The next-gen bioplastic invention surpassed the abilities of some conventional plastic packaging in repelling water and oxygen.

By Emma Bryce November 28, 2025 Anthropocene

A new film that can be made from widely-available food waste is as effective as conventional plastics at shielding food from moisture and oxygen, its inventors say. 

The novel material was made by combining cellulose from wood pulp and chitin from crustacean shells or mushrooms, and builds on the team’s previous research to develop an alternative to petroleum-based plastic that can extend the shelflife of fresh produce. 

In their ten years of work so far, they have made progress, developing materials that have become successively stronger and less permeable. However, they’ve battled to overcome one significant hurdle, which is that as humidity rises, the material they’ve invented becomes more permeable to both oxygen and water, threatening the contents within. 

This time they tried a different approach, first of all adding a new ingredient, citric acid, to the mixture, and combining the three ingredients using a method called ‘crosslinking’, which bonds elements tightly to form a dense network. “Cross-linking has been shown to be effective in controlling moisture sensitivity of biopolymers at high humidity, generally by reducing swelling in the presence of water vapor,” they explain in their research.

The result of this three-part cellulose-chitin-citric acid matrix was a fine plastic sheet, suitable for covering food. Next, they needed to test out the resilience of this film-like material, by exposing it to varying degrees of humidity and heat. 

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Most strikingly, their experiments showed that at humidity levels of 80%—reminiscient of some tropical countries—the biobased film was even less permeable to oxygen than some mainstream plastic packaging like EVOH (ethylene-vinyl alcohol), commonly used to package fresh produce. 

Also impressively, compared to polyethylene terephthalate, or PET, one of the most widely-used plastics in food packaging, the permeability to water vapor in the bio-based plastic was only slightly higher. And when contrasted with other bioplastic products like polylactic acid and cellulose acetate, the new material was at least two orders of magnitude more resistant to oxygen, the researchers say.

All this suggests a serious potential contender to conventional plastic packaging—and if it relies on food waste streams, this new material could help tackle that mounting global problem, too. 

What’s less clear from the study is how far it would go to tackle the problem of plastic pollution, given that the paper doesn’t explore how quickly this material biodegrades, and whether that can happen naturally, or if it would require more resource-intensive industrial composting processes.

The researchers do hint that it solves this problem, saying, “We’re using materials that are already abundant in nature and degrade there to produce packaging that won’t pollute the environment for hundreds or even thousands of years.” 

If that’s accurate, then alongside efforts to reduce the reliance on unnecessary single-use packaging in the first place, their invention could help shift the needle on plastic waste. 

Meredith et. al. “Transforming Renewable Carbohydrate-Based Polymers into Oxygen and Moisture Barriers at Elevated Humidity.” ACS Applied Polymer Materials. 2025. 

Transforming Renewable Carbohydrate-Based Polymers into Oxygen and Moisture Barriers at Elevated Humidity

• Yang Lu
• Javaz T. Rolle
• Tanner Hickman
• Yue Ji
• Eric Klingenberg
• Natalie Stingelin
• J. Carson Meredith*

Open PDFSupporting Information (1)

Abstract

The widespread usage of nonrenewable plastics in packaging has resulted in a significant environmental burden, and the industry is working to adopt renewable biopolymers in place of traditional plastics. However, renewable biopolymers often lack sufficient gas-barrier properties at an elevated relative humidity (RH). Here, we demonstrate that the introduction of citric acid (CA) cross-linkers to cellulose nanocrystal (CNC)/chitosan (Ch) blends significantly reduces the oxygen permeability (OP) and water vapor transmission rate (WVTR) at high RH. Specifically, in CNC/Ch binary systems (without CA), as in many plastic packaging materials, the OP value increases dramatically (approximately 45×) when increasing RH from 50 to 80%. In contrast, CNC/Ch/CA ternariesfeature low OP of 0.59 cm³ μm·m^–2 day^–1 kPa^–1 at 23 °C/80% RH, similar to the OP at 50% RH. This ternary system, with additional heat treatment, also exhibits an extremely low thickness-normalized WVTR of 0.005 g·mm·m^–2 day^–1 at 23 °C and 50% RH. The WVTR rises to 14 g·mm·m^–2 day^–1 at 38 °C/80% RH, still approximately 10× lower than that of neat CNCs.