“Popping the back” is a term used for a technique used on certain fruits to be dried.
It inverts the cavity of the raw fruit half.
It shortens the drying time by exposing more flesh to the air.
To do it, you first wash the fruit, (then optionally peel it), and then cut the fruit in half and pit it.
Then, you press the rounded side of the half inward to invert the fruit half so that it bulges out the other side.
Then you place the fruit on the drying tray.
If you have left the skin on the fruit, place the piece of fruit on the tray skin side down.
“Popping the back” is practised with fruit that has large pits or cavities in it such as apricots, nectarines, pears, peaches, and plums.
Hendley, Alice Jane. Drying Foods. College of Agricultural, Consumer and Environmental Sciences, New Mexico State University. Guide E-322. Revised April 2016.
“Certain fruits, such as peaches, nectarines, pears, plums, and apricots can be dried as halves; to shorten drying time, flatten the halves (“pop the backs”) by pressing in the rounded side with your thumb to expose more surface. Dry the fruit skin side down.” — Foodworks. Bite 5 – Food Preservation. Drying Fruits. West Lafayette, Indiana: Purdue University. 2002. Accessed April 2020 at https://www.four-h.purdue.edu/foods/Drying%20fruits.htm
“Dehydrating time can be shortened even further by flattening or “popping the backs” of [larger pitted fruits]. Use your thumbs to press the rounded side in. This process exposes more drying surface to the air.” — Excalibur. Preserve it naturally. 4th edition, 2012. Page 21.