New study finds chemical migration from wine packaging materials raises safety and quality concerns

Recent research led by Niki C. Maragou and colleagues from the National and Kapodistrian University of Athens, the University of West Attica, and Aarhus University has brought new attention to the migration of chemical substances from materials that come into contact with wine. The study, published in July 2024 in the journal Applied Sciences, reviews how various packaging and storage materials can transfer both industrial and naturally occurring chemicals into wine, potentially affecting its safety and quality.

Wine is a globally consumed beverage, with an estimated 232 million hectoliters consumed worldwide in 2022. From production to consumption, wine interacts with a range of materials including glass bottles, cork stoppers, plastic closures, stainless steel vats, oak barrels, PET bottles, paperboard cartons, and aluminum cans. These materials are designed to protect wine from hazards and preserve its composition. However, the migration of chemicals from these materials into wine is a recognized phenomenon that requires monitoring.

The review distinguishes between two main categories of migrating substances: those of industrial origin—such as additives, monomers, plasticizers, antioxidants, and by-products used in manufacturing—and those of natural occurrence, mainly from cork (like tannins), which can affect the sensory qualities of wine. The focus of the review is on industrial contaminants due to their potential safety risks.

Migration testing has primarily been applied to cork stoppers and their tops. Other materials such as PET bottles with aluminum caps, paperboard cartons, stainless steel vats, and oak casks have been studied for chemical migration mainly through direct analysis of wine rather than controlled migration tests. Analytical techniques most commonly used include gas chromatography (GC) and liquid chromatography (LC) coupled with mass spectrometry (MS) for organic compounds, as well as inductively coupled plasma atomic emission spectroscopy (ICP-AES) and ICP-MS for elemental analysis.

The substances identified as migrating into wine include authorized additives like phthalate plasticizers (used to make plastics flexible), monomers such as bisphenol A (BPA), antioxidants like Irganox 1010, non-authorized substances such as butylparaben, breakdown products like nonylphenol, polyurethane adhesive by-products, oligomers, ink photoinitiators from labels or packaging prints, and inorganic elements including metals. There is also preliminary evidence for the migration of microplastics.

The review highlights that while glass remains the most traditional packaging material due to its inertness and consumer perception of quality, alternative packaging solutions are increasingly popular for economic and environmental reasons. These alternatives include lightweight glass bottles, bag-in-box systems (which use composite plastic bags inside cardboard boxes), PET bottles (including those made from recycled material), aseptic cartons like TetraPak®, paper-based bottles such as Frugalpac®, and aluminum cans. Each material presents unique challenges regarding chemical migration.

For example, cork stoppers can release both beneficial polyphenols and undesirable compounds known as “cork taint,” such as 2,4,6-trichloroanisole (TCA), which imparts musty flavors. These taint compounds often originate from microbial activity or environmental contaminants like pesticides or bleaching agents used in cork processing.

Plastic closures and PET bottles may release phthalates or other plasticizers. Aluminum cans require internal linings to prevent corrosion; these linings often contain BPA or similar chemicals that can migrate into acidic beverages like wine. Paperboard cartons use layers of polyethylene and aluminum foil for barrier properties but may also contribute migrating substances.

European regulations set strict limits on the types and amounts of chemicals that can migrate from food contact materials into consumables. The Framework Regulation (EC) 1935/2004 requires that materials do not transfer constituents to food in quantities that could endanger health or alter food composition or taste. Specific rules exist for plastics (EU No. 10/2011), ceramics (Council Directive 84/500/EEC), recycled plastics (EU 2022/1616), and maximum levels for certain metals in wine (EU 2023/915).

Migration depends on several factors: the type of material (its composition, thickness, permeability), the nature of the wine (alcohol content, pH), contact conditions (temperature and duration), and whether the substance is intentionally added during manufacturing or present as a non-intentionally added substance (NIAS). NIAS can include breakdown products from polymer degradation or impurities from recycled materials.

Analytical studies reviewed by Maragou’s team show that migration tests typically use simulants such as ethanol-water mixtures or acetic acid solutions to mimic wine’s properties under controlled conditions. Tests often involve exposing corks or closures to these simulants at elevated temperatures for set periods before analyzing the extracts using GC-MS or LC-MS methods.

Targeted analyses focus on specific known contaminants using reference standards; untargeted approaches screen for unknown migrants using high-resolution mass spectrometry combined with advanced data analysis tools. For example, recent studies have identified not only known additives but also previously unreported oligomers and reaction by-products formed during storage.

The review notes significant gaps in current knowledge: most migration studies focus on corks or closures rather than the full range of packaging materials now used in the industry; there is limited research on wines with higher alcohol content; and comprehensive workflows combining targeted, suspect screening, and non-targeted analysis are still under development.

The authors call for further research using advanced analytical techniques to better understand chemical migration from all types of wine contact materials. This will support more effective risk assessment and management strategies to ensure both the safety and quality of wines as packaging technologies continue to evolve.