7 Moreover, the things which are hung up at idol festivals, either meat or bread, or other such things polluted by the invocation of the unclean spirits, are reckoned in the pomp of the devil. For as the Bread and Wine of the Eucharist before the invocation of the Holy and Adorable Trinity were simple bread and wine, while after the invocation the Bread becomes the Body of Christ, and the Wine the Blood of Christ, so in like manner such meats belonging to the pomp of Satan, though in their own nature simple, become profane by the invocation of the evil spirit.
Source: Catechetical Lectures (New Advent)