When your workday out of the blue fills with back-to-back conferences and roughly 347 unread emails to return, it may be all too simple to overlook about that cup of espresso sitting in your desk. When that occurs (and in case you’re nonetheless craving a caffeine hit), the answer appears apparent: Reheat it within the microwave.

Positive, it’s a fast and simple approach to flip that lukewarm liquid piping scorching, however the last end result may not be fairly as delectable as you hoped: Nuking your espresso (or espresso, macchiato, cappuccino, Americano, or another sort of “-o”) could cause chemical adjustments that might heighten the bitterness, Masha Zanozina, a Los Angeles–based mostly regional gross sales and account supervisor for Counter Tradition Espresso and a espresso championship choose, tells SELF.

However the microwave is just a part of the story. Espresso is a posh beverage that incorporates greater than 2,000 compounds, together with carbohydrates, fat, amino acids, nutritional vitamins, and minerals. Once you brew it, you extract compounds from the grounds, and people, in flip, “create that taste of the espresso,” Zanozina says—like how bitter, acidic, and astringent it’s.

Water temperature issues quite a bit for that extraction. Too chilly? Too few compounds can be launched (underextraction). Too scorching? Too many compounds can be launched (overextraction). Both method, the end result probably received’t style too good, so it’s necessary to discover a completely happy medium, Zanozina says. You need the ultimate temp to fall someplace between 195 and 205 levels Fahrenheit, in keeping with the Nationwide Espresso Affiliation—7 to 17 levels beneath the boiling level. If your own home espresso maker doesn’t provide the choice to set it your self and also you’re out there for one which does, Zanozina recommends the Fellow Aiden precision espresso maker, which comes out in October however is out there for preorder now ($365, fellowproducts.com), Moccamaster KGBV Choose ($359, amazon.com), xBloom Studio ($499, xbloom.com), and—her private fave—the Ratio Six espresso machine ($339, amazon.com). For a less expensive choice, we just like the Cuisinart glass carafe espresso maker, which specialists say it persistently will get your brew scorching sufficient ($75, amazon.com).

Nonetheless with us? Good, as a result of water temperature and a microwave discipline journey aren’t the one elements that may affect the palatability of espresso: Letting yours sit out for an prolonged time frame will itself damage the style because it turns into “kind of the [coffee] equal of stale,” espresso knowledgeable Christopher Hendon, PhD, an affiliate professor within the division of chemistry and biochemistry on the College of Oregon, tells SELF.

One purpose is that risky compounds, the stuff chargeable for that distinct espresso odor, dwindle with time, temperature, and air publicity—“simply evaporation, mainly,” Dr. Hendon says. Concurrently, one other, slower course of often known as oxidation can be occurring. “It takes the form of candy, fruity flavors and form of blunts them,” Dr. Hendon says. (To maintain from falling into this lure, attempt to drink espresso inside an hour of brewing it, in keeping with Zanozina.)