Properties and release kinetics of pine bark incorporated agar and carrageenan film

Effects of plasticisers (glycerol, sorbitol and polypropylene glycol) and blend ratios on release behaviour, molecular vibration, mechanical and water barrier properties in agar and carrageenan films incorporating pine bark extract were investigated. Infrared spectra indicated hydrogen bonding of sorbitol and polypropylene glycol with film polymers which improved water diffusion and agar solubility but showed no effect in carrageenan films due to high water affinity. Hydrophilicity of the plasticisers modified dissolution of films and strongly affected the release behaviours of polyphenols and antioxidant capacity (DPPH• and FRAP). Film solubility showed high correlation to release behaviours. Fick’s diffusion kinetics fitted well to release behaviour of pine bark to aqueous media (water, 3% acetic acid and 10% ethanol). Agar gave a higher diffusion coefficient that was improved by the addition of sorbitol and polypropylene glycol. Increased diffusion coefficients enhanced degree of release, with some diversions suggesting that solvent modified matrices and, hence, release properties.     

Quality and biochemical changes of longan (Dimocarpus longan Lour cv. Daw) fruit under different controlled atmosphere conditions

Sulphur dioxide has been used to control pericarp browning in longan fruit. However, due to health and regulatory concerns, alternative treatments should be tested. The objective of this study was to find the tolerance levels of longan fruit to low O₂ (2%, 5%, 10% and 15%) and elevated CO₂ (5%, 10%, 15% and 20%) at 2 °C. According to the tolerance study, controlled atmospheres (CA) of 5% O₂ + 5% CO₂, 5% O₂ + 10% CO₂ and 5% O₂ + 15% CO₂ were compared with normal air (control) at 2 °C. Pericarp browning and decay incidence of longan were significantly (P ≤ 0.05) higher in control than all the CA treatments. CA storage reduced polyphenol oxidase (PPO) activity, maintained L* value and slowed down a decrease in total phenolic contents (TPC). Pericarp browning was highly correlated with PPO, L* and TPC.     

Transport Coefficients of Eucalyptol through Various Polymeric Films

This study presents the determination of the transport properties of eucalyptol, which is a key aroma compound in fresh tropical herbs through different polymeric packaging materials. Packaging films used in this study were polyethylene, polypropylene, Nylon, polyethylene terephthalate and polylactide (PLA1 and PLA2). Test films were immersed in the 1000 ppm of aroma compound and stored in amber vials. The concentrations of aroma compounds extracted from films were determined using gas chromatography. Diffusion, solubility, permeability and partition coefficients were calculated from sorption kinetics. Results show that the diffusion and solubility coefficients of eucalyptol were lowest in PLA1 and highest in polyethylene. Solubility coefficients were associated with partition coefficients as well as solubility parameters and contact angle values. Primary factor determining solubility was affinity between the aroma compounds and the polymeric films. Transport coefficients of eucalyptol in the vapor phase followed the same trends as in the liquid phase with about 3‐fold greater. Understanding interaction phenomenon between the key aroma compound and major packaging films may contribute to improvements in film selection and the design of food packaging applications. Finding from this research contributes toward future development of the high‐aroma barrier materials. Copyright © 2011 John Wiley & Sons, Ltd.