Active PLA Packaging Films: Effect of Processing and the Addition of Natural Antimicrobials and Antioxidants on Physical Properties, Release Kinetics, and Compostability

Abstract

The performance characteristics of polylactic acid (PLA) as an active food packaging film can be highly influenced by the incorporation of active agents (AAs) into PLA, and the type of processing technique. In this review, the effect of processing techniques and the addition of natural AAs on the properties related to PLA performance as a packaging material are summarized and described through a systematic analysis, giving new insights about the relation between processing techniques, types of AA, physical–mechanical properties, barriers, optical properties, compostability, controlled release, and functionalities in order to contribute to the progress made in designing antioxidant and antimicrobial PLA packaging films. The addition of AAs into PLA films affected their optical properties and influenced polymer chain reordering, modifying their thermal properties, functionality, and compostability in terms of the chemical nature of AAs. The mechanical and barrier performance of PLA was affected by the AA’s dispersion degree and crystallinity changes resulting from specific processing techniques. In addition, hydrophobicity and AA concentration also modified the barrier properties of PLA. The release kinetics of AAs from PLA were tuned, modifying diffusion coefficient of the AAs in terms of the different physical properties of the films that resulted from specific processing techniques. Several developments based on the incorporation of antimicrobial and antioxidant substances into PLA have displayed outstanding activities for food protection against microbial growth and oxidation.

Preparation and characterization of poly(lactic acid)/boron oxide nanocomposites: Thermal, mechanical, crystallization, and flammability properties

“…49 Different amounts of residual solvent in the PLA films could cause different plasticization effects and T g values. 47 In our study, T g value of It is known that the glass transition is a complex phenomenon which depends on several factors including intermolecular interactions, steric effects, the chain flexibility, the molecular weight, the branching, and the cross-linking density. 52 As before mentioned, the reduction in T g might be attributed to plasticizing effect of residual solvent in the casted films.…”

“…45,46 In the literature, significant differences have mainly been found in terms of thermal properties between PLA films obtained using PLA of the same grade by different processing techniques such as extrusion, electrospinning, and solvent casting. 47 The T g of PLA films obtained by electrospinning tend to be at lower temperature values around 40 C 48 than the T g of PLA films obtained through extrusion around 61 C. 49 The T g of solvent casted PLA films varied as 44.3 C, 50 49.34 C, 26 59.66 C, 51 which could be associated with the residual solvent in the PLA. 49 Different amounts of residual solvent in the PLA films could cause different plasticization effects and T g values.…”

“…52 As before mentioned, the reduction in T g might be attributed to plasticizing effect of residual solvent in the casted films. 47 It might also be related to the plasticizing effect of OA 41 and silane coupling agent. 53 Besides the amount of residual solvent in the PLA film, solvent volatility, and casting conditions strongly influenced the thermal parameters of the casted PLA films in some studies.…”

“…The decrease might be attributed to the presence of residual solvent that act as plasticizer. 47 According to the crystallinity values (Table 3) calculated from Equation (2), the degree of crystallinity for neat PLA was 13.68%. It slightly increased to 15.21% and 16.25% for PLA/BONPs0.5 and PLA/BONPs1, respectively.…”

Maleic Anhydride Polylactic Acid Coupling Agent Prepared from Solvent Reaction: Synthesis, Characterization and Composite Performance

“…PLA is, nowadays, the most promising biobased, biodegradable and compostable polymer to substitute those based on petrol [ 12 , 13 , 14 , 15 ]. These properties, along with the mechanical performance of the polymer, allow it to be a sustainable replacement for a large variety of uses and applications, from packaging to structural applications.…”