On Food and Cooking

growing season. The outer seed coat gets very
water-resistant, so it takes much longer for
water to move into the bean interior. Hard-
seed beans are usually smaller than normal
beans, so they can sometimes be avoided by
picking over the beans and discarding the
smallest ones before cooking.
“Hard-to-cook” beans, on the other hand,
are normal when harvested, but become
resistant to softening when they’re stored for
a long time — months — at warm
temperatures and high humidities. This
resistance results from a number of changes in
bean cell walls and interiors, including the
formation of woody lignin, the conversion of
phenolic compounds into tannins that cross-
link proteins, and the denaturation of storage
proteins to form a water-resistant coating
around the starch granules. There’s no way to
reverse these changes and make hard-to-cook
beans as soft as regular beans. And there’s no
way to spot them before cooking. Once