What are the requirements for the wine used at Mass?
Canon 924 §3 states that:
The wine must be natural, made from grapes of the vine, and not corrupt.
The comments on this canon say that the same principals concerning the bread apply to the wine. (It should be all natural and not have any additives.)
Inaestimabile donum (1980) states that "The wine for the Eucharistic celebration must be of "the fruit of the vine" (Lk 22:18) and be natural and genuine, that is to say not mixed with other substances." (n. 8)