Thomas Trotter, another expert, thought sauerkraut and portable soup were 'mere placebo.

Trotter can't have been any sort of expert. Just look it up. A normal meal portion of sauerkraut contains far more vitamin C than the RDA. It's one of the best sources available without access to modern technology.

Quétel's History of Scurvy and Vitamin C covers all this. I don't have a copy to check but there may well be songs referenced in it.