MACHINE FOR AUTOMATIC SORTING ‘BARHI’ DATES ACCORDING TO MATURITY BY NEAR INFRARED SPECTROMETRY

In the framework of an effort to improve the quality of shipments of ‘Barhi’ dates (Phoenix dactylifera L.), and in the course of studying their storage and post-harvest processing, the need for non-destructive massive sorting according to maturity was recognized. A preliminary experiment on the sorting of ‘Barhi’ dates was conducted with a semi-automatic system, which had been developed and operated for maturity determination of ‘Hayani’ dates. The results of this study showed that ‘Barhi’ dates could be sorted by the NIR (Near Infra-Red) system developed for ‘Hayani’ dates, with SEP (Standard Error of Prediction) of 1% for total soluble solids (TSS). The ‘Hayani’ system was developed in response to the requirements in Israel, where fresh dates are normally harvested unripe and are then stored in a controlled environment to await marketing. The ‘Hayani’ system is based on NIR spectrometry and gives an estimate of the TSS content of the dates in a non-destructive and labor-saving manner. Based on the 'Hayani' machine, a novel sorter was developed, tested and operated. The sorting rate was 1.7 s per fruit. The system included special detachable cells for alternating tests of the 'Hayani' and 'Barhi' varieties, a distribution system and dedicated software which sorted the dates into four quality groups according to user-programmable ranges of TSS content. A PC controlled the NIR scanner, the conveyor and the special divider that directed the sorted fruits into four separate containers. The machine sorted about 30,000 dates, which were immediately delivered to the chemo-physical researchers for further treatment and analysis. The machine which was developed will serve as a basis for future on-line, NIR sorters of dates, according to quality and maturity.