A Stellenbosch University (SU) doctoral student has discovered an innovative way of preserving food products for longer shelf life by using wheat straws and mango peels. Ordinarily, these residues are thrown away or used as fertilisers or animal feed.
But according to Dr Lindleen Mugwagwa’s recent doctoral study the mango peels and the wheat straws have the potential to be used in the development of “renewable, biodegradable and non-toxic active food packaging that could help keep products fresher and for longer”.
This is because they have the ability to respond to temperature and time changes in food storage, according to her study. She said the research will benefit bio-refineries, the food packaging industry including farmers and consumers.
Mugwagwa’s achievement represents a huge milestone in her field and adds to the numbers of women in science and technology who are impacting lives with their innovations and research.
A post-doctoral fellow in the department of process engineering, Mugwagwa has recently obtained her doctorate in chemical engineering at SU.
Her discovery could not have come at the opportune time as the world is currently facing a serious environmental problem caused by single-use and disposable plastics. According to the World Wildlife Fund, plastics harm the environment because they take years to disintegrate and they also affect the marine ecosystems. In addition, said the fund, the chemicals used to manufacture the plastics also get transferred to animals tissues.
“There’s a move towards renewable and biodegradable food packaging in a bid to replace non-renewable and non-biodegradable petroleum-based packaging materials. We should consider using agricultural-residues like wheat straws and mango peels, which are rich in bio or natural polymers and antioxidants, as alternative raw materials to petroleum-based packaging materials,” said Mugwagwa.
According to SU, Mugwagwa’s study* was the first to develop methods for extracting the necessary bio or natural polymers and antioxidants from both wheat straw and mango peels that contain properties which are suitable for developing an active food packaging material. It was also the first time that these products were integrated to form a bio-composite film (a material composite consisting of biodegradable polymers and bio-based reinforcing agents) that was tested in a food environment, it added.
As part of her study, said SU, Mugwagwa developed and optimised processes for extracting these polymers and antioxidants. She then combined them to make a food packaging material and tested the stability of the bio-composite films when in contact with food as well as their potential to release antioxidants into packaged food over time. Low-density polyethylene film, a commonly used plastic, was used as a benchmark.
Mugwagwa said her study showed that the properties of polymers and antioxidants in wheat straw and mango peels can be tailor-made during extraction to suit their application in food packaging. The polymers and antioxidants can be extracted simultaneously from the same feedstock without affecting their use in food packaging.
She said the bio-based films that she developed were capable of releasing more antioxidants into food over a short period of time when compared to low-density polyethylene plastic. This suggests that they can be a replacement for packaging perishables, she added.
“The release of antioxidants into food by packaging material is becoming an important aspect to consider when choosing packaging material. Packaging material capable of releasing antioxidants into food in response to storage conditions has the potential to increase the shelf life of products because the released antioxidants act upon free radicals and micro-organisms which may develop when food is improperly stored or when food is stored for longer periods,” said Mugwagwa.
My research, Mugwagwa added, provides cheap, sustainable and biodegradable polymers that can be used in the development of food packaging and also presents methods for recovering natural antioxidants and their application as additives to food packaging material.
“These natural antioxidants have the potential to replace artificial antioxidants in packaging material that could cause cancer,” she said, adding that the type of food packaging material proposed in her study could be ideal to replace environmentally hazardous petroleum-based packaging materials.
*Mugwagwa’s study was conducted under the supervision of Prof A.F.A Chimphango with the financial support from the Organisation for Women in Science for the Developing World, the Swedish International Development Cooperation Agency (SIDA), the National research Foundation of South Africa, the Department of Science and Technology/Council for Scientific and Industrial Research Waste Road Map and SU’s Department of Process Engineering.