Troubleshooting Weak brew - Check your grind. It may need to be finer or the brewing temperature of the water may be too low. In espresso coffee, the pump pressure in the machine and the amount of force used when tamping the coffee may be too little. Often people who have been drinking coffee for several years will develop their palate to a point where a darker roast will be more satisfying. Bitter taste - Again, check your grind.
Bitterness is often the result of too fine a grind.
Espresso coffees which have been extracted for more than 18-22 seconds will also take on a bitter taste. Never re-use the spent grounds. In contrast to OCR's arabica coffees, robusta coffees naturally have a harsher taste. A quality cup requires a quality coffee. Burnt taste - Brewed coffee sitting on a burner starts to losing flavor after about 15 minutes.