Investigating the Influence of Packaging on the Volatile Profile of Oats

Volatile compounds from packaging materials can migrate into packaged oats, influencing both flavour and safety. In the testing of six different oat brands, headspace sorptive extraction and comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC–TOF-MS) reveal how various packaging types—cardboard, paperƒ, and plastic—can affect and alter the oats’ volatile profile, underscoring the potential impact of packaging on food quality.

Investigating the migration of volatiles from food packaging is essential for ensuring the safety, quality, and sensory integrity of food products. Packaging materials that include plastics, adhesives, and inks can release volatiles that migrate into food. These can potentially lead to the contamination and alteration of sensory characteristics such as taste and aroma.

Understanding these mechanisms is essential for complying with food safety regulations and for developing packaging to reduce these interactions. With the rise in recycled packaging use, concerns about chemical interactions throughout a product’s shelf life have increased. This is particularly relevant for rolled oats, which readily absorb volatiles, potentially affecting their flavour.

The study of volatiles in complex food matrices such as oats requires advanced analytical techniques because of the low concentrations and diverse nature of these compounds. Traditional methods, such as solid-phase microextraction (SPME) combined with gas chromatography–mass spectrometry (GC–MS), often lack the sensitivity and chromatographic resolution needed to fully characterize the volatile composition (1).

To address these challenges, headspace sorptive extraction was paired with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC–TOF-MS). The high-capacity sorptive extraction probes enable extraction and pre-concentration of a wide range of trace-level volatiles, while GC×GC–TOF-MS provides the separation and identification capabilities. This allows for a detailed investigation of the volatile profile of foods and the potential impact of packaging materials on these profiles.

This advanced approach was used to analyze volatiles from six different brands of packaged oats. By employing chemometrics software, key differences in oats packaged in cardboard, paper, and plastic were identified, and the volatiles emitted from each packaging type examined to confirm and better understand migration patterns.

Experimental

Samples

Six store-bought packs of rolled oats, labelled as brands A–F, were investigated. Brands A and B were packaged in cardboard, brand C in paper, and brands D–F in plastic.

Headspace Sampling

Sampling of the oats (approximately 1 g) and packaging (approximately 0.5 g) was performed in triplicate using HiSorb high-capacity sorptive extraction probes (Markes International) containing 30 μL of PDMS/CWR/DVB as the sorptive phase. Incubation time: 45 min; incubation temperature: 70 °C.

GCxGC

Insight-Flow modulator (SepSolve Analytical); P_M 3.0 s.

MS

Instrument: BenchTOF2 (SepSolve Analytical); Mass range: m/z 35–400.

Software

Full instrument control and data processing in ChromSpace, with chemometric comparisons in ChromCompare+ (SepSolve Analytical).

Results and Discussion

Headspace sorptive extraction and GC×GC–TOF-MS revealed approximately 250–300 components from each oat sample, ranging from volatiles including acetone and sulfur dioxide, to semi-volatiles such as 1,2-diphenoxyethane. A representative chromatogram for each brand is shown in Figure 1.

In non-target screening, capturing the full spectrum of information is crucial. Traditional GC–MS often overlooks key details or misidentifies trace compounds. However, GC×GC–TOF-MS enhances confidence in results by offering superior separation and high-sensitivity detection with full-range mass spectra. Figure 2 highlights an enhanced section of the volatile profile from plastic-packaged oats. In GC–MS, the two circled peaks would have coeluted with other compounds and most likely would have gone unnoticed because of their trace levels. With GC×GC–TOF-MS, these analytes are physically separated, producing cleaner spectra and more reliable identification, backed by powerful mass accuracy. This is crucial for accurate aroma profiling—such as for gamma-terpinene which contributes a terpenic, sweet, citrus (2) aroma—as well as for the identification of possible contaminants, such as p-chlorotoluene.

Given the sample complexity, automated data processing workflows were needed to interpret the results in a reasonable timeframe and to identify any trends based on packaging material. The dataset was processed using a tile-based chemometrics workflow (3) to highlight the significant differences between the sample classes (brand and packaging type).

The resulting principal component analysis (PCA) score plot displayed in Figure 3 shows that the samples cluster not only by brand but also by packaging type. The plastic, paper, and cardboard packaged oats are well-separated along principal component 1 (PC1), suggesting that the packaging is likely to be influencing the volatile profiles of the oats. The two brands of cardboard packaged oats clustered closely, but the plastic-packaged oats had greater diversity, with brand D separated on PC2.

After eliminating duplicate tiles and false positives, 33 compounds were identified as key markers differentiating the sample classes, as summarized in Table 1. These compounds included a combination of aroma-active species, unique to specific brands (for example, 2,5-dimethyl pyrazine elevated in brand B), and potential contaminants linked to packaging types (for example, styrene elevated in oats packaged in cardboard).

Notable Correlations

To test the theory that these compounds originated from the packaging, the volatiles from each packaging type were also captured using the same analytical workflow. Several notable correlations were observed, as shown in Figure 4:

• 2-Ethyl hexanol was the most intense peak in the cardboard packaging (accounting for >20% of the total peak area) and was elevated in both brands of cardboard-packaged oats.
• α-Methylstyrene levels were also increased in both types of cardboard packaging, with a corresponding increase in these oats.
• Triacetin was the dominant peak in the plastic packaging of brand D and was similarly elevated in the oats from that brand.

It is therefore likely that the packaging materials were the source of these volatiles, which were subsequently absorbed by the oats packaged within them. Table 1 shows that among the 33 differentiators of the oats, 25 of these compounds were also identified in the respective packaging. The remaining eight compounds were only found in the headspace of the oats themselves and are likely a result of growing conditions or processing (for example, kiln drying temperature) that are specific to that brand.

Conclusions

In conclusion, this study highlights the importance of efforts to understand and reduce the migration of volatile compounds from packaging into food. This is a critical factor for ensuring food safety and consumer satisfaction. The complexity of volatile profiles makes it clear that advanced analytical tools such as headspace sorptive extraction and GC×GC–TOF-MS are essential. This method provides enhanced resolution and sensitivity, allowing for the confident identification of both aroma-related volatiles and packaging contaminants in a single platform, making it ideal for comprehensive, non-target screening.

References

(1) Starowicz, M. Analysis of Volatiles in Food Products. Separations 2021, 8, 157. DOI: 10.3390/separations8090157

(2) The Good Scents Company Information System. TGSC Information System search facility. https://www.thegoodscentscompany.com/search2.html (accessed 2024-09-11)

(3) SepSolve Analytical Webinar. From Data to Decisions: Automated non-target workflows for comparing GC(-MS) and GC×GC data, January 2022. https://register.gotowebinar.com/rt/3749043699222152717?source=Website (accessed 2024-11-19)

About the Authors

Laura McGregor completed a Ph.D. in environmental forensics at the University of Strathclyde in 2012. Her research interests include the chemical fingerprinting of coal tar contamination using GC×GC–TOF-MS. In her current role at SepSolve Analytical, she oversees marketing activities for the full product portfolio and specializes in applying GCxGC and chemometrics to challenging samples.

Meriem Gaida earned her PhD in August 2023, specializing in advanced theoretical modelling and innovative data processing workflows for GC×GC–TOF-MS. She joined SepSolve in September 2023 as an applications specialist at the Peterborough demo laboratory, where she developed and demonstrated customized analytical methods for clients. In September 2024, she transitioned to LUZI AG, a fragrance house in Zurich, Switzerland, taking on the role of product safety scientist.

James Ogden spent nine years working within an environmental analytical laboratory, where he was responsible for method testing, development, and implementation. In his current role at SepSolve Analytical, James supports customers through the development, demonstration, and handover of analytical methods across the company’s portfolio of instruments and software.

Direct correspondence to: hello@sepsolve.com