Water vapor adsorption of ready-to-cook wheat Original Research Article

Water vapor adsorption of bulgur and hedik samples made from Triticum durum (Gediz 75) and Triticum aestivum (Panda) wheat were investigated. Experiments were conducted at 5, 15, 20, 30, and 40 °C for bulgur and at 20 °C for hedik samples between relative humidity (RH) of 11% and 100%. Bulgur samples became moldy before attaining equilibrium above 5 °C and 81% RH between 4 and 28 d depending on temperature (T). Hedik samples did not become apparently moldy and always had smaller equilibrium moisture content (X) than their bulgur counterparts at 20 °C and same RH. Type of wheat governed adsorption of the products. Bulgur and hedik of Gediz wheat always exhibited higher water adsorption capacity than bulgur and hedik of Panda wheat, respectively. The Guggenheim–Anderson–Boer model fitted all samples very well under the given conditions. The monolayer moisture content (Xm) was 9.7% and 9.6% (d.b.) for bulgur and hedik of Gediz wheat, and 7.5% and 6.5% (d.b.) for bulgur and hedik of Panda wheat, respectively. The heat of adsorption (Q) of bulgur samples was not affected by temperature and decreased with increasing X. Gediz bulgur had higher Q values than Panda bulgur up to the capillary condensation region. The average Q was obtained as 75, 50, and 45 kJ/mol for Gediz bulgur, and 73, 49, and 45 kJ/mol Panda bulgur for the monolayer, multilayer, and capillary adsorption regions, respectively.