Scoping study of a disorder that reduces shelf life and consumption of green beans (VG14040)

What was it all about?

This project, which was carried out in 2015, investigated an as yet unknown post-harvest disorder of green beans that damages the appearance of beans and reduces their shelf life. The disorder is known to affect green beans, French beans, dwarf beans, and snap beans.

The project team spoke with researchers, growers, company staff responsible for production and produce quality, and agronomists involved with green bean production to determine the extent of the problem and capture the key symptoms of the disorder. They produced a literature review on what is known about post-harvest disorders of green beans.

The researchers found that the disorder was well known throughout the industry, and often referred to as rust. It was reported most commonly by Victorian growers. It was generally reported back to growers by the supermarket distribution centres, wholesalers and retailers after produce leaves the farm.

Symptoms include a general opaque discolouration of the entire bean, pitting of the surface, discrete rusty brown spots, and rust-coloured diagonal lines. Exposure of mature bean pods to chilling temperatures before harvest exacerbates the problem.

Although a tentative diagnosis at this stage, this study has identified two possible causes of the symptoms that can affect the quality of fresh green beans post-harvest: chilling injury of bean pods post-harvest; and a bacterial disease of leaves and pods.

The symptoms are, for the most part, consistent with symptoms of chilling injury and beans are known to be particularly sensitive to cold temperatures.

The expected shelf life for beans is eight to 12 days when stored at 5 to 7.5^oC. Beans can be stored for two days at 1^oC, for four days at 2.5^oC or eight to ten 10 days at 5^oC before chilling symptoms occur.

The research team had limited samples to work from during the study but they recommend that effort is put ensuring that produce is handled carefully along the entire supply chain. They noted that green beans are a specialist crop that perishes readily once harvested especially with poor handling.