Chilean researchers have applied natural ingredients to clamshells in a bid to keep blueberries in better shape for long distance travel, as part of a government-backed project that has shown positive results in the R&D stage.

Innovation agency CORFO now aims to help get the packaging sector involved with the technology, which consists of a natural coating in the polymer matrix of the packaging as well as an organic additive introduced inside.

The Regional Center for Food and Health Research (CREAS), a group that executed the project with the Federico Santa María Technical University (UTFSM), said the development would favor export profitability.

Chile is the world's leading exporter of the antioxidant-rich fruit, but the tyranny of distance is always a challenge with travel times of up to 45 days in shipping blueberries to far-flung continents. When defects occur on arrival, fruit softening is a problem around 68% of the time, while other issues like dehydration and rot tend to be present in 55% and 12% of defective blueberry cases respectively.

CREAS researcher Dr. Mónika Valdenegro said to tackle this issue her team worked with a wide range of natural extracts to identify plant materials that could have antimicrobial and antifungal properties.

"One of the most significant problems during the cold storage of fruit products in general, and in blueberries in particular, is Botrytis cinerea and the resistance this fungus has to the (certified) products that exist in the market today for its control," Valdenegro said, adding the trick was to find a product that could mitigate the problem without having the fruit's bloom deteriorate.

The first tests involved propolis, pomegranate skin and the fruit and leaves of maqui berries; propolis won out at the end of the day, due to its effectiveness in in-vitro antifungal tests.

"Diverse coverings were prepared and the fruits were given a bath in them, and afterwards a drying process was done (on a laboratory scale). Refrigerated preservation was monitored with different formulations of this incorporated extract, and with other elements to give a better covering over the fruit.

"At first, we saw this component [propolis] was very good for controlling the fungus but it removed the bloom, which was not a viable commercial alternative."

In the second stage, the researchers bet on other extracts that in addition to having antimicrobial and antifungal activity, had the characteristic of being volatile so they could move within the PET clamshell packaging that blueberries are currently sold in. As part of this process the team worked with anise oil, thyme extracts and fennel extracts.

Felipe Castro, who led the project from Fundación Chile, said edible films were then made as a means of transport for the active natural ingredients with antifungal properties, and the extract was applied to PET sheets, fixing the compounds to the polymer matrix for evaluating the effects on fruit.

"A technology was developed based on the emulsion and micro-encapsulation of volatile compounds with antifungal properties, forming micro-spheres that were incorporated in a sachet to be introduced in the clamshells blueberries are currently available in," Castro said.

He added the anise oil was introduced in the clamshell through a sachet capsule, while thyme extract was selected for preparing dispersions of natural extracts. Both these processes were undertaken by experts from the Plastic Technology Institute (AIMPLAS) of Spain.

Universidad de Chile's Dr. Luis Luschinger was in charge of cold storage systems in the tests, and said another fundamental aspect of the packaging development was research into the dynamics of pallet cooling. As part of this, a comparative study was undertaken using traditional packaging, modified packaging with the extracts, and a packaging with modified design.

CORFO regional director Carlos Leppe concluded the project's results would contribute to improving the profitability of the export process, and the use of 'active' packaging could lead to greater opportunities for differentiation amongst exporters, and therefore improving competitiveness.

"I believe the second stage is to work in Line 4 of CORFO to go to the packaging sector from research and development. In this way, we ensure massification and in turn, a positioning in the international market," Leppe said.

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