International Journal of Advance Agricultural Research
ISSN: 2053-1265
Vol. 10(1), pp. 10-19, January 2022
doi.org/10.33500/ijaar.2022.10.002

Drying kinetics and physiology of Cowpea seeds (Vigna unguiculata L. Walp) at different temperatures

Geraldo Acácio Mabasso¹*, Yardy Isac Artur Lacita Estofo Covane¹, Geraldo Luís Charles de Cangela¹, Valdiney Cambuy Siqueira², Gonçalves Albino Dauala¹, Indira da Paz Salgado¹, Joaquim Francisco Mazunga¹ and Luís Miguel Estevão Cristóvão¹

¹Faculty of Environmental Engineering and Natural Resources, Zambezi University, Regional street 535, Km 5, Chimoio city, Manica, Mozambique.
²Federal University of Grande Dourados, Dourados-MS, Brazil, CEP 79804-970.

*To whom correspondence should be addressed. E-mail: mabasso.geraldo@uzambeze.onmicrosoft.com, mabasso.geraldo@uzambeze.ac.mz, geral.do@hotmail.com.

Received 06 December, 2021; Received in revised form 29 December, 2021; Accepted 04 January, 2022.

Abstract

Keywords:
Vigna unguiculata, Mathematical modeling, AIC and BIC, Germination.

The objective of this work was to describe the drying kinetics and evaluate the physiological quality of Vigna unguiculata L. Walp seeds after drying. Seeds were harvested with a moisture content of 0.31±0.02 (dry base) and subjected to drying in a forced circulation oven under different conditions of temperature and relative humidity: 40ºC, 28.62%; 45°C, 26.62%; 50°C, 17.46%; 55°C, 16.57% and 60°C, 9.28%, until their moisture content reached 0.12±0.01 (dry base). Different mathematical models were fitted to represent the seed drying kinetics, based on the Gauss-Newton method and complemented by Akaike Information Criterion (AIC) and Schwarz’s Bayesian Information Criterion (BIC). Physiological properties were determined by assessing their electrical conductivity, germination percentage, emergence, germination speed index, and emergence speed index. It was concluded that the drying rate was higher for higher drying air temperatures and reduced along the drying time; the Midilli model presented the best fit to describe the drying kinetics of cowpea seeds at the temperature of 40°C and the Two-term model for the temperatures of 45, 50, 55 and 60°C. The effective diffusion coefficient ranged from 1.1378×10^-11 to 3.3698×10^-11 m²/s. The activation energy was 41.9894 kJ/mol. Electrical conductivity increased with an increase in drying air temperature, while germination, emergence, germination speed index, and emergence speed index with an increase in drying air temperature.