when's fruit ripe for the picking?

Hi, I have a Pilosocereus palmerii with a nice looking fruit thats been developing for some weeks, but I'm not sure how to harvest the seeds.This is the second fruit this season - I picked the first one off and had a peek inside, not really knowing the deal, the insides were white and it soon rotted to nothing!This second fruit is still on the plant, it's turning dark blue/purple and hard.Any tips and suggestions appreciated! 

only one suggestion

1) dont eat the fruit unless it is edible

regards
Darren

I think most cacti fruit should be edible, only problem really being glochids or spines. Most of em are rather tasteless though.
Anyway back to original question, the fruit will be ready when it's soft, split and/or fallen off the plant. if it falls make sure you get it before the ants.
To clean up the seed, place fruit pulp in small takeaway container cover with water. blend briefly using barmix. let settle, seed should fall to bottom, plant crap to top. seperate layers. and ya done.

cactus candy? http://opuntiads.com/oblog/?p=2939 http://www.cactuscandy.com/oscommerce/

does the barmix damage the seeds??

If you do it quickly the seeds should be fine. If you leave it on too long you can turn your seeds to mush. sorry, should have put a warning with that post.

I just mush the pulp & mix it into a flask of water, let sit overnight then do the swirl n pour trick, the seeds are heavier. then dry on a fine mesh screen or old silk hanky, don't use paper towel because once dry you wont get them off without damaging the seed.
I usually try to recover as much of the pulp as i can as well.
Oh & P palmeri is quite edible, although the palatability varies a lot from clone to clone

this sounds heaps better than the way i have been doing it! i have been picking every individual seed from the fruit with a stanley knife blade... it takes me ages!!! i had 12 fruit off my golden barrel and got hundreds of seeds... there is another 20 or so fruit almost ready to come off again so i will do your methods next time.

I wouldn't bother doing this method with golden barrel fruit. let the fruit dry and the seed will just fall out.

Sorry i should have said that the above technique is good on non-dehiscent fruits.
Anything that produces a dry fruit is best left to dry & just shake the seed out once the fruit splits/opens.
horses for courses

OK cool that sounds like a better option

Great thoughts.

Do you know if Ferocacti need another Fero to get polinated and fertilised or whether multiflowers will do?? My F.latispinus made 5 fruits and they are all blank, hollow. I guess they were not fertilised right with my hand pollination, I just forced them to quit the flower and make false fruits!