Developing a plant for processing PGI 'Cipolla Rossa di Tropea Calabria' spring onions using compressed air

One of the best-known Italian products is 'Cipolla Rossa di Tropea Calabria PGI', which refers to the Allium cepa L. onion, limited to the local ecotypes of Tondo Piatta (early), Mezza Campana (medium) and Allungata (late). A mark identifying red onion bulbs in spring onion, fresh onion and onion for preserving that meet the conditions and requirements of this specification, following Regulation (EC) No 510/2006. Depending on the stage and type of product being processed, the mechanical plant plays a key role in the processing chain. In post-harvest operation, plants based on large quantities of water are widely used for processing spring onions, allowing them to be washed, rooted, and peeled simultaneously. They generally consist of cutting, peeling, and cleaning equipment. Two pairs of shearing blades usually carry out both root and leaf-cutting. Peeling is carried out by 2 pairs of rotating rollers, usually of the brush type, and during the peeling phase, washing is also carried out through a series of special sprayers. However, a problem with this type of system is that the water stagnating in the cut onions tends to spoil them, reducing their shelf life. A processing line that uses compressed air to clean the onions was developed to solve this problem. A processing line that uses compressed air to clean the onions was developed to solve this problem. This research reports on the functional structure of the realised plant.