In order to better understand and optimize the sorption of limonin (the major navel orange juice bitter principle) by various plasticized polymeric films, a sorption and plasticizer migration study was carried out using high-performance liquid chromatography (HPLC) and gas chromatography (GC). Low molecular weight (LMW) poly (vinyl chloride) (PVC) plasticized with dioctyl adipate (DOA) gave the best results for both limonin sorption and low DOA migration. Thick films did not significantly sorb more limonin than thin films in the timeframe of our experiments, as the absorption involved rapid surface sorption followed by slow bulk diffusion. The debittering efficiency was a 1000-fold greater than that obtained with current polystyrene divinylbenzene resin beads, with potential for industrial scale debittering.
A new sensitive method is described for measuring the permeation and diffusion of oxygen through polymer films. For these measurements an ethyl cellulose film containing 9,lO-dimethylanthracene (DMA) and erythrosin may be either tightly sealed between two pieces of sample film in a simple cell or sealed in a pouch made from the test material, and is used to absorb oxygen which has passed through the polymer film sample from the air. On illumination this oxygen is converted by the erythrosin to singlet oxygen which then reacts with the DMA. After an initial scavenging period, the rate of permeation of oxygen under the atmospheric pressure gradient across the film is monitored by determining the rate of disappearance of DMA spectrophotometrically.
ZUSAMMENFASSUNG:Es wird eine neue, empfindliche Methode fur die Messung der Durchdringung und Diffusion von Sauerstoff durch Polymerfilme beschrieben. Ein Ethylcellulosefilm, der 9,lO-Dimethylanthrazen (DMA) und Erythrosin enthdt, wird fur die Absorption von Sauerstoff venvendet, der aus der Luft durch die Polymerfilmprobe dringt. Bei Belichtung wird der Sauerstoff durch das Erythrosin in die Singulettform uberfuhrt, die dann mit dem DMA reagiert. Nach einer anfanglichen Reinigungsperiode wird die Durchdringungsgeschwindigkeit vom Sauerstoff unter dem atmosphLischen Druckgefdle durch den Film verfolgt, indem man die Geschwindigkeit des Verschwindens vom DMA spektrophotometrisch bestimmt. Fur diese Messungen kann der Ethylcellulosefilm entweder in einer einfachen Zelle dicht zwischen zwei Probefilmstucken eingefugt oder in einem Beutel von Probematerial eingeschlossen sein.
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