The effect of storage temperature and thermal processing on catechins, procyanidins and total flavonoid stability in commercially available cocoa powders

Abstract

Storage stability of catechin, epicatechin, procyanidins B1-B4 and total flavonoids in cocoa powder samples was studied over the temperature range 4-35 oC. Thermal stability of total flavonoids was studied over the temperature range 95-125 oC. Total flavonoids concentration decreased as a function of time and the degradation was accelerated at higher temperatures: a half-life (t 1/2 ) of total flavonoids was much shorter at room temperature than during cold storage. A first-order kinetic model fitted well to all the data. Temperature dependence of the degradation rate constants, described by the Arrhenius equation, was more pronounced during heating than during storage. In the temperature interval from 4 oC to 35 oC, the calculated activation energies (E a ) for catechin, epicatechin and procyanidins B1-B4 were 20.4 kJ/mol, 12.5 kJ/mol, 9.4 kJ/mol, 21.6 kJ/mol, 19.4 kJ/mol, 23.7 kJ/mol, respectively. UTICAJ TEMPERTURE CUVANJA I ZAGREVANJA NA SADRŽAJ KATEHINA; PROCIJANIDINA I UKUPNIH FENOLA KOMERCIJALNIM UZORCIMA KAKAOA U PRAHU Uticaj temperature cuvanja na stabilnost katehina, epikatehina, procijanidina B1-B4 i ukupnih flavonoida u uzorcima kakaoa u prahu pracen je u temperaturnom opsegu od 4 oC do 35 oC. Uticaj zagrevanja na sadržaj ukupnih flavonoida je pracen u temperaturnom opsegu od 95 oC do 125 oC. U toku skladistenja uzoraka je doslo do smanjenja u sadržaju ukupnih flavonoida. Pomenuta promena je bila izraženija na visim temperaturama: vreme polu-života (t 1/2 ) ukupnih flavonoida u ispitivanom uzorku kakaoa u prahu bilo je krace kada je on cuvan na sobnoj temperaturi nego kada je cuvan u frižideru. Promene u sadržaju flavonoida u ispitivanim uzorcima prate kinetiku prvog reda. Konstante brzine degradacije, izracunate pomocu Arenijusove jednacine, vece su tokom zagrevanja nego tokom cuvanja ispitivanih uzoraka na nižim temperaturama. Izracunate energije aktivacije (E a ) za katehin, epikatehin i procijanidine B1, B2, B3 i B4 u temperaturnom intevalu od 4 oC do 35 oC  bile su: 20,4 kJ/mol, 12,5 kJ/mol, 9,4 kJ/mol, 21,6 kJ/mol, 19,4 kJ/mol i 23,7 kJ/mol. HIGHLIGHTS Storage stability of (epi)catechin, procyanidins B1-B4 and total flavonoids in cocoa powder samples was studied(temperature range 4-35 °C) The stability of the total flavonoids was studied over the temperature range 95-125 °C The degradation of the total flavonoids was significantly accelerated at higher temperatures Temperature dependence of the degradation rate constants was more pronounced during heating than during storage