Depending on the type of beer, you may want to drink it from a bottle than a can. A new study finds that amber ale is fresher when drunk out of a bottle whereas the flavor of an India Pale Ale (IPA) does not change when it’s consumed out of a can.

Beyond water and ethanol, beer has thousands of flavor compounds created from metabolites made by yeasts, hops, and other ingredients. The flavor of beer starts to change as soon as it is packaged and stored. Chemical reactions break down flavor compounds and form others, which contributes to the aging or stale beer taste people get when they open a drink.
Brewers have long been working on ways to increase shelf life and avoid stale beer. However, most research on beer-aging has focused largely on light lagers and a limited group of chemicals. In this current study, researchers at Colorado State University looked at other types of beer such as amber ale and IPA. They also tested to see the chemical stability of beer packaged in glass bottles versus aluminum cans.

Can and bottles of amber ale and IPA were chilled for a month and left at room temperature for another five months to imitate typical storage conditions. Every two weeks, the researchers looked at metabolites in newly opened containers. As time passed, the concentration of metabolites —including amino acids and esters — in amber ale differed greatly depending on whether it was packaged in a bottle or can.

The chemical stability of IPAs barely changed when it was stored in a can or bottle, a finding the authors suggest is because of their higher concentration of polyphenols from hops. Polyphenols help prevent oxidation and bind to amino acids, allowing them to stay in the beer than having them get stuck to the inside of a container.

The metabolic profile of both amber ale and IPA changed over time, regardless of whether it was boxed in a can or bottle. However, amber ale in cans had the greatest variation in flavor compounds the longer it was stored. According to the study authors, once scientists figure out how metabolites and other compounds affect a beer’s flavor profile, it might help with making more informed decisions about the best type of packing for their particular type of beer.