When assessing a beer’s quality, home-brewers will often speak of esters. But what exactly are esters, you may wonder. Esters are the fruity sweet aroma you experience when selecting the ripest carton of strawberries, for example. In beer, esters are created during fermentation when alcohol reacts with organic acids to create fruity aromas — though they can also be introduced by adding fruit to the brew.

Esters are naturally present in flowers and fruits, and chemically derived esters are used in flavorings and aromas in many foods and household products. That lemon-scented dish detergent you just used likely got its pleasant smell from esters. And the delightful aromas in esters are an all-important component for some styles of beer.

Perhaps you want to make the perfect beer to bring to a barbecue that’ll pair well with everything. Or you want to make a strong lager for some grilled mesquite beer brats. No matter what your plans, be forewarned: When brewing beer, esters can be a blessing or a curse depending on the style you intend to make.

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Introducing esters into beer without the use of fruits is a deliberate decision in crafting specific beer types such as German wheat beers, hefeweizens, Belgian pale ales, English bitters, and strong lagers. When produced, esters impart flavors and aromas perceived by beer experts and enthusiasts as citrus, fruity, or reminiscent of banana, pear, apple, and even bubble gum. These characteristics are integral and expected in these beer varietals.

However, esters in home brewing need careful management to avoid undesirable tastes. Flavors akin to solvents, plastics, heavy perfumes, or acetone can result, which are generally unpleasant. Moreover, while fruity tastes might enhance some beer styles, they are inappropriate and unwanted in others; for instance, an American pilsner should not exhibit such sweet or fruity notes.

Brewing is both a craft and a science. The American Homebrewers Association explains that ester production can be influenced by wort composition, choice of yeast, and the conditions under which fermentation occurs. For instance, ester formation tends to decrease using tall, narrow fermenting vessels, while broader, shallower vessels promote higher ester production.

The production of fermented drinks like wine, hard ciders, spirits, and beer starts from a sugary substance; grape juice for wine, apple juice for cider, and wort for beer. Wort is a highly sweetened liquid extracted from grains, and it feeds the yeast during fermentation to produce carbon dioxide, flavors, and alcohol. Managing sugar levels, zinc, and specific acids in the wort can manipulate ester levels. Factors such as oxygen and lipids can also affect ester formation, thus the selection of malts, yeast, and hops is crucial for ester control.

There are thousands of yeast strains though not all are commercially available. Some yeast strains produce more esters than others. So, if you’re making a wheat beer, you probably want to choose one with high ester-producing characteristics. Your home-brew supplier should be able to guide you to the appropriate ingredients to use for the style you want to brew. And don’t forget, when brewing your own beer, sanitation is key.

Read the original article on The Daily Meal.