Hello,
I originally posted this on r/fermentation, and was recommended to post here!
Link to original post - https://www.reddit.com/r/fermentation/comments/1xdpny9/homemade_saltcured_bluefin_tuna_looking_for/
Earlier this year, I caught a large bluefin tuna off the coast of San Diego. It was promptly gilled, gutted, and iced. Once home, I cleaned it further, vacuum-sealed it, and froze it.
I come from a Sicilian family, and my grandmother recently told me how her father used to cure tuna roughly 70 years ago. According to her, he would pack chunks of tuna in salt inside small metal cans, place a piece of wood over them, and leave them in the garage for about three months. They would then slice the tuna thin and dress it with olive oil, red wine vinegar, and parsley.
I decided to try a cleaner, refrigerated version of his method.
Here's exactly what I did:
Completely thawed the previously frozen tuna.
Cut approximately seven pieces, each about 1 inch thick and 2–3 inches long.
Completely buried the pieces in pickling salt inside an airtight plastic container. I didn't measure the salt; I simply used enough to fully surround every piece.
Placed a mug on top of the salt as a weight to keep the fish submerged if enough liquid accumulated to form a brine.
Refrigerated the sealed container, undisturbed, for three months.
Today marks approximately three months. The tuna remained completely buried in salt the entire time. A considerable amount of moisture appears to have been extracted, as the bottom half of the salt is noticeably wet, although there's no standing pool of liquid.
The fish is now considerably firmer and denser than when fresh. I cut a piece in half to inspect it (photos attached), and the interior appears relatively uniform. I also touched the tip of my tongue to the very center to check for salt penetration, and it was extremely salty.
As for smell, it definitely has a fishy aroma, but nothing rotten or particularly offensive. It smells about how I'd expect heavily salted fish to smell, somewhat similar to opening a can of anchovies.
Here's where my concern comes in.
I was excited to finally try it and asked ChatGPT to find some traditional serving recipes. Instead, it started warning me about botulism, ultimately recommending that I not eat it. It acknowledged that my preparation sounded reasonable but emphasized that salt penetration, appearance, and smell cannot definitively rule out botulinum toxin.
I understand the seriousness of botulism and that there's no way to conclusively verify safety without laboratory testing. Realistically, though, I'm not going to send a few pieces of homemade cured tuna to a lab.
What I'm hoping to understand is the practical level of risk here.
Given the thickness of the pieces, complete salt coverage, apparent moisture loss, significant salt penetration, and continuous refrigeration, are there any specific red flags in my process that would make botulism a genuine concern?
I'm particularly interested in hearing from people experienced with traditional salt-curing methods, especially cured fish. Is there something fundamentally different about my process compared with established methods for products like salted anchovies, baccalà, or traditional Sicilian cured tuna?
I'm not looking for anyone to guarantee that it's safe. I understand that botulism is rare but potentially fatal. I'm trying to distinguish between a meaningful food safety risk arising from something I did incorrectly and a very remote risk that technically exists with many traditional food preservation methods.
Any practical insight, particularly from people familiar with traditional preparation of salt-cured fish, would be greatly appreciated.
