Antioxidant, antibacterial and antifungal electrospun nanofibers for food packaging applications

Highlights

• A comprehensive review of functional electrospun nanofibers for food packaging.

• Nanofibers with antioxidant, antibacterial and antifungal functionalities via electrospinning.

• Bioactive agents are encapsulated in electrospun nanofibers for active food packaging.

Abstract

Food packaging is a multidisciplinary area that encompasses food science and engineering, microbiology, as well as chemistry, and ignited tremendous interest in maintaining the freshness and quality of foods and their raw materials from oxidation and microbial spoilage. With the advances in the packaging industry, they could be engineered as easy-to-open, resealable, active, as well as intelligent with the incorporation of sensory elements while offering desired barrier properties against oxygen and water vapor. In this regard, the use of the electrospinning approach allows producing nanofibrous packaging materials with large surface-to-volume ratios and enables the higher loading of active agents into packaging materials. Electrospun packaging materials have been produced from various polymers (i.e., synthetic and natural) and their (nano)composites, and were mainly exploited for the encapsulation of active agents for their use as active food packaging materials. The electrospinning process was also used for the deposition of electrospun fibers on films to enhance their performance (e.g., as reinforcement material, or to enhance barrier properties). They could be even engineered to provide nutraceuticals to food, or antioxidant, antimicrobial or antifungal protection to the packaged food. In this article, first, introductory descriptions of food packaging, barrier properties, and electrospinning are given. Afterward, active and intelligent food packaging materials are briefly discussed, and the use of electrospinning for the fabrication of active food packaging materials is elaborated. Particular interest has been given to the polymer-type used in the production of electrospun fibers and active properties of the resultant packaging materials (e.g., antioxidant, antibacterial, antifungal). Finally, this review paper concludes with a summary and future outlook towards the development of electrospun food packaging materials.

Introduction

Food packaging comprises an important portion of the packaging industry, and innovation in this field has been motivated mainly by consumer needs and preferences, as well as variations in global trends, including increased population number and the need of long-distance transportation while maintaining the freshness of the packaged food without spoilage symptoms (Marsh & Bugusu, 2007). The main intention of food packaging is to prolong the shelf-life of food during storage and transportation. In this context, the definition of the “shelf-life” becomes critical for a better understanding of food preservation. Shelf-life is a term used to refer to the time interval between the packaging after production and the storage of the food with approved specifications (e.g., without spoilage symptoms) under certain storage conditions. Hence, the shelf-life of foods is highly associated with the inherent features of the packaged foods and exposed environmental conditions during their transportation and storage, and most importantly, the quality of the packaging system used (Robertson, 2014).

The packaging sector has become an important part of the global industry and constitutes 2% of the Gross National Products (GNP) for the developed countries (Robertson, 2006). In this regard, particularly, in the last decade, there has been a growing demand given to the extension of shelf-life of food, product safety, environmental issues, and cost-efficiency. For this purpose, many different material systems have been developed and exploited for the fabrication of high-efficiency food packaging materials. In recent years, special interest has been given to the electrospinning technique for the preparation of nanostructured food packaging materials or the surface functionalization of the packaging materials with functional electrospun nanofibers (Senthil Muthu Kumar et al., 2019).

Progress in research and development on novel packaging materials has grown drastically to meet the demands of effective food protection against oxidation and the attacks of microorganisms while intelligent food packaging materials with embedded or decorated sensory elements can indicate the instantaneous freshness of food and its characteristics (Müller & Schmid, 2019). Food packaging materials, beyond the basic necessity of their barrier function against humidity and O₂, they can be engineered to be active with the incorporation of active ingredients, such as antimicrobial nanoparticles to keep microbes away from food (Rooney, 1995, Rooney, 2005, Yildirim et al., 2018, Zhong et al., 2017). Such active packaging materials can kill or inhibit pathogenic microorganisms growing on food (Malhotra, Keshwani, & Kharkwal, 2015). In the last decade, the electrospinning technique has also been exploited for the preparation of packaging materials to extend the shelf-life of the treated and raw food either using the packaging materials produced by electrospinning (Moreira, Morais, Morais, Vaz, & Costa, 2018) or the deposition of electrospun fibers on the film surface to create bi- or multilayered packaging films (Cherpinski, Torres-Giner, Cabedo, Méndez, & Lagaron, 2018). Electrospun materials can be produced with desired structural properties by the parameters employed in the electrospinning process and solution properties, and owing to their higher surface-to-volume ratio and structurally tunable properties, electrospun materials can offer many benefits in food packaging (Tang et al., 2019).

Electrospinning is a fiber fabrication technique that produces fibrous non-woven materials by the deposition of an electrically-charged single jet on a negatively charged grounded collector (Xue, Wu, Dai, & Xia, 2019). It allows the production of electrospun fibers in nano- or micron-sized in diameter, and gives rise to the development of fibrous non-woven materials with a high surface area to mass ratio than their film counterparts and the fibers produced by mechanical extrusion. Owing to the continuity of the process, the electrospinning ends up with an electrospun mat composed of entangled long fibers. Based on the electrospinning system and solution formulation used, the resultant fibers can be porous (Celebioglu & Uyar, 2011), hollow (Homaeigohar, Davoudpour, Habibi, & Elbahri, 2017), aligned (Cai et al., 2017), core-shell (Hwang, Lee, Kong, Seo, & Choi, 2012), and in multilayer coaxial structures (Yang et al., 2019). Furthermore, various (bio)active molecules can be incorporated into the matrix of electrospun nanofibers so they become useful materials in drug delivery (Topuz & Uyar, 2018a), tissue engineering (Jun, Han, Edwards, & Jeon, 2018), water treatment (Celebioglu, Topuz, & Uyar, 2019), textile (Lee & Obendorf, 2007), food industry (Weiss, Kanjanapongkul, Wongsasulak, & Yoovidhya, 2012), and food packaging (Torres-Giner, 2011).

Several natural and synthetic polymers, as well as their composites, were exploited for the production of electrospun materials for food packaging. Most studies used zein (Dias Antunes et al., 2017) or gelatin zein (Alp-Erbay, Yeşi̇lsu, & Türe, 2019) and their combination with other (bio)polymers (Moreno, Orqueda, Gómez-Mascaraque, Isla, & López-Rubio, 2019). Likewise, cellulose (Azeredo, Barud, Farinas, Vasconcellos, & Claro, 2019) and chitosan (Díez-Pascual & Díez-Vicente, 2015) were commonly employed for the fabrication of many bio-based electrospun materials for food packaging applications. Synthetics polymers, such as poly(L-lactic acid) (PLA) (Kara et al., 2016), poly(vinyl alcohol) (PVA) (Lan et al., 2019), and polycaprolactone (PCL) (Salević, Prieto, Cabedo, Nedović, & Lagaron, 2019) were also used for the development of electrospun food packaging materials. Each of these polymers has its own intrinsic benefits, such as biodegradability, bioactivity, barrier and mechanical properties. The characteristics of electrospun fibers can further be improved with the addition of nanoparticles, particularly for enhancing the barrier and mechanical properties of the resultant packaging materials. In this regard, nanoclays (e.g., montmorillonite) are employed as additives during the preparation of food packaging materials since they can interact physically with polymer chains, resulting in a dense membrane structure (Agarwal, Raheja, Natarajan, & Chandra, 2014).

In this paper, a comprehensive overview of the use of electrospun nanofibers in food packaging applications was reported. The review first begins with introductory descriptions on active (e.g., antioxidant, antibacterial and antifungal food packaging) and intelligent packaging systems. Afterward, the applications of electrospun food packaging materials are categorized by the polymer-type used in the fabrication of electrospun food packaging materials. Finally, the review concludes with a summary, challenges, and outlook towards the development of electrospun food packaging materials.