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BACKGROUND: The article reviews the recent developments in bioplastic food packaging. Several bioplastic materials (polylactide, polyhydroxyalkanoates, and starch) have been successfully converted into food packaging using conventional plastic conversion technologies including extrusion, injection molding, and compression molding. Recently, bioplastic packaging has been developed into active packaging which can either control the release of active ingredients or scavenge undesirable substances. This review emphasizes the advances in bioplastic packaging with regard to active packaging applications and applications requiring gas and water barrier. RESULTS: The review shows that antioxidant and antimicrobial functions are major developments for the control-release application in bioplastic packaging. Factors affecting the release of active ingredients have been reviewed. The sorption of low molecular weight substances such as humidity, aromas, and gases, also affects the properties of packaging materials. Some patents are available for oxygen-scavenging bioplastic packaging. Moreover, improved high-barrier packaging technologies (modified polymer, coating, and lamination) have been developed to increase the shelf-life of food products. CONCLUSION: The finding shows that the development of bioplastic into food packaging included control-release (desorption), scavenging (absorption) and permeation technologies.

The objective of this work was to investigate blend ratio and storage time effects on the morphological, mechanical, and thermal properties of thermoplastic starch/poly(butylene adipate- co -terephthalate) (TPS/PBAT) films. TPS was prepared from plasticized cassava starch using a twin-screw extruder. TPS was subsequently melt-blended with PBAT with varied weight ratios (i.e., 20/80, 40/60 and 60/40) and blown to form TPS/PBAT films. It was found that increasing the TPS/PBAT ratio to 40/60 led to improved distributions of polymeric components and increased PBAT crystallization temperatures while reducing TPS melting transitions and tensile properties of TPS/PBAT films. After three months of storage at 30 °C, the tensile strength and secant modulus at 2% strain of TPS/PBAT films increased due to recrystallization of both TPS and PBAT. Blend ratios were the primary determinant for changes in TPS/PBAT film elongation at break with this storage time. Elongation at break decreased at low TPS:PBAT ratios (i.e., 20/80) and increased at high blend ratios (i.e., 60/40). The recrystallization of both TPS and PBAT components were observed from XRD and DSC analyses. Results obtained from both techniques confirmed the formation of additional crystalline structures of individual components during storage. The recrystallization phenomena also affected thermal transition temperatures of blend components. The crystallization temperature of PBAT-rich phase increased as starch could act as nucleating sites for PBAT. Using DMA, the tan δ curve of TPS/PBAT film exhibited two sharp individual peaks corresponding to the glass transitions of PBAT-rich and starch-rich phases. The tan δ of TPS-rich phase shifted to higher temperature due to recrystallization of TPS-rich phase.

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