They said lettuce are best eaten when crispy. Yes! I think so.
It is crispy when at peak of vegetative growth, still attached to soil, getting enough water and needed nutrients. For the hydroponic lettuce – still submerged to water… It is still crispy right after harvest, a short time after harvesting, and not after a certain period.
The reason for crispiness. Plant contains million cells. Each cell is filled water, more than 70% I think. Imagine each cell as filled cellophane bag. Many will break in rapid succession when applied with outside force. The same happens to leaf with plumbed cells. Biting breaks the cells easily in very fast sequence thus giving the impression of crispiness.
The plant on ground absorbs and loses water continuously When pulled up, water loss still continues resulting to wilting afterwards. Cells become more flacid and more elastic as their water content decrease. Then tend to resist breakage and less enjoyable to eat.
Okay, the appearance is enough reason to dump this. It is ugly and seems not enjoyable.
Now, lets turn it to a wilted but crispy lettuce. Hold it with left hand. Then twist it slowly with the right hand. Stop and hold before the rupture begin. Take a bite to enjoy.