Thermal degradation kinetics of carotenoids: Acrocomia aculeata oil in the context of nutraceutical food and bioprocess technology

In the present study, the kinetics of β-carotene and β-cryptoxanthin degradation were investigated in edible oil mechanically extracted from the mesocarp of macauba fruit. The crop has a similar productive potential to African palm (Elaeis guineensis), which is among the highest oil-yielding plants in the world. The heating process was conducted under a nitrogen atmosphere, without light exposure. Heat treatments were assumed isothermal and performed at five temperatures, ranging from 110 to 150 °C. HPLC analyses were carried out in addition to spectrophotometric determinations to monitor the carotenoid variations over the heating time. The initial composition of the oil was also highlighted for tocols, peroxide, and trace metal contents. Thermodynamic parameters were obtained from the expression of rate constant derived from transition state theory. The results indicated that the first-order kinetic model is appropriate for describing the oxidative degradation of the compounds in the macauba oil. The carotenoid concentrations decreased for all the treatments as a function of heating time, becoming faster at higher temperatures. A definite influence of temperature on the reaction rates of β-carotene and β-cryptoxanthin was determined, based on the Arrhenius model. The apparent activation energy estimated for β-cryptoxanthin (87 kJ mol−1) was higher as compared to β-carotene (80 kJ mol−1) and the sum of β-carotene + β-cryptoxanthin (84 kJ mol−1). Correlated combinations of kref and Ea indicate that the kinetic parameters estimated for overall carotenoids might predict the retention of the individual compounds with relative accuracy in the context of industrial-scale processes.