How Does Pre-washed Salad Mix Stay So Fresh?

In our world of pre-packaged/prepared/prewashed convenience, there is one strange phenomenon that has always made me go hmmm. Why does prewashed lettuce/salad mix seemingly stay fresh for inordinate amounts of time? I mean if you really think about it, that stuff has to be picked, travel to a processing plant where it’s sorted and washed and packaged, travel to a warehouse, then travel again to your supermarket, then travel again to your kitchen. With all that time elapsing, how can salad greens appear as though they were picked this morning once I open the plastic container or bag?

prewashed saladIn the early days of our conventional to organic transition, we lived in an extremely cold, northern climate that didn’t allow for many months of fresh vegetational growth. To compensate, we, like many others, found it extremely convenient to waltz into our local Costco and buy the big tub of organic salad greens, all the while ignoring the little voice in the back of my head screaming at me to question this WAY too convenient addition to our meal.

In my search for answers I began with what seemed like the most logical starting point: Earthbound Organics, the mothership of prewashed, organic convenience! They supply to huge chains like Costco across the US and Canada and that alone raises red flags for me. In scouring their website, they definitely want it known that they test their seeds, fields and water for Ecoli, Salmonella etc… A clear attempt to calm any public concerns in light of recalls and E Coli outbreaks that have gone on in their industry in recent memory. They go on to say that harvested plants are then tested once again for pathogens….so far so good! Wait! Apparently their salads are kept in an “unbroken cold chain” that includes washing in cold, chlorinated water. The chlorine works in synchronicity with the cold water to keep the bacteria and pathogens at bay. Hmmmm Is this the magic ingredient that keeps the lettuce so fresh? Chlorine is definitely something we avoid, so naturally I had to find out what ratio of chlorine to water is used. Is it simply just your run of the mill tap water or is it more ‘enhanced’ with chlorine? As of post date, I have not received a response, so this still remains a mystery.

Perhaps a more important consideration to eating this ‘fast food’ is the environmental foot print created by this large scale producer and others like it. According to Cornell ecologist David Pimental, growing, chilling, washing, packaging and transporting your box of organic salad requires more than 4600 calories of fossil fuel energy or 57 calories of fossil fuel energy for every calorie of food! Certainly a valid argument for eating local and seasonal!

But let’s be realistic, we aren’t all going to go without salad for an entire winter. In our family we find it efficient to buy full heads of lettuce and tear, wash and dry enough for a couple days. This way we are more inclined to include lettuce with each meal.


Also shared on: Fight Back Friday, Intoxicated on Life, kelly the Kitchen Kop, This Chick Cooks, Ann Kroeker, Food Renegade, Veggie Nook, Joy in my Kitchen, Ann Kroeker,



  • Debra

    A very interesting read. I’ve always wondered the same thing but being a working mom I just kind of turned a blind eye to the possibilities. It really does make me wonder if chlorine is the only offensive “ingredient” in here…although that is bad enough :(

    • eatplaylovemore

      Thanks Debra!
      As of today I have yet to receive a reply from Earth Bound Organics about the level of chlorine that is used. It always makes me wonder when companies don’t take the time to respond to a consumer’s direct question.

  • Waking Up

    OH NO Libby! This stuff just makes me mad! Corporations get away with so much behind the scenes that they don’t disclose. I thought I was doing myself a big favor by buying these premixes (Especially the spinach) and having 2 salads a day. I didn’t know I was having a side of chlorine too! Any word from the company yet Libby? I’m curious. :)

    • eatplaylovemore

      Unfortunately, but not surprisingly, Earthbound Organics has not gotten back to me. Which only leaves me to assume that they may not want to disclose the deets on the amount of chlorine that they use.

  • Hazel Irene Moon

    Hey, I will be making my own baking powder too! Thanks so much!

  • Gurpreet

    Great post! I think we should all squeeze big industry out of our lives. Vote with our dollar!

  • BB

    Just like Debra I also turned a blind eye, thinking that it was organic it was safe to eat. I guess when it states “prewashed” I assumed it was with just water. I no longer purchase these products anymore.

  • rlshumer .

    My Aunt gave me a tip for cleaning/preserving my produce just a bit longer. Soak briefly & rinse in pure water with vinegar. Dry & store. My organic stuff stayed fresher on average 3 to 5 days longer. I used cider vinegar on most, but berries I splurged & used basalmic. Great experiment.

    • eatplaylovemore

      Great tip! I’ve only ever used a vinegar soak to give produce a better wash I had no idea it also preserved. How did the berries do? Did they get water logged at all?

  • Ann Kroeker

    Well, the things you learn (when you really dig). Thanks for doing the digging! I guess any tap water is somewhat chlorinated to sterilize it, yes?

    • eatplaylovemore

      Yes. It seems that most, if not all municipalities ‘disinfect’ their tap water with chlorine and some also use chloramine. My assumption (I never did hear back from Earthbound Organics), is that they use a much larger percentage of chlorine because my (tap) washed lettuce certainly does not last anywhere close to the amount of time that pre-washed salad mix does.
      Thanks for stopping by Ann!

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  • Phoebe

    I believe it is in the Omnivore’s Dilemma that explains how the Cascadian Farms/Earthbound Organic’s process works (though I don’t think they divulge the level of chlorine in the water). I don’t remember all the details exactly but I do remember they pump the containers/bags with certain gasses that extend the shelf life/preserve the greens before shipping. The things they are doing to try to compete with the non-organic options probably aren’t helping us as much as we think!

    • eatplaylovemore

      Very interesting Phoebe! Preserving the greens with gases would definitely make sense. It’s amazing what they can get away with and still call a product ‘organic’. I still say it’s best to buy either local or at the very least a head of lettuce and wash it yourself.
      Thanks for sharing.

    • LS650

      The gas is simply CO2, carbon dioxide, the same stuff your body exhales when you consume oxygen. If the bacteria in the salad bag are deprived of oxygen, they can’t multiply and decay the food inside.