Effects of PLA Film Incorporated with ZnO Nanoparticle on the Quality Attributes of Fresh-Cut Apple.

Wenhui Li,Tianqing Lan,Yun Cao,Haiyan Chen,Yuyue Qin,Lin Li

doi:10.3390/nano7080207

Abstract

A novel nanopackaging film was synthesized by incorporating ZnO nanoparticles into a poly-lactic acid (PLA) matrix, and its effect on the quality of fresh-cut apple during the period of preservation was investigated at 4 ± 1 °C for 14 days. Six wt % cinnamaldehyde was added into the nano-blend film. Scanning electron microscope (SEM) analysis showed a rougher cross-section of the nano-blend films and an X-ray diffraction (XRD) was carried out to determine the structure of the ZnO nanoparticles. Compared to the pure PLA film, the nano-blend film had a higher water vapor permeability (WVP) and lower oxygen permeability. With the increase of the nanoparticles (NPs) in the PLA, the elongation at break (ε) and elastic modulus (EM) increased, while tensile strength (TS) decreased. Thermogravimetric analysis (TGA) presented a relatively good thermostability. Most importantly, the physical and biochemical properties of the fresh-cut apple were also measured, such as weight loss, firmness, polyphenol oxidase (PPO), total phenolic content, browning index (BI), sensory quality, and microbiological level. The results indicated that nano-blend packaging films had the highest weight loss at the end of storage compared to the pure PLA film; however, nanopackaging provided a better retention of firmness, total phenolic countent, color, and sensory quality. It also had a remarkable inhibition on the growth of microorganisms. Therefore, Nano-ZnO active packaging could be used to improve the shelf-life of fresh-cut produce.

Highlights

The consumption of fresh-cut vegetables and fruits has become more and more popular over the past decades
The cross-section of the Poly-lactic acid (PLA)/cinnamaldehyde blend films (Figure 1b) showed rougher surfaces and was heterogeneous with certain cavities and pores, which lead to a higher water vapor permeability (WVP) of the film compared to the pure PLA
PLA/nano-ZnO films showed rougher surfaces and that many voids were formed in the films

Summary

Introduction

The consumption of fresh-cut vegetables and fruits has become more and more popular over the past decades. Poly-lactic acid (PLA) is one of the most extensively studied bio-based polyesters, which was derived from lactic acid monomer [11] It is one of the polymers with the highest potential because of its superior mechanical properties, versatility, and low cost [12,13]. Cinnamaldehyde is derived from cinnamon and is a naturally occurring aromatic α,β-unsaturated aldehyde and has been certified by the Food and Agriculture Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives (JECFA) for use as a food-flavoring agent. It is the major ingredient of cinnamon bark extract [15]. It has been approved that cinnamaldehyde can work against a broad spectrum of food-borne pathogens effectively, and it is a well-known natural antimicrobial compound [16]

Methods

Results

Conclusion