ARS | Publication request: Sensor for Detection of Pits in Dried Plums

Submitted to: Asae Annual International Meeting
Publication Acceptance Date: April 8, 2004
Publication Date: August 1, 2004
Citation: Jackson, E.S., Haff, R.P. 2004. Sensor For Detection Of Pits In Dried Plums. Asae Annual International Meeting.

Interpretive Summary: An inexpensive, non-destructive device was designed and built that can detect and remove dried plums that contain pits from the processing line in real-time. Dried plums were placed on a conveyor belt and compressed with two overhead rollers. The rollers were situated over the conveyor to form a gap smaller than pits but larger than would completely flatten the fruit. The first roller functioned to compress the meat of the fruit down to the size of the pit. The second roller was placed over a force transducer, which measured the amount of force applied to it when fruit was forced through the gap. This served to distinguish between pits and meat, as the pits were harder to force through the gap than the softer meat. The device was tested in a dried plum processing plant, and correctly identified 89% of the 400 dried plums tested. While not 100% effective, used in conjunction with other technology already in place this device has the potential to help reduce the overall pit count in the final product. The low cost to build and implement this technology, compared to others already in use, increases the likelihood of adoption by the industry.

Technical Abstract: An inexpensive, non-destructive device was designed and built that can detect and remove dried plums that contain pits from the processing line in real-time. The device consists of a conveyor system, a series of rollers, and a force transducer that measures the force applied to the belt as the fruit passes below the rollers. Testing with 400 dried plums in a processing plant correctly identified approximately 70% of the fruit containing pits while maintaining false positive results below 1.5%. Only large fragments can be detected without damaging the fruit. While not 100% effective, used in conjunction with other technology already in place this device has the potential to help reduce the overall pit count in the final product. The low cost to build and implement this technology, compared to others already in use, increases the likelihood of adoption by the industry.