|
|
ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Published monthly
|
TG-DTA-FTIR analysis and isoconversional reaction profiles for thermal and thermo-oxidative degradation processes in black chokeberry (Aroniamelanocarpa)
Bojan Janković, Milena Marinović-Cincović, and Marija Janković
Department for Dynamics and Matter Structure, Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12–16, P. O. Box 137, 11001 Belgrade, Serbia
E-mail: bojanjan@ffh.bg.ac.rs
Abstract: The thermal and thermo-oxidative processes in Aroniamelanocarpa (black chokeberry) were investigated using combined thermo-analytical (TG-DTA) and spectroscopic (FTIR) experimental techniques. Isoconversional analysis revealed that the process in an inert (argon) atmosphere was probably governed by chlorogenic acid degradation, where autocatalysis (described by the empirical Šesták–Berggren model) might occur due to water already present in the early stages of the process through hydrolysis. Thermal degradation is described by the intrinsic kinetic parameters, where the degradation rate increases proportionally with an increase in the heating rate. Under oxidative conditions, the process was found to be primarily driven by neochlorogenic acid degradation. The thermo-oxidative degradation of Aroniamelanocarpa fresh samples can be described by two competitive reactions, where it was established that a cyanidin-3-glucosylrutinoside degradation made a significant contribution to a comprehensive kinetics. This study showed the targeting of the neochlorogenic acid in Aroniamelanocarpa fresh samples to have a strong hydrogen-donating activity, thereby rendering it capable of very efficiently entrapping the peroxy radicals. Current research has demonstrated that the relative contribution of the two competitive reactions to the overall process is highly dependent on the heating rate of the system under consideration.
Keywords: black chokeberry thermal stress – TG-FTIR – intrinsic kinetic parameters – autocatalytic mechanism – hydrogen-donating activity – competitive reactions
Full paper is available at www.springerlink.com.
DOI: 10.1515/chempap-2016-0046
Chemical Papers 70 (8) 1094–1105 (2016)
|