Octopus can be tough and tasteless, but when cooked sous-vide more flavor is retained and it will be tender with the right combination of time and temperature. So far I have always used 4 to 5 hours at 77C/170F or 3-4 hours at 85C/185F with good results. But because octopus loses so much liquid when cooking it and because I saw Italians advising 8 hours at 72C/162F, I thought it would be interesting to try lower temperatures. Since an octopus has 8 legs, I tried 8 different combinations of time and temperature.
For this experiment I used the octopus above, which was frozen and after thawing weighed 1.7 kilos (3.7 lbs). Freezing is known to have a tenderizing effect on octopus, so if you use a fresh octopus, you may need to increase the time or temperature. The size also matters: a higher temperature or longer time may be needed for a larger specimen.
I cleaned the octopus and cut it into the 8 legs, head, and ‘connecting part. For the experiment I used only the 8 legs. There was quite a bit of difference between the weight of the legs, with the smallest at 121 grams and the heaviest almost double that at 221 grams. However, I did not notice any pattern in the loss of juices or tenderness that could be attributed to the difference in weight.
I vacuum sealed the legs without adding anything to the bag and I wrote down the weight of each bag.
Initially I cooked only 7, and wanted to decided on the last one based on the results of the others.
I gathered all the liquid to use for a risotto, and weighed and tasted all of the octopus legs. Based on the results I opted to cook the final one for 24 hours at 60C/140F. The results for all 8 time and temperature combinations are shown in the table below.
- the differences in tenderness were very small. The tenderness is written down as my subjective judgement of the tenderness on a scale of 1 = very tough to 10 = very tender, with 6 being sufficiently tender but with still quite a bit of bite. All of these were fine and I really had to taste them side by side to tell the difference. This is why I rated them only in the range of 7 to 8 on a scale of 1 to 10.
- the octopus loses a lot of liquid when cooked for all time and temperature combinations, about two thirds of the starting weight. Although the difference in weight indicates that there is some difference, I could not taste that in the juiciness of the octopus. The yield for 3 hours at 85C/185F seems to be an anomaly; I’m not really sure what happened there. In general it seems that a longer time means a slightly higher loss of juices.
- When you decrease the temperature by about 7C/13F, the cooking time roughly doubles to achieve the same tenderness. This can even be extrapolated to boiling the octopus (i.e. cook it at 100C/212F), it will be as tender after 1 hour as it is after 4 hours at 85C/185F.
The main conclusion is that if you adjust the time appropriately, any temperature of 60C/140F or higher will work to cook octopus sous-vide, and the results will be very similar no matter what temperature you pick! So you can pick a time and temperature that is most convenient for you, or perhaps cook the octopus along with something else that requires a specific temperature.
This is a remarkable conclusion that shows that octopus is very different from meat, because for meat the difference between cooking it for example 24 hours at 60C/140F or 3 hours at 85C/185F will be VERY easy to notice!
Some people have reported that octopus cooked sous-vide was tough. If this happens to you when using a time and temperature combination listed above, you could simply increase the time and/or temperature when cooking octopus from the same source the next time around.
(Please note that if you cook the octopus below 60C/140F, you would have to cook it for a very long time and a bad smell can occur. That is why I advise against it. I know because I’ve tried. At 55C/131F the loss of liquid was still similar, so there is no use for it anyway.)