Browning usually results from oxidation caused by exposure to air when the leaves have been bruised or cut. Eliminating the air exposure will keep your lettuce fresh longer. You could go out and purchase a food saver machine or the age-old suck the air out of the bag works. These days I use a straw.
Needless to say, this works for everything, not just lettuce.
When purchased bagged cut lettuce, choose a bag that it tight and flat. If it is a loose bag, it is already starting the browning process.
I use a plastic straw from plastic with a lid that a family member no longer uses.
I’ve also been known to just put my lips together and suck the air out.
Comments will be approved before showing up.