The seed of the pistachio plant, commonly thought of as a nut, is actually not a botanical nut. The fruit naturally has a hard shell that is whitish in color. The seed has light green flesh, with a very distinctive taste. When the fruit ripens, the shell splits part way open with an audible pop. Each pistachio tree averages around 50 kg of seeds, or around 50,000, every two years.
The shell of the pistachio is naturally a beige or whitish color. Commercial pistachios used to be dyed red or green and would stain ones fingers when eating them. Originally the dye was used by importers to camouflage stains on the shells. The seeds used to be picked by hand and this often caused marks or stains on the shells. Most pistachios are now picked by machine and the shells are therefore no longer stained by hands, making dyeing unnecessary.
Some consumers got used to red pistachios and to meet this ingrained expectation, some pistachios may still be dyed, but this is very rare. Roasted pistachio seeds can be artificially turned red if they are marinated (before being roasted) in a salt and strawberry marinade, or in salt and citrus salts.
