Identification and Thermal Degradation Kinetics of Chlorophyll Pigments and Ascorbic Acid from Ditax Nectar (Detarium senegalense J.F. Gmel)

Abstract

Detarium senegalense J.F. Gmel (ditax) is a forest tree found in Senegal the fruits of which are characterized by an attractive green flesh with a high amount in ascorbic acid. It is generally consumed as a nectar in Senegal. In this study, the main pigments of ditax pulp were identified and quantified by HPLC-DAD. Pheophytin a (128 mg/kg), which represents 58% of the total pigments, followed by hydroxypheophytin a' (33 mg/kg), chlorophyll b (24 mg/kg), and chlorophyll a (20 mg/kg) was the major pigment of ditax pulp. Lutein and β-carotene were present in lower amounts (4.6 and 3.6 mg/kg, respectively). The thermal degradation kinetics of pheophytin a, hydroxypheophytin a', and ascorbic acid were determined at temperatures ranging from 60 to 95 °C in ditax nectar. Pheophytin a was the most heat sensitive. Thermal processing induced the formation of degradation products such as pyropheophytin a and pyropheophytin b. The kinetics parameters have been calculated according to the models of Arrhenius, Eyring, and Ball. Following the Arrhenius relation, activation energies of pheophytin a, hydroxypheophytin a', and ascorbic acid were, respectively, 79, 74, and 46 kJ mol(-1). Losses calculated during isothermal treatments were close to experimental losses in pheophytin a, hydroxypheophytin a', and ascorbic acid. The Eyring model can then be used to predict chlorophyll pigments and vitamin C losses during pasteurization of the nectar (<10%).

Drying kinetics and thermal degradation of phenolic compounds and anthocyanins in pomegranate arils dried under vacuum conditions

“…This is also reflected with the decrease of t 1/2 values with increasing temperature (Table ). Similar results were also determined by the authors studied anthocyanin, vitamin C and for other bioactive compounds' degradation kinetics for various food materials (Erenturk et al ., ; Verbeyst et al ., ; Ndiaye et al ., ). Figs and demonstrate the effect of temperature on the rate constants estimated by Arrhenius and Eyring–Polanyi equations to TPC and TA loss in arils.…”

“…Degradation rate constants were estimated using first-order kinetic model. Arrhenius model is the classic approach used for chemical reactions and often considered as reference, and Eyring-Polanyi model is based on the transition state theory (Cisse et al, 2009;Ndiaye et al, 2011). Drying equipment and pretreatment condition dependence of the degradation rate constants were expressed as activation energies, enthalpy and entropy according to Arrhenius (eqn 8) and Eyring (eqn 9) equations.…”

“…Eyring-Polanyi model is based on the transition state theory in which the enthalpy of activation (DH*) and entropy of activation (DS*) are the model parameters (Cisse et al, 2009). Eyring-Polanyi model was applied in various thermal degradation studies, such as thermal degradation kinetics of anthocyanins from blood orange, blackberry, roselle (Cisse et al, 2009) and thermal degradation kinetics of chlorophyll pigments and ascorbic acid in ditax nectar (Ndiaye et al, 2011).…”

Effect of heat exposure on the colour intensity of red pigments produced by Penicillium purpurogenum GH2

“…Many authors have stated that thermal colour degradation also follows first order kinetics (Yoon et al, 2003;Sharma et al, 2008;Ndiaye et al, 2011). The important measure of quality for red pigments is the intensity of its red colour.…”

“…Reyes and Cisneros-Zevallos (2007) reported D values of 50-108 h at 80°C for the thermal stability of anthocyanins of purple and red-flesh potatoes in aqueous extracts, which would be much more stable. Ndiaye et al (2011) studied the thermal degradation kinetics of chlorophyll pigments and found values of 91-6 h at a temperature range of 60-95°C, which corresponds to a higher sensitivity to temperature than Table 3 indicates (lower value of z, or around 20°C only), so those pigments would be less stable than the ones used in this work at higher temperatures (from Table 1, D values at 60 and 95°C would be 42.7 and 8.7 h), and would be the same at 72°C.…”