A group of chemists from RUDN University has developed an antibacterial coating for food products. The mixture contains a pair of components that are safe for human health and create a thin, biodegradable and non-toxic film.
The film does not have any flavor or color and can enhance the shelf life of various products by as much as 2.5 to 8 times. The study results were published in the Food Packaging and Shelf Life journal.
Generally, food wraps are produced from chemical compounds that are based on synthetic polymers, like polypropylene and polyethylene. Such materials are not good for the environment and take dozens, if not thousands, of years to decay.
A food coating should naturally protect the food and should not contain any toxins that can possibly contaminate it, but it is also significant for it to disintegrate without a trace once it is used.
At RUDN University, a group of chemists developed such a coating from polysaccharides—natural macromolecules that act as the building blocks of living organisms. Polysaccharides are non-toxic and biodegradable and do not have a negative impact on health.
The antibacterial coatings recommended by the researchers are based on a polysaccharide called chitosan that is present in lower fungi or in carapaces of crabs. The chemists particularly used two derivatives of chitosan: chitosan succinyl sodium salt (SC-Na) and a compound of triazole, betaine, and chitosan (TBC).
The latter has antibacterial properties similar to those of present-day antibiotics. According to the researchers, TBC nanoparticles entrench into a matrix or SC-Na grid, producing a thin even film.
It is relatively powerful when compared to any of its individual components and allows only minimal steam and oxygen in. During the course of the experiments, the researchers verified that the film is the most efficient when the SC-Na to TBC ratio is 1 to 1.
We managed to obtain non-toxic chitosan derivatives with extraordinary antibacterial properties almost similar to those of commercial antibiotics and suggested that they could be used to increase film durability and antibacterial characteristics.
Andreii Kritchenkov, Candidate of Chemical Sciences and Research Assistant, Department of Inorganic Chemistry, RUDN University
Kritchenkov added, “We based our coating on SC-Na, a salt with high film-forming ability. Moreover, it is not toxic and works as an antioxidant, increasing the shelf life of food products. By changing the TBC/SC-Na ratio, we developed multifunctional food coatings with improved antibacterial, protective, and mechanical properties.”
To validate their invention, the researchers placed a number of bananas in the film for a period of 10 days. During the course of the experiment, the researchers quantified the vitamin C content, weight, and the concentration of carbon dioxide emission in the fruit.
Following 10 days, these parameters were compared to the outcomes from the control group that was kept without coating. It was observed that the coated fruit lost eight times less vitamin C and three times less weight and that the frequency of its “breathing” was 2.6 times lower (that is, metabolic processes related to reduced CO2 emissions).
Due to these properties, chitosan-based films can be utilized for storing food products. Once a film has been utilized, it will decay without causing damage to the surrounding.
Kritchenkov, A. S., et al. (2020) Active antibacterial food coatings based on blends of succinyl chitosan and triazole betaine chitosan derivatives. Food Packaging and Shelf Life. doi.org/10.1016/j.fpsl.2020.100534.