Does it bother you every time you pick up an item in the local produce department? The product often cannot be purchased without food packaging designed to preserve the produce from bruises, breakage, and rot. The perfectly evolved natural package has been overwhelmed by our modern supply chain, so that such food packaging serves a real need in reducing food waste.
But as waste plastics build up in our natural environment, the benefits of food packaging pale in comparison to the problems.
Enter chitosan, a sugar polymer derived from shrimp exoskeletons. Promising developments using chitosan to replace fossil fuel derived polymers have been reported.
Now, a new study tests chitosan bioplastic films as a coating on produce. The benefits are many. The study found that:
- eating the chitosan-coated carrots compares to eating uncoated carrots
- the chitosan coating improves the color and texture of the carrots, and
- chitosan delays microbial spoilage.
Chitosan is biodegradable and has natural antimicrobial properties which probably help to delay rotting. The solution is not yet optimal. Itsaso Leceta, lead author of the study notes:
"Chitosan film is better than plastic film in terms of the environmental impact, in a range of categories, but that does not mean it does not pollute. The manufacturing of chitosan, unlike the production of conventional plastics, has yet to be optimised. Once it has been optimised, the environmental impact of chitosan will be reduced even further"
A good part of any expansion into chitosan as a plastic substitute will involve examining the environmental footprint of shrimp farming.
Leceta's study indicates that the biofilm works best when applied in a modified atmosphere -- a process known by the acronym MAP, for modified atmosphere packaging. This basically means that the packaging is applied in the presence of a gas mixture other than our normal breathing air. For example, meats are best packaged in high oxygen to maintain color while other foods benefit from low oxygen, to deter microbial growth.
Chitosan as food packaging offers another potential advantage, even if only as a marketing ploy: controversial research suggests that the chitosan can reduce fat absorption. You can bet the controversial nature of the research will be ignored by marketing claims, so you can look for fat-reducing chitosan-coated vegetables coming to a market near you!
You can read the whole study: Quality attributes of map packaged ready-to-eat baby carrots by using chitosan-based coatings (paid content) in Postharvest Biology and Technology.