Michael Laurence Rooney

ASCORBIC ACID AS A PHOTOOXIDATION INHIBITOR

Abstract— The rate constant for total quenching of singlet oxygen by ascorbic acid has been determined using the inhibition of the bleaching of 9, 10‐dimethylanthracene by AA in pyridine. The rate constant was 8.4 × 10‐6M‐1 s‐1, as determined photochemically, and 1.06 10‐7M‐1 s‐1 as determined in a dark reaction.

Improved oxidative stability of sunflower oil in the presence of an oxygen-scavenging film

The oxidative stability of sunflower oil (SFO) was measured during storage at 23 and 37°C in the presence of a novel oxygen-scavenging film that contained polyfuryloxirane (PFO). Commercially refined and deodorized SFO was stored in a lighted room in sealed transparent packages containing either PFO film or an antioxidant, 0.02% butylated hydroxytoluene (BHT). Oxidative stability was evaluated by determination of peroxide values and gas-chromatographic measurement of headspace hexanal. SFO stored in the presence of the oxygen-scavenging film was more stable than oil stored without the film, or than film stored with 0.02% BHT. The PFO film scavenges oxygen through energy-transfer sensitization of singlet oxygen. The film is doped with eosin and the naturally-occurring dye, curcumin, which absorb over a wide range of visible wavelengths. Curcumin transfers its absorbed energy to eosin, which sensitizes the production of singlet oxygen. The singlet oxygen is scavenged by PFO. The use of two dyes increases the efficiency of the sensitization process, reducing the illumination time and intensity required for effective oxygen scavenging.

Oxygen-scavenging packaging

Publisher Summary This chapter describes oxygen-scavenging packaging that focuses on the quantity of oxygen in a package without consideration of the widely different rates at which food quality can be degraded. The quantity of oxygen, which must be taken up by a food to limit its shelf life to one year, has been estimated for a range of foods. The quantities lie in a range from a few ppm to a few hundred ppm based on the weight of the food. The development of oxygen-scavenging systems has followed two lines, depending on whether the oxidizable substance was designed to be a part of the package or to be inserted into it with the food. The insert approach includes self-adhesive labels, adhesive devices, or free sachets included with the food. Modification of packaging materials to confer oxygen-scavenging capability includes monolayer and multilayer materials, and reactive closure liners for bottles and jars. The field of oxygen scavenging using plastics is still largely under development, even though the use of sachets, labels, and closure liners is well established.