This is getting far off-topic, since English-language folksongs very rarely argue the antiscorbutic properties of sauerkraut, but still....

Jack Campin wrote:

Cook's sauerkraut was sealed in barrels. No way light could affect it. It would not be affected by storage as badly as citrus juice; the salt content preserves it.

There are two different issues. The salt content assuredly preserves the food, and the acidity of the sauerkraut also reduces decay.

But as far as Vitamin C is concerned, that's not true. Salt reacts with Vitamin C. In fact, Sodium ascorbate is a less acidic relative of Vitamin C, which apparently has some antiscorbutic effect. Some -- but less than ascorbic acid (or so internet sources assure me; I don't claim to know of my own knowledge). And the chlorine ions can't have been helpful....

So, while sauerkraut would remain edible for a long time, in a hot, salty environment, it would lose its antiscorbutic properties, just as lemon juice would. Not entirely, of course -- but the older your antiscorbutic (whatever it was), the larger the dose you needed.

And even though Lind had discovered antiscorbutics, he hadn't discovered the aging problem. Look up the Nares Arctic Expedition (1875). They had antiscorbutics -- and they didn't work, and scurvy almost doomed the expedition. Best guess is that the antiscorbutics lost their effectiveness because of light and heat. Yes, it was a British expedition, and would have used lemon juice (I think), but the point stands for all antiscorbutics.