Why would fresh tuna be salted?

Question

I bought a big piece of tuna about a week ago. I carved it up and put most in the freezer. However, as I am the proud owner of a vacuum sealer (as of a week ago), the worst part of the tuna got vacuum sealed and put into the fridge.

Six days later, I took it out of the fridge to cook, and found that the vacuum was gone (it had been the first item I had sealed). I made a fish-pie out of the tuna. As this was the worst part, I didn't expect anything great of it, but it was salted, apart from having a strong flavor. I attribute the strong flavor to the cut (the dark part, mostly) and from having been in the fridge for a week).

One piece of prime cut that I had sealed in with the other meat, I reserved and grilled the next day. It was also salted.

Would this be because I salted it too heavily, or can it be because it had been sitting during one week? Is tuna meat salty on it's own? Any other suggestion?

Just checked: without added salt, another prime cut was salty. Could it be that 'they' add some conservative to the fish that would add salinity? — BaffledCook, Jun 03 '11 at 11:42
Oops. This second prime cut was frozen on the buy date. -18ºC — BaffledCook, Jun 03 '11 at 14:35

score 10 · Accepted Answer · edited Oct 14 '22 at 18:21

10

As far as I know, raw tuna is not usually salted and/or pre-treated.

What may be happening is a case of perceived salinity. For example, there are numerous studies that suggest foods with certain odors can be perceived as much saltier than they actually are. If you have access to that second article (it is copyrighted and behind a paywall, so I can't post it here), it has a great figure on page 3 depicting the perceived sourness, bitterness, sweetness, and saltiness of a number of common foods, including tuna. The aroma of plain tuna alone ranked higher than soy sauce on the saltiness scale, for example. Tuna is relatively high in fat, and other studies suggest that high fat foods can also increase perceived saltiness. Perhaps you were using a fattier part of the fish?

Finally, there is evidence that dehydration increases the saltiness of tuna (which actually seems somewhat intuitive), especially if extra salt is added before cooking. Was your tuna previously frozen? Freezing—especially if done improperly and/or if there are multiple freeze/thaw cycles—can act like dehydration.

edited Oct 14 '22 at 18:21

Glorfindel

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answered Jun 03 '11 at 12:46

ESultanik

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That must be it. As said, the first batch was not frozen as far as I know. The second batch (today) was frozen in cling-film on a tray. So I hope that was the correct procedure. – BaffledCook Jun 03 '11 at 14:33
Ultimately, the quicker the tuna freezes the less cell damage will occur, and thereby the less dehydration. Your method should be fine, as long as the freezer was cold enough and you didn't over-crowd the tray. Also, if the tuna was previously frozen (which is quite likely, especially if it is from one of the large varieties) that could also be a contributing factor. – ESultanik Jun 03 '11 at 14:36
The link to `springerlink.com` is broken. I'm also unable to find any copy saved on the Wayback Machine. The link to `sciencelinks.jp` is is also broken, but in this case I found a copy on the [Wayback Machine](https://web.archive.org/web/20100429125458/http://sciencelinks.jp:80/j-east/article/200508/000020050805A0250446.php). – Jul 21 '22 at 05:32

score 3 · Answer 2 · answered Jan 22 '14 at 06:28

Tuna captured by purse seiners or baitboats or jigboats in many cases are preserved and frozen in salt brine. it would have absorbed salt, just a fact. Other fresh tuna could have been stored in chilled seawater and would have picked up salt a well. In these cases the salt would have been higher on the skin edge.

Well described in: http://docs.lib.noaa.gov/noaa_documents/NMFS/SWFSC/TM_NMFS_SWFSC/NOAA-TM-NMFS-SWR-011.pdf

You may have gotten a portion of some large YF out of Ecuador that was chilld or frozen in dense brine.

I am in the business.

score 0 · Answer 3 · answered Jun 03 '11 at 12:33

I haven't heard of it with fish filets, but I know that scallops are often brined before sale to keep them looking moist and increase (marginally) their display life (I choose to think fishmongers are honest and aren't just increasing the weight of the scallops with water). It does nothing good for the scallops, of course, and I try to get unbrined ones whenever I can.

And of course whole chickens and turkeys are often brined before packaging.

Maybe this is the same kind of deal.

Why would fresh tuna be salted?

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