Effect of ultrahigh‐pressure treatment on the functional properties of poly(lactic acid)/ZnO nanocomposite food packaging film

Abstract

BACKGROUND Our living environment is being increasingly polluted by petroleum‐based plastics and there is an increasing demand for biodegradable food packaging. In this study, the effect of various ultrahigh‐pressure (UHP) treatments (0, 200 and 400 MPa) on the microstructure and thermal, barrier and mechanical properties of poly(lactic acid) (PLA)/ZnO nanocomposite films was studied. RESULTS The film‐forming solution was processed using UHP technology. The crystallinity, strength and stiffness of the composite film after UHP treatment increased. In addition, barrier property analysis showed that the UHP treatment significantly (P < 0.05) reduced the oxygen permeability and water vapor permeability (WVP) coefficient of the PLA/ZnO nanocomposite film. Furthermore, the WVP value of the film treated at 400 MPa (50 g kg−1 nano‐ZnO content) was the lowest and reduced by 47.3% compared with that of pure PLA film. The improvement in these properties might be due to the interaction between nano‐ZnO and PLA matrix promoted by UHP treatment. CONCLUSIONS Therefore, the application of UHP technology on the film‐forming solution could improve the crystallinity and functional properties of the nanocomposite film, and has great potential in the production of food packaging films with ideal functions. © 2021 Society of Chemical Industry

Effect of High-Pressure Processing on the Packaging Properties of Biopolymer-Based Films: A Review

“…Similarly, TS of PLA-Ag-3% or PLA-Ag-5% when subjected to 200 and 400 MPa increased the TS but decreased the EAB as shown in Table 1 [ 32 ]. Such a trend in mechanical properties where TS increased and EAB decreased with the increased pressure level (0, 200, and 400) also was reported for PLA film loaded with ZnO NPs at 0, 2.5, 5.0, and 10.0 % of PLA [ 42 ]. Such variation in the mechanical properties of the nanocomposite film exposed to HPP can be ascribed to the enhancement in the crystallinity, development of ordered molecular chain arrangement, and reduction in porosity as well as the increase in the intermolecular interaction resulting in the restricted chain mobility [ 32 , 42 ].…”

“…PLA-AgNPs-5% FFS when subjected to 400 MPa at 25 °C for 15 min showed a significant increment in T g from 50.1 ± 0.2 to 51.9 ± 0.2 °C, which could be due to the application of HP that might have restricted the PLA chain mobility and increased the T g [ 32 ]. Such increment in T g was also observed for PLA/ZnO nanocomposite film prepared from FFS subjected to 400 MPa [ 42 ]. It was also observed that the application of HPP in FFS of PLA nanocomposite film, increased the T c , as evident in PLA-Ag-5% nanocomposite film, where T c increased from 110.4 ± 0.4 to 112.9 ± 0.5 °C, also in PLA-ZnO-5% nanocomposite film, T c increased from 95.9 ± 0.30 to 100.9 ± 0.70 °C, where FFS for both the films were subjected to 400 MPa.…”

“…Similarly, PLA/ZnO NPs FFS treated with HP maintained at 200 and 400 MPa showed that WVP and oxygen permeability (OP) decreased by almost 45 and 38%, respectively, with the addition of 50 g/kg ZnO NPs and application of 400 MPa. The decrease in the WVP and OP can be attributed to the increase in the crystallinity of the film leading to higher tortuosity in the transportation path and the interaction between PLA and hydroxyl groups on the surface of ZnO NPs resulting in the compactness of the film [ 42 ]. Overall, it can be seen that the incorporation of NPs at optimal concentration and simultaneous HP treatment can increase the crystallinity and interaction between the components of the film matrix resulting in the improvement of the barrier properties.…”

An intelligent pH indicator film based on cassava starch/polyvinyl alcohol incorporating anthocyanin extracts for monitoring pork freshness

“…The cassava starch/PVA/GSE composite film (CPG) and cassava starch/PVA/MRE composite film (CPM) were developed according to Lu et al (2021) and Cui et al (2021). In brief, dissolved 4 g of cassava starch in 100 ml of distilled water and add 1.2 g of glycerin.…”

A comparative study of the interaction between the dried ink layer and PLA film used for packaging purposes

“…[ 8,9 ] Hence, biodegradable and bio‐based materials, such as polylactide (PLA), starch and cellulose, and paper and board materials [ 10 ] seem to be good alternatives for traditional fossil‐based plastics. [ 11,12 ] Furthermore, also PE–starch–PLA [ 13 ] or PLA–nanofillers blends [ 14,15 ] may be an option for packaging materials. Unfortunately, the biodegradation process of PLA is the subject of intense discussion.…”