Zapped by a Zapote

i cannot imagine anything tasting better than a ripe crimson red zapote.  but more often than not when you slice one open you'll find a sickly looking brown.  my success rate from supermarket purchases used to be about fifty fifty.  it gradually droped to 90% uneatable.

what's the deal with zapotes?  is there a season for zapotes?  does it have to be ripe when you buy one?  how effective is the technique of digging our a piece of the shell with a fingernail to get a look at what's inside?

Sorry, no idea. Never bought one. Better to ask a Dominican!!!