If someone had a brew made with ascorbic acid to acidify. If the brew's PH started at 4 and ended up at 2 because of boiling off water. How could one neutralize the ascorbic acid in the final product and bring the ph back to 5/6. Is there something that could react with the ascorbic acid to turn it into calcium acerbate or something?

any base would neutralize it in the right amounts. Maybe try sodium bicarbonate or carbonate, add slowly.