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Kinetics of the Degradation of Anthocyanins, Phenolic Acids and Flavonols During Heat Treatments of Freeze-Dried Sour Cherry Marasca Paste

Zoran Zorić1*, Verica Dragović-Uzelac2, Sandra Pedisić1, Želimir Kurtanjek2 and Ivona Elez Garofulić2

1Faculty of Food Technology and Biotechnology, University of Zagreb, Petra Kasandrića 6, HR-23000 Zadar, Croatia
2Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia

Article history:
Received June 18, 2013
Accepted December 16, 2013

Key words:
anthocyanins, phenolic acids, flavonol glycoside, freeze-drying, thermal degradation, sour cherry, Prunus cerasus var. Marasca

Summary:
The effect of heating temperature (80–120 °C) and processing time (5–50 min) on the stability of anthocyanins (cyanidin-3-glucosylrutinoside, cyanidin-3-rutinoside and cyanidin-3-glucoside), quercetin-3-glucoside and phenolic acids (chlorogenic, neochlorogenic,p-coumaric and ferulic acids) in freeze-dried Marasca sour cherry pastes was studied. The degradation rates of individual anthocyanins, quercetin-3-glucoside and phenolic acids followed the first order reaction kinetics. Cyanidin-3-glucoside was found to be the most unstable among the anthocyanins, together with p-coumaric and neochlorogenic acids among other phenols. Activation energies for anthocyanin degradation ranged from 42 (cyanidin-3-glucosylrutinoside) to 55 kJ/mol (cyanidin-3-glucoside), and for other phenols from 8.12 (chlorogenic acid) to 27 kJ/mol (neochlorogenic acid). By increasing the temperature from 80 to 120 °C, the reaction rate constant of cyanidin-3-glucosylrutinoside increased from 2.2·10–2 to 8.5·10–2 min–1, of p-coumaric acid from 1.12·10–2 to 2.5·10–2 min–1 and of quercetin-3-glucoside from 1.5·10–2 to 2.6·10–2 min–1. The obtained results demonstrate that at 80°C the half-life of anthocyanins ranges from 32.10 min for cyanidin-3-glucosylrutinoside to 45.69 min for cyanidin-3-rutinoside, and of other phenolic compounds from 43.39 for neochlorogenic acid to 66.99 min for chlorogenic acid. The results show that the heating temperature and duration affect the anthocyanins considerably more than the other phenols in terms of degradation.

 

 

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