Grape juice. All grape juice has trace amounts of alcohol. So does orange juice. He wasn't "drinking alcohol". Grape juice/wine for sacrament.
Discussion
Grape juice would have spoiled or fermented, without refrigeration.
And it did. They also used it fresh. It fermented. New grape juice has fermentation already. There is alcohol is all grape juice. Saying he drank wine regularly is a bit disingenuous. He took sacrament regularity. He was sober...