Baking Soda does indeed cut acidity. Sugar will also do this. My Italian grandmother always used sugar to cut the acidity of the 'maters in her spaghet sauce. Other Italian cooks use baking soda for the same purpose.
The Chinese joints also use cornstarch to tenderize. I had always thought this was for a breading-like coating, but it is for tenderizing.
Not sure why you would want to cut the acidity. After all, that is what is doing the tenderizing, so why cut it? Besides, it will take a very long time to turn your meat mushy.
I prepare steaks by coating with olive oil and then adding garlic and some all-natutral meat tenderizer(Papaine, I think). I then vacuum seal it for 4 days and cook. Never had a problem with mushy meat even though all 3 of the ingredients are considered tenderizer's.
I always keep in mind one statement when talking about tenderizing meats.......You CANNOT marinate a cut of meat to tenderness.
In the research that has been done by Merle Ellis, the Nation's Butcher, it has been proven that marinades and rubs only penetrate up to 5mm(That's 0.19"). That means that only the very top surface of the meat will get tenderized. He claims the reason is because of the low acidity of the foods used in the marinades. Anything food-grade, does not conatin enough acid to penetrate the meat.
Anyway, just thought I would add this to the comments.
