No other sense is as important in determining roast level as the flavor. The problem is that you can’t brew your coffee until it’s done roasting. Some folks can actually tell quite a bit about roast level by crunching a roasted bean between their teeth and eating it, but the most important information about your roast results must be tasted by brewing your coffee. Rest your coffee for 24-48 hours after roasting before making any judgment about your roast level. If you are really curious and can’t wait, you should be able to roughly assess the roast level by brewing and tasting your roasts once the beans cooled. Again, the coffee will not be as enjoyable directly after roasting, so please be patient.
City and City+ roasts generally have brighter and more acidic characteristics. They should be sweet and if you detect grassy or astringent notes, you’ve roasted too light. The body or mouthfeel should be light, and if the coffee has any fruit-like characteristics they will be most evident at these roast levels. Often times, roasts that are this light benefit from longer resting times after roasting. Try your light roasts after 1 day and 3 days and compare the differences. Jot down a few of your impressions when you first taste a roast, then brew it again after another day or two and see how the flavors may have changed or “opened” up. Similar to letting wine breath, coffee needs to rest to taste great.
Full City and Full City+ roasts have more balanced and chocolatey characteristics. They should still be sweet but will have a nice bittersweet compliment. If they just taste bitter you may have roasted too dark. The body or mouthfeel will be more substantial, and if the coffee has fruit-like characteristics they may be a bit more. When you make tasting notes on your darker roasts, take note of the balance of sweet and bittersweet.
Light Vienna, Vienna, and French roasts mostly have a “roasty” character. Most of the sweetness will be gone and bittersweet flavors will dominate (this is why people often roast to these levels when they intend to add milk and sugar to their brewed coffee). These roast levels are really only suited for espresso and should not be the goal for most home roasters. Even if you do drink Espresso exclusively we encourage you to try Full City+ roasts for your espresso. We find them to be so much more enjoyable, with sweetness and fruit flavors that are obliterated in darker roasts. If you want dark, bitter, carbony tasting coffee to dump milk and sugar into then these roast levels might be for you. Don’t worry, we won’t tell the hard working farmers what you did to their coffee beans.