Scientists have developed a new non-toxic, biodegradable and antimicrobial food coating that can reduce food waste and foodborne illness without adding plastic to the environment. A new study shows that this material can be effectively sprayed onto vegetables. Before eating them, the composition is easily washed off with water. The results of the study were published June 20, 2022 at nature food.
The plastic may remain in the environment for a long time, but the new coating is biodegradable. It is based on pullulan, a polysaccharide polymer derived from starch. The coating also includes natural antimicrobial ingredients (citric acid and thyme oil) as well as nisin preservative, all of which are considered safe for humans (when consumed in reasonable amounts).
To produce the coating, the scientists used a system called focused rotary jet spinning, or FRJS. The FRJS system can be compared to a cotton candy machine that rapidly spins melted sugar through small holes to produce thin threads that can be wrapped around a paper cone. FRJS also creates a focused stream of spider web fibers (in this case made from pullulan, not flavored sugar) that can be wrapped around a food item.
The team also tested how the coating improved food safety. When the researchers ran the necessary tests, they saw a reduction in both bacterial and fungal populations on the surface of the products. The scientists also found that coated avocados were less prone to rotting, with only 50% of the fruit spoiled within a week compared to 90% of uncoated avocados. Coated avocados were more likely to retain their green inner color.
Although this is not the first antimicrobial coating for food, the researchers believe that they have created the most effective and easily recyclable option to date. They claim that the spray technology requires less starting material, making it more efficient than silk fiber coatings, which require products to be first dipped into the material and then dried. Other attempts at plastic-free food packaging have included cellulose-based films; they cannot be washed off, and some even need to be recycled.
The team is currently working on refining the coating process for the simultaneous processing of multiple product items. The scientists are considering several options, including a pipeline-based system, but this is still in the early stages of planning.