The Temperature Influence on Drying Kinetics and Physico-Chemical Properties of Pomegranate Peels and Seeds

Abstract

Pomegranate is a fruit desirable for its nutritional and medicinal properties which has a great industrial potential that is yet under-explored. Notable for its integral use, the peels are used in medicinal infusions and the seeds consumed without restrictions. In this sense, the objective of this work is to determine the drying kinetics of pomegranate peels and seeds in a hot air circulation oven, at temperatures of 50, 60, and 70 °C, adjust mathematical models to experimental data, determine the effective diffusivities and thermodynamic properties of the process and the physicochemical characteristics of peels and seeds of fresh pomegranates and in their flours. Twelve models were used to adjust the drying kinetics, obtaining better results with the Diffusion Approximation model, Verma, and modified Henderson and Pabis. The effective diffusivities were well represented by an Arrhenius equation, with activation energies of 31.39 kJ/mol for seeds and 10.60 kJ/mol for peels. In the drying process, the seeds showed higher values of enthalpy, entropy, and Gibbs free energy concerning peels. Pomegranate peel and seed flours have proximal composition and distinct physicochemical characteristics, with high fiber, carbohydrate, and energy content. In addition, peel flours stand out for their mineral content, and seed flours do for their lipid and protein content.

Drying Kinetics of Industrial Pineapple Waste: Effective Diffusivity and Thermodynamic Properties Resulting from New Mathematical Models Derived from the Fick Equation

“…The results of this study are in line with the findings of Araújo et al (2017) for peanut drying [31], Guimarães et al (2018) for okara drying [32], Quequeto et al (2019) for noni seed drying [33], Almeida et al (2020) for azuki bean drying [34], Gilago et al (2023) for carrot slice drying [26], and Wanderley et al (2023) for pomegranate peel and seed drying [24]. These authors also observed an increase in Gibbs free energy with an increase in the drying air temperature.…”

“…Additionally, Wanderley et al (2023) investigated the drying kinetics of pomegranate peels and seeds. They reported effective diffusion coefficients of 3.758 × 10 −12 to 4.680 × 10 −12 m 2 s −1 and 1.3106 × 10 −9 to 2.591 × 10 −9 m 2 s −1 for temperatures ranging from 50 to 70 • C [24]. The Fick diffusion model for a flat plate geometry was used to determine effective diffusivity in these studies.…”

Developing ultrasound‐assisted infrared drying technology for bitter melon (Momordica charantia)

“…For this reason, the enthalpy value for the control sample at the dry temperature was higher 50°C with a distance of 20 cm from the infrared lamps (36.06 kJ.mol −1 ), and the lowest value for the sample under ultrasound treatment for 20 min at a temperature of 70°C, and with a distance of 10 cm from the infrared lamps (10.93 kJ.mol −1 ) was obtained. Almost similar values in dried okra 79.31–32.04 kJ.mol −1 (Ovando‐Medina, 2023; Santos et al, 2022), dried pomegranate peels, and seeds 28.53–70.28 kJ.mol −1 (Wanderley et al, 2023), different varieties of coconut from 12.58 to 22.31 kJ.mol −1 (Sarpong et al, 2022), and dried sweet potato from 24.20 to 24.37 kJ.mol −1 (Rashid et al, 2020). Entropy evaluates the movement of absorbed water molecules, and shows the level of interactions between water, and food.…”

Smelling Peppers and Pout Submitted to Convective Drying: Mathematical Modeling, Thermodynamic Properties and Proximal Composition

“…The thermodynamic properties (enthalpy, entropy, and Gibbs free energy) of the seed drying process at temperatures of 50, 60, 70, and 80 • C were quantified using the method described by Wanderley et al [20], according to Equations ( 18)- (20):…”