For small lots I usually try to float out most of the pulp in a tall glass of water, repeat the process of tipping out the floating pulp, refill and tip again.
I usually pick out floating seed and keep, as I am not convinced all are non viable.
For the last of the seed, washing them through a strainer helps. A fine mesh tea strainer will grab pulp on the mesh but not seed. Tip off the seed, then clean the strainer and repeat till pulp is gone.
For large seeds, some pulp will wash thru a spaghetti strainer with bigger holes. You can pick out the seed from the pulp, and wash some pulp thru until you get all the seed.
It seems best to use fresh fruit for seed extraction. Older broken down semi dry fruit are harder to deal with, and seem to be prone to mould and bacteria infection of the seed. Seeds often already discoloured and stained at the pointy end where the root emerges.
I have received commercial seed, some with Hydroxyquinoline sulphate treatment which seems the better method compared to Thiram treatment of others.
Thiram seems to prevent some moulds forming on stored seed, but does not prevent other moulds attacking the planted seed. You can still get a high rate of induced albinism.
Hydroxyquinoline sulphate is used in some acne medications, but not in Australia as far as I can find.