Where do the bacteria come from? I assume these veg & fruit were likely frozen at Walmart and killed off most what was alive in them?
Aren’t all the chains freezing them though?
Even if the bacteria are just from the random air etc, then it would be a very different outcome if one were to use fresh veggies wouldn’t it?
I’m not sure what you are referring to. The question could use some more explanation, I think. But if you are asking about fermentation, then it’s not bacteria, it’s yeast. Wild yeasts are abundant. If fermentation is being done on purpose, like for home wine or cider making, then typically specific yeasts are added based on what final product is desired.
Or you can get spores just drifting around in the air.
And what sorts of fruits are you buying frozen? That’ll ruin most fruits.
The only vegetables I ferment are fresh cabbages. They have different organisms that give sauerkraut its characteristic taste. The desired bacteria create an environment inhospitable to undesirable organisms. I don’t know that frozen vegetable would have the same bacteria. I don’t think chain stores freeze fresh produce, although they do keep them chilled.
The air would be enough.
Bacteria from the air would probably be a different population than those found on fresh fruit and vegetables, but does that matter? You mention fermentation. Are you drying to brew wine? If so, you don’t want any bacteria in the batch. If you’re worried about food going bad, fresh food left out might go bad a bit sooner, but you still don’t want to leave frozen food out.
Freezing doesn’t kill bacteria. Various microorganisms (bacteria, yeast) can cause fermentation.
Your OP seems to be missing something…
Yeasts and bacteria are pretty much ubiquitous. Freezing them slows them down, it doesn’t kill them. And yes, they come from the air. And yes, a fermentation using wild organisms will indeed vary from batch to batch. If you want consistency, you need to use a specific strain; or in some cases a specific location that’s routinely used and continues to harbor desired strains.
ETA: A lot of fruits freeze quite well if handled properly. The texture won’t be the same as with fresh fruit, but they can definitely be worth eating.