When beetroot cylinders are washed and then kept in cold water, the anthocyanins do not come out. This indicates that the plasma membrane is

Beetroot contains the pigment anthocyanins. It is present in cell vacuole in fruits and flower. It has a protective role in plants against extreme temperatures. When beetroot cylinders are washed and placed inside cold water then there is no leakage of anthocyanins because plasma membrane is impermeable to anthocyanin.

So the correct answer is 'Impermeable to anthocyanin'.