Factors determining the transport coefficients of aroma compounds through polyethylene films

Use of alimentary film for selective sorption of haloanisoles from contaminated red wine

Haloanisoles (HAs) are known to compromise wine quality because of their mouldy off-flavours. Up to now no treatment exists to eliminate the presence of these unpleasant volatiles in wine. This research aimed i) to assess the alimentary plastic film efficacy to remove or lessen HAs content in polluted wines; and ii) to evaluate its impact on wine quality. The film-treatment reduced significantly (p < 0,05) the 2,4,6-trichloroanisole (TCA) content of initial wine. This decrease became more noticeable as the contact time film-wine increased. Chromatic characteristics, phenolic and proanthocyanidin contents, and woody aroma profile did not change because of the film-treatment. A significant sorption of certain esters was observed, but as HAs were removed under detection thresholds, fruity perception of wines was improved. Globally, the alimentary plastic film was able to improve the organoleptic quality of wines contaminated with HAs, by reducing the cork taint and enhancing their overall fruity aroma.

Red turpentine beetle primary attraction to (-)-β-pinene+ethanol in US Pacific Northwest ponderosa pine forests

Red turpentine beetle, Dendroctonus valens (Coleoptera: Curculionidae: Scolytinae) is a non-aggressive pine bark beetle native to North America, and more aggressive invader in China. Dispersing pioneer beetles are attracted to potential host trees by oleoresin monoterpene kairomones, but respond more strongly to those combined with ethanol, a mixture often released from stressed, dying, or recently dead trees. (+)-3-Carene, usually the dominant or co-dominant monoterpene in ponderosa pine, Pinus ponderosa, is a stronger attractant than α-pinene or β-pinene where tested over a large portion of the D. valens range, while (+)-3-carene+ethanol was shown previously to attract twice the beetles of (+)-3-carene. A field test comparing D. valens attraction among the three monoterpenes when all are released with ethanol has never been reported, and was our objective. In three US Pacific Northwestern pine forests, (–)-β-pinene+ethanol lures attracted 1.4 to 1.9 times more beetles than (+)-3-carene+ethanol. (+)- or (±)-α-pinene+ethanol lures were least attractive. A 1:1:1 monoterpene mixture+ethanol lure attracted more beetles than the 1:1:1 lure, but it was not statistically higher. Monoterpenes were dispensed from low density polyethylene bottles and their release rates monitored in laboratory and field tests. Under laboratory conditions (+)-3-carene was released much more rapidly than (+)-α-pinene or (–)-β-pinene when dispensed separately, or in a 1:1:1 mixture. (+)-3-Carene in the 1:1:1 mixture increased the release of both pinenes over their rates when dispensed separately. (–)-β-Pinene+ethanol is currently the strongest kairomone lure for D. valens attraction in US northwest pine forests, and has value for beetle detection, monitoring, research, and management.

Molecular Dynamics Simulation on the Diffusion of Flavor, O2 and H2O Molecules in LDPE Film

The diffusion of five flavor organic molecules, including D-limonene, myrcene, ethyl hexanoate, 2-nonanone, and linalool in low density polyethylene (LDPE) film were investigated by combined experimental and molecular dynamics (MD) simulation studies. The diffusion coefficients derived from the prediction model, experimental determination, and MD simulation were compared, and the related microscopic diffusion mechanism was investigated. The effects of the presence of the flavor organic molecules on the diffusion of O₂ and H₂O in polyethylene (PE) were also studied by MD simulation. Results show that: The diffusion of five flavor molecules in LDPE is well followed to Fick’s second law by the immersion experiment; MD simulation indicates the dual mode diffusion mechanism of the flavor molecules is in LDPE; the diffusion coefficients from MD simulation are close to those from the experimental determination, but are slightly larger than those values; the presence of the flavor organic molecules hinders the diffusion of O₂ and H₂O, which can be well explained from the fraction of free volume (FFV) and interaction energy calculation results derived from MD simulation.

Preliminary quantification of the permeability, solubility and diffusion coefficients of major aroma compounds present in herbs through various plastic packaging materials

BACKGROUND

Aroma permeation through packaging material is an important factor when designing a package for food products. The masses of aroma compounds permeating through films over time were measured at 25 °C using a quasi-isostatic system. A model was proposed for estimating the permeability coefficients (P) of key aroma compounds present in fresh herbs (i.e. eucalyptol, estragole, linalool and citral) through major plastic films used by the food industry [i.e. low-density polyethylene (LDPE), polypropylene (PP), nylon (Nylon), polyethylene terephthalate (PET), metalised-polyethylene terephthalate (MPET) and poly(lactic acid) (PLA)]. Solubility coefficients (S) were estimated from the amount of aroma compound sorbed in the films. Diffusion coefficients (D) were estimated following from the relation P = D*S.

RESULTS

P and D for all four aroma compounds were highest in LDPE, except for eucalyptol, which P was slightly higher in PLA. The solubility coefficients and contact angles were highest in PLA suggesting the highest affinity of PLA to these aroma compounds. The theoretical solubility parameters were correlated with the solubility coefficients for estragole and citral, but not for eucalyptol and linalool.

CONCLUSION

The preliminary P, D and S of eucalyptol, estragole, linalool and citral through LDPE, PP, Nylon, PET, MPET and PLA can be useful in selecting the proper packaging material for preserving these specific aroma compounds in food products and can potentially be used for estimating the shelf life of food products based on aroma loss. © 2017 Society of Chemical Industry.

Effects of packaging materials on the aroma stability of Thai 'tom yam' seasoning powder as determined by descriptive sensory analysis and gas chromatography-mass spectrometry

BACKGROUND

Changes in the aroma characteristics of Thai 'tom yam' seasoning powder, containing lemongrass, galangal and kaffir lime leaf, as affected by different packaging materials were assessed using quantitative descriptive analysis (QDA) and gas chromatography-mass spectrometry (GC-MS). The descriptive aroma attributes for lemongrass, galangal and kaffir lime leaf powders were developed by the QDA panel. The mixed herb and spice seasoning powder was kept in glass jars closed with different packaging materials (Nylon 6, polyethylene terephthalate (PET) and polylactic acid (PLA)) stored at 38 °C (accelerated storage condition), and evaluated by the trained QDA panel during storage for 49 days.

RESULTS

The descriptive words for Thai 'tom yam' seasoning powder developed by the trained panelists were lemongrass, vinegary and leafy for lemongrass, galangal and kaffir lime leaf dried powder, respectively. The aroma intensities significantly (P ≤ 0.05) decreased with increased storage time. However, the intensity scores for aroma attributes were not significantly (P > 0.05) different among the packaging materials studied. The major components in Thai 'tom yam' seasoning powder, quantified by GC-MS, were estragole, bicyclo[3.1.1]heptane, β-bisabolene, benzoic acid and 2-ethylhexyl salicylate. The concentrations of major aroma compounds significantly (P ≤ 0.05) decreased with storage time.

CONCLUSION

Aroma stability of Thai 'tom yam' powder can be determined by descriptive sensory evaluation and GC-MS analysis. Nylon, PET and PLA exhibited similar aroma barrier properties against key aroma compounds in Thai 'tom yam'. This information can be used for prediction of aroma loss through packaging materials during storage of Thai 'tom yam'. © 2016 Society of Chemical Industry.

Effect of ethanol on the sorption of four targeted wine volatile compounds in a polyethylene film

The objectives of this study were to demonstrate that the presence of ethanol in a solution containing two esters and two aromatic alcohols has several consequences on the sorption of these compounds into polyethylene (PE) film. First, sorption of ethanol into the PE film occurred at the same time as water and reached 8 kg m(-3) using 12% v/v of ethanol. This sorption was associated with an increase in PE crystallinity, which may have prevented the sorption of volatile compounds despite their strong affinity with PE film, as evaluated by Hansen solubility parameters. Moreover, increasing the ethanol concentration increased the solubility of the four volatile compounds. In the case of aromatic alcohols, the sorption was decreased in the presence of ethanol as expected. In the case of esters, as their hydrolysis was substantial in the presence of water, the consequence was a higher sorption into the PE film in the presence of ethanol than in its absence. Nevertheless, the sorption also depended on the concentration of ethanol and the heterogeneity of the ethanol-water mixture as well as the presence of other volatile compounds, as in the case of 4-ethylphenol. In conditions simulating wine packaging, losses of volatile compound by sorption and by permeation estimated after only 5 days of contact varied between 0.08 and 25% for 2-phenylethanol and ethyl hexanoate, respectively.

Critical review of low-density polyethylene's partitioning and diffusion coefficients for trace organic contaminants and implications for its use as a passive sampler

Polyethylene (PE)-water equilibrium partitioning constants, K(PEw), were reviewed for trace hydrophobic organic contaminants (HOCs). Relative standard deviations were <30% for phenanthrene, anthracene, fluoranthene, and pyrene implying excellent reproducibility of K(PEw) across laboratories and PE sources. Averaged K(PEw) values of various HOCs were best correlated with aqueous solubility, logC(w)(sat)(L): logK(PEw) = -0.99(±0.029)logC(w)(sat)(L) + 2.39(±0.096) (r(2) = 0.92, SE = 0.35, n = 100). For 80% of analytes, this equation predicted logK(PEw) within a factor of 2. A first-order estimation of K(PEw) can be obtained assuming constant solubility of the compounds in the PE, such that the variation in C(w)(sat)(L) determines the differences in K(PEw). For PE samplers, K(PEw) values do not change with the thickness of the PE sampler. The influence of temperature on K(PEw) seems dominated by solubility-changes of the compound in water, not in PE. The effect of salt is rather well understood, using a Schetschenow-style approach. The air-PE partitioning constant, K(PEa), can be approximated as the ratio of K(PEw)/K(aw) (the air-water partitioning constant). A critical review of diffusivities in PE, D(PE), suggests that best results are obtained when using the film-stacking method. A good correlation is then found between D(PE) and molar volume, V(m) (Ǻ(3)/mol): logD(PE) (m(2)/s) = 0.0145(±0.001)V(m) + 10.1(±0.20) (r(2) = 0.76, SE = 0.24, n = 74).