Sorry for insisting but I have been thinking about this.
If you use
wine corks maybe the tanines that help the meat to tenderize are not of the corks but of the wine!!!
Well, I haven't heard of using corks in preparing octopus but a glass of wine is highly recommended

I mean in greek recipes we never use water to cook octopus but wine!
What do you think about that?
Oh useless to say that in stews all the greek recipes have a glass of wine!!