Characterization of gamma irradiated plasticized starch/poly(vinyl alcohol) (PLST/PVA) blends and their application as protected edible materials

摘要

Blends based on different ratios of plasticized starch (PLST) and poly(vinyl alcohol) (PVA) were prepared in the form of thin films by casting solutions. The effect of gamma-irradiation on thermal, mechanical and morphological properties was investigated. The results of thermogravimetric analysis (TGA), in terms of weight loss and rate of reaction, indicated that the thermal stability of PLST/PVA blends is higher than pure PLST. The differential scanning calorimetry (DSC) scans do not show the glass transition temperature (T_g) of PVA or PLST, but instead a new single glass transition, indicating the occurrence of compatibility. The mechanical testing of PLST/PVA blends showed that tensile strength and elongation at break were increased by increasing the ratio of PVA. At any ratio of PLST/PVA, the tensile strength and elongation at break was found to increase with increasing irradiation dose. As an application in the field of prolonging food preservation lifetime, solutions of gamma irradiated PLST/PVA blends in the presence of chitosan, as an antimicrobial material, were applied to Mango fruits by surface coating. The results showed that this technique would provide suitable materials for food preservation that withstanding the temperature and stresses.