Why Diner Coffee Tastes Different In A Weird Way

If you are a regular coffee consumer, you've probably tried your fair share of different brews. Beyond the familiar coffee flavor you get at every Starbucks you go into, it can feel like a gamble when you order coffee at a restaurant. You never know if it will taste burnt, sour, weak, or weird until you try it. When it comes to the coffee you get at your average diner, it might never seem to taste quite right. 

While there are certain drinks you should never order at a diner, coffee is usually a pretty common go-to. Unfortunately, the flavor is often not great, with the smokey bitterness of the watered-down grounds leaving an unpleasant taste in your mouth. Many people have theorized about how American diners achieve their distinct coffee flavor. One possibility is the mixture between overroasted grounds and a weak ratio of coffee to water in the brewing process. 

Diners are typically open for very long hours, if not overnight. With this weak coffee sitting atop a burner for hours on end, it can create that day-old coffee taste that's easily accessible for refills but compromising on quality. On top of that, diners are usually using cheaper robusta beans over arabica beans. Robusta coffee beans usually contain double the caffeine of their superior counterparts, but the more you roast these beans, the more caffeine they lose and the harsher they taste.

Since the actual coffee beans that diners use are poor quality, it wouldn't necessarily be fixed by simply brewing a more potent pot. Since diners aren't paying for quality beans from roasters, customers are not paying for a premium drink.

Instead, the cheaply sourced coffee beans are typically roasted at too-high temperatures in order to make brews that are more uniform, but this negatively affects the flavor. The roasting temperature of coffee beans shouldn't exceed 465 degrees. However, certain roasters want to speed up the process by using higher heat for a shorter amount of time, resulting in that burnt, bitter flavor profile that's all too common in cheap diner coffees.

With so many people ordering coffee at diners, it seems peculiar that they don't invest in a better product or better equipment. And depending on the diner's cleaning protocol, they could be going far too long without properly washing their coffee pot or changing its filter, which can impact the taste of the brew as well. The truth about diners is that their coffee has an oddly familiar flavor that can definitely taste weird, but is the nostalgic cup of comfort we've grown to know and love.