Singapore scientists develop antibacterial food packs from upcycled fruit waste that change color during spoilage

NTU Singapore scientists have created a biodegradable food wrap that changes color when the food it protects has spoiled. The wrap also has antibacterial properties that could protect the food from microbial contamination.

The food wrap is upcycled from discarded avocado pits and starch from durian and jackfruit seeds.

The researchers explain that the avocado seed extract used in the food wrap contains catechin and chlorogenic acid, which help prevent oxidation and stop the growth of harmful bacteria like Staphylococcus aureus, which produces toxins that can lead to food poisoning.

Industry partners who were not involved in the study affirm the NTU innovation’s broad applicability.

“Fortifying a more secure, sustainable and just food system, while minimizing waste, is not merely a choice in Asia — it is necessary,” says Mirte Gosker, managing director of The Good Food Institute Asia Pacific.

“The wrap could serve food producers well, as they look increasingly to reduce waste, and further optimize overlooked elements of the food production cycle – such as seeds. 

“By utilizing previously discarded jackfruit seeds, durian seeds and avocado pits, the novel food wrap production method created by NTU’s Prof William Chen is a compelling example of how we can look to nature to achieve a bigger green impact with less.”

Color-changing properties

The avocado seeds contain a natural compound named “perseorangin”. This compound is sensitive to changes in pH value and changes its color at different pH levels – depending on how alkaline or acidic it is.

To indicate food spoilage, the wrapping turns from a translucent yellow to a deep brown color when the nitrogen compounds are produced by bacteria when amino acids in protein-rich foods such as seafood and meat are broken down.

The smart wrap was able to warn of food spoilage up to two days before the shrimp was discolored and emitted foul odors. This visual alert could significantly improve the monitoring of food freshness and potentially avert illness by dissuading people from eating food that may look fresh but has started rotting.

Lead author professor William Chen, director of NTU’s Food Science and Technology program, who led the study, says: “We have developed a new food wrap expected to have a profound impact on reducing food wastage by harnessing the power of nature, namely the antimicrobial and anti-spoilage compounds in discarded avocado pits.”