Why does frost make some veg taste better? In the past, veg gardeners often would not harvest winter root crops until there had been several hard frosts. They knew that if harvested earlier, vegetables such as parsnips might have a chewy, starchy taste, whereas after a frost this would have transformed into a much sweeter, more palatable flavour.
From the vegetable’s point of view, converting some starch to sugar makes sense in cold weather because the sugar helps to prevent water in its cells from freezing. The sugar molecules mix with water in the vegetable, and this stops the water molecules rising and freezing: in effect, sugar lowers the freezing point of the vegetable.
This extra sweetness occurs in both root and green vegetables. The technical reasons are not always the same: in brussels sprouts, for example, the sweeter flavour is
Frost bite: the flavour of kohlrabi is said to improve after a freeze