Students invent colour-changing food wrap to warn against food spoilage

Lecturer Lê Quang Phong instructs his students on their experiments with the eco food wrap. Photo giaoducthoidai.vn

HCM CITY A team of students at the Vietnam National University (VNU), HCM City has invented food wrap from agricultural byproducts that can change its colour when food spoils.

Dragon fruit and passion fruit peels have been used by Nguyễn Hoàng Kim Long, Nguyễn Ngọc Thùy Dương and Lê Thùy Linh from the Department of Biotechnology, VNU International University to make the wrap.

Long said they realised that farmers mostly focus on economic values of farm produce and ignore its byproducts, which can be recycled to make environmentally-friendly items.

Learning that passion fruit peel contains a lot of pectin – a natural fibre often used to improve consistency and create gel in many dishes – they started to experiment.

Thanks to the instruction of lecturer Lê Quang Phong, head of the Applied Chemistry Department, International University, in four months, the students conducted tests to check the growth rate of microorganisms and quality management to prove the safety of the product.

Dương, one of the students, said the process of creating food wrap includes collecting, cleaning and drying fruit peels. Through the extraction process, pectin from the passion fruit peel and betacyanin in red dragon fruit peel are obtained.

These extracts are mixed with water then poured into moulds and dried at 60 degrees Celsius for 24 hours. After obtaining the finished product, it will be laminated and shaped to complete the biological food wrap, she said.

“This process lasts about seven to ten days. The highlight of the biological food wrap developed by the team is its ability to change colour when food is damaged.

“The betacyanin pigment in red dragon fruit peel has the ability to change colour based on the pH of the environment. If foods such as meat, fish are spoiled, the pH level will gradually decrease. When food begins to spoil, the wrap will gradually change from pinkish red to yellow or transparent,” she told Giáo Dục&Thời Đại (Education and Times) newspaper.

Just by observing the food wrap’s colour, users can recognise to what extent the food is spoiled, thereby preventing food poisoning cases. The food wrap also has good antibacterial and antioxidant properties, helping to extend food life, Dương said.

With 200 grams of fruit peel, the team can create a 20-metre roll of food wrap with an estimated cost of VNĐ70,000 per roll. Compared to plastic wrap, this product is more costly, but compared to other types of biofilm on the market, their eco food wrap has a more competitive price.

Dương admitted that her wrap is not as smooth as nylon wrap. The product has a shelf life of three to four weeks under low temperature conditions (in a refrigerator environment) and must avoid direct exposure to sunlight.

If the above conditions are not met, the wrapping film will lose its colour and change features, she said.

Dương said: “Our team wants to be able to solve waste peels in farming, helping farmers have a new source of income from discarded products. We also hope that people can reduce plastic waste, change living habits and use friendly products to make the environment greener.”

Lecturer Lê Quang Phong said the project was creative and the students knew how to use renewable and organic materials that are friendly to humans. The group took advantage of fruit peels to make products with high economic value, supporting farmers and meeting consumer needs.

“Today, consumers are very concerned about health and the environment, so there is a high demand for green products. The eco food wrap is completely capable of being commercialised and sold to the market,” he said. VNS