I thought about vacuum sealing a salad, but I was a bit concerned about all the plastic bags and the salad getting totally squished. Then I found the interesting idea of "salad in a jar."
The idea is fairly clever: The Tilia Food Saver vacuum sealer has a mason jar sealer attachment. You take a regular canning jar, put on the regular lid, then the vacuum attachment, and it sucks the air out of the jar, vacuuming the lid to the top of the jar. Then you remove the attachment. You can put on the screw on ring at this point, though it doesn't really need it. It's fast and doesn't require any plastic bags.
This works with any regular mouth mason jar - I was making small side salads so I used 16 oz. (pint) jars, but if you're making a meal-replacement salad, the 32 oz. (quart) jars would be a better choice.
The salad-in-a-jar woman only put lettuce in her jar. I put in romaine lettuce, a little piece of paper towel, then the rest of my veggies, which included: celery, carrot, broccoli (blanched), cucumber, green pepper, mushrooms, and sweet onions. I didn't add tomato since that was the least likely to succeed and tomatoes are best not refrigerated, anyway.
While I was at it, I also prepared two jars, one with romaine lettuce cut with a knife, and one with lettuce that was torn. Both were vacuum sealed. I was skeptical about the whole cutting lettuce with a metal knife causes it to turn brown claim.
After preparing my five complete side salads and two jars of lettuce I still had half a cucumber, half a green pepper, half an onion, and a little lettuce left. I decided to vacuum seal those to see if they held up better than they do normally.
I packaged everything on a Monday morning and the plan was to see if I could make a whole week's salads in advance, and find out what does and does not keep. Here's what the salad looked like when it was made fresh:
You can click on any picture to get a larger view of it, by the way.
Tuesday - Day 1 (about 32 hours)
The salad looks great! The lettuce is basically indistinguishable from when it was fresh. The cucumber and green pepper dried out a little, but are still acceptable. Nothing got slimy, brown, or otherwise unhappy. Taste and texture is good. Success so far.
Thursday - Day 3 (about 80 hours)
The lettuce is holding up very well. Everything, except the cucumber, is looking good. I'd say cucumbers only last a couple days at most, which is not too surprising.
Vacuum sealing your own cut lettuce appears to be significantly better than buying bagged, prepared salad mix, which always looks fairly questionable in my supermarket, even before bringing it home. And making your own is much cheaper, too.
Friday - Day 4 (about 104 hours)
The lettuce is still flawless. I'd say the cucumber and mushrooms are beginning to show their age, and we're getting to the limit for the fragile vegetables. We're looking good for lettuce to last a whole week, but salad with veggies is looking to be more of a half-week deal, for best results.
This seems like about as long as the vegetables ought to be left cut in a jar. They look OK, the texture is normal, but it just seems like a good upper limit. And I was hungry for a salad and this was the last jar in the fridge.
I still have the two jars of lettuce... I think I'll just leave them and see how long they last! The followup after two weeks is in part 2 of the great salad experiment.
Update: I blanched my broccoli because I find raw broccoli in a salad is just too crunchy. As it turns out, it's really important because vacuum sealed uncooked broccoli smells really, really bad. I eventually found the technical reason for it, but should you feel tempted to put raw broccoli in your salad veggie mix, just say no.
Update: I've found this technique for opening vacuum sealed jars to work very well.
Update 6/20/2012: I've made a new vacuum sealed salad post with my latest best practices, too.
Update 4/21/2014: I was reading Ideas in Food and it pointed out that there is a danger of botulism in vacuum sealed food, because botulinum toxin thrives in an air-free environment. I haven't killed myself yet, but botulism is very serious stuff, so it probably is a good idea to limit your refrigerated vacuum sealed vegetables to a few days to be safe.