The taste is sour but not acidic, a tartness that promotes saliva in the mouth without impacting on the stomach, the way vinegar or even kalamansi often does. This is the kind of sourness only batwan can deliver. An important part of the souring arsenal of cooks in Negros Occidental and some parts of Panay, batwan is actually found in abundance in Bohol and Mindanao. However, there is no tradition of eating this fruit in these places said Ponchit Ponce-Enrile, general manager of the Eduardo Cojuanco, Jr. and Sons Farms in Negros Occidental. It seems that only Negrenses and cooks in certain parts of Panay have discovered the flavors of batwan. Batwan is close cousin of mangosteen, being under the genus garcinia. And indeed, they have similarities; batwan actually looks like green and stunted mangosteen.
Usually selling between P30 to P40 a kilo, seasonal batwan can command as much as P80 a kilo when it disappears from the markets, which cannot be forecasted. The manner to propagate batwan has remained a mystery, except in the ECJ and Sons farms here in Negros Occidental, where some 10 hectares have been planted to this fruit in what could very well be the country’s first batwan plantation. Ponce Enrile said salting is one way of preserving batwan. However, while this traps its one of a kind sourness, it also retains its saltiness. Souce: http://www.filipinoheritage.com