Solids Loss with Water Uptake during Soaking of Soybeans

대두의 침지과정중 침출액의 성분변화

  • Published : 1987.12.01


Dried soybeans (varieties: Saeal, Kwanggyo, Tanyob) took up water rapidly for first 3hr followed by a slower rate of uptake. The beans took up an equal weight of water (100% hydration)after approximately 3.5hr at $50^{\circ}C$, 5hr at $30^{\circ}C$ and 7.5hr at $20^{\circ}C$ respectively. pH of the soaking solutions decreased during the soaking period. This was undoubtedly caused by the ionization of the cellular components resulting in increased levels of hydrogen ions in the liquor. Soluble solids were leached out of the beans at fairly steady rate throughout the hydration and the amount was greater with higher temperature. This amounted to 0.4-0.7g at $20^{\circ}C$ and 10.2-15.0g at $50^{\circ}C$ per 100g soybeans. Temperature was the most important factor in determining the rate of water absorption and of solid losses. Of the total solids lost, 12-25% was protein. The proportion of protein loss increased as the soaking time and temperature increase. Amount of protein loss was 80-200mg at $20^{\circ}C$ and 440-480mg at $50^{\circ}C$ after 24hr soaking per 100g soybeans. About 5% of soluble sugars, including fructose, sucrose, raffinose, and stachyose, was removed from the beans after 24hr soaking at $20^{\circ}C$.