SAOWALUK TAECHUTRAKULThis original research developed active polylactic acid (PLA) film strips for use inside food packaging to extend the shelflife of bananas (Musa AAA group). Multibranched PLA functionalized with gallic acid (GA) (mPLAGA) was prepared by ringopening polymerization and functionalization. mPLAGA was compounded with PLA and fabricated into PLA/mPLAGA film strips by melt processing using different mPLAGA contents (1, 2 and 4 wt). The morphology, antioxidant activity, freeradical scavenging ability under a radiation sterilization dose (25 kGy), migration behavior, mechanical properties, and O2 scavenging capacity of PLA/mPLAGA film strips were determined and compared with neat PLA and PLA/GA film strips. Bananas were vacuumpacked using commercial plastic packaging together with the PLAbased film strips and kept at room temperature for 14 days. The performance of the PLA/mPLAGA film strips in extending the shelflife of bananas was investigated by physical appearance, peel color difference (Eab), ripening index (RI), and firmness. Analysis of variance at the 0.05 level of significance (p 0.05) was conducted to compare mean values. PLA/mPLAGA film strips exhibited a homogeneous matrix with improved mechanical properties and showed outstanding antioxidant as well as O2 scavenging effects by preventing the bloating of packaging, delaying fruit ripening, and extending the shelflife of bananas. Under vacuum packaging with PLA/mPLAGA film strips, bananas retained their green peel color and firmness after storing for 14 days. The results suggest that PLA/mPLAGA film strips show promise as an active bioplastic for extending the shelflife of bananas as well as other fruits and food items.
Multibranched PLA (mPLA) was synthesized by ringopening polymerization (ROP) of LLA onto the 4arms PETH core molecule. GA was dissolved in dichloromethane and magnetically stirred. EDC and NHS coupling agents were added into the GA solution. Different mPLAGA contents of 1, 2 and 4 wt were mixed with PLA pellets to obtain PLA/mPLAGA compounds.
Functional PLA/mPLAGA bioplastics with significantly enhanced antioxidant activity and O2 scavenging capacity were developed as active film strips to extend the shelf life of bananas. mPLAGA was successfully synthesized using ROP of LLA and GA conjugation. The chemical structure, functional groups, MW, and thermal stability of mPLAGA were elucidated. mPLAGA with MW of 2527 kDa was homogeneously compounded with PLA to obtain a transparent PLA/mPLAGA film with a thickness of approximately 15 m. The mPLAGA film exhibited antioxidant and O2 scavenging capacities comparable to free GA however, mPLAGA showed better compatibility with PLA than free GA. The PLA/mPLAGA film containing 2 wt of mPLAGA exhibited improved mechanical properties compared to PLA and scavenged free radicals and O2 gas to prevent banana ripening without browning for up to 14 days. Bananas stored in vacuum packaging with PLA/mPLAGA film strips showed green peel color and retained firmness compared with bananas stored outside the packaging and inside vacuum packaging without PLA active film strips. The PLA/mPLAGA film strip was beneficial and showed potential as a new type of active film strip to extend the shelf life of bananas as well as other fruits and foods. Functional PLA/mPLAGA can be further applied as an active bioplastic in other food packaging applications.
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