Moisture sorption isotherm characteristics of moringa seed at two different temperatures

The moisture sorption isotherm experiments of moringa seed were conducted in a climate test chamber (CTS), the relative humidity of which is regulated by an atomizing humidifier, at temperatures of 25 and 60°C and a relative humidity range of 25 to 95%. The sorption isotherms were sigmoidal in shape (Type II). The experimental sorption data was applied to various isotherm equations (BET, Oswin, Modified Oswin, GAB, MGAB, Fraction Linear (FL), Modified Chung-Pfost and Modified Henderson) and were evaluated for their ability to fit the experimental data using non-linear regression techniques. Comparisons were made on the basis of coefficient of fit (R²), mean relative error (MRE) value, standard error of moisture (SEM) and residual plots. The comparison showed that the Fraction Linear (FL) equation was the most appropriate equation followed by the Modified Oswin equation for modeling the EMC/ERH (water activity) adsorption isotherms of moringa seed. The adsorption EMC data obtained in this work agree with previous published data and therefore will be helpful for future work on drying and for predicting the quality change during the storage of moringa seed.