Seed from immature hips

I have been collecting hips that are going off on the plants this season and extracting any seeds in them.

Originally I was just interested to see if there was any viable seed in the hips. I stored the hips in bags on the bench but they became very mouldy so I started to remove the seeds and store them dry in a little sand to dry them out.

Some seeds have little colour but many appear mature and vary from very small to moderately large in size. A lot of the seeds are forming almost outside the hip and may be affected by the sun. I have been impressed by the number of seeds collected (over 100 seeds from some varietys when I am lucky to get that many from my main harvest)

As the numbers have built up, I now think it worth coming up with a plan for storage and handling them and would like any suggestions from others on how to handle these seeds.

I am also getting lots of hips which have split open down the side and exposed the seeds to the elements. Will these retain viability?

Any advice would help.