Try drying fruits yourself!
Thought I would just try to dry 1 grapefruit and 1 orange first and see what the result is like.
Halfway during the process, I took a smallest ring of grapefruit to try. Yucks! So bitter!
But since already half done, might as well just continue till done. Left the dryer on through the night.
This morning, I tried another piece to see whether it is truly dry. To my surprise, the fruit slices tasted very good! So I can dry all others that I have bought!