Stone detection is the inspection step applied to pitted fruit to identify and remove residual stone fragments or whole stones that survive the pitting process, reducing the risk of tooth injury and product liability.
In trade practice
Most pitted fruit lines use X-ray inspection systems, which can detect dense stone fragments that optical cameras miss, particularly in dark-coloured fruit such as sour cherry or plum. Some facilities combine X-ray with laser or metal detection as a secondary check. Buyers commonly require a written stone-free guarantee backed by documented X-ray calibration records and regular test-piece challenges using reference stones of defined size. A frequent audit finding is that challenge tests are performed too infrequently or with test pieces that are larger than the stated detection threshold.
In a specification
A specification for pitted frozen fruit typically states that the product must be free from stones and stone fragments above a defined indicative size, with X-ray inspection confirmed as a mandatory processing step and calibration records available on request.