Before we go into the causes of ethyl acetate, it is important to note that it is not always a negative attribute in beer. When present in moderate levels, ethyl acetate can add complexity and depth to the flavour profile of a beer. However, when present in high levels, it’s usually a sign of a problem, and should be avoided.

What Is Ethyl Acetate?

Ethyl acetate is a common ester found in beer that can contribute to a fruity aroma and flavour. It’s often found as a beer fault and described as solvent-like, or nail polish remover.

High levels of ethyl acetate typically indicate an overworked or stressed yeast strain. Causes can be attributed to an environment that is too warm for the yeast. It can be attributed to wild yeast and are common when using brettanomyces.

How is Ethyl Acetate Formed?

Ethyl acetate is formed during fermentation, when yeast breaks down sugars and produces ethanol and acetic acid.

Common causes of higher levels of ethyl acetate in beer are yeast stress. This can be from:

• Too high fermentation temperature versus the specified tolerance
• Under-pitching yeast
• Oxygen levels too low
• High gravity wort
• Leaching from non-food grade plastic fermenters or transfer tubes

Experiencing Ethyl Acetate In Beer

Aroma

A beer with high levels of ethyl acetate may have a fruity, solvent-like smell, similar to nail polish remover or glue. However, when present in moderate levels, it can add a pleasant fruity aroma to the beer, like ripe bananas, apples, or pears.

Flavour

A beer with high levels of ethyl acetate will have a strong solvent-like ester taste. It may be harsh and overpowering. Moderate levels can give the beer a pleasant fruity or sweet taste.

Mouthfeel

A beer with high levels of ethyl acetate may have a thin and watery mouthfeel. Moderate levels can enhance the mouthfeel, even add a smoothness of the beer.