# Chemical Migration from Wine Contact Materials
## 2 Wine Packaging Materials
Boxed wine can be found in various formats, commonly ranging from 3 to 20 L, with 3L and 5L containers considered to be the most popular ones. Over the last decades, PET packaging materials have been extensively used for beverages, including wine, as an alternative to glass. PET is produced through a series of reactions, including ethylene glycol and terephthalatic acid, which result in the formation of a condensation polymer [20]. The polymer is then transformed into easily moldable PET small pellets and then into bottles through various processes, including extrusion, heating, and cooling [21]. PET bottles present various advantages, including shatter resistance, chemical resistance, flexibility, lightweight, low production and transport cost, and recyclability. Their permeability to light, gases, vapors, and low molecular weight molecules can be improved [22]. The main approaches, in sole or in combination, to improve the gas barrier properties of PET bottles are considered to be the use of coatings, additional layers, blending [23], or the employment of active oxygen scavengers [9; 23]. Closures employed in wine packaging in PET bottles can include a variety of options, such as aluminum, polyvinyl chloride (PVC), PET, LDPE, HDPE, and tin capsules [19]. Lately, PET bottles have been subjected to a renaissance with the application of modern packaging approaches. As a result, nowadays, PET bottles can be found in the market in various shapes, from classic round to flat bottles, made of either virgin or recycled material [24]. The impact of recycled PET bottles on wine's aroma profile [25] and on sustainability with regard to greenhouse gas emissions have been investigated [26]. Aseptic cartons are multilayer composite packaging solutions [27]. The traditional representative of this category, TetraPak(r), comprises 70-75% paperboard (cellulose), 20-25% LDPE, and 5% aluminum foil layers [28; 29]. Paperboard is used for its mechanical properties, which provide stability and a smooth printing surface. LDPE serves as a barrier against moisture and helps the paperboard to stick to the aluminum foil [28]. The aluminum foil forms a barrier against oxygen and light, protecting wine from oxidation. Lately, other paper-based packaging systems have been proposed under the collective term paper bottles [30]. For example, in 2020, Cantina Goccia was the first winery to adopt Frugalpac(r)'s Frugal paper bottle packaging approach [31]. The Frugal Bottle comprises of an outer recycled paperboard shell and an inner pouch. It is claimed that Frugal bottles are five times lighter than normal glass bottles, present a considerably lower carbon footprint than conventional glass bottles, and demand significantly less plastic for their production in comparison to plastic bottles [31]. Another material used in wine packaging is cans. Wine packaged in cans is a practice initially adopted during World War One and afterward found commercial applications in the mid-1930s [32]. Commonly, the cans are made of aluminum alloys, an easily available, durable, environmentally sustainable metal that features increased barrier properties and is lightweight [33]. Nonetheless, aluminum is not inert [34]. When exposed to oxygen, it quickly forms a thin layer of aluminum oxide, which acts as a protective barrier; however, the remaining exposed aluminum is prone to corrosion in acidic media such as wine. As a solution, inner linings are employed to prevent the aluminum-wine interaction and its migration to the matrix. It should be noted that the linings often contain Bisphenol A (BPA), a substance prone to migration that presents endocrine- and reprotoxic-disrupting properties [35; 36]. Despite increasing market shares, the canned wine industry has faced product quality issues owing to aluminum haze formation [33] as well as sensorial degradation related to the formation of reductive sulfur-based off-odors after a reaction between aluminum and sulfur dioxide [37].