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MOISTURE ADSORPTION THERMODYNAMICS OF FRACTIONATED SESAME HULLS ( SESAMUM INDICUM L.)
Author(s) -
ALMAHASNEH M.A.,
RABABAH T.M.,
ALU'DATT M.H.,
YANG W.
Publication year - 2010
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/j.1745-4530.2008.00306.x
Subject(s) - equilibrium moisture content , enthalpy , thermodynamics , water content , chemistry , moisture , relative humidity , humidity , adsorption , mathematics , analytical chemistry (journal) , chromatography , physics , organic chemistry , engineering , sorption , geotechnical engineering
Sesame hulls are a useful byproduct of sesame processing industry. Moisture adsorption isotherms (MSIs) for whole sesame hulls (WSHs) and powdered sesame hulls (PSHs) were obtained at 15, 30 and 45C, and 0.05 to 1.5 moisture content (decimal dry basis) using a water activity meter. Four MSI models were tested. Halsey model was found to provide the best fit for experimental data for both WSHs and PSHs. Standard error of estimate, %P and pseudo‐ R 2 values were: 0.00168 and 0.00248, 4.7 and 5.7%, and 0.963 and 0.974, respectively. Equilibrium relative humidity (ERH) values of PSHs were greater than those of WSHs at constant moisture content. Differential enthalpy ( q st ) and entropy (Δ S d ) decreased exponentially with the increase in equilibrium moisture content, then became constant beyond 0.7 moisture content. q st and Δ S d values were larger for WSHs than PSHs. Enthalpy–entropy compensation was found to exist for both PSHs and WSHs. An entropy‐driven process was observed, with the free energy change (Δ G ) for WSHs and PSHs of + 0.0183 kJ/kg and − 0.0284 kJ/kg, respectively. The spreading pressure was found to increase with the increase in ERH and decrease in temperature. The net integral enthalpy (Δ H i ) decreased then reached an asymptote beyond a moisture content of 0.15 for both PSHs and WSHs. Net integral enthalpy was larger for WSHs. The net integral entropy (Δ S i ) was negative for PSHs and WSHs, and Δ S i was greater in magnitude for PSHs.PRACTICAL APPLICATIONS Sesame hulls are useful byproducts of sesame processing industry. Large amounts of this effluent are produced yearly in Jordan. They are used as livestock feed, but they require further dehydration to reduce moisture content and water activity into safe levels. In this project, drying thermodynamics of sesame hulls were discussed.