Is transubstantiation faithfully Aristotelian?

Question

Transubstantiation is a concept that Roman Catholic scholastics, most notably Thomas Aquinas, developed for the doctrine of Communion. Catholics state that when a priest blesses the elements of bread and wine, they become the body and blood of Christ.

Catholics admit that chemically they would still be considered bread and wine. But they believe nonetheless that the elements have ceased to be bread and wine and have been converted¹ into flesh and blood. They say that the substance has been converted¹ (hence the term transubstantiation) but that the accidents of the bread and wine remain as they were. Those accidents include all the ways the senses (touch, taste, etc.) interact with the elements, and all the ways a chemist (for example) would classify the elements in the absence of knowing that a priest has blessed them.

The categories of substance and accidents were borrowed from Aristotle. My question is, is transubstantiation faithful to his categories? I'm not asking if it was intended to be - I think Catholics are aware that they may have borrowed philosophical concepts from others and changed them for their own use - I'm asking if Aristotle's formulation of those concepts is consistent with the philosophical defense of transubstantiation. Specifically, I want to know, if nothing changed outwardly about those elements, could the substance still be said to have changed (from Aristotle's perspective) as Catholics say it could?

_{¹ Originally this question had "transformed" and not "converted." This was sloppy terminology, as transformation would mean a change of shape or form, which is expressly not what happens in transubstantiation. "Conversion" is a better term.}

Answer 1

St. Thomas Aquinas's Summa Theologica question "Of the Accidents Which Remain in This Sacrament" should help.

Relevant to your question "Is transubstantiation faithful to Aristotle's categories?," its article "Whether the accidents remain in this sacrament without a subject?" contains an objection that cites Aristotle:

[N]ot even by miracle can the definition of a thing be severed from it, or the definition of another thing be applied to it; for instance, that, while man remains a man, he can be an irrational animal. For it would follow that contradictories can exist at the one time: for the "definition of a thing is what its name expresses," as is said in Metaph. iv. But it belongs to the definition of an accident for it to be in a subject, while the definition of substance is that it must subsist of itself, and not in another. Therefore it cannot come to pass, even by miracle, that the accidents exist without a subject in this sacrament.

Thus, transubstantiation would seem to contradict Aristotle.

But St. Thomas replies to this objection:

Since being is not a genus, then being cannot be of itself the essence of either substance or accident. Consequently, the definition of substance is not---"a being of itself without a subject," nor is the definition of accident---"a being in a subject"; but it belongs to the quiddity or essence of substance "to have existence not in a subject"; while it belongs to the quiddity or essence of accident "to have existence in a subject." But in this sacrament it is not in virtue of their essence that accidents are not in a subject, but through the Divine power sustaining them; and consequently they do not cease to be accidents, because neither is the definition of accident withdrawn from them, nor does the definition of substance apply to them.

His argument hinges on the real distinction between being and essence, which he overviews in, e.g., De Ente et Essentia.