Can a priest, who is a recovering alcoholic and who has a congregation that is mostly recovering alcoholics validly substitute grape fruit juice in lieu of wine for the consecration ?
No, only valid matter can be used for confecting the Eucharist. With permission from his Bishop, a priest may substitute mustem, which is wine that has just barely started to ferment.
Mustum is defined as grape juice in which fermentation has begun, but has been suspended with the result that its alcohol content (usually less than 1.0%) does not reach the levels found in most table wines. … Pasteurized grape juice in which all alcohol has been evaporated through high temperature preparations is invalid matter for Mass. …
Permission for priests, deacons, or the lay faithful without distinction to use mustum or low-gluten hosts is within the competence of the diocesan Bishop. The authority to permit the lay faithful to use mustum and low-gluten hosts in the reception of Holy Communion may be delegated to pastors under canon 137 §1 of the Code of Canon Law.
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