30 miles,4-5 hours
Interesting. I'm wondering if it's the type of oranges you're using. I could see a juicy thin skinned orange getting moldy. Try finding a variety with thick skin. Also, this is over a heat source that causes it to dry out quickly, that will avoid mold.If it's still a problem. Spraying a 50:50 mix of vinegar on any fruit is a great way to stop mold.
Daylight Visible Bike Light - Front/Rear Combo - 100 Lumens on 2 AA's