Packaging solutions for citrus and deciduous fruit

CONTACT DETAILS: +27 21 887 1134 / +27 82 886 7094 /
DURATION: Three years
LEAD INSTITUTION: ExperiCo (Fruit Technology Solutions)
BENEFICIATY: The citrus and deciduous fruit sectors

Packaging plays an integral role in the maintenance of fruit quality. It should be structurally sound to protect fruit from mechanical damage and also be able to facilitate cooling and ventilation. There is the added demand for environmentally friendly alternatives and the need to reduce the carbon footprint. These considerations, coupled with the number of commercial packaging options available, complicate the selection process. To assist producers and exporters in making the best packaging choices, a collaborated project between Fruitgro Science and ExperiCo was initiated.

Green economy principles applied to export fruit packaging

The ExperiCo research team, led by Dawie Moelich, tested the properties of various packaging formats. A range of the major apple, pear, plum and citrus cultivars were included in the trials. The project focused on sustainability to determine opportunities for better efficiency in post-storage quality, energy and logistics. Green economy principles were therefore applied, which includes the four R’s of packaging: removing, reducing, re-using and replacing.

  • The influence of venting levels on the cooling characteristics of transport packaging (plastic crates and corrugated boxes) and forced-air cooling (FAC) rates was evaluated.
  • The ability of newly developed inner packaging (plastic liners) to maintain fruit quality was assessed to find opportunities for removing, reducing, re-using or replacement with Biobags; manufactured with environmentally compatible bioplastic material.
  • Cooling rates were determined in high and low vent transport packaging, in combination with inner packaging selected from 60 µm polyethylene (PE), 37 µm PE, 20 µm PE bags, the 20 µm plum wrapper, 40 µm Biobags and control treatments without liners.

Export packaging test results

  • FAC rates were consistently faster in high vent than in low vent packaging. The faster cooling rate varied between 50% (‘Bon Chretien’ pear packaging) and 9% (plum packaging).
  • The large variation in FAC rates is attributed to the variation in free headspace in transport packaging, which depends on fruit size (count) and the extent to which the packaging and fruit are optimised for maximum pallet payload.
  • Inner plastic liners had a prominent effect on cooling rates – fruit cooled several times faster without bags (by factors 4 to 8 x).
  • The faster cooling rates, achieved by high vent or the removal of plastic liners, influenced the ripening rate of ‘Bon Chretien’ pears only and had no significant influence on post-storage parameters of other cultivars. There is therefore no urgent, broad requirement for faster FAC rates than what is currently used in deciduous fruit pack houses; from a fruit quality maintenance point of view.
  • After simulated fruit export conditions, shrivelling occurred in most deciduous fruit samples due to moisture loss, with a higher incidence in high vent transport packaging. It proves that packaging liners are essential in most instances.

Benefits to industry

  • A one-page matrix was drawn up according to the ‘four R’ principles. It is a significant development and a very useful tool – it helps growers, exporters and pack houses to easily select the most suitable packaging options for plum and pome fruit cultivars.
  • The appropriate packaging helps to minimise losses.
  • There is no urgent need to change to extremely fast forced-air cooling for fruit quality maintenance, provided that cold chain requirements are adhered to.
  • Plastic liners can only be removed from current packaging combinations if fruit is stored for a short pre-packaging period, delivered to the export market in the shortest possible time and if relative humidity is maintained until retail.
  • Plastic liners and biofilm are not recommended for citrus, since their only benefit was control of moisture loss.
  • Bioplastic film can potentially replace petroleum based film in deciduous fruit packaging, but optimised atmosphere modification will be developed in another project.
  • Further experimentation is required to measure cooling rates in new citrus packaging, super-vented and regular corrugated cartons.