The Real Reason Your Shortbread Tastes Bitter
A good shortbread cookie should be buttery, delicately sweet, and have a bit of gritty texture thanks to crystals of granulated sugar. Extremely crumbly, extremely rich, and extremely delicious, good shortbread should never taste bitter. Why then do your batches of shortbread sometimes taste bitter?
Shortbread is often baked as round cookies, wedges or fingers, but its shape isn't as important as its heavenly taste. A treat that's been baked since the Middle Ages, Bake From Scratch notes that shortbread's origins can be traced back to Scotland, where the cookies were eaten during celebrations like Hogmanay, the Scottish New Year's Eve.
Made with one part sugar, two parts butter and three parts flour, baking shortbread cookies is as easy as one-two-three. According to Food Crumbles, this ratio is what makes shortbread so irresistible as the sugar contributes to the cookies' sweetness and crispness, meanwhile higher amounts of butter add flavor and consistency, while flour binds these two malleable ingredients together. Despite the simplicity of the ingredients and the recipe itself, there is still the risk of baking bitter shortbread cookies.
Slow and steady baking is key
Butter is usually the source of shortbread baking qualms. Whether it's a quality issue or a processing issue, butter can be especially fickle given its unique composition (solid when cold and liquid when heated.) By better understanding butter's role in baking, you can solve the bitter shortbread conundrum.
Naturally, starting with fresh ingredients is the main way to ensure that every batch of shortbread you bake is a winner. According to Well+Good, butter can be kept for extended periods of time because its exterior fat protects the internal moisture content, however, it can still go off, which can give it a bitter flavor.
However, most often it isn't old butter that's the culprit when it comes to bitter shortbread, but rather duration and temperature. Bake Club claims that over-baking, or even baking shortbread on too high a heat, can cause the butter to burn, leading to a sour or pungent aftertaste in the cookies. As it turns out, slow and steady does win the [shortbread] race.