olor changes and 5-hydroxymethyl furfural formation in zile pekmezi during storage

Abstract

Zile pekmezi (white hard pekmez) is a traditional Turkish food which is produced from grape juice. Color, flavour and 5-hydroxymethyl furfural (HMF) contents are the most important quality parameters in Zile pekmezi. Browning is the most common quality problem in pekmez. In this study, reaction orders, rate constants and activation energies were evaluated for HMF formation and color difference ( ? E) variation in Zile pekmezi stored at 55, 65 and 75 °C over 9 days. The results indicated that HMF formation and ?E variation during thermal processing of Zile pekmezi followed zero order reaction kinetics at 55, 65 and 75 °C . Calculated activation energy for HMF and ?E were 158.63 kJ mol^-1 and 40.04 kJ mol^-1, respectively.