ARS | Publication request: Gelatin-Pectin Composite Films from Polyion Complex Hydrogels

Submitted to: Food Hydrocolloids Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 13, 2010
Publication Date: June 18, 2010
Citation: Farris, S., Schaich, K.M., Liu, L.S., Cooke, P.H., Yam, K.L. 2010. Gelatin-Pectin Composite Films from Polyion Complex Hydrogels. Food Hydrocolloids Journal. 25:1761-1770.

Interpretive Summary: Petroleum-derived plastics have long history in the use as food packaging materials. However, the use of these materials has caused serious environmental problems, because there are no longer enough lands for plastics to be disposed of due to their non-biodegradable nature. Bio-renewable materials are considered as an alternative of plastics, if their mechanical properties and water resistance can be improved. The present study explored two approaches in the production of biodegradable packaging materials from pectin and gelatin. The ionic cross-linking resulted in a homogeneous structure, in comparison with that from covalently cross-linking. Both the methods improved the tensile strength that meets the standard for food packaging. Furthermore, the chemical cross-linking between pectin and gelatin enhanced the water resistance of the resultant composites. The methods can be extended to make other structural materials from other biopolymers. The present research will benefit the food industries, and expand the market for agricultural byproducts.

Technical Abstract: Composite films from gelatin and low-methoxyl pectin were prepared by either ionic complexation or covalent cross-linking. The ionic interactions between positively charged gelatin and negatively charged pectin produced physically reversible hydrogels. The resultant homogeneous gels had improved mechanical properties and water resistance, and were able to retain the thermal stability of the two biopolymers. The subsequent addition of glutaraldehyde resulted in physically and chemically permanent gels. The gels were heterogeneously. This could be attributed to the uneven cross-linking introduced by the present processing technology. The hydrogels showed a decreased swelling attitude by nearly 10-fold relative to films from gelatin alone and further improved mechanical performance (tensile strength and elongation at break). These results presented strategies to create unique structures from naturally occurring biopolymers by controlling the interaction of functional groups attached to the biopolymers.