They become biologically available when bacteria in the intestine acts on the digested grain. You have probably eaten tofu and not realized it. It is common in Asian cooking. Firm consistencies are good to use cubed served in soups, stir fried or grilled. Firm tofu is higher in protein, fat and calcium than other forms of tofu.
Soft tofu is good for recipes that call for blended tofu.
Silken tofu is a creamy product that is a good replacement for sour cream in many dip recipes. You can purchase tofu in most grocery stores. It's made of curdled soymilk and has a custard-like consistency. Tofu tends to pick up the flavors of other food with which it is cooked, which is one reason why it's good for stir fry recipes. Tempeh Tempeh is a flat cake made from fermented soybeans.