The unnamed suspect was fined 466,509 Turkish lira after being caught trying to take the aromatic fungus across the border to Bulgaria, the Istanbul forest region management authority said in a statement.
The authority said the truffle was worth €250 a kilo in some European countries and the individual had illegally collected nearly 29 kilos of it.
"After the incident, the Istanbul forest region management authority tightened protection and monitoring activities against those illegally searching for truffles," the statement said.
Recep Ates, an Istanbul forest region official, urged locals to inform the authorities if they see foreigners walking around the area with dogs.
Dogs or specially trained pigs are used to dig truffles from the ground.
Truffle hunting in northern Italy. Photo: Marco Bertorello/AFP