A smart food wrap that changes colour

The avocado-based material alerts users when a food product has gone bad

Spotted: Foodborne diseases are considered one of the biggest public health problems worldwide, causing around 600 million cases of illness every year. There are many different causes of food contamination from toxins to pathogens, and unsafe food can be difficult to detect with the naked eye. Now, however, a team at Nanyang Technological University (NTU) in Singapore may have an answer.

Scientists from NTU have developed a food wrap, made from avocado pits and starch from durian and jackfruit seeds, which changes colour depending on the edibility of an item. The key ingredient is avocado seeds, which contain a natural compound named Perseorangin that changes colour depending on pH levels. When protein-rich foods such as seafood or meat are good, the wrapper is translucent yellow, but when the food begins to spoil, nitrogen compounds are produced by bacteria and the wrapper turns a deep brown.

Wrapping that offers a visual alert could significantly improve the monitoring of food freshness for consumers and suppliers, even before a food visibly starts to rot. During tests, the researchers found that the wrapping changed colour up to two days before expired shrimp looked or smelt off.

Avocado seed extract also contains catechin and chlorogenic acid, which have anti-oxidation properties and prevent the growth of Staphylococcus aureus – a harmful bacteria that can cause food poisoning. As well as helping to protect consumers from dangerous foodborne diseases, the innovative wrap could also be an effective way to repurpose seeds, an often overlooked waste source in the food industry.

Written By: Jessica Wallis