Thermal degradation kinetics of total anthocyanins in açaí pulp and transient processing simulations

Abstract

The aim of this study was to investigate the thermal degradation of açaí pulp anthocyanins in experimental level and to simulate its degradation in a tubular pasteurizer starting from the transient regime. Thermal degradation was experimentally performed at 60, 70, 80, and 90 °C, in which samples were collected throughout 90 min. Anthocyanin concentration was determined using the differential pH method. The first-order kinetic model with low activation energy (42.8 kJ mol −1) and the thermodynamic parameters obtained (∆H > 0, ∆G > 0, and ∆S < 0) confirmed the high thermal stability of anthocyanin in açaí pulp. For the simulations, the mass and energy balances took into consideration a transient regime and also variation of anthocyanin concentration with the tube length. The finite difference method was used to solve the partial derivates. Were evaluated the effects of flow rate, solid content, heat exchange temperature, and tube length and diameter ratio. Our finds indicated that even considering the critical processing conditions, the losses of anthocyanins do not reach 1%, confirming its high thermal stability.

A Review of the Current Knowledge of Thermal Stability of Anthocyanins and Approaches to Their Stabilization to Heat

“…The Arrhenius plot of Equation ( 4), lnk vs. 1/T, allows the prediction of the reaction rate at a given temperature, and the calculation of E a from the slope of the line (E a /R): the lower the E a , the higher the reaction rate (anthocyanin degradation) and viceversa. Some reported activation energies (E a ) of anthocyanin degradation during heating at temperatures up to 80, 90 or 100 • C of fruits intended for juice production, are as follow: 94 [10,[27][28][29][30][31][32]. Other values of E a and in addition of k and t 1/2 are presented in Table 1 for a selection of food issues.…”

“…The Arrhenius plot of Equation (4), lnk vs. 1/ T , allows the prediction of the reaction rate at a given temperature, and the calculation of E a from the slope of the line ( E a /R): the lower the E a , the higher the reaction rate (anthocyanin degradation) and viceversa . Some reported activation energies ( E a ) of anthocyanin degradation during heating at temperatures up to 80, 90 or 100 °C of fruits intended for juice production, are as follow: 94 kJ/mol (blackcurrant), 92 kJ/mol (blueberry), 81 kJ/mol (Maqui), 68.042 kJ/mol (acerola), 66.04 or 55.81 kJ/mol (blood orange), 64.89 kJ/mol (grape), 58.95, 36.99 or 23.96 kJ/mol (blackberry), 42.8 kJ/mol (açaí), 21.6 kJ/mol (wild strawberry) [ 10 , 27 , 28 , 29 , 30 , 31 , 32 ]. Other values of E a and in addition of k and t 1/2 are presented in Table 1 for a selection of food issues.…”

Recovery of phenolic compounds from purple onion peel using bio‐based solvents: Thermal degradation kinetics and color stability of anthocyanins

“…Alteration of the disturbance of molecules in a system is determined by the parameter ∆ S . The negative values obtained for ∆ S in this study show that the transition state of the molecules has less structural freedom in relation to the reactants, providing lower reactivity (Marangoni Júnior et al, 2020; Oliveira & Antelo, 2020). Furthermore, an increase in storage temperature can increase the absolute values of ∆ S , modifying the thermodynamic equilibrium of the samples in relation to the initial system, promoting higher anthocyanin degradation rates (Qiu et al, 2018).…”

Sustainable development in the Legal Amazon: energy recovery from açaí seeds

“…Table 3 shows that the most used term was ‘ açaí ’, which is the popular name of the fruit; another most used word, either by the authors or by the WoS, is ‘ anthocyanins ’, the main bioactive compound in açaí, important due to the sensory attributes from the violet color and biological properties 56 . The presence of these substances is mainly linked to antioxidant, anti‐inflammatory, anti‐proliferative, and cardio‐protective activities 26,27 .…”