Elucidation of Volatile Changes in Soybean Oil Stored in Polypropylene-Clay Nanocomposite

The permeation of oxygen and the effects of nanoclay on volatile retention through a PP (polypropylene)-clay nanocomposite were investigated. A nanocomposite film of 1.465 mm thickness was prepared by heat-pressing PP granules containing 500 mg/kg nanoclay at 280°C. Inductively coupled plasma-optical emission spectrometry showed that the nanoclay was mainly composed of Ca (40.7%). Also, transmission electron microscopy revealed that the nanoparticles were well dispersed in the nanocomposite container whereas fourier transform infrared spectrometry demonstrated that the PP intermolecular bonds were not significantly affected by the addition of nanoclay. Diaphragm diffusion analysis explained that the addition of nanoclay reduced the oxygen permeability of the PP container by 20% at 20 and 40°C. Based on the results of SMPE/GC-MS, the relative amounts of volatiles from lipid oxidation, including pentanal, hexanal, and (E)-2-heptenal, were higher in neat PP than those in PP/clay nanocomposite containers. After 5 weeks, the POV, CDA values, and p-AV of the sample in the nanocomposite container were lower than those of the neat PP container at 20°C. The POV, CDA values, and p-AV of the samples continuously increased over 3 weeks for the neat PP container and 5 weeks for the nanocomposite container at 40°C.