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Limonin is the major naval orange juice bitter principle and to better understand and optimize the sorption of limonin, a sorption and plasticizer migration study was carried out. Results showed that the best debittering was obtained by using low molecular weight poly plasticized with dioctyl adipate and that the debittering efficiency was greater than that obtained with current polystyrene divinylbenzene resin beads.

The migration (diffusion and equilibrium) processes of antioxidants (AOs) from polypropylene (PP) films of different thicknesses into n-heptane and 95% ethanol as fatty food simulants were analysed at 20, 37 and 60°C. Heptane fully extracted the AOs from the polymer while a partition equilibrium described the migration to ethanol. The kinetics of migration were also studied via the diffusion coefficients. As expected, diffusion was found to be faster when the polymer was in contact with heptane, due to polymer swelling by the solvent. The kinetics of the process in ethanol was described by different theoretical expressions which are discussed. Equations disregarding partition equilibrium failed to describe the process and the diffusion coefficient values obtained through them were much smaller than the actual ones and dependent on film thickness. The results also showed the significance of food simulant selection in the analysis of food-packaging interactions and migration variability with thickness. [ABSTRACT FROM AUTHOR]

Presents a study in which a flow-through vapor exposure system was developed to evaluate the effects of 2-nonanone vapor on the decay of apple slices inoculated with Penicillium expansum Link and Botrytis cinerea Pers. Conditions under which the study was conducted; Description of the various reactions that occured.

Studies the development and characterization of biodegradable and edible protein films from wheat flour. Types of wheat flour; Film preparation; Color measurements; Oxygen permeability; Tensile measurements; Film attributes.

Presents three experimental techniques employed to determine the partition coefficient of organic compounds in water. Gas chromatography; Gel permeation chromatography; Dynamic thermal stripping-thermal desorption procedure; Applicability and limitations of each technique; Statistical analysis of results and kinetics of the sorption process.

The steady-state permeability experiment is the method recom mended to evaluate the barrier properties of polymeric films which are ex pressed as a permeability coefficient (Hernandez et al., 1986). Besides the permeability coefficient, the diffusion coefficient can also be determined from the unsteady-state values of a permeability study. Since the correctness of the set of permeability data will affect the numerical values of both diffusion and permeability coefficients, a procedure to determine the consistency of a set of data obtained from a continuous flow permeability experiment is proposed in this article. The interest of a simple consistency test arises from the need to de tect variations of the system parameters such as temperature or concentration changes, during the permeation experiment. Further, an analysis of the consis tency of the data will provide information on the applicability of the Henry's law of solubility and the invariability and uniqueness of the diffusion coeffi cient, and may lead to a better understanding of the diffusion and solubility mechanisms that are controlling the permeation system. [ABSTRACT FROM PUBLISHER]

The dynamic headspace thermal desorption (DHS-TD) apparatus using Tenax-TA and Carbotrap-300 traps, connected to a gas chromatography (GC)-ion trap-mass spectrometry (MS) equipment, as well as the solid phase micro-extraction (SPME) tool, with polydimethylsiloxane (PDMS) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibers and connected to a GC-time of flight-MS equipment were implemented for the isolation and identification of virgin olive oil volatile compounds under various sampling conditions. Applying the DHS-TD Tenax-TA procedure separated a higher number of compounds compared to the SPME-PDMS-DVB, which on the other hand required shorter total times for the analysis. High ratio of gas flow rate/amount of oil gave better results for DHS-TD, while a high ratio of headspace/amount of oil worked better for SPME. PDMS exhibited a low sensitivity to olive oil polar volatile compounds while PDMS-DVB showed the overall best sensitivity for all classes of volatile compounds. Results indicate that SPME may find a wide application as an analytical technique for quick analysis of quality related volatile compounds of olive oil. The analyses performed on the GC-TOF-MS-system demonstrated high sensitivity and also high selectivity due to the high quality of mass spectra obtained. The SPME-GC/TOFMS technique appears to be faster and simpler than DHS-TD/GC/MS but the latter provides higher efficiency. [Copyright &y& Elsevier]

The sorption of selected polychlorinated biphenyl (PCB) congeners (from tri to deca chlorinated) by three food-packaging plastic films [polyethylene, polyvinyl chloride (PVC), and polystyrene] from an aqueous solution was investigated. From the data generated, PCB uptake, partition, and diffusion coefficients were calculated for the various films. Polyethylene exhibited the highest PCB uptake, diffusion, and partition coefficients when compared to the other materials. Although PVC indicated larger sorption diffusion and partition coefficients for the lower chlorinated congeners than polystyrene, a reversal of this trend was observed for the higher congeners. For polyethylene and PVC, the PCB uptake decreased as the chlorine numbers in the congeners increased, confirming the correlation between increasing chlorination and increasing cohesive density within the PCB molecules. For polystyrene, the uptake decreased from tri to penta congeners, but showed an increase for the hexa, and then a decreased uptake until the deca chlorination. A comparison of the molecular sizes of the PCB congeners showed that the partition (Ke) and sorption diffusion (Ds) coefficients generally decreased with their increasing molar volumes. The resulting Ke values were used to determine the extent of sorption because these values indicate the affinity of PCBs for the plastic films. Results from this study can be of practical importance for cases of product quality related to the transfer of contaminants from the product to the packaging materials.