Mood Enhancement
The Sim will get a positive boost to his mood just by carrying the flame fruit in his inventory. When you place a flame fruit in a Sim's inventory, he receives a +5 mood boost. The fruit also gives your Sim the positive moodlet "'Cozy Fire" -- the same moodlet given to your Sim when he relaxes by the fireplace or campfire. Fruit will spoil if left in your inventory for too long, so refresh your flame fruit supply when the fruit goes bad.
Cooking
Flame fruit is used in multiple recipes on "The Sims 3." It is a required ingredient for baked angel food cake. Eating baked angel food cake gives a Sim a +15 boost to mood and the "Warm Fuzzies" positive moodlet. Sims must have a cooking level of 10 and have read the recipe to make the cake. Flame fruit can also be added to any dish that requires fruit including pancakes, cobbler and peanut butter and jelly.
Gardening
Flame fruit can be used to cultivate other flame fruits. Your Sim must be at level 7 for the gardening skill to plant one. Go into Build and Buy Mode, select your Family Inventory, select a flame fruit and place it on the ground. Return to Live Mode, click the fruit and select "Plant Here." The fruit is also a fertilizer. If there's one in your inventory, you can click on any other plant and select the flame fruit as a fertilizer.
Profit
The crops your Sims cultivate can be sold for a profit at the market. Go into your inventory to sell crops immediately. You also have the option of sending your Sim to the market. Click on the building and select "Sell Crops." The higher the quality the flame fruit is, the more money your Sim will receive per item. The food items you make with flame fruit can also be sold at the market for a greater profit than the fruit by itself.