Enhanced antioxidant activity of polyolefin films integrated with grape tannins.
BACKGROUND
A natural antioxidant derived from an agro-waste of the wine industry, grape tannin, was incorporated by melt blending into three different polyolefins (high-density polyethylene, linear low-density polyethylene and polypropylene) to introduce antioxidant functionality.


RESULTS
Significant antioxidant activity was observed at 1% tannin inclusion in all polymer blends. The antioxidant activity was observed to increase steadily with a greater concentration of grape tannins, the highest increases being seen with polypropylene. The mechanical and thermal properties of the polymer films following antioxidant incorporation were minimally altered with up to 3% grape tannins. All of the polyolefin-grape tannin films successfully passed the leachability test following USP661 standard protocol.


CONCLUSIONS
Superior antioxidant activity was established in polyolefin thin films by utilization of a bulk grape extract obtained from winery waste. Significant increases in antioxidant activity were seen with 1% extract inclusion. This not only demonstrates the potential for food packaging applications of the polyolefin blends, but also valorizes the agro-waste. © 2015 Society of Chemical Industry.
Biocide Toolbox and School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Kenneth J
KJ
Olejar
Biocide Toolbox and School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Sudip
S
Ray
Biocide Toolbox and School of Chemical Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Paul A
PA
Kilmartin
D000975:Antioxidants / Q000737:chemistry*; D006358:Hot Temperature; D008567:Membranes, Artificial; D011090:Polyenes / Q000737:chemistry*; D013634:Tannins / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry*
D000975:Antioxidants; D008567:Membranes, Artificial; D011090:Polyenes; D013634:Tannins; C035051:PL 732
antioxidant activity; grape tannins; polymer blends; polyolefin