Glass vs aluminium: what's best for beer packaging?

The flavour of beer begins to change as soon as it’s packaged, so does a bottle or can keep the ale fresher for longer? Researchers report in ACS Food Science & Technology that the answer to the question is complicated and depends on the type of beer. In their study, an amber ale stayed fresher in bottles, whereas container choice made much less difference to the stability of an India Pale Ale (IPA).

In addition to water and ethanol, beer contains thousands of flavour compounds, which are metabolites produced by yeast, hops and other ingredients. During storage, chemical reactions break down some of those components while forming others. This reduces the content of some tasty flavours while generating unappetising ones, contributing to the aging or staling, of beer. To help brewers prolong shelf life, researchers have studied beer aging, but they’ve concentrated on light lagers and a limited group of chemicals. Jessica Prenni and colleagues wanted to extend that work to amber ale and IPA, as well as additional compounds. The team also wanted to conduct a stability comparison of beer packaged in glass bottles versus aluminium cans.

In the study, cans and brown bottles of amber ale and IPA were chilled for a month and then kept at room temperature for five months to mimic typical storage conditions. Every two weeks, the researchers analysed the metabolites in newly opened containers. Throughout this time, the concentration of certain metabolites in amber ale — including some amino acids and esters — differed significantly depending on whether it was packaged in a bottle or can. IPA, however, 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, thus retaining them in the beer rather than allowing them to get stuck to the inside of a container.

The researchers also found that the metabolic profile of both amber ale and IPA changed over time, whether packaged in a can or bottle. However, amber ale in cans showed the greatest variation during aging. Once scientists find out how all of these changes affect flavour, brewers will be able to make more-informed decisions about the best type of packaging for their particular type of beer.

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