Rice bran—source for antimicrobial, biodegradable food packaging film

Rice bran, a common agricultural byproduct often disregarded, may hold potential for biodegradable food packaging with inherent antimicrobial properties, according to research from the Arkansas Agricultural Experiment Station. The study, funded by the Arkansas Biosciences Institute, reveals that plasma technology could enhance the value-added qualities of rice bran and rice bran protein.

Cold plasma treatment using argon gas, a state of matter observable in phenomena like the Northern Lights, was applied to films made from rice bran and rice bran protein. The treatment effectively inhibited foodborne bacterial pathogens, including E. coli, Staphylococcus aureus, and Pseudomonas aeruginosa, within eight hours and prevented regrowth 24 hours post-application. Untreated films, in contrast, exhibited significant bacterial growth.

The plasma treatment created microscopic spikes on the films and triggered a chemical reaction producing hydrogen peroxide, a potent antimicrobial agent. The study found that rice bran protein films exhibited more pronounced antibacterial effects, with 3.3-fold increased surface roughness and higher hydrogen peroxide concentrations compared to films made solely from rice bran.

While cold plasma is known for improving the physical and chemical properties of synthetic polymer films, its antibacterial effects in rice bran-based biopolymer films have not been previously documented. The research also examined the impact of treatment on the films' physical properties, such as water vapor transmission rate, tensile strength, and thermal stability.

The antibacterial effect is attributed to a combination of retained reactive species, enhanced wettability, increased surface roughness, and changes in surface chemistry.

The findings contribute to the development of sustainable, functional materials from rice-processing byproducts and address the challenge of creating effective antimicrobial films that do not incorporate harmful additives. The research team, led by Mahfuzur Rahman, an assistant professor at the University of Arkansas, expressed gratitude for the support received from the Arkansas Biosciences Institute.