Control of Lipid Oxidation by Nonmigratory Active Packaging Films Prepared by Photoinitiated Graft Polymerization

Abstract

Transition metal-promoted oxidation impacts the quality, shelf life, and nutrition of many packaged foods. Metalchelating active packaging therefore offers a means to protect foods against oxidation. Herein, we report the development and characterization of nonmigratory metal-chelating active packaging. To prepare the films, carboxylic acids were grafted onto the surfaces of polypropylene films by photoinitiated graft polymerization of acrylic acid. Attenuated total reflectance/Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, and iron-chelating assay were used to characterize film properties. Graft polymerization yielded a carboxylic acid density of 68.67 ± 9.99 nmol per cm 2 film, with ferrous ironchelating activity of 71.07 ± 12.95 nmol per cm 2 . The functionalized films extended the lag phase of lipid oxidation in a soybean oil-in-water emulsion system from 2 to 9 days. The application of such nonmigratory active packaging films represents a promising approach to reduce additive use while maintaining food quality.

Retaining Oxidative Stability of Emulsified Foods by Novel Nonmigratory Polyphenol Coated Active Packaging

“…The ferric iron (Fe 3+ ) and ferrous iron (Fe 2+ ) chelating capacity of polyphenol coated films were determined using a previously described method. 9 Each film (1 × 2 cm 2 ) was submerged in buffered iron solution (0.08 mM ferric chloride or ferrous sulfate in 0.05 M sodium acetate/imidazole buffer, pH 5) and allowed to chelate in the dark for 24 h with shaking and then rinsed with copious amounts of DI water. Iron chelating capacity of each film was quantified by ICP-MS analysis (PerkinElmer Elan 9000, Waltham, MA).…”

Metal-Chelating Active Packaging Film Enhances Lysozyme Inhibition of Listeria monocytogenes

“…M etal chelators may enhance food antim icrobial activity by sequestering essential nutrients (e.g., iron) and/ or rem oving m em brane-stabilizing cations (e.g., m agne sium , calcium ) (22). Branen and D avidson (4) R ecently, nonm igratory m etal-chelating active packag ing was developed as a prom ising alternative to synthetic m etal chelators (21,24,25). Because the chelator is covalently attached to the packaging, this type o f packaging w ould require food contact notification rather than direct additive approval, w hich m ay m ake it suitable for use with natural and organic foods (15).…”

“…Because the chelator is covalently attached to the packaging, this type o f packaging w ould require food contact notification rather than direct additive approval, w hich m ay m ake it suitable for use with natural and organic foods (15). M etal-chelating polypropyl ene (PP) films were synthesized by photoinitiated graft polym erization o f acrylic acid onto PP (PP-g-PA A ) (24). Tian et al (24) reported that metal-chelating film with a ferrous iron-chelating activity o f 71.07 + 12.95 nmol cm -2 extended the lag phase o f lipid oxidation in a soybean o ilin -w ater em ulsion from 2 to 9 days (using accelerated storage conditions).…”

Active Packaging Coatings

“…In other work, Arrua et al utilized photoinitiated graft polymerization of a polymer functionalized with caffeic acid to coat polypropylene packaging materials and demonstrated its ability to prevent oxidative degradation of ascorbic acid in orange juice [79]. Photoinitiated graft polymerization has also been used to fabricate metal chelating active packaging coatings that extended the lag phase of lipid oxidation in oil-in-water emulsions by chelating transition metals, which are the most influential prooxidants in food emulsions [83,87]. Further research in this area demonstrated that active packaging coatings composed of photografted polyhydroxamate chelators retain activity in a wide range of pH values (3-5), viscosity (~1-10 4 CP) and competing ion (Na, Mg, Ca) conditions typically found in food and consumer products [97].…”