Mathematical Models of Moisture Sorption Isotherms of Grains Sorghum (Sorghum bicolor (L.) Moench)

Abstract

1
U. of K. J. Agric. Sci. 22(1), 1-12, 2014
Mathematical Models of Moisture Sorption Isotherms of Grains
Sorghum (Sorghum bicolor (L.) Moench)
Eman Abdu Abdalla1 , Mohamed Ayoub Ismail and Abdelmoniem
Elamin Mohamed2
Department of Agricultural Engineering, Faculty of Agriculture,
University of Khartoum, Sudan
Abstract: The objective of the study was to fit or test the experimental
data of adsorption and desorption isotherms of grains sorghum The study
was carried out at the Department of Agricultural Engineering, Faculty of
Agriculture, University of Khartoum and the Food Processing Research
Center, Shambat, Sudan, during January 2007 - March 2008. Four
mathematical models namely modified Henderson, modified Chung-
Pfost, modified Oswin and modified Halsey were used to predict sorption
isotherms. The adsorption and desorption isotherms were determined
using standard static gravimetric method, six levels of water activities
rang 0.112- 0.865 were maintained by using saturated salt solutions inside
air-tight glass desiccators, while incubators were used to maintain three a
constant temperature namely 25o
C,35 o
C and 45o
C. A non-linear
regression analysis was used to evaluate the parameters of the four
selected models. The models were compared by using statistical
parameters: mean relative percentage deviation (P%), standard error of
estimates (Es), coefficient of determination (R2 ) and randomness of
residual plots of difference between measured and predicted values. For
the mathematical models, the results indicated that the modified Chung-
Pfost model satisfactorily predicts the adsorption and desorption
isotherms of grains sorghum