@msolga,
Something I didn't know before, but now do ...
I always thought wine (in a marinade) was for the sole purpose of adding flavour to a dish. But apparently it tenderizes the meat, too. In fact (according to my culinary expert friend) that's it's most important function.
Anyway, the red wine I purchased this morning was put to very good use ... Boeuf Bourguignon, a recipe from my
Slow Food Bible. Had I known about the tenderizing process, I would have marinated the beef overnight, as recommended. But it was fine, anyway.