Plastic vs. Metal: Which Knife Keeps Lettuce Fresher?
Sneak Preview: Can a plastic lettuce knife really prevent browning, or is vacuum-sealing the only way to keep lettuce crisp? I put both to the test—here’s what happened!

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Does a Plastic Lettuce Knife Prevent Browning?
I’ve received a lot of questions about my method for vacuum-sealing lettuce in Mason jars. Some people swear by using a plastic knife instead, claiming it slows browning and eliminates the need for vacuum-sealing.
So, I put it to the test!
The Experiment
I prepped three jars of chopped romaine lettuce:
- Jar #1: Cut with a plastic knife, stored in a sealed glass jar (but NOT vacuum-sealed).
- Jar #2: Cut with a plastic knife and vacuum-sealed.
- Jar #3: Cut with a metal knife and vacuum-sealed (my usual method).
All jars went into the fridge on Sunday. By Friday, I opened them up.

The Results

- Both vacuum-sealed jars (plastic and metal knife) looked just as fresh as the day I packed them—no browning at all.
- The non-vacuum-sealed jar? Brown, wilted, and unappetizing.

Final Verdict
A plastic knife makes no difference if you’re not vacuum-sealing. Oxygen exposure is the real culprit behind browning—not the type of knife you use.
I’ll be sticking to my sharp metal knife (it’s quicker and easier), along with vacuum-sealing for crisp, long-lasting lettuce!
Related Posts:
- How to Vacuum-Seal Chopped Lettuce for Freshness
- Can You Add Other Foods to a Vacuum-Sealed Jar of Lettuce?
- Best Way to Store Chopped Lettuce: Vacuum-Seal or Plastic Bag?
Questions? Email me: Paula at saladinajar.com. Hope to see you again soon!
Paula Rhodes, owner
As a retired home economist, I created Saladinajar.com to share my belief that you don’t have to be a chef to find joy in creating homemade food worth sharing. Bread machines (used in an unconventional way), homemade yogurt, and quick microwave recipes are my specialty.