Changes in properties of soaking water during production of soy-bulgur

Changes in soaking water properties (pH, absorbance, soluble solids content, conductivity and colour "L, ci h and YI values") were investigated during soaking of soybean to produce soy-bulgur (as a new type food product) at 30degrees, 50degrees and 70degrees for 120 min. All the properties of soaking water were significantly affected by soaking time and temperature (P < 0.05). Leaching of some nutritional compounds was also observed from soybean to the soaking water. pH, conductivity and soluble solids content of the water increased with increase in temperature indicating leaching of the acidic compounds, minerals and total soluble compounds, respectively. Maximum absorbance (turbidity) was obtained at 50 degreesC soaking. Yellowness and yellowness index were increased as temperature is increased in contrast to a decrease in lightness. Results reveal the fact that leaching and reabsorption of some nutritional compounds occurs simultaneously. Hence, the initial quantity of the soaking water should be adjusted to limit the loss of the nutritional compounds in the discharging water. (C) 2003 Elsevier Ltd. All rights reserved.