Processors and packagers are inconvenienced by rogue pits and stones found in dried fruit, such as prunes and apricots, because they lower product quality and disrupt production when used as an ingredient.
Dried fruit has a long shelf life and therefore can provide a good alternate to fresh fruit when out of season fruits is unavailable.
Dried fruit is often added to baking mixes and breakfast cereals and increasingly seen as a healthy snack by the public.
Removing single stones or pits, called drupes, from fruit can be performed mechanically, but inspection can only be perfomed manually, or using expensive imaging equipment.
Agricultural Research Service (ARS) engineers have invented a new way of detecting whole and large pieces of pits left in fruit through a combination of touch and mathematics.
The computerized device applies pressure to the fruit measuring the resistance and then uses a mathematical formula written by ARS scientists to determine whether and automatic sorter should remove the suspect item, while allowing stoned fruit to pass.
The detector in prototype form can process about one piece of fruit per second, although commercial development would improve speed, they say.
Thousands of dried plums were tested with false positive accuracy rate of about one per cent, claims the ARS scientists.
Now successful testing is complete, commercial development to improve the technology for industrial use is expected.
The inspection prototype, which cost less that $500 in parts to build, is now open for development by a number of companies, which are considering a license for the patent.
Ron Haff, an ARS spokesman said the tester would theoretically work for any dried fruit with pits, such as apricots, although testing has been limited to prunes so far.
"The detector could be commercially available almost immediately upon an interested party licensing the patent and adapting it to a commercial processing plant envi ron ment," he told FoodProductionDaily-USA.com .
The detector would be an inexpensive addition to dried fruit packing houses, as well as processors using dried fruit, the ARS scientists claim.