Bluish tinge in turnip or radish or 萝卜(luó bo)

Now that the weather is intensely hot, with temperatures ranging from 34 deg C to 36 deg C especially in my (small, stuffy kitchen!!!) I bought some turnip or radish or 白 萝卜(bái luó bo) to add to some spare ribs for a “cooling” soup.

白 萝卜(bái luó bo) soup is NOT a favourite among the Hubby or the kids but since it’s something I can easily buy from the wet market, this soup makes its appearance about once a fortnight. I’ll add in some wolfberries 枸杞 (gǒu qǐ) to add a bit of colour and added nutrition to an otherwise white and grey soup!

However, I noticed that the turnip had a bluish tinge in its heart when I sliced it through:

Googling this up, I found nothing much except for this guide by the New Brunswick Department of Agriculture, Aquaculture and Fisheries about “club root” disease in turnips. However, club root symptoms occur in the turnip plant, not its root.

Since I could find no answers and didn’t want to risk poisoning my family with a simple turnip soup, I decided to bin it. I’m sure Hubby was happy to have his sweetcorn and carrots soup tonight 😀

Does anyone know what causes the bluish tinge and also whether it’s harmful or harmless?