Beer contains numerous flavor compounds produced by yeast, hops, and other ingredients. During storage, chemical reactions occur, resulting in the breakdown of some components and the formation of others, leading to the aging or staling of beer. To help brewers extend the shelf life of beer, researchers have studied beer aging, but most of these studies have focused on light lagers and a limited group of chemicals.
Jessica E. Prenni, Colorado State University, Fort Collins, CO, USA, and colleagues have expanded on this research by investigating amber ale (AA) and India Pale Ale (IPA), as well as additional compounds, to determine whether beer stays fresher and more stable in an aluminum can or glass bottle over a 6-month aging period.
Sample beer was brewed at New Belgium Brewing Company in Fort Collins. The team stored cans and brown bottles of AA and IPA for a month under cold conditions (3 °C) and then at room temperature (20 °C) for five months to simulate typical storage conditions. They analyzed the metabolites in newly opened containers every two weeks.
The concentration of certain metabolites in AA, including some amino acids (glycine, tyrosine, and asparagine) and esters (isobutyl isobutyrate, 2-methylbutyl butyrate, and ethyl decanoate), differed significantly depending on whether it was packaged in a bottle or can. AA stayed fresher in a bottle. IPA was much less sensitive to packaging type, possibly because of its higher concentration of polyphenols from hops. These compounds not only prevent oxidation but also bind to amino acids, retaining them in the beer instead of than allowing them to stick to the inside of a container.
The team found that packaging material affects beer terpenes’ flavor (humulene, pinocarvone, and α-calacorene) due to their water solubility, resulting in flavor scalping (flavor compounds move from the product to the packaging material, causing a decrease in taste intensity). This phenomenon also occurs in other packaged foods and drinks.
Overall, the results demonstrate that beer metabolites, and thus stability, are significantly impacted by package type. The team says their results are relevant to modern breweries and beer styles and provide valuable information to enable scientifically backed decision-making around packaging and package-type best practices.
- Characterizing the Impact of Package Type on Beer Stability,
Kathryn Fromuth, Jacqueline M. Chaparro, Dana Sedin, Charlene Van Buiten, Jessica E. Prenni,
ACS Food Sci. Technol. 2023.