Engineering Functional Nanothin Multilayers on Food Packaging: Ice-Nucleating Polyethylene Films

Abstract

Polyethylene is the most prevalent plastic and is commonly used as a packaging material. Despite its common use, there are not many studies on imparting functionalities to those films which can make them more desirable for frozen food packaging. Here, commercial low-density polyethylene (LDPE) films were oxidized by UV-ozone (UVO) treatment to obtain a negatively charged hydrophilic surface to allow fabrication of functional multilayers. An increase in hydrophilicity was observed when films were exposed to UVO for 4 min and longer. Thin multilayers were formed by dipping the UVO-treated films into biopolymer solutions, and extracellular ice nucleators (ECINs) were immobilized onto the film surface to form a functional top layer. Polyelectrolyte adsorption was studied and confirmed on silicon wafers by measuring the water contact angles of the layers and investigating the surface morphology via atomic force microscopy. An up to 4-5 °C increase in ice nucleation temperatures and an up to 10 min decrease in freezing times were observed with high-purity deionized water samples frozen in ECIN-coated LDPE films. Films retained their ice nucleation activity up to 50 freeze-thaw cycles. Our results demonstrate the potential of using ECIN-coated polymer films for frozen food application.

Nanoscale properties of biopolymer multilayers

“…Our previous work demonstrated that building more bilayers had an effect on both on the surface morphology and the absorption of ECINs as top layer on the PDDA/PSS system (Gezgin et al, 2013). Here the observations were similar with the AFM images showing more concentrated carrageenan gel networks with thicker and more elevated threads on the surface of higher contrast as the number of bilayers increase ( Figure 2).…”

“…They are used in food systems to increase freeze-thaw resistance, modify food texture and deliver energy savings in freeze drying and concentration applications (Li-Jung, Chen, Tzeng, Chiou & Jiang, 2005;Zhu & Lee, 2007) There are no reports regarding the activity of ice nucleators when applied as a nano-thin layers in food products. ECIN nano-thin films have been fabricated using non-food grade synthetic oppositely charged cationic poly (diallyldimethylammonium chloride) and anionic poly (styrenesulfonate) (Gezgin, Lee & Huang, 2013). Thus it is of importance to consider the fabrication of ECIN nano-thin films using food grade polyelectrolytes.…”

Advances in Electrochemical Nano-Biosensors for Biomedical and Environmental Applications: From Current Work to Future Perspectives

“…In two dimensions (2D), two dimensions are in nanoscale, and one dimension is in macroscale. Coating solid surfaces with nanomaterials creates 2D-like structures (e.g., nano-sheets, nano-walls, nano-thin-films, or nano-thin-multilayers) [ 61 ]. Keeping the thickness constant in the nanoscale range, the total area of nanomaterials’ 2D-like structures could be within some square micrometers.…”

AFM imaging of extracellular ice nucleators

“…We have demonstrated earlier that ECIN nano‐thin films can be fabricated on a surface through electrostatic interactions using nonfood grade synthetic oppositely charged cationic poly (diallyldimethylammonium chloride) (PDDA) and anionic poly(styrenesulfonate) (PSS; Gezgin, Lee, & Huang, 2013). A similar work on ice propagation had been conducted using the layer by layer (LbL) deposition of polyelectrolyte pairs PSS/poly(allylamine hydrochloride) (PAH) and PSS/PDDA without using ECINs, where authors concluded that ice propagation can be tuned by modifying the outermost polymer layer (Jin, He, Guo, & Wang, 2017), which in fact was performed in our above cited work by adding a single layer of ECINs on the PSS/PDDA multilayers.…”