sao paulo, brazil — Could a simple citrus peel be the key to keeping food fresh longer? That’s what researchers in Brazil are investigating amid growing concerns about the buildup of non-degradable plastic waste.
Scientists at São Paulo’s Campinas State University School of Chemical Engineering and Institute of Food Technology have developed a film made from limonene, found in citrus peels, and chitosan, a substance derived from the exoskeletons of crustaceans.
“We focused on limonene because Brazil is one of the world’s largest producers of oranges. [if not the largest] And São Paulo is the main orange-producing state,” said study author Ronieric Pioli Vieira, professor at FEQ-UNICAMP. media release.
However, despite limonene’s promising antioxidant and antimicrobial properties, its volatility poses challenges for food packaging applications. To address this limitation, the research team turned to poly(limonene), a limonene derivative known for its stability.
“To solve this problem, we came up with the idea of using a derivative of limonene called poly(limonene), which is neither volatile nor particularly unstable,” explains Vieira.
Chitosan was chosen as the substrate due to its natural origin and protective properties. The researchers hypothesized that this combination could result in a film with superior bioactive properties. Lab tests involved mixing limonene and poly(limonene) with chitosan and comparing different ratios given their inherent incompatibility. The research team employed polymerization using polar compounds to increase the cohesive strength of the mixture. The obtained film was analyzed and good results were obtained.
“Films with poly(limonene) additives outperformed those with limonene, especially in terms of antioxidant activity, and were about twice as strong,” Vieira reports.
In addition to its strong antioxidant capacity, this substance also showed potential as a UV screener. Despite the promising findings, these films are not ready for the commercial market. Challenges remain in scaling up chitosan-based plastic production and optimizing the poly(limonene) production process.
“This is what our group is working on. We are trying to demonstrate the multifunctionality of this additive of renewable origin,” concludes Vieira, adding that it could be used in other fields such as biomedicine. He added that he is also exploring applications for (limonene).
The research will be published in a journal Food packaging and expiration dates.
