Chapter VI-A. Bread and Wine
281. Following the example of Christ, the Church has always used bread and wine with water to celebrate the Lord's Supper.
282. The bread must be made only from wheat and must be baked recently; according to the longstanding tradition of the Latin Church, it must be unleavened.
283. The nature of the sign demands that the material for the eucharistic celebration truly have the appearance of food. Accordingly, even though unleavened and baked in the traditional shape, the eucharistic bread should be made in such a way that in a Mass with a congregation the priest is able actually to break the host into parts and distribute them to at least some of the faithful. (When, however, the number of the communicants is large or other pastoral needs require it, small hosts are in no way ruled out.) The action of the breaking of the bread, the simple term for the Eucharist in apostolic times, will more clearly bring out the force and meaning of the sign of the unity of all in the one bread and of their charity, since the one bread is being distributed among the members of one family.
284. The wine for the Eucharist must be from the fruit of the vine (See Lk 22:18), natural, and pure, that is not mixed with any foreign substance.
285. Care must be taken to ensure that the elements are kept in good condition: that the wine does not turn to vinegar or the bread spoil or become too hard to be broken easily.
286. If the priest notices after the consecration or as he receives communion that water instead of wine was poured into the chalice, he pours the water into another container, then pours wine with water into the chalice and consecrates it. He says only the part of the institution narrative related to the consecration of the chalice, without being obliged to consecrate the bread again.