scholarly journals The effect of storage temperature and thermal processing on catechins, procyanidins and total flavonoid stability in commercially available cocoa powders

2015 ◽  
Vol 13 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Jelena Mrmosanin ◽  
Aleksandra Pavlovic ◽  
Jovana Veljkovic ◽  
Snezana Mitic ◽  
Snezana Tosic ◽  
...  
Keyword(s):  
Room Temperature ◽  
Storage Temperature ◽  
Total Flavonoids ◽  
Order Kinetic ◽  
First Order ◽  
Temperature Range ◽  
Powder Samples ◽  
Order Kinetic Model ◽  
Calculated Activation ◽  
Thermal Stability Of

Storage stability of catechin, epicatechin, procyanidins B1-B4 and total flavonoids in cocoa powder samples was studied over the temperature range 4-35?C. Thermal stability of total flavonoids was studied over the temperature range 95-125?C. Total flavonoids concentration decreased as a function of time and the degradation was accelerated at higher temperatures: a half-life (t1/2) of total flavonoids was much shorter at room temperature than during cold storage. A first-order kinetic model fitted well to all the data. Temperature dependence of the degradation rate constants, described by the Arrhenius equation, was more pronounced during heating than during storage. In the temperature interval from 4?C to 35?C, the calculated activation energies (Ea) for catechin, epicatechin and procyanidins B1-B4 were 20.4 kJ/mol, 12.5 kJ/mol, 9.4 kJ/mol, 21.6 kJ/mol, 19.4 kJ/mol, 23.7 kJ/mol, respectively.

scholarly journals Thermostability of the visual color and anthocyanins from Rio-Grande-Cherry (Eugenia involucrata DC)

2020 ◽  
Vol 23 ◽  
Author(s):  
Lauren Menegon de Oliveira ◽  
Francine Antelo
Keyword(s):  
Rio Grande ◽  
Color Difference ◽  
Order Kinetic ◽  
First Order ◽  
Color Parameters ◽  
Visual Color ◽  
Order Kinetic Model ◽  
Degradation Reaction ◽  
Thermal Stability Of ◽  
Total Color Difference

Abstract The extract of Rio-Grande-Cherry (Eugenia involucrata DC), pure and with stevia addition (0.75% and 1.5%) and sucrose addition (20% and 40%), was subjected to heat treatment at 10 °C, 25 °C and between 50 °C and 90 °C. Anthocyanins and the color parameters C* and TCD (total color difference) followed first-order reaction kinetics while h° followed a zero order kinetic model, under all conditions. The addition of sweeteners, through the reduction of water activity, influenced the thermal stability of the anthocyanins and of the color parameters C*, h° and TCD was the most pronounced effect in the latter. The lower the temperatures, the most relevant was the effect of the sweeteners on increasing half-life. Thermodynamically, the degradation reaction of anthocyanins was defined as endothermic, as well as non-spontaneous and transition state of the molecules more structurally organized than the reactants.

Kinetics of bioactive compounds in functional spice Jiangpo during thermal processing

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Xiaoyan Dai ◽  
Chenhuan Yu ◽  
Qiaofeng Wu
Keyword(s):  
Kinetic Parameters ◽  
Bioactive Compounds ◽  
Thermal Processing ◽  
Order Rate Constant ◽  
Heat Processing ◽  
Order Kinetic ◽  
Time Intervals ◽  
First Order ◽  
Order Kinetic Model ◽  
Kinetics Of

Abstract Jiangpo is an increasingly popular East Asian spice which is made from Mangnolia officinalis bark and ginger juice. Since it induces bioactive compounds decomposition and has influence on final flavor and fragrance, cooking is regarded as the key operation in preparation of Jiangpo. To evaluate the bioactive compounds content changes of Jiangpo during thermal processing, kinetic parameters including reaction order, rate constant, T1/2 and activation energy of bioactive markers namely honokiol, magnolol and curcumin were determined. Cooking was set at temperatures 60, 90 and 120 °C for selected time intervals. Results displayed the thermal kinetic characteristics of the three compounds. Thermal degradation of Honokiol and magnolol both followed first order kinetic model and the loss of curcumin fitted second order. A mathematical model based on the obtained kinetic parameters has also been developed to predict the degradation of honokiol, magnolol and curcumin in non-isothermal state. All the information in this paper could contribute necessary information for optimizing the existing heat processing of Jiangpo.

scholarly journals Municipal Leachate Treatment by Fenton Process: Effect of Some Variable and Kinetics

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mohammad Ahmadian ◽  
Sohyla Reshadat ◽  
Nader Yousefi ◽  
Seyed Hamed Mirhossieni ◽  
Mohammad Reza Zare ◽  
...  
Keyword(s):  
Reaction Time ◽  
Color Removal ◽  
Molar Ratio ◽  
Order Kinetic ◽  
Fenton Process ◽  
Solution Ph ◽  
Leachate Treatment ◽  
First Order ◽  
Order Kinetic Model ◽  
Better Than

Due to complex composition of leachate, the comprehensive leachate treatment methods have been not demonstrated. Moreover, the improper management of leachate can lead to many environmental problems. The aim of this study was application of Fenton process for decreasing the major pollutants of landfill leachate on Kermanshah city. The leachate was collected from Kermanshah landfill site and treated by Fenton process. The effect of various parameters including solution pH, Fe2+and H2O2dosage, Fe2+/H2O2molar ratio, and reaction time was investigated. The result showed that with increasing Fe2+and H2O2dosage, Fe2+/H2O2molar ratio, and reaction time, the COD, TOC, TSS, and color removal increased. The maximum COD, TOC, TSS, and color removal were obtained at low pH (pH: 3). The kinetic data were analyzed in term of zero-order, first-order, and second-order expressions. First-order kinetic model described the removal of COD, TOC, TSS, and color from leachate better than two other kinetic models. In spite of extremely difficulty of leachate treatment, the previous results seem rather encouraging on the application of Fenton’s oxidation.

Performance of poly-o-phenylenediamine and its carbon dot composite electrode in the removal of Cu2+ from its aqueous solution

2021 ◽  
pp. 2151037
Author(s):  
Yu Meng ◽  
Qing Zhong ◽  
Arzugul Muslim
Keyword(s):  
Aqueous Solution ◽  
Electrochemical Reduction ◽  
Composite Electrode ◽  
Reduction Process ◽  
Order Kinetic ◽  
Carbon Dot ◽  
First Order ◽  
Oxidation Reduction ◽  
Order Kinetic Model ◽  
Optimal Ph

Because −NH2 and −NH− in poly-[Formula: see text]-phenylenediamine (P[Formula: see text]PD) can interact strongly with the empty orbitals of Cu to show unique electrochemical activity, P[Formula: see text]PD is suitable for the removal of Cu[Formula: see text] by electrochemical oxidation–reduction process. In this study, with P[Formula: see text]PD and its carbon dot composite (CDs/P[Formula: see text]PD) as working electrodes, the electrochemical reduction and removal of Cu[Formula: see text] in the aqueous solution were carried out with the potentiostatic method. According to effects of voltage, pH of the solution, initial concentration of Cu[Formula: see text], and electrochemical reduction time on the Cu[Formula: see text] removal, the Cu[Formula: see text] removal ratios of P[Formula: see text]PD and CDs/P[Formula: see text]PD were up to 64.69% and 73.34%, respectively, at −0.2 V and the optimal pH. Additionally, results showed that these processes were in line with the quasi-first order kinetic model. Both P[Formula: see text]PD and CDs/P[Formula: see text]PD showed good reproducibility in six cycles. After five times of repeated usage, the regeneration efficiencies of P[Formula: see text]PD and CDs/P[Formula: see text]PD dropped to 77.04% and 79.36%, respectively.

scholarly journals Effects of heat treatment and storage temperature on the use of açaí drink by nutraceutical and beverage industries

2012 ◽  
Vol 32 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Tatiane Regina Albarici ◽  
José Dalton Cruz Pessoa
Keyword(s):  
Temperature Effect ◽  
Storage Temperature ◽  
Life Time ◽  
Reaction Rate Constant ◽  
Anthocyanin Content ◽  
Order Kinetic ◽  
First Order ◽  
The Stability ◽  
And Storage ◽  
Anthocyanin Degradation

This study assesses the storage temperature effect on the anthocyanins of pasteurized and unpasteurized açaí pulp. The data was obtained using a pasteurized and lyophilized pulp (PLP) to evaluate the temperature effect (0, 25, and 40 °C). Part of non-pasteurized frozen pulp (NPP) was pasteurized (NPP-P) at 90 °C for 30 seconds; both pulps were stored at 40 °C. The anthocyanin content reduction in the drink was evaluated from the half-life time (t1/2), activation energy (Ea), temperature quotient (Q10), and the reaction rate constant (k). The t1/2 of the PLP anthocyanins stored at 40 °C was 1.8 times less than that stored at 25 °C and 15 times less than that stored at 0 °C; therefore, the higher temperatures decreased the stability of anthocyanins. The pasteurization increased the t1/2 by 6.6 times (10.14 hours for NPP and 67.28 hours for NPP-P). The anthocyanin degradation on NPP-P followed a first order kinetic, while NPP followed a second order kinetic; thus it can be said that the pasteurization process can improve the preservation of anthocyanins in the pulp.

scholarly journals Enhanced photocatalytic activity of wool-ball-like TiO2 microspheres on carbon fabric and FTO substrates

2018 ◽  
Vol 38 ◽  
pp. 02014
Author(s):  
Yu Zhang ◽  
Jian Gu ◽  
Mengqi Zhang
Keyword(s):  
Hydrothermal Method ◽  
Order Kinetic ◽  
Carbon Fabric ◽  
Facile Hydrothermal Method ◽  
Sem Images ◽  
First Order ◽  
Good Crystallinity ◽  
Degradation Rate Constant ◽  
Order Kinetic Model ◽  
Pseudo First Order

The wool-ball-like TiO2 microspheres on carbon fabric (TiO2-CF) and FTO substrates (TiO2-FTO) have been synthesized by a facile hydrothermal method in alkali environment, using commercial TiO2 (P25) as precursors. The XRD results indicate that the as-prepared TiO2 have good crystallinity. And the SEM images show that the wool-ball-like TiO2 microspheres with a diameter of 2-3 μm are composed of TiO2 nanowires, which have a diameter of ~50 nm. The photocatalytic behavior of the wool-ball-like TiO2 microspheres, TiO2-CF and TiO2-FTO under ultraviolet light was investigated by a pseudo first-order kinetic model, using methyl orange (MO) as pollutant. The wool-ball-like TiO2 microspheres obtained a degradation rate constant (Kap) of 6.91×10-3 min-1 . The Kap values of TiO2-FTO and TiO2-CF reach 13.97×10-3 min-1 and 11.80×10-3 min-1, which are 2.0 and 1.7 times higher than that of pristine wool-ball-like TiO2 microspheres due to the “sum effect” between TiO2 and substrates. This study offers a facile hydrothermal method to prepare wool-ball-like TiO2 microspheres on CF and FTO substrates, which will improve the recyclability of phtocatalysts and can be extended to other fields.

APPLICATION OF CVD DIAMOND FILMS FOR UV THERMOLUMINESCENCE DOSIMETER

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1003-1007 ◽  
Author(s):  
J. AHN ◽  
B. GAN ◽  
Q. ZHANG ◽  
S. F. YOON ◽  
V. LIGATCHEV ◽  
...  
Keyword(s):  
Activation Energy ◽  
Glow Curve ◽  
Diamond Films ◽  
Frequency Factor ◽  
Cvd Diamond ◽  
Order Kinetic ◽  
First Order ◽  
Order Kinetic Model ◽  
Ionizing Radiations ◽  
Trap Activation

This study presents the investigation of CVD diamond for the application of an UV TL dosimeter. A 9-μm-thick film used in this study presents a TL glow curve with a well-defined first-order kinetic peak (at about 273 K), which norm ally presents in the glow curve from ionizing radiations, is not observed. By fitting the glow curve to a first-order kinetic model, the trap activation energy E t = 0.95 eV and frequency factor s = 5.6 x 106 s -1 have been resolved.

scholarly journals Waste to Carbon: Influence of Structural Modification on VOC Emission Kinetics from Stored Carbonized Refuse-Derived Fuel

2019 ◽  
Vol 11 (3) ◽  
pp. 935 ◽  
Author(s):  
Andrzej Białowiec ◽  
Monika Micuda ◽  
Antoni Szumny ◽  
Jacek Łyczko ◽  
Jacek Koziel
Keyword(s):  
Structural Modification ◽  
Solid Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Order Kinetic ◽  
Voc Emissions ◽  
Voc Emission ◽  
First Order ◽  
Refuse Derived Fuel ◽  
Volatile Organic ◽  
Order Kinetic Model

The torrefaction of municipal solid waste is one of the solutions related to the Waste to Carbon concept, where high-quality fuel—carbonized refuse-derived fuel (CRDF)—is produced. An identified potential problem is the emission of volatile organic compounds (VOCs) during CRDF storage. Kinetic emission parameters have not yet been determined. It was also shown that CRDF can be pelletized for energy densification and reduced volume during storage and transportation. Thus, our working hypothesis was that structural modification (via pelletization) might mitigate VOC emissions and influence emission kinetics during CRDF storage. Two scenarios of CRDF structural modification on VOC emission kinetics were tested, (i) pelletization and (ii) pelletization with 10% binder addition and compared to ground (loose) CRDF (control). VOC emissions from simulated sealed CRDF storage were measured with headspace solid-phase microextraction and gas chromatography–mass spectrometry. It was found that total VOC emissions from stored CRDF follow the first-order kinetic model for both ground and pelletized material, while individual VOC emissions may deviate from this model. Pelletization significantly decreased (63%~86%) the maximum total VOC emission potential from stored CDRF. Research on improved sustainable CRDF storage is warranted. This could involve VOC emission mechanisms and environmental-risk management.

scholarly journals Zeolite-Based Fast-Responding Sensors for Respiratory Rate Monitoring

Proceedings ◽  
2019 ◽  
Vol 42 (1) ◽  
pp. 9
Author(s):  
Gianfranco Carotenuto ◽  
Carlo Camerlingo
Keyword(s):  
Kinetic Analysis ◽  
Water Concentration ◽  
Adsorbed Water ◽  
Current Intensity ◽  
Specific Rate ◽  
Order Kinetic ◽  
First Order ◽  
Order Kinetic Model ◽  
Water Sensor ◽  
Breath Monitoring

Wearable electrical sensors based on zeolites can be used for breath monitoring. The high silicon content of clinoptilolite makes this type of zeolite very adequate for fabricating sensitive water sensors. In addition to sensitivity, response fastness also represents a sensor characteristic of fundamental importance for breath monitoring. Here, the response fastness of a clinoptilolite-based water sensor has been evaluated by measuring the current intensity behavior upon exposition to a constant humidity atmosphere (75%). In particular, the clinoptilolite surface has been biased with a sinusoidal signal (20 Vpp, 5 kHz), and the true-RMS current intensity value has been recorded during exposition to the constant humidity atmosphere. Since current intensity is proportional to the adsorbed water concentration (only hydrated cations are charge carriers) a kinetic analysis has been possible. The clinoptilolite dehydration kinetics in a dry atmosphere have been evaluated too. According to this kinetic analysis, water adsorption is described by a Lagergren pseudo-first-order model with a rate constant of (58.6 ± 0.9)·10−4 min−1, while desorption in dry air follows a first-order kinetic model with a specific rate of (202.7 ± 0.3)·10−4 min−1 at 25 °C.

Sign in / Sign up

Export Citation Format

Share Document