Before revision: Thus, while he recognised the benefits of citrus fruit (although he weakened the effect by switching to a boiled concentrated or "rob", the production of which destroys vitamin C), he never advocated citrus juice as a single solution.
After revision: Thus, while he recognised the benefits of citrus fruit (although he weakened the effect by switching to a boiled concentrate or "rob", in which the boiling process destroys vitamin C), he never advocated citrus juice as a single solution.