Un revêtement d'algues maintient les fraises plus fraîches qu'un réfrigérateur

University of British Columbia researchers have created an edible, seaweed-derived coating that extends the freshness of strawberries by up to four days at room temperature, surpassing the performance of refrigeration. The innovation, detailed in a study published in the Journal of Agricultural and Food Chemistry, offers a promising solution to reduce food waste and lessen the environmental impact of cold storage systems. The coating, made from agar, a substance extracted from red seaweed, is combined with zinc and tannic acid to form microparticles that create a thin, protective layer around the fruit. This process transforms the normally thick gel-like agar into a transparent, edible film that dries quickly and adheres to the surface of the strawberries. The technique was tested on strawberries, grapes, and apple slices, with the best results observed in the berries. In controlled experiments, coated strawberries retained significantly more moisture compared to uncoated ones, remaining firm and preserving higher levels of vitamin C and antioxidants over four days. Uncoated strawberries, in contrast, began to develop mold within two days at room temperature, while refrigeration only delayed spoilage slightly, with most untreated berries deteriorating by day four. Coated strawberries stored without refrigeration remained mold-free for at least four days, whereas refrigerated strawberries stayed fresh for up to six days. The coating also demonstrated antibacterial properties and showed no signs of toxicity in preliminary tests using human intestinal cells. Consumers who wish to remove the coating before eating can easily wash it off with tap water within two minutes. The coating’s biodegradability and ease of removal make it appealing for both commercial and household use. A life cycle assessment revealed that the coating has a 14% smaller carbon footprint than traditional refrigeration methods and reduces freshwater ecotoxicity by approximately 85%. These reductions stem primarily from the decreased need for electricity and refrigerants typically associated with cold storage. The findings highlight a potential shift toward more sustainable practices in the food supply chain, particularly for perishable items like fresh fruits and vegetables. To evaluate the coating’s practicality, the research team substituted laboratory-grade agar with commercially available food-grade agar. The results were consistent, with coated strawberries exhibiting reduced moisture loss and spoilage while maintaining high quality. This step marks progress toward scaling the technology for broader application in the food industry. The development comes amid growing concerns over food waste and the environmental costs of refrigeration. In Canada alone, nearly half of all food produced is lost or wasted, contributing to an annual economic loss of about $58 billion. Fresh produce, including strawberries, is particularly prone to spoilage due to its high water content and sensitivity to temperature fluctuations. Dr. Tianxi Yang, a senior researcher on the project, emphasized the simplicity and effectiveness of the new method. “We wanted to find a simple alternative to cold storage,” she explained. “Once we added the coating, the fruit became far less sensitive to changes in temperature and moisture and stayed fresh longer.” Ivy Chiu, the study’s lead author, described the transformation of the agar solution into a uniform protective layer as “exciting.” She noted that the self-assembling microparticles formed in real time, creating a stable and effective barrier against spoilage. “To our knowledge, no one had made an agar-based microparticle coating like this before,” she said. As the research moves forward, the team aims to refine the coating further and explore its applicability to other types of produce. With its ability to extend shelf life, reduce waste, and lower environmental impact, the seaweed-derived coating represents a significant advancement in sustainable food preservation.