At 100% performance, a Starf Berry will contribute 1500 units of powder.
At 100% performance, a Starf Berry can produce a Level 28 (probably higher) Spicy-Sweet Poffin when cooking alone.
If blended with a Lansat Berry at the Lumiose Juice Shoppe, it will become a Rare Soda, increasing the drinker's level by 3.
Dream World artwork
In Generation III, the colors of the Starf Berry's star match the five flavors: red for spicy, blue for dry, pink for sweet, green for bitter, and yellow for sour. For unknown reasons, the pink part was changed to yellow in Generation IV.