What I'm getting it is I reject the entire notion that the nature of the discussion is Catholic Doctrine vs. Scripture. That's the false dichotomy of the protesant movement. Protestants amputate half of the Deposit of the Faith when they use sola scriptura as the sole rule of faith and reject the oral tradition of the Apostles. Which they have no scriptural warrant to do, by the way.
So if you want support for Transubstantian from Sacred Scripture then you accede to Sacred Tradition.
I have a better idea...just give up the Roman dream. You guys have the kookiest organization around. First, they claim that the support for their organization is based on Scripture, then backpedal and say, "Well, the Scripture has given us carte blanche authority to make up stuff we want to believe...irrespective of Scripture. How do we know this? Scripture!!! And, now we believe our Tradition eclipses the Scripture." Huh? There's a self-justifying pile of warm material if one has eyes to see.
Leave the dream world of Rome and come back to the Book. It does not support half of the junk Rome sells. Go read the text...your claims ain't there.
That tradition had to start somewhere...It certainly didn't start with the apostles...Where did it originate???
I am sure you don’t mean a tradition handed down in spoken words which change with each telling (remember the experiment you may have done as a kid, wherein you got everyone in a circle, whispered a message to the first kid, then had him whisper the message to the next person and so on ‘round the circle? Remember the results when you compared what you had said with what the last person HEARD? ), do you? How many changes have been made to oral traditions that we cannot recognize til we hear the actual message in Glory? THAT is why God gave us a WRITTEN Bible to depend upon, rather than fallible, changeable oral “tradition”.