The Philippine farm ministry’s bureau of post-harvest research and extension and the country’s post-harvest training and research centre have developed a non-refrigerated cooling system for vegetables. It can be used for short-term cooling of aubergines, tomatoes, cucumbers, capsicum, legumes and cabbage.

Using the principle of evaporative cooling, it works with charcoal as a cooling pad, a water reservoir, a submersible pump, fan and storage chamber.

“The concept of the technology is to allow air to flow past the wet pad surfaces and let water evaporate into the airstreams,” said Lorena Miranda, one of the researchers involved in the project. “Heat escapes during the process and leaves the pad at a lower temperature with higher moisture. This prevents the vegetables from wilting, thus extending their shelf life.”

Miranda and her colleagues have developed two prototype designs: a display-type and a cabinet-type evaporative cooler. The display version has a 50-80kg capacity and is suitable for use by retailers and the cabinet style with a capacity of 240-400kg is suitable for trade applications.

The field tests have been extremely positive and both research organisations believe that their technology offers a viable alternative to mechanical refrigeration of fresh produce lines.