Spots on Moka Pot, I suspect they are mold

Question

I have this Bialetti Moka pot for over a year. I wasn't using it very frequently until a couple of months ago. Now I use it almost every day.

I think in last December, I made coffee and forget to remove the old coffee from the funnel and noticed it after one week. I cleaned it immediately with detergent and even rubbed it with a dishwashing brush... Then I made coffee again and it smelled horrible, like I wasn't able to remove all the leftover coffee. I noticed that some coffee was actually in the filter and I put one of the hairs of the brush inside every hole to get rid of the old coffee residues. Some of them were attached to each other with mold. It was a terrible experience to clean it, it took more than one hour. Then I brewed 2-3 times and throw away the coffee I made, just to make sure everything is actually cleaned.

I also noticed these spots at this incident. I am not sure if they were there before. I did some research on how to get rid of these spots and realised I shouldn't be cleaning the pot with soap... I don't use soap anymore.

I don't know what these spots are. I couldn't get rid of them and I thought maybe it is just oxidation. I still use the pot and coffee tastes normal, as it should be, but rarely I still get the smell.

Is there a way to get rid of these spots? How can I make sure that they are really oxidation? Should I keep using it?

Answer 1

After the first instance of boiling the water in the bottom part, any mold will be dead. Using a soft brush will easily remove it. So this looks like oxidation damage.

As for the smell, the filter basket has a layer with holes in it, the underside of which is very hard to clean as you have to get to through the funnel.

However, I suspect the top part. There is a filter and a rubber seal. Remove the seal and clean the "hidden" part of the top filter as well as the the area all the way up. The rubber seal is very likely to have picked up a bad odour. This happens quite often when the moka pot was too hot and burned the seal, making subsequent cups taste (and smell) like burnt rubber. These rubber seals are cheaply available as a replacement part.

Answer 2

Your problem falls into two categories.

1. The bottom part with the suspicious spots.
   I think this is just another example of oxidation as mentioned here and here. Follow the instructions in the linked Q/As to remove them. In the unlikely case of them being mold (unlikely, because the mold wouldn't have anything to cling to or feed on), scrubbing should take care of them as well.

2. The mold colony in the funnel and the resulting smell.
   The funnel part of a Moka has a very specific setup, the part below the perforated bottom of the grounds container is very hard to reach. This is where you dug out your lumps of mold from before. See this Wikipedia image to understand where exactly the problem sits - literally:
   -> see part B, under the dotted line.
   If you have the kind of mold buildup you described, poking through the holes from the top will not remove all residue, you need to find a way to access the part from below, though the funnel, making sure to reach all the way to the edges with a suitable tool. A sturdy pipe cleaner comes to mind, for example. If you don't manage to remove the mold residue, there's a good chance that you will not get rid of the smell and even if you sterilized the existing material via boiling, it may still a) impact proper water flow during brewing and b) be a breeding ground for future buildup. Of course we can't judge the amount of mold via the internet, so use common sense. Be careful with chemicals, the aluminum is not well-suited to corrosive cleaners.
   There's probably a second mold colony under the top sieve, the part held in place by the rubber gasket (upper dotted line in the image above). This is much easier to remove and clean, although you will want to get up the coffee channel as well. As it's nearly impossible to remove mold from the gasket, I recommend you replace the gasket - you want a few spare gaskets anyway, as they need to be replaced every now and then.

After a thorough cleaning and scrubbing, run the Moka a few times with water only, until you get a smell-free brew. Then you can start again with coffee, treating the Moka as if it was a new pot. (Some users insist on discarding the first few batches to build up the patina first, claiming either taste or health reasons.)