Effect of soaking time and temperature on water absorption capacity and dimensional changes of bulgur

Abstract

AbstractBackground and objectivesSoaking is a processing treatment used in different grain. The objective of the present work is to study the water absorption of bulgur (precooked, dried, and debranned durum wheat), at various temperatures (35, 50, 60 and 65°C) by measuring the moisture content with respect to time. The effect of soaking time and temperature on three dimensions was examined (length: “a (mm)”; crease side width: “b (mm)”; secondary width: “c (mm)”). Weight, volume, sphericity, and density of the precooked, dried, and debranned wheat kernel were also measured.FindingsThe results indicated higher water absorption capacity at higher temperature. Peleg's model was successfully used to evaluate water absorption during soaking. Peleg's model constants were investigated relative to temperature and confirmed a higher absorption capacity of water. Moreover, during soaking, all the dimensions as well as weight and volume percentages increased with time and temperature. The percent change of secondary width “c” was affected by both temperature and time soaked, indicating that it was the most important parameter controlling the deformation and shape of the kernel.ConclusionBulgur kernel had higher water absorption due to the absence of the outer bran layer, which acts as a barrier for water absorption.Significance and novetlyModeling the water absorption of bulgur during soaking and measuring its size is important since it help industries to control the soaking operation and further cooking operation and then to optimize industrial process dishes based with bulgur.