Natural Active Ingredients for Poly (Lactic Acid)-Based Materials: State of the Art and Perspectives

Abstract

This review describes the state of the art in the field of poly (lactic acid) (PLA)-based materials activated by natural compounds and extracts (active ingredients, AIs) from plant sources for food and biomedical applications. With a multidisciplinary approach, after a description of the synthesis and properties of PLA, special attention was paid to the chemical properties and unconventional extraction technologies of AIs used for PLA activation. Innovative techniques for the incorporation of AIs into PLA; characterization and the antioxidant and antimicrobial properties of the novel materials were discussed. In view of future perspectives, this study has evidenced that some aspects need to be further investigated from joint research between academia and industry, according to the green chemistry principles and circular economy strategy.

Keywords: PLA-based materials; active ingredients; antimicrobial activity; antioxidant activity; circular economy; essential oils; green chemistry; phenols; poly (lactic acid) (PLA); sustainable materials; terpenes.

Figure 1

Structure of enantiomers of LA.

Scheme 1

Possible routes of PLA production.

Figure 2

Stereoisomers of lactide.

Figure 3

Different opening positions of the lactide ring.

Scheme 2

Coordination-insertion mechanism of ROP of lactide.

Figure 4

Phenolic compounds found in Olea europaea L.

Figure 5

Chemical structures of the most common flavonoids.

Figure 6

Chemical structure of the most important stilbenes.

Figure 7

Chemical structure of α-tocopherol and curcumin.

Figure 8

Chemical structures of terpenes.

Figure 9

Chemical structures of terpenes.

Figure 10

Chemical structure of the most important carotenoids.

Figure 11

Antioxidant activity (%) of electrospun fibers of PLA with different carvacrol content (a); growth inhibition rate (%) of aerobic bacteria and mold and yeast of zein and PLA electrospun fibers (b); and images of whole wheat bread samples packed with electrospun PLA fibers with different carvacrol content stored at 25 °C for 7 days (c). Reprinted with permission from Ref. [144], Copyright 2018 Elsevier Ltd.

Figure 12

(a) Chemical structure of modified CD, eugenol, and schematic illustration of IC formation between CD and eugenol; Reprinted with permission from Ref. [178], Copyright 2020 Shahla Ataei et al. (b) schematic representations of γ-CD and α-TC/γ-CD–IC, electrospinning of nanofibers from a PLA/α-TC/γ-CD–IC solution and cumulative release of α-TC from PLA/α-TC–NF and PLA/α-TC/γ-CD–IC–NF into 95% ethanol. Reprinted with permission from Ref. [187], Copyright 2017 Wiley Periodicals, Inc., [187].