I have just opened an expired can of beans trying to clean the food stock due to epidemic situation. It expired approximately 6 months. The food looks alright, the outlook of the can doesn't have any sign of rust, looks as if new, the shape didn't transform also due to any form of chemical reaction like food releasing gas to pressure out.

But the wall inside the catch my attention. It has random black spots or pattern. I wonder if anyone have experience? Is this a sign of metal corrosion?

Inside look of an opened can of bean

  • I'm pretty sure that's just the tin, where the sauce didn't stick to the walls of the container. Commented Jul 10, 2021 at 2:58
  • 1
    @personjerry thanks, I finally found the clues with right keywords in search engine. I assume it is tin. If so Tin has no known natural biological role in living organisms. It is not easily absorbed by animals and humans. Keywords tried why tin look like black spot, why use tin can Commented Jul 10, 2021 at 6:02
  • What does it look like after you rinse the can?
    – Kat
    Commented Jul 10, 2021 at 17:24
  • @kat it looks around the same except the source, still have black patches, those patches seems embedded. Commented Jul 11, 2021 at 3:12


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