Need help with making apple fruit leather in a dehydrator?

Cracking and thinning is going to happen as the leather loses its moisture. I have found that if you catch it before it completely dries out, it is better. If you buy leather in the store, it is generally moist.

My mixtures also start out very thick, so I would not worry about that. I dry my fruit leather at 135 degrees for around 7 hours. Perhaps you are drying too hot if it is cracking after 4.5 hours.

I found this recipe on allrecipes.com. It was originally made to be baked in an oven, but I'm pretty sure you will be able to dry in the dehydrator. I looks like you may have to add another fruit and sugar to your mixture.

Fruit Leather

1 cup sugar

1/4 cup lemon juice

4 cups peeled, cored and chopped apple

4 cups peeled, cored and chopped pears

Cover a baking sheet with a layer of plastic wrap. In the container of a blender, combine the sugar, lemon juice, apple and pear. Cover and puree until smooth. Spread evenly on the prepared pan. Dry for 5-6 hours. Fruit is dry when the surface is no longer tacky and you can tear it like leather. Roll up on the plastic wrap and store in an airtight jar.

http://www.seasonalchef.com/appleleather.htm

Hope this helps