"Jennifer Sparkes" wrote in a message:

When we used to make Rosehip Wine - many years ago - before
boiling them up we put them in the freezer. IIRC it did help.
---
I too have made quite a few gallons of rose hip wine using fresh and dried
hips. When making wine with fresh hips, I always used Rohament 'P', an
enzyme that breaks down the cellular structure in fruit, as does placing the
hips in a freezer for a few days. Rohament 'P', readily available from most
good home wine shops, also helps to retain the colour of the hips and
ensures excellent flavour and juice extraction.

MikeCT