I bought a bag of potatoes and a hand of bananas on Sunday (from Costco)
and just let them sit in the kitchen until Friday, when I noticed water
oozing out of a few of the bananas.
Then, the next day, I found that a few thumb-sized spots on the potatoes
had also become mushy and had a terrible smell. This ooze is pure white,
feeling and looking like mashed potatoes (but I never cooked them),
not the normal darkening I am used to in potato rot.
It's like something just spoiled these two produce products and cut short
the full aging/ripening process after one week.
Why?
So, I focused on the potatoes, since they had the strangest spoilage, and went
online to understand this. I could only find one match, which is also very recent (written just 1 month ago, but I believe the experience was 10 months ago) and even
has a video of this mush.
That match suspects either "freezing injury" or "rot bacteria". I wonder if this bacteria is known to spread to bananas.
Additionally, I wonder
if "water droplets" left on the potato could simply dissolve the potato if stored a little
on the warm side. Maybe the potatoes were somehow stored over the last few months or even the entire winter…maybe this year's hot summer is special…I'm sure that there are many other possible explanations here.
So, what is the most likely explanation?
More details:
The bananas were a ripe yellow even from purchase, and did get some brown
spots of ripening, but never seemed to go through the full blackening
spoiling process I am used to.
The banana fruit itself behind the peel had not darkened like normal
over-ripened bananas. It was standard "ripe yellow", just somehow decomposing
to liquid/mush throughout the bottom half of the banana. The peels had some
brown spots like normal ripening, but never developed black spots (black spots
are my usual indicator that I need to eat them within a few days or the interior
will start to get mushy, but these particular bananas never had this indicator).
I did not see any eyes/sprouts grow from the potatoes like I normally do
(and they had no green on them, these are huge perfectly-tan russet
potatoes).
For both, the unspoiled parts tasted good.
As for the kitchen temperature, it has been a bit hot (maybe as high as
80F inside) for the first few days and normal (about 72F) for the last
few days. As for the kitchen humidity, it has been normal always
(about 55%). The purchase and storage was in Minnesota.
If this ever happens again, I will make a video of the spoiling mush to
help explain this better.
Best Answer
This sounds like soft rot on the potatoes. Soft rot tends to ooze "water" from the lesion and release a foul smell as it breaks down the potato. The potato will still look white and be mushy, like very loose mashed potato. This is caused by a few genera of bacteria, but commonly Pectobacterium carotovorum.
Freezing damage doesn't smell unless also infected with something, and usually is "glassy"/translucent looking rather than white.
Pectobacterium does infect bananas, but as far as I can tell, mainly manifests as infection of the plant itself, causing wilting and death of the whole plant overall, rather than just the fruit. If there was no smell from the fruit, it might not have been rotten with this genus of bacteria, though other genera are possible. "Water" leakage without the outside being blackened (if you've ever frozen a banana to store for later baking, you will know they go completely brown at the frozen area) indicates rot rather than freezing in this case too.
It is possible that one contaminated the other, but it equally likely that you have a coincidental infection of both.