Soybean soaking is a traditional process that is mainly used to
soften the grains and to facilitate their subsequent cooking. In the
Illinois process that is used in the production of soymilk, the soybean
grains are soaked for 12 h at room temperature (Nelson,
Steinberg, & Wei, 1976). Texture changes in the grains result from
water absorption, which is affected by the soaking time and temperature
(Pan & Tangratanavalee, 2003), and continue throughout
the cooking step, with the added effect of the cooking temperature.
Lengthy soaking time until reaching equilibrium moisture content
in the soaked soybeans is not necessary to promote additional
softening of the grains because it does not produce further improvements
in cooking rate or cooking quality of the soybeans