• Vakalopoulou, Efthymia
• Borisov, Sergey
• Slugovc, Christian

Abstract

Oxygen can have considerable detrimental effects on goods prone to oxidization, in particular food. Oxygen scavengers (sometimes referred to as oxygen absorbers) are therefore a mean to maintain food product quality. Reduced oxygen contents decrease the food metabolism, reduce oxidative rancidity, inhibits oxidation of labile vitamins and pigments, and, maybe most importantly, inhibits the growth of aerobic microorganisms. Most oxygen scavengers are based on iron powders containing catalysts, which react with some water from the surroundings to produce a reactive hydrated metallic reducing agent that scavenges oxygen and irreversibly converts it to a stable oxide. Such oxygen scavengers are capable of reducing oxygen levels to less than 0.01% (100 ppm(v)) which is much lower than the typical 0.3–3.0% (3000 – 30000 ppm(v)) residual oxygen levels achievable by modified atmosphere packaging (MAP). However, the oxygen scavenging capability is rapidly lost in case too much water is present. The iron powder is packed in a highly oxygen permeable sachet to separate it from the food, which constitutes another disadvantage of possible accidental ingestion of the contents by the consumer. This has considerably hampered their commercial success, particularly in North America and Europe. As an alternative, in particular for protecting liquids, various non-metallic reagents and organometallic compounds that have an affinity for oxygen have been incorporated into bottle closures, crown and caps or blended into polymer materials so that oxygen is scavenged from the bottle headspace and any ingressing oxygen is also scavenged. However, it should be noted that the speed and capacity of oxygen scavenging plastic films and laminated trays are considerably lower compared to iron based oxygen scavenger sachets or labels.[1]<br/>Herein, a hitherto unprecedented polymeric material for oxygen removal, namely a macroporous poly(norbornadiene) foam prepared by curing of a high internal phase emulsion of norbornadiene (NBD) in water via Ring-opening Metathesis polymerization (ROMP) is described.[2]<br/><br/>Literature: [1] a) Ramos, M.; Valdés, A.; Mellinas, A. C.; Garrigós, M. C. Beverages 2015, 1, 248-272; b) Gaikwad, K. K.; Singh, S.; Lee, Y. S. Environ. Chem. Lett. 2018, 16, 523-538.<br/>[2] preparation analogously to: Kovačič, S.; Matsko, N. B.; Jeřabek, K.; Krajnc, P.; Slugovc, C. J. Mater. Chem. A 2013, 1, 487-490.

Topics

• impedance spectroscopy
• compound
• polymer
• phase
• Oxygen
• laser emission spectroscopy
• iron
• oxygen content
• curing
• organometallic
• iron powder