Greaseproof paper products: A review emphasizing ecofriendly approaches

Abstract

A cost-effective, eco-friendly, and health-promoting packaging system that prevents the passage of greases and oils would fulfill an urgent need. This review discusses what is known about the highly divergent technological paths that have been studied to achieve these objectives. Before the emergence of plastic films, the paper industry addressed these objectives in two ways, by parchmentizing and by high levels of refining of the fibers. Parchmentizing means passing the paper through a bath of concentrated sulfuric acid, followed by rinsing out the acid and drying the sheet. Though both parchmentized paper and highly refined greaseproof paper products are still made, they have been substantially displaced by oil-repellent fluorocarbon treatments of paper. The fluorocarbon treatments have allowed papermakers to achieve greaseproof properties with ordinary paper machine equipment at ordinary refining levels and without a need to immerse the paper in strong acid. Now, however, due to environmental concerns and regulations, the paper industry needs more options. Some promising directions in published research include advances in chemistry, superoleophobic surfaces, nanocellulose films, and systems to protect nanocellulose films from the effects of moisture.

Per‐ and polyfluoroalkyl substances and their alternatives in paper food packaging

“…A higher contact angle means that it is less energetically favorable for a liquid to spread over a surface. Generally, a liquid is unable to pass through pores in a coated paper when the contact angle of the test liquid is around 90 degrees or greater (Hubbe & Pruszynski, 2020).…”

“…Most sizing agents are applied in the form of aqueous solutions or dispersions since water is inexpensive and environmentally benign. Several reviews discussing biopolymeric paper coatings have been published in the last 10 years (Andersson, 2008; Helanto et al., 2019; Hubbe & Pruszynski, 2020; Johansson et al., 2012; Khwaldia et al., 2010; OECD, 2020; Rastogi & Samyn, 2015; Vartiainen et al., 2014), so this review article will emphasize more recent or different research as well as newer products coming to market.…”

“…The cellulose fiber network in conventional paper contains numerous pores so that oils can easily flow through these. However, grease‐resistant papers are produced commercially by extensive refining and/or calendaring to produce smaller, densely packed fiber mats called glassine paper or by passing paper through a concentrated sulfuric acid bath followed by a water wash to swell the fibers and close the pores to produce parchment paper (Hubbe & Pruszynski, 2020). Drawbacks of glassine paper are a highly energy and time‐consuming production process.…”

“…In an extension of the glassine paper concept, much work on microfibrillar cellulose (MFC), nanofibrillar cellulose (NFC), and cellulose nanocrystals (CNC) has been conducted to prepare barriers to oxygen and grease (Helanto et al., 2019; Hubbe et al., 2017; Hubbe & Pruszynski, 2020). MFC and NFC coatings have very low permeability to oil when dry but can lose strength and barrier properties when wet.…”

“…Fillers create a tortuous path for diffusion, so WVTR can be reduced by up to about 50%. Nanoparticulate minerals, particularly plate‐like ones such as clays, can exhibit very large surface areas and provide improved film barrier and mechanical properties at lower filler levels (Andersson, 2008; Hubbe & Pruszynski, 2020). Coatings made from silica nanoparticles coated with silanes or polydimethylsiloxane were shown to be superhydrophobic (Bayer, 2020).…”