The blind-ended ventriculus is reserved for arthropod food, where it is subject to the usual peptic digestion.
From the guardian.co.uk
Birds possess a ventriculus, or gizzard, composed of four muscular bands that rotate and crush food by shifting the food from one area to the next within the gizzard.
From the en.wikipedia.org
Yeah, apparently, when they eat these fruits, they bypass the ventriculus, which is closed off by a special sphincter, so that the fruits'seeds pass through in a matter of minutes, unharmed.
From the guardian.co.uk
More examples
Gizzard: thick-walled muscular pouch below the crop in many birds and reptiles for grinding food
A digestive cavity or stomach
This is another name for a bird's gizzard. It is sometimes called the 'true stomach.