o:1627 Analiza katehina, procijanidina, makro i mikroelemenata u crnoj, mlečnoj, i beloj čokoladi i kakaou u prahu i njihov antioksidativni potencijal Analysis of catechins, procyanidins, macro, and microelements in dark, milk and whitechocolate and cocoa powder and their antioxidant potential : doctoral dissertation sr 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. The 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). Biografija sa bibliografijom: str. 295-302;Bibliografija: str. 275-294. Datum odbrane: 25.10.2019. Analytical Chemistry 1025836777 91552101 7241 91552100 1025836777 2020-02-21T12:37:03.053Z 45 no 46 mentor Jelena Mrmošanin 2019 63 mentor Snežana Tošić 2019 63 član komisije Aleksandra Pavlović 2019 63 član komisije Biljana Kaličanin 2019 63 predsednik komisije Snežana Mitić 2019 63 član komisije Milan Mitić 2019 302 str. 7487242 http://phaidrabg.bg.ac.rs/o:1627 no yes 4 2020-02-21T12:37:03.320Z 70 Kakao u prahu, crna čokolada, mlečna čokolada, bela čokolada,polifenoli, metali, antioksidativna aktivnost, cikličnavoltametrija, UV/Vis spektrofotometrija, HPLC, ICP-OES,analiza glavnih komponenata, klaster analiza Cocoa powder, dark chocolate, milk chocolate, white chocolate,polyphenols, metals, antioxidant activity, cyclic voltammetry, UV/Visspectrophotometry, HPLC, ICP-OES, principal component analysis,cluster analysis 547.56(577.118+663.91)(043.3)542.943ʼ78(577.118+663.91)(043.3) Р 003, Р 300 1738 18A07 18A0703 2019