Influence of Aroma Compound Sorption on the Thermal Properties of Biopolymer Films

Abstract

In a polymeric packaging system, interactions occur between product, package and environment. The interactions between these phases involve mass transfer processes described as permeation, migration and sorption. The permeation of aroma compounds through the packaging materials relates to the the diffusion and sorption phenomena. The sorption is the uptake of aroma compound into the packaging materials which this phenomenon could effect on the properties of the packaging materials. This study determined solubility coefficients of citral for poly(lactide) (PLA) and poly(butylene succinate) (PBS) films and also determined their thermal properties before and after the sorption phenomenon occurred during the storage time. The extraction method was used to extract the sorbed compound from the film samples by dichloromethane. The sorption of citral mass into the PLA and PBS films was analyzed using a gas chromatograph with a flame ionization detector (GCFID) at the interval time. The solubility coefficients of citral into the PLA and PBS films were determined. In the meantime, the thermal properties of PLA and PBS films were characterized by differential scanning calorimetry (DSC). The results showed similar trends with the amount of the sorbed citral into the PLA and PBS films. The solubility coefficients of citral were lower in PLA film than in PBS films. Solubility increased with decreasing the glass transition temperature (Tg) and melting temperature (Tm) of the PLA and PBS films. The results suggest that the citral acts as a plasticizer affecting the interactions between the aroma compound and film samples. It can be concluded that the thermal properties of biopolymers were primarily affected by the sorption of aroma compound into the biopolymer films.