If pickling destroys Vitamin C, how is Sauerkraut rich in Vitamin C?

My understanding is that pickling destroys Vitamin C. However, apparently Sauerkraut is very rich in Vitamin C and is used by the German Navy to offset scurvy. What am I missing here?

Because early sailors suffered from scurvy and I must assume they brought preserved fruits and vegetables with them but that wasn't enough (or maybe they didn't? But if they did not I do not know why unless Europeans did not know about pickling but that seems unlikely). What is it about Sauerkraut that is different?

EDIT: Question has been extended to Why weren't pickled fruits and vegetables part of (European) rations during the Age of Sail?

Best Answer

Vitamin C is destroyed by heat and light. If you use a preservation method that relies on heating the sauerkraut at any stage (hot pickling liquid, water bath or pressure canning the jars) then some vitamin C is destroyed. Exactly how much depends on the process: not all vitamin C is lost immediately so different processes will have different amounts of vitamin C left. And if you use a preservation method that doesn't rely on heat like lacto-fermentation, no vitamin C is lost to heat (some may be lost to light, depending on how you store it).