Roastiness is one of the three basic properties of coffee commonly checked by coffee tasters in coffee production. The other two are acidity and coffeeness.
Roastiness refers to the degree of roasting applied on the coffee beans. If you call a coffee ‘roasty’ you’re saying it has a bittersweet or smoky taste that it gets from being roasted. Too much roastiness tastes burnt.
Roasting is a critical part of coffee processing as it develops and brings out the full flavour and aroma of the bean. Proper roasting requires the right temperature and the right length of roasting time. Different varieties of beans also involve different levels of roasting.
For instance, Arabica beans should not be roasted too dark in order to preserve the original characteristics of the beans. On the other hand, increasing the roast would increase the bitterness. Roasting the coffee too dark would make the coffee too bitter.