Starch coating gives grease the skid

Packaging industry alternative helps recycling.

Current use of perfluoro compounds impregnated on paper or paperboard to package greasy or oily foods could see a challenge from a starch coating in providing the needed protective barrier. Such packaging is often used for dry animal feeds, pet food, bakery products such as cookies, and chocolates.

In a project funded by the German federal government, researchers at the Fraunhofer Institute for Process Engineering and Packaging (IVV; Freising, Germany), with industrial partners, have come up with this grease barrier alternative.

Claudia Schönweitz, who directs the project, says low to medium grease-proof properties can be provided by coating paperboard with high-density polyethylene. But very high barrier generally requires several layers of cardboard impregnated with perfluorinated compounds. These make recycling difficult due to their inert character. Additional concerns revolve around studies indicating fluorine compounds have been detected in human serum, she says.

Fraunhofer IVV and its sister institute Fraunhofer IAP developed hydroxypropylated starches, extracted from tubers, cereals, and leguminous plants, to act as grease barriers. These have good film formation properties and coat well. And the starch is biodegradable.

Fraunhofer scientists coated two commercially available cardboards provided by industrial partners VG Nicholaus (Kempten, Germany) and Moritz J. Weig (Mayen, Germany). Starches with high amylose content, such as amylomaize starch and wrinkled pea starch, modified by Emsland-Stärke (Emlichheim, Germany), gave the best results, says Schönweitz.

"The weight of starch that is applied has a key influence on the effectiveness of the grease barrier and costs. Starch derivatives that were developed provide good grease barrier when applied in amounts up to 20 g/m2," she says. This barrier remains intact when the packaging is subjected to extreme climate conditions (60°C at 60% relative humidity/5 days).

High amylose-content starches had the highest resistance to mechanical loads. This material is being run on a pilot plant using a slot die in further tests, although Fraunhofer IVV is still seeking additional industrial partners with the focus on coated cardboard and paper packaging for dry pet foods containing high levels of surface oils, a market that Schönweitz says has high growth potential.

Robert Colvin [email protected]

Contact information

Fraunhofer Institute for Process Engineering and Packaging

www.ivv.fraunhofer.de