scholarly journals Thermal stability of anthocyanin in mixed raspberry-pomegranate-banana nectar in the presence of ascorbic acid and citric acid

Author(s):  
Thuy Nguyen Minh ◽  
Han Lu Ngoc ◽  
Tai Ngo Van
2011 ◽  
Vol 694 ◽  
pp. 73-78
Author(s):  
Dan Li

Hydrophobic silver nanoparticles have been carried out by use of ascorbic acid in cyclohexylamine and aqueous medium. Nanosilver can be effectively coated with oleic acid and possesses oil-soluble property. Oleic acid as an extractant is also effective at stabilizing particles of similar size in an oil phase when the AgNO3 is reduced in a coexisting aqueous phase. Stable spherical silver nanoparticles 15~25 nm in diameter with a well-crystallized structure were obtained at 120 °C. The thermal stability of surface-coated silver prepared in cyclohexylamine solution was monitored by UV-vis spectral analysis.


2011 ◽  
Vol 59 (5) ◽  
pp. 1774-1783 ◽  
Author(s):  
Michael Wawire ◽  
Indrawati Oey ◽  
Francis Mathooko ◽  
Charles Njoroge ◽  
Douglas Shitanda ◽  
...  

2019 ◽  
Vol 86 ◽  
pp. 116-123 ◽  
Author(s):  
Xue-Jiao Xu ◽  
Sheng Fang ◽  
Yan-Hua Li ◽  
Fan Zhang ◽  
Zhi-Peng Shao ◽  
...  

2010 ◽  
pp. NA-NA ◽  
Author(s):  
A. S. El-Khouly ◽  
Y. Takahashi ◽  
A. Takada ◽  
A. A. Safaan ◽  
E. Kenawy ◽  
...  

2018 ◽  
Vol 3 (1) ◽  
pp. 50-59
Author(s):  
S. Hassan ◽  
F. Adam ◽  
M.R. Abu Bakar

Melting temperature (Tmelt) and enthalpy of fussion (ΔHf ) are important parameters to determine the quality and the thermal stability of active pharmaceutical ingredient (API) crystals. In this study, different habit of ascorbic acid was prepared by using different polar solvents namely water, methanol, ethanol and 2-propanol. Ascorbic acid crystal was then been physically and thermally characterised by using microscopic analysis, thermo gravimetric analysis (TGA) and differential scanning calometry analysis (DSC). This provides an insight into the formation of crystal habit across four different polar protic solvents. The ascorbic acid is found to grow as a cubic or prism crystal when grown in water that provides high hydrogen bond between solvent and solute. As the polarity of the solvents decrease, the hydrogen bond weaken and the width of the crystal become narrower, forming almost a needle like crystal. The thermal stability of ascorbic acid crystal is found to be the most stable when ascorbic acid is crystallized from water (prism) and the weakest from 2-propanol (needle) due to the molecule arrangement in crystal lattice in which resulted from decreasing intermolecular forces in the liquid phase


Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2872 ◽  
Author(s):  
Pabla A. Barra ◽  
Katherine Márquez ◽  
Oscar Gil-Castell ◽  
Javiera Mujica ◽  
Amparo Ribes-Greus ◽  
...  

The potential of sodium alginate (ALG) and gum arabic (GA) as wall polymers for L-ascorbic acid (AA) encapsulation as a tool for their preservation against the thermo-oxidative degradation was investigated. The influence of such polymers used as wall material on the AA-content, size, encapsulation efficiency, encapsulation yield and thermo-oxidative stability were evaluated. The AA-microparticles were obtained using the spray-drying technique. An experimental Taguchi design was employed to assess the influence of the variables in the encapsulation process. The microparticles morphology and size distribution were characterized by scanning electron microscopy and laser diffraction. The thermal stability of AA microparticles was studied by differential scanning calorimetry and thermogravimetry analysis. This work points out the viability to encapsulate AA using GA and ALG through a spray-drying process. In general, a product yield ranging from 35.1% to 83.2% and an encapsulation efficiency above 90% were reached. Spherical microparticles with a smooth surface were obtained with a mean diameter around 6 μm and 9 μm for the those prepared with GA and ALG, respectively. The thermo-oxidative analysis showed that both polymers allow maintaining AA stable up to 188 °C, which is higher than the traditional processing temperature used in the fish feed industry.


Author(s):  
Pabla Barra ◽  
Katherine Márquez ◽  
Oscar Gil-Castell ◽  
Javiera Mujica ◽  
Amparo Ribes-Greus ◽  
...  

The potential of sodium alginate (ALG) and gum arabic (GA) as wall polymers for L-ascorbic acid (AA) encapsulation as a tool for their preservation against the thermo-oxidative degradation was investigated. The influence of such polymers used as wall material on the AA-content, size, encapsulation efficiency, encapsulation yield and thermo-oxidative stability were evaluated. The AA-microparticles were obtained using the spray-drying technique. An experimental Taguchi design was employed to assess the influence of the variables in the encapsulation process. The microparticles morphology and size distribution were characterized by scanning electron microscopy and laser diffraction. The thermal stability of AA microparticles was studied by differential scanning calorimetry and thermogravimetry analysis. This work points out the viability to encapsulate AA using GA and ALG through a spray-drying process. In general, a product yield ranging from 35.1% to 83.2% and an encapsulation efficiency above 90% was reached. Spherical microparticles with a smooth surface were obtained with a mean diameter around 6 μm and 9 μm for the those prepared with GA and ALG, respectively. The thermo-oxidative analysis showed that both polymers allow maintaining AA stable up to 188 °C, which is higher than the traditional processing temperature used in the fish feed industry.


2010 ◽  
Vol 75 (4) ◽  
pp. C336-C340 ◽  
Author(s):  
Ann Wambui Munyaka ◽  
Edna Edward Makule ◽  
Indrawati Oey ◽  
Ann Van Loey ◽  
Marc Hendrickx

Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization


Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.


Sign in / Sign up

Export Citation Format

Share Document