The use of edible coatings as a viable replacement for plastic liners to maintain pome fruit quality

The drive to minimize or replace the use of single-use plastics necessitates the identification of alternative technologies to safely export packed fruit whilst maintaining fruit quality. The aim of this project was to scan edible coatings that are fit to apply to pome fruit cultivars.

Packed fruit were sourced from pack houses prior to re-cooling, re-packed/ coated, and cold stored to simulate worst case scenario delay for fruit during export to reach its intended market. Humidity was measured and mass loss was determined by weighing fruit at packing and at simulated arrival (SOS).

Post-storage quality parameters of various populations of pear and apple cultivars were examined over the course of two seasons, with five edible coatings, compared to fruit stored with or without the addition of a liner. The preparation and application of all edible coatings was easy and uncomplicated. The fruit dried easily post application, exhibiting a natural appearance and feel, with no stickiness or artificial shine and no visible product residues or tearing. Although sometimes significant, marginal differences in flesh firmness, skin ground colour and shrivel incidence was exhibited, with sometimes inconsistent ripening retention benefits across the coatings tested. This could be ascribed to the fruit being subjected to 1-MCP at harvest. Internal defect results found in fruit where an edible coating was applied was sometimes inconsistent; in some instances, reducing- and in other instances increasing incidence. These results could be linked to maturity and respiration rate at packing, and seasonal variation could possibly play a roll. Mass loss measured over the two seasons consistently indicated a trend that fruit stored with the addition of an edible coating exhibited average mass loss levels measuring between fruit packed with standard liners, and fruit packed without.

Over the past two seasons, results from fruit packed with the addition of edible coatings have periodically proved beneficial for flesh firmness and skin ground colour retention, reduced shrivel, or reduced mass loss in pome fruit. Although edible coatings have shown promise, the cause for sometimes inconsistent results is not well understood.

Results found with fruit stored in standard liners proved to be most consistent to maintain post-storage quality of pome fruit in the populations tested over two seasons. Although, packing fruit into liners could not always prevent postharvest disorders from developing and sometimes increased incidence. Should single-use liners be banned, edible coatings could be a viable alternative to consider, but a potential risk for increased post-storage disorder incidence was found. The reason for this is not yet fully understood but could possibly be linked to fruit maturity and respiration rates at time of packing, similar to consideration required when applying MAP technologies.