The effect of temperature on the okra drying process: kinetic study and physical properties of powders

Autor: Francislaine Suelia dos Santos, Rossana Maria Feitosa de Figueirêdo, Alexandre José de Melo Queiroz, Ana Raquel Carmo de Lima, Thalis Leandro Bezerra de Lima
Rok vydání: 2021
Předmět:
Zdroj: MAY 2021. :649-660
ISSN: 1835-2707
1835-2693
Popis: This study aimed to evaluate the effect of drying temperature (50, 60, 70 and 80 °C) on okra dehydration by comparing its powder’s physical properties obtained from a sample produced by a lyophilization process. Ten drying models were adjusted to the experimental data of the drying kinetics. As a result, effective diffusivity and activation energy were determined in addition to thermodynamic parameters: entropy, enthalpy and Gibbs free energy. A physical characterization, as well as the pigments and colorimetry analyses of the aforementioned powders were made, by comparing them with samples produced by lyophilization. The powders were characterized for hygroscopicity, solubility, wettability, apparent and compacted density, fluidity and cohesiveness, pigments, colorimetric, morphological analysis (SEM) and X-ray diffraction. Midilli model was the one that best adjusted to the drying kinetic curves. There was a booster in the effective diffusion coefficient with the increase of temperature. Enthalpy and entropy were reduced with the increase of both drying temperature and Gibbs free energy. The powders presented high luminosity, and the lyophilized powder had higher pigments retention and greater solubility. All powders presented poor fluidity and intermediate cohesiveness, with amorphous, irregular and asymmetric particles. Thus, from the present study it was possible to evaluate the best drying method, the one that should be applied for the drying of okra, considering the costs involved, its quality and the final application of the product, meeting the specific needs of each consumer
Databáze: OpenAIRE
Externí odkaz: