Orange juice loses 30 per cent of its vitamin C soon after it is squeezed, and commercial orange juice has almost no natural vitamin C left, according to "The Real Vitamin and Mineral Book", a HealthScout report states this week. According to the book,potatoes when freshly dug may have 30 milligrams of vitamin C per 100 grams, but go down to 8 milligrams by spring and almost none by summer. The C content in apples falls by 60 per cent a couple of months after picking. Green vegetables lose almost all their vitamin C after a few days at room temperature. And blanching vegetables before canning or freezing can destroy up to 60 per cent of vitamin C. By the time fresh peas are cooked, only 44 per cent of the original vitamin C may remain; 17 per cent remains in frozen peas and only 6 per cent is left in canned peas.