Soybeans have higher nutrient values than millet, but a lower rate of digestion

The Zhou people's tendency to boil everything would not be all that helpful with soybeans, and would lead to tasteless sludge. Soybeans have higher nutrient values than millet, but a lower rate of digestion, at 22 per cent if they are merely boiled, but rising to 65 per cent with fermentation. In other words, they can only come into their own with the introduction of more advanced technology for cooking and preparation. When they do, they offer the best yield per acre of protein, compared to the same land used for rearing milk, eggs, or meat.    

J. Clements, The Emperor's feast (2021), 28