Dehydrate sliced bananas in an oven that is set to the lowest possible temperature setting. Cook the bananas for 1 hour and 30 minutes or until they have achieved the desired texture.
Slice the bananas into 1/4-inch-thick slices. Bananas can also be cut thinner than 1/4 inch to make them cook faster. Lay the banana slices onto a baking tray that you have covered with parchment paper or aluminum foil. Brush lemon juice onto both sides of each banana slice. The lemon juice keeps the banana slices from browning as they bake in the oven.
Cooking time varies depending on the thickness of the banana slices and the lowest temperature setting of the oven. Banana slices that cook at 200 degrees Fahrenheit take approximately 1 hour and 30 minutes to dehydrate fully. Crispier dehydrated banana slices should stay in the oven for an additional 15 to 30 minutes. Remove the banana slices from the oven and let them cool. Dehydrated banana slices may have a slightly chewy texture if they are not allowed to cool and are instead eaten immediately after they are done cooking.
You can also use a food dehydrator to dehydrate bananas. Some food dehydrators include the Nesco SnackMaster Pro Food Dehydrator, Excalibur Food Dehydrator and the L'Equip Dehydrator.