Analiza katehina, procijanidina, makro i mikroelemenata u crnoj, mlečnoj, i beloj čokoladi i kakaou u prahu i njihov antioksidativni potencijal
Author
Mrmošanin, JelenaMentor
Tošić, SnežanaCommittee members
Pavlović, AleksandraKaličanin, Biljana
Mitić, Snežana
Mitić, Milan
Metadata
Show full item recordAbstract
The aim of this doctoral dissertation was то determinе the chemical
composition, as well as то investigatе of the antioxidative activity of
white, milk, dark chocolate and cocoa powder samples. The total
polyphenols, flavonoids, as well as total and monomer anthocyanins,
were determined using UV/Vis spectrophotometry.
Spectrophotometric methods (ABTS, DPPH, FRAP, and PFRAP) and
electrochemistry method – cyclic voltammetry (CV) were used to test
antioxidant activity. Тhere were three anode peaks оn cyclic
voltammograms. The first and the third anodic current peaks can be
ascribed to the oxidation of catechin-type flavonoids, while the
second peak can be ascribed to the oxidation of phenolic acids.
Procyanidins did not show any visible waves. The highest antioxidant
activity was present in dark chocolate and cocoa powder samples,
followed by milk and white chocolate samples. This is in agreement
with the total content of polyphenols and flavonoids in the tested
samples. Th...e identification and quantification of polyphenolic
compounds (protocatechuic acid, (+)-catechin, (-)-epicatechin,
procyanidins B1, B2, B3 and B4, cyanidin-3-O-galactoside and
cyanidin-3-O-arabinoside) and alkaloid theobromine were carried out
using HPLC chromatography. The influence of storage temperature (4
°С – 35 °С) and thermal processing (95 °С – 125 °С) on the stability
of catechin-type flavonoids, total flavonoids, and anthocyanins in
dark chocolate and cocoa powder samples was also studied. During
storage and heating, the cocoa powder and dark chocolate flavonoids
and anthocyanins degraded more quickly with an increase in
temperature. To determine macro and microelements, the ICP-OES
methods were optimized and validated. Among macroelements, K is
most abudant in the samples of cocoa powder, followed by samples of
dark, milk and white chocolate. This suggests that the content of K is
directly related to the contribution of cocoa parts. After K, the content
of P, Ca, Na, Mg is highest in white chocolate, followed by the milk
chocolate, dark chocolate, and cocoa powder samples. Among the
microelements, the most abundant are Fe, Si, and Zn. The content of
potentially toxic metals, Pb and Cd, is below the maximum
permissible levels (MPL) prescribed by national and world
regulations. The differentiation of the tested samples based on the
content of metals and polyphenol compounds, as well as based on
their antioxidative activity, was done using principal component
analysis (PCA) and cluster analysis (CA).
Faculty:
Универзитет у Нишу, Природно-математички факултетDate:
25-10-2019Projects:
- Natural products of plants and lichens: isolation, identification, biological activity and application (RS-MESTD-Basic Research (BR or ON)-172047)
- Development of new and improvement of existing electrochemical, spectroscopic and flow injection (FIA) methods on environmental quality monitoring (RS-MESTD-Basic Research (BR or ON)-172051)