Once harvested, asparagus spears are highly perishable. They also continue to develop after harvest making cool chain management essential. Wet hessian bags or weights are often placed on the top of asparagus-filled crates to prevent the horizontally laid spears from bending upwards in search of light before packing. Full crates are sometimes passed through a pre-wash to loosen any dirt or debris and help reduce any field heat before packing.
Traditionally, asparagus was sorted and packed manually. However most growers now have computerised grading systems. The spears are placed onto a header belt with all the spearheads touching the top edge so that they can be trimmed to a set length (24 or 25cm).
The spears are washed thoroughly with clean water, straightened and loaded into individual cups of the grader. Any spears with obvious defects are removed at this stage. A photo is taken of each spear and the computer measures the length and diameter of the spear and the presence of white on the butt, then it designates a chute where that spear will be released. Spears that are too short, or still have a white butt, pass through the line and are trimmed at a later stage. Spears are collected from the chutes and packed according to their grade and market destination.
For export, loose and bunched spears are packed upright into specially designed wooden boxes. For the domestic market spears may be packed, loose or bunched, into polystyrene rectangular boxes. Alternatively they may be packed into recyclable ‘pyramid boxes’, which have a flared base to accommodate the asparagus butts that are thicker in diameter than the spearheads.
Once packed, the asparagus is hydro-cooled to remove any field heat and prolong shelf life and immediately placed in cool storage. Maintenance of the cool chain is vital to prevent continued growth of the spears and deterioration in quality and storage life. Pallets destined for export are sent by refrigerated transport to Sydney, Melbourne or Brisbane airports.