An Olian guava was a food native to the Delta Quadrant.
Neelix received some Olian guavas, and kept them preserved, although they were not a favorite among the crew. In 2377 when replicator rations were at a premium, he served B'Elanna Torres one of the few preserved Olian guavas he had left. She was less than enthusiastic, but was called to the bridge before she could take a bite. (VOY: "The Void")
In reality, the Olian guava actually appears to be dish of dried persimmons, which is eaten as a snack or mixed with desserts in Chinese communities. (citation needed • edit)