Researchers from the US and Singapore have developed a method to extend the shelf life of vegetables by injecting them with biodegradable microneedles containing the hormone melatonin.
The researchers, based at Massachusetts Institute of Technology (MIT) and the Singapore-MIT Alliance for Research and Technology, found their method was able to roughly double the unrefrigerated shelf life of the vegetable pak choi.
Melatonin is a natural hormone that delays growth and ageing in plants. In the study, the researchers boosted the pak choi's melatonin concentration by inserting the chemical into patches of silk microneedles which could penetrate the plant's skin without causing a stress response. They placed the patches at the bottom of the stem to allow the melatonin to spread up through the vegetable's inner tissues.
Their results, published in Nano Letters last month, showed that the shelf life of pak choi at room temperature was roughly doubled to around eight days when fortified with melatonin microneedles. When refrigerated, the shelf life was extended by ten days, remaining "relatively green" after 25 days. They measured shelf life by monitoring the pak choi's weight, visual appearance and concentration of chlorophyll – the pigment that gives plants their green colour, which decreases as plants age and wilt.
Read more at The Chemical Engineer