed on a Nikon model Eclipse LV100POL optical polarizing microscope or a KEYENCE model VHX-5000 digital microscope. Photoinduced radical polymerization was conducted by using an USHIO model OPM2-502H high-pressure mercury arc lamp (500 W). Unless otherwise noted, all reagents were used as received from TCI (tetramethylammonium chloride) and Wako (hydrochloric acid, N,N-dimethylacrylamide and N,N'-methylenebis(acrylamide)). Water was obtained from a Millipore model Milli-Q integral water purification system. TiNSs were prepared according to literature methods2 .
9
Micronization of High-Reflective Sunscreen Oil
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As purchased, the average particle diameter of HRSO is approximately 100 μm, which is large compared to the CS core particles. We therefore micronized HRSO by first suspending 15 g of HRSO in 100 mL of ethanol at approximately 70°C and stirring until the solution formed a transparent emulsion. After terminating heating and agitation, the cloudy suspension (caused by separation of the HRSO) was processed for 30 min using an homogenizer (T10 basic Ultra-Turrax; IKA-Werke GmbH & Co. KG, Staufen, Germany). The suspension was transferred to a centrifuge tube and centrifuged at 3000 rpm for 10 min at 5°C (CF16RX II; Hitachi Koki Co., Ltd., Tokyo, Japan). The clear supernatant was removed and the sediment was vacuum-dried and lightly ground in an agate mortar to produce the micronized HRSO used for dry coating.
10
DPA Release Determination by Fluorescence
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The DPA release was measured using the fluorescence method (Hindle and Hall, 1999 (link)). The treated spores were centrifuged at 7000 × g and 4°C for 10 min (CF16RXII, Hitachi, Japan), and assaying DPA in the supernatant solution was carried out by its fluorescence with Tb3+ in a 96-well plate. One hundred μL of supernatant solution were added to 100 μL 20 μmol/L terbium (III) chloride hexahydrate (99.9%, Aladdin Industrial Corporation, Shanghai, China) buffered with 1 mol/L acetic acid (99.8%, Beijing Chemical Works, Beijing, China) at pH 5.6. All the samples were analyzed with a Multiskan MK3 microplate reader (Thermo, MA, USA). Samples were excited at 270 nm, and emission spectra were collected at 545 nm. The total amount of DPA in each individual batch was determined after autoclaving at 121°C for 20 min (Zhang et al., 2006a (link)), which was used as a positive control while the one in untreated spores was used as a negative control. HPCD-induced DPA release ratio was calculated by the equation as follows:
Where F0, F1, and F2 were the fluorescence intensity of untreated spores, HPCD-treated spores and autoclaved-spores, respectively.
Where F0, F1, and F2 were the fluorescence intensity of untreated spores, HPCD-treated spores and autoclaved-spores, respectively.
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