Bread, A Substance?

Or an aggregate/mixture, even if it is one made through human skill? Of what relevance is the question? Transubstantiation. A doctrine of the Latin churches, or a theologoumenon given much weight? If bread is not a substance, I would think that Trent's teaching would need to be reconsidered, as the 'physics' is inaccurate, or "substance" as applied to bread would need to be understood analogously, as referring more properly to the components of bread that are substances in themselves.

The Antiquity of the Doctrine of Transubstantiation