Natural, biodegradable, and highly functional — modified starches are emerging as a key solution for developing eco-friendly barrier coatings in paper-based packaging. Suitable for a wide range of applications — from wrapping papers to coated boards — these starches have been specially engineered to deliver effective barrier properties for food contact materials, while replacing fossil-based products and hazardous substances such as PFAS
Beyond enhancing mechanical properties such as strength and durability, modified starches also reduce environmental impact, aligning with the growing global shift toward sustainable packaging solutions.
The rise of “paperization”
In recent years, consumer awareness of environmental issues and the resulting demand for sustainable products have fueled a trend known as paperization — the gradual replacement of plastic and other materials with paper, especially in the packaging sector.
This transition is further reinforced by EU policies aimed at reducing plastic consumption, positioning paper as one of the most sustainable alternatives available today. Consumers perceive paper packaging as recyclable, renewable, and safe — making it the preferred choice for eco-conscious brands and manufacturers.
Packaging and the barrier challenge
The drive to eliminate petroleum-based components has prompted packaging producers to seek new sustainable barrier technologies. The goal is to design paper packaging that can replace multilayer plastic structures and remove harmful substances like PFAS (per- and polyfluoroalkyl substances) — persistent pollutants with serious implications for both human health and ecosystems.
Despite major research progress, achieving equivalent performance to fossil-based barriers remains challenging — particularly for oil, grease, and moisture resistance. This is the focus of Cargill’s recent research, which introduces an innovative bio-based alternative for the paper and board industry.
At the Aticelca Congress 2025, Maurizio Andreoli Scipioni, Senior Technical Account Manager at Cargill, presented the company’s findings.
«When we talk about food barriers, we’re referring to a broad spectrum» explains Andreoli Scipioni. «There are barriers against mineral oils, fats, oxygen, water vapor, and water. Depending on the end-use, one or more of these barriers may be required.»
Among these, oil and grease resistance (OGR) barriers are particularly complex. For instance, fast-food wrapping papers, with short food contact times, demand moderate performance. But longer shelf-life applications — or products displayed for extended periods — require coatings that deliver superior and durable protection.
From concept to coating: a stepwise development approach
Cargill’s development process begins with customer needs analysis, followed by laboratory trials and pilot-scale validation.
«We started by identifying the specific performance and sustainability requirements of our customers» says Andreoli Scipioni. «From there, we conducted lab trials to pinpoint the most effective starch formulations, then scaled up testing on a pilot coater to verify industrial feasibility.»
Through interviews with paper mills and brand owners, Cargill identified key requirements for the new coatings:
- Excellent oil and grease resistance;
- Fully bio-based and biodegradable composition;
- Compatibility with existing papermaking and coating equipment;
- Compliance with strict food-contact and environmental standards, including industrial compostability, biodegradability according to EU Regulation 2023/2055 on microplastics, and marine biodegradation per Directive (EU) 2019/904.
Laboratory & pilot testing
In the laboratory phase, Cargill’s researchers evaluated starches with varying ionic charges and molecular structures, discovering that the type and surface of the paper substrate had a significant impact on barrier performance.
Smoother and denser papers produced more uniform coatings and superior barrier properties.
To validate these findings, pilot-scale tests were conducted at KCL (Finland). Two modified corn starches — Cargill Barrier Coating OGE and OGR 11 — were tested on different paper grades. Each was applied at roughly 5 g/m² using three coating technologies:
- Metering Size Press (MSP)
- Jet Coater with Stiff Blade
- Curtain Coater
«With MSP we reached 800 m/min at 20 % solids» explains Andreoli Scipioni. «The jet coater ran at the same speed with 27 % solids, while the curtain coater achieved 390 m/min at 20 % solids.»
Kit test results confirmed laboratory data: paper structure and coating uniformity are decisive factors. Base Paper 1, with its smoother surface, outperformed Base Paper 2.
Among application methods, the curtain coater consistently yielded the best results, thanks to its ability to form a continuous and even barrier film. The jet coater performed well but slightly lower, while the MSP showed higher penetration of the coating, resulting in reduced barrier performance — though still suitable for short-contact food wraps (e.g., burger or fries packaging).
Performance validation and comparative testing
Additional tests examined barrier performance after folding. Both Cargill’s bio-based coatings and conventional synthetic coatings showed reduced resistance along fold lines — more pronounced in the cross direction (CD) than the machine direction (MD).
In Cobb Unger tests (using castor oil), untreated paper with absorption values of 40–45 g/m² dropped dramatically to 3–4 g/m² after coating with either OGE or OGR 11.
Drop tests using water and sunflower oil demonstrated significant improvement as well, particularly when OGR 11 was applied via jet coater — also enhancing water resistance, a particularly noteworthy outcome.
Barrier evaluation methods
Several standardized methods are available to assess barrier performance, including:
- Kit Test (TAPPI T559) – the industry standard for fluorochemical treatments;
- Turpentine Test (TAPPI T454) – using turpentine as a solvent;
- Permeability Test (ISO 16532-1) and ASTM F119-82(2022) – which measure the rate of grease penetration using substances such as chicken fat or palm oil.
«It’s essential that barrier evaluations reflect real application conditions» concludes Andreoli Scipioni. «Parameters such as contact temperature and the actual type of oil or fat must be considered to ensure reliable results.»
Cargill’s study ultimately confirmed that the synergy between paper substrate and coating technology is fundamental to achieving optimal barrier performance in sustainable, PFAS-free, bio-based packaging.