Effect of ohmic heating processing conditions on color stability of fungal pigments

2017 ◽  
Vol 23 (4) ◽  
pp. 338-348 ◽  
Author(s):  
Diederich Aguilar-Machado ◽  
Lourdes Morales-Oyervides ◽  
Juan C Contreras-Esquivel ◽  
Cristóbal Aguilar ◽  
Alejandro Méndez-Zavala ◽  
...  
Keyword(s):  
Ohmic Heating ◽  
Degradation Mechanism ◽  
Color Stability ◽  
Model System ◽  
Processing Conditions ◽  
Buffer Solution ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Good Thermal Stability ◽  
Heating Treatment

The aim of this work was to analyze the effect of ohmic heating processing conditions on the color stability of a red pigment extract produced by Penicillium purpurogenum GH2 suspended in a buffer solution (pH 6) and in a beverage model system (pH 4). Color stability of pigmented extract was evaluated in the range of 60–90 ℃. The degradation pattern of pigments was well described by the first-order (fractional conversion) and Bigelow model. Degradation rate constants ranged between 0.009 and 0.088 min−1 in systems evaluated. Significant differences in the rate constant values of the ohmic heating-treated samples in comparison with conventional thermal treatment suggested a possible effect of the oscillating electric field generated during ohmic heating. The thermodynamic analysis also indicated differences in the color degradation mechanism during ohmic heating specifically when the pigment was suspended in the beverage model system. In general, red pigments produced by P. purpurogenum GH2 presented good thermal stability under the range of the evaluated experimental conditions, showing potential future applications in pasteurized food matrices using ohmic heating treatment.

scholarly journals Color Stability of Phycoerythrin Crude Extract (PECE) from Rhodomonas Salina Toward Physicochemical Factors

2019 ◽  
Vol 14 (1) ◽  
pp. 21
Author(s):  
Endar Marraskuranto ◽  
Tri Joko Raharjo ◽  
Rina Sri Kasiamdari ◽  
Tri Rini Nuringtyas
Keyword(s):  
Phosphate Buffer Solution ◽  
Color Stability ◽  
Ethanol Solution ◽  
Future Application ◽  
Buffer Solution ◽  
Solution Ph ◽  
Rhodomonas Salina ◽  
Freeze Dried ◽  
Physicochemical Factors ◽  
The Stability

Rhodomonas salina produces Cr-phycoerythrin545 as its designated phycoerythrin (PE) with an absorption maximum at 545 nm and a shoulder 564 nm. PE has potential to be applied as colorants, pharmaceutical agents, and fluorescent dye tags. The stability of the PE color is influenced by the physicochemical factors of the solution. This study aimed to analyze the color stability of PECE against chemical (ethanol and pH) and physical (light and temperature) factors. PECE was prepared from freeze-dried biomass of R. salina and was extracted in phosphate buffer solution (pH = 6.0) using a freeze-thaw method in -25 oC (2 hours) and 4 oC (24 hours). The resulting extract was concentrated and dried in a freeze-dryer. Analyses were conducted using UV-visible and fluorescence spectrophotometer. PECE showed color stability against light of white fluorescent lamp exposure up to 8 hours, temperature exposure up to 40 oC, ethanol solution up to concentration of 20 % (v/v), and pH range 3.9-8.42. Results from this study can be useful for extraction, purification, and future application of Cr-PE545.

Hydrolytic and Color Stability of Resin Infiltration: A Preliminary in vitro Trial

2016 ◽  
Vol 17 (5) ◽  
pp. 377-381 ◽  
Author(s):  
Priyanshi Ritwik ◽  
Christopher M Jones ◽  
Yuwei Fan ◽  
Nikhil K Sarkar
Keyword(s):  
Weight Loss ◽  
Color Change ◽  
Color Stability ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Resin Infiltration ◽  
Dental Sealant ◽  
Group 3 ◽  
Group 2

ABSTRACT Aims Resin infiltration is an emerging technique for management of noncavitated lesions. This study evaluated the in vitro hydrolytic and color stability of the ICON® resin infiltration system (IC) in 42 extracted human teeth. Materials and methods ICON® resin infiltration system was compared with dental adhesive (DA) and dental sealant (DS). The products were applied according to manufacturer's instructions. The baseline weight and color of the samples were recorded. Color was recorded by spectoral colorimeter. The samples were subjected to four experimental conditions: (1) group 1: Stored in lactic acid solution (pH 4.9) for 24 hours; (2) group 2: Thermocycled for 100 cycles (temperatures: 5°C, 55°C, and dwell time of 15 seconds); (3) group 3: Stored in 0.1 N sodium hydroxide solution (pH 12.48) for 14 days at 60°C; (4) group 4: Stored in phosphate-buffered saline solution (pH 7.2) at 37°C for 4 months. The weight and color were recorded again after removal of the samples from the experimental conditions. Two-factor analysis of variance models and Tukey's Honestly Significant Difference were performed to assess statistical differences among the groups. Scanning electron microscopy imaging was performed for samples from groups 1, 3, and 4. Results All the samples showed loss of material and change in color. In the demineralizing solution, IC showed significantly greater weight loss (p = 0.032) and color change (p = 0.038) compared with DA. Dental Sealant showed significantly greater weight loss than IC (p = 0.027) after thermocycling. Teeth in group 3 exhibited the greatest weight loss (p < 0.001). Teeth in group 2 exhibited the greatest color change (p < 0.001). Conclusion All tested materials showed loss of retention and color change in the experimental conditions. Infiltration system exhibited greatest weight loss and color change in demineralizing solution. Dental sealant exhibited greatest weight loss upon thermocycling. Clinical significance Clinicians should be cautious about the limitations of retention and color stability when considering resin infiltration for incipient lesions. How to cite this article Ritwik P, Jones CM, Fan Y, Sarkar NK. Hydrolytic and Color Stability of Resin Infiltration: A Preliminary in vitro Trial. J Contemp Dent Pract 2016;17(5):377-381.

scholarly journals Color Characteristics and Stability of Anthocyanin in Fresh Thunbergia erecta Flower Extract

2020 ◽  
Vol 2 (02) ◽  
pp. 31
Author(s):  
Abdullah Muzi Marpaung ◽  
Rizal Pauzan Ramdhani
Keyword(s):  
Spectral Characteristic ◽  
Half Life ◽  
Color Stability ◽  
Aqueous System ◽  
Buffer Solution ◽  
Solution Ph ◽  
Flower Extract ◽  
Food Colorant ◽  
Color Characteristics

The main purpose of the present research was to evaluate the color characteristics of anthocyanin in Thunbergia erecta flower extract at various pH to know its potentiality as a food colorant. The fresh petal was macerated in 0.1 N HCl-Ethanol 96% (1:9) for an hour, filtrated and diluted in a buffer solution pH 1 to 12, then scanned by a spectrophotometer at 400 – 700 nm. The extract was almost colorless at pH 4 to 6 and show extremely low color stability at pH 7 and 8 (the half-life was 6.69 and 16.66 minutes, respectively). In contrast, the extract was very stable at pH 3. There was no significant color decrease after the extract being stored for 14 days at pH 3. An important spectral characteristic of Thunbergia erecta flower extract appeared at pH 7 to 10 by showing all the three colored species of anthocyanin. At pH 8, the red flavylium cation detected as λshoulder at around 537 nm, the purple quinonoidal base as the λpeak at 577 nm and blue anionic quinonoidal base as the λpeak at 614 nm. The unique spectral characteristic promoted the Thunbergia erecta flower as a potential anthocyanin-source to be used in the study of anthocyanin transformation in an aqueous system.

scholarly journals Electrochemical Degradation of Tetracycline Using a Ti/Ta2O5-IrO2 Anode: Performance, Kinetics, and Degradation Mechanism

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4325
Author(s):  
Hao Dong ◽  
Wanqiang Chi ◽  
Ang Gao ◽  
Tianyu Xie ◽  
Bo Gao
Keyword(s):  
Current Density ◽  
High Performance ◽  
Removal Rate ◽  
Degradation Mechanism ◽  
Influence Factors ◽  
High Volume ◽  
Electrode Spacing ◽  
Electrochemical Degradation ◽  
Solution Ph ◽  
Experimental Conditions

Tetracycline (TC) is widely used in production and in life. The high volume of its use and the difficulty of its disposal have become the most important causes of environmental pollution. A suitable method needs to be found to solve this problem. In this study, the Ti/Ta2O5-IrO2 electrode was characterized for its surface morphology and crystal composition. The electrochemical catalytic ability of the Ti/Ta2O5-IrO2 electrode was investigated using LSV and CV tests. The electrochemical degradation of tetracycline (TC) in water with a Ti/Ta2O5-IrO2 anode was investigated. The main influence factors, such as current density (2.5–10 mA/cm2), electrode spacing (20–40 mm), initial TC concentration (20–80 mg/L) and initial solution pH (4.74–9.48) were analyzed in detail and their influences on reaction kinetics was summed up. The removal rate increased along with the increasing current density, decreasing initial TC concentration and decreasing of electrode distance under the experimental conditions. The optimum pH was 4.74. UV–vis, total organic carbon (TOC) and high-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses were used to reveal the mechanism of TC degradation. Nine main intermediates were identified, and the degradation pathways were proposed. A new insight has been postulated for the safe and efficient degradation of TC using the Ti/Ta2O5-IrO2 electrode.

scholarly journals DETERMINAÇÃO COLORIMÉTRICA DE METABISSULFITO

2018 ◽  
Vol 35 (3) ◽  
pp. 133
Author(s):  
Humberto Da Silva Junior ◽  
Gutto Raffyson Silva De Freitas ◽  
Francisco Régis Da Silva Pereira ◽  
Robson Fernandes De Farias ◽  
Francisco Claudece Pereira
Keyword(s):  
Detection Limit ◽  
Absorption Band ◽  
Buffer Solution ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Real Samples ◽  
Antioxidant Agent ◽  
Visible Area

Metabisulfite anion is widely used as an antioxidant agent and preservative of anumber of industrialized products. The interaction of this agent with pararosaniline dye can reduce the absorption band of the pigment within the visible area. From the best experimental conditions such as Britton-Robinson buffer solution, pH 5.0, and dye in a solution of 1.0x10-4 mol L-1, it was possible to obtain a relation between concentration of metabisulfite and absorbance in a range from 1,3x10-6 mol L-1 to 3.0x10-5 mol L-1. The detection limit was calculated in 5.0x10-7 mol L-1. The methodology was applied on real samples.

scholarly journals Study on the fluorescence properties of the interaction between felodipine and bovine serum protein

2021 ◽  
Vol 300 ◽  
pp. 01023
Author(s):  
Shuxian Li ◽  
Jialuo Bu ◽  
Wenbin Liu ◽  
Cuijuan Liu ◽  
Yuguang Lv
Keyword(s):  
Fluorescence Quenching ◽  
Serum Protein ◽  
Bovine Serum ◽  
Control Variable ◽  
Complex Compounds ◽  
Uv Spectrophotometry ◽  
Buffer Solution ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Bovine Serum Protein

The interaction between felodipine and bovine serum protein was studied, the optimal experimental conditions were selected, and the fluorescence quenching mechanism was discussed. The interaction between filodipine and bovine serum protein was determined by UV spectrophotometry, and the optimal experimental conditions were selected by control variable method. The mechanism of fluorescence quenching in the system was explored by fluorescence spectrophotometry. The fluorescence intensity of the system between felodipine and bovine serum protein was the most obvious under the experimental conditions of buffer solution pH 7.4, felodipine concentration 8.0*10-4mol/L, reaction time 30min and 25°C. Static fluorescence quenching caused by the formation of complex compounds.

Detection of Hepatitis a Virus in Drinking Water by Enzyme -Immunoassay Using Ultracentrifugation for Virus Concentration

1985 ◽  
Vol 17 (10) ◽  
pp. 39-41 ◽  
Author(s):  
A. Schnattinger
Keyword(s):  
Membrane Filtration ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Solid Phase ◽  
Phosphate Buffer Solution ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virus Concentration ◽  
Buffer Solution ◽  
Solution Ph ◽  
Two Stage

Ten litres of tapwater were seeded with 200 µl (8×108 HAV particles) of a commercial (Organon Teknika) suspension of hepatitis A virus. Following WALTER and RÜDIGER (1981), the contaminated tapwater was treated with a two-stage technique for concentration of viruses from solutions with low virus titers. The two-stage technique consists of aluminium hydroxideflocculation (200 mg/l Al2(SO4)3. 18 H2O, pH 5,4-5,6) as first stage, the second stage of a lysis of aluminium hydroxidegel with citric acid/sodium citrate-buffer (pH 4,7; 1 ml/l sample), separation of viruses from the lysate by ultracentrifugation and suspension in 1 ml phosphate buffer solution (pH 7,2). A commercial solid phase enzyme-linked immunosorbent assay (ELISA) was used for the detection of HAV. HAV was detecterl in the 10.000:1 concentrates, but not in the seeded 101 samples. Approximately 4×108 of the inoculated 8×108 HAV particles were found in the 1 ml concentrates. The efficiency of detection is about 50%, the virus concentration 5000-fold. Although the percentage loss of HAV in comparison with concentration by means of membrane filtration is similar, the ultracentrifugation method yields a larger sample/concentrate ratio, so that smaller amounts of HAV can be detected more efficiently because of the smaller end-volume.

Development and Validation of Stability Indicating HPLC Method for the Determination of Impurities in the Sterile Mixture of Cefoperazone and Sulbactam

2019 ◽  
Vol 15 (7) ◽  
pp. 762-775
Author(s):  
Ramu Ivaturi ◽  
Thuttagunta Manikya Sastry ◽  
Satyaveni Sunkara
Keyword(s):  
Quantitative Estimation ◽  
Ammonium Hydroxide ◽  
Hplc Method ◽  
Forced Degradation ◽  
Buffer Solution ◽  
Solution Ph ◽  
Pharmaceutical Dosage Forms ◽  
Stability Indicating ◽  
Validation Parameters ◽  
Abdominal Infections

Background: Cefoperazone Sulbactam injection is a cephalosporin antibiotic with a β- lactamase inhibitor used in the treatment for intra abdominal infections, Urinary track infections, surgical infections, etc. The combination is not official in any of the pharmacopeia for their content and impurities determination. Introduction: The present study involves the development of a simple, rapid, accurate, sensitive and stability indicating RP-HPLC method for the quantitative estimation of Cefoperazone Sulbactam mixture and its impurities in bulk and pharmaceutical dosage forms. Methods: 0.005 M Tetrabutyl ammonium hydroxide buffer solution pH adjusted to 6.80 and Acetonitrile combination has been used in a gradient programme with a flow rate of 1.0 ml/min. The retention time of Cefoperazone and Sulbactam were observed at around 8.5 and 19.5 minutes respectively. The UV detection was carried out at a wavelength of 230 nm. The chromatographic separation was achieved using Waters xbridge C18-150*4.6 mm, 3.5 µm HPLC column. The method has been validated according to the current International Council for Harmonization (ICH) guidelines for the method validation parameters such as Specificity, linearity, range, accuracy, precision, robustness and sensitivity. Results: The validation results indicate that the method is specific, as the known impurities and other impurities formed during the forced degradation studies were not co-eluting with the main components. Moreover, all these impurities were found to be spectrally pure, proving the stability indicating power of the method. The linearity and range of the method is in the range of 0.01-150%, highly accurate (100.2%), precise (<1%) and robust. Conclusion: The proposed method was accurate and specific for the quantitative analysis of Cefoperazone and Sulbactam and their related impurities in the sterile mixture. Hence the proposed method can be used for the quantification of impurities in routine as well as stability analysis in the development as well as quality control laboratories.

Non-enzymatic determination of purine nucleotides using a carbon dot modified glassy carbon electrode

2019 ◽  
Vol 11 (30) ◽  
pp. 3866-3873 ◽  
Author(s):  
R. Karthikeyan ◽  
D. James Nelson ◽  
S. Abraham John
Keyword(s):  
Glassy Carbon ◽  
Low Cost ◽  
Phosphate Buffer Solution ◽  
Purine Nucleotides ◽  
Buffer Solution ◽  
Solution Ph ◽  
Carbon Dot ◽  
Enzymatic Determination ◽  
Sensitive Determination

Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.

scholarly journals Electro-Polymerized Titan Yellow Modified Carbon Paste Electrode for the Analysis of Curcumin

Surfaces ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 191-204
Author(s):  
Edwin S. D’Souza ◽  
Jamballi G. Manjunatha ◽  
Chenthattil Raril ◽  
Girish Tigari ◽  
Huligerepura J. Arpitha ◽  
...  
Keyword(s):  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Modified Carbon Paste Electrode ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Solution Ph ◽  
Real Sample Analysis ◽  
Titan Yellow ◽  
Paste Electrode

A modest, efficient, and sensitive chemically modified electrode was fabricated for sensing curcumin (CRC) through an electrochemically polymerized titan yellow (TY) modified carbon paste electrode (PTYMCPE) in phosphate buffer solution (pH 7.0). Cyclic voltammetry (CV) linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) approaches were used for CRC detection. PTYMCPE interaction with CRC suggests that the electrode exhibits admirable electrochemical response as compared to bare carbon paste electrode (BCPE). Under the optimized circumstances, a linear response of the electrode was observed for CRC in the concentration range 2 × 10−6 M to 10 × 10−6 M with a limit of detection (LOD) of 10.94 × 10−7 M. Moreover, the effort explains that the PTYMCPE electrode has a hopeful approach for the electrochemical resolution of biologically significant compounds. Additionally, the proposed electrode has demonstrated many advantages such as easy preparation, elevated sensitivity, stability, and enhanced catalytic activity, and can be successfully applied in real sample analysis.

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