Grape Juice?

[Oik]

Hi, I was at Mass and the wine din't taste like wine, but grape juice. I asked my girlfriend who was at a different Mass that same week if she had the same experience and she said yes. We have both been going to Mass several times a week for about a month or so and this never happened.

So, my questios are:

What are the ramifications for the Priest to (deliberatly and not deliberately)consecrate Grape Juice?

Is this acceptable if the Chruch had no wine (which I realize is unlikely) or if the Priest saying the Mass was a visiting Priest?

Is there ever and exception for this?

[cappie]

This is from the Code of Canon Law

Can. 924 §1 The most holy Sacrifice of the Eucharist must be celebrated in bread, and in wine to which a small quantity of water is to be added.

§2 The bread must be wheaten only, and recently made, so that there is no danger of corruption.

§3 The wine must be natural, made from grapes of the vine, and not corrupt.

This is from the recently produced Document Redemptionis Sacramentum

THE PROPER CELEBRATION OF MASS
1. The Matter of the Most Holy Eucharist
The bread used in the celebration of the Most Holy Eucharistic Sacrifice must be unleavened, purely of wheat, and recently made so that there is no danger of decomposition. It follows therefore that bread made from another substance, even if it is grain, or if it is mixed with another substance different from wheat to such an extent that it would not commonly be considered wheat bread, does not constitute valid matter for confecting the Sacrifice and the Eucharistic Sacrament.] It is a grave abuse to introduce other substances, such as fruit or sugar or honey, into the bread for confecting the Eucharist. Hosts should obviously be made by those who are not only distinguished by their integrity, but also skilled in making them and furnished with suitable tools.
By reason of the sign, it is appropriate that at least some parts of the Eucharistic Bread coming from the fraction should be distributed to at least some of the faithful in Communion. “Small hosts are, however, in no way ruled out when the number of those receiving Holy Communion or other pastoral needs require it”, and indeed small hosts requiring no further fraction ought customarily to be used for the most part.
[50.] The wine that is used in the most sacred celebration of the Eucharistic Sacrifice must be natural, from the fruit of the grape, pure and incorrupt, not mixed with other substances. During the celebration itself, a small quantity of water is to be mixed with it. Great care should be taken so that the wine intended for the celebration of the Eucharist is well conserved and has not soured. It is altogether forbidden to use wine of doubtful authenticity or provenance, for the Church requires certainty regarding the conditions necessary for the validity of the sacraments. Nor are other drinks of any kind to be admitted for any reason, as they do not constitute valid matter.

The Mass is invalid, there are no exceptions. The priest at least from what you have said on the surface has committed a grave sin.