I don't think there is a trick to prevent them from turning brown. I can't use a whole bag at once, so I just don't buy them. The only lettuce I buy anymore is by the heads or whole leaves in those plastic boxes.

I only buy the Spring Mix. I have some in the crisper that's a week old. I just looked at it and it's not slimy or limpy.

First I buy it on the day I'm going to use it. Then I dig in the back of the display to get the freshest according to Use By date. I put a paper towel in one of the green bagscolor> then transfer the unused salad in to the green bag, pushing out most of the air.

I know there has been plenty of pro and con discussion about these bags but they work for me.

I have used my canister that came with the Food Saver and it works very well.
But I have been buying the romaine at Costco's and it lasts a long, long time just in the bag the six heads came in.

My biggest pet peeve = those bagged salads! They smell funny to me.

Shaun, That's why I only buy the Spring Mix. Most of the others smell like a salad bar--yuck.

I have the best success with bagged spinach and romaine hearts.
Otherwise, I plan on us eating the bag in a day or two. Dh will eat a bag a day if I buy it for him- which I certainly don't.
To me, some brands have the "smell" and others don't.

I, too, dig in the back for the best sell-by date/least smashed for baby spinach and some mix with "ruby red." I've used the Hefty "fresh extend" bags, but switched back to wrapping in paper towels in a regular ziploc bag. We usually eat fresh romaine/bagged spinach/bagged mix every night and it usually lasts 5 days, but if it starts to go ... it all goes quickly.

I try not to be neurotic, but I've seen people sneeze on produce, cough on produce, drop it on the floor and put it back, etc. Some days the bagged stuff is better and what I don't know won't hurt me:)

Good luck!

Cathy in SWPA

I don't buy the bagged lettuces at the grocer. I have tried them but they don't work (for me). I do have good success with the mixed greens (that are in a plastic container) and Romaine from Costco. That I like. They keep very well in my crisper in the frig.

The only thing from the grocer that I buy is baby spinach in the bag and that is good for about a day or two. After that - it really starts looking pretty bad.

I've been able to keep the bags fresh(er) for a few days by putting a damp paper towel inside the bag. The greens stay pretty crispy that way.

I'll try the Spring Mix Cathy.

I don't buy them anymore. I hate the smell, and I just end up washing them again anyway because I don't believe a syllable of "prewashed". Also, since it's just me eating them, I find they go bad too fast. The only exception I've found to both the smell and fast demise is Earthbound Farms sping mix in the hard plastic box. I do sometimes buy loose baby spinach from the grovery (they have it in bins, loose) and keep that in a green bag.

The romaine from Costco or TJ's lasts a long time! So does TJ's head of Red & Green Oak Lettuce.

You could try spritzing it with a weak solution of water/hydrogen peroxide. I'm not sure how it would work on the stuff but it seems to work well on other items like celery and carrots that I keep in the frig.

Sealing them airtight is actually part of the problem. I find that greens last longer if they have a little air. Of course, it's a catch 22. Air causes some browning, but airtight causes slimy.