getting a really bitter, burnt taste in every shot even with fresh beans and clean machine.

Diagnosis

The bitter, burnt taste in the Breville Oracle Jet BES750BSS is typically caused by "over-extraction," where the water temperature exceeds the ideal range for the specific coffee bean, causing the organic compounds to burn rather than dissolve. In the Oracle Jet, this is often a result of the ThermoJet heating system delivering water that is too hot for medium or dark roasts, or a buildup of thermal mass in the group head that scorches the coffee puck during the initial contact. Because the Oracle Jet uses a high-speed heating element, the water can sometimes overshoot the target temperature if the machine has been idling for a long period. If you are seeing a very fast flow rate combined with this burnt taste, you are likely experiencing "channeling" where hot water blasts through a hole in the puck, over-extracting that specific area. However, if the flow is steady but the taste is acrid, the PID (Proportional-Integral-Derivative) controller is simply set too high for your specific roast profile.

How to Fix It

To eliminate the burnt taste, you must calibrate the brew temperature and manage the thermal energy of the group head. Follow these exact steps:

1. Access the Temperature Menu: Press the "Settings" button on the display. Navigate using the dial to "Brew Temperature."
2. Lower the Set Point: The default is usually set to a medium level. Rotate the dial to decrease the temperature by 2°C (approximately 4°F). For dark roasts, you may need to drop it by as much as 4-6°C to avoid the "burnt" profile. Save the setting and exit the menu.
3. Perform a Thermal Flush: Before locking in the portafilter, press the "1 Cup" button to run a 3-second burst of water through the group head. This clears out any stagnant, super-heated water sitting in the shower screen and stabilizes the temperature.
4. Adjust Grind Size: If the taste persists, move the grind adjustment dial one notch coarser. A grind that is too fine increases the contact time between the water and the coffee, leading to over-extraction and bitterness.
5. Verify Dose: Ensure you are using the provided dosing disk to get a precise 18g-20g dose. Overfilling the basket can cause the coffee to press against the shower screen, creating "hot spots" that burn the top layer of the puck.

If That Didn't Work

• Switch Your Beans: If you are using a "Dark Roast" or "Italian Roast," these beans are more porous and extract much faster. Try a "Medium Roast" or a "Light Roast" bean. If the burnt taste disappears with lighter beans, your temperature settings were simply too aggressive for the oily, dark-roasted beans.
• Check Water Hardness: High mineral content in your water can alter the extraction chemistry, making coffee taste more bitter. Replace the charcoal water filter in the reservoir and consider using a filtered pitchers (like Brita) to reduce the TDS (Total Dissolved Solids) in your brew water.
• Inspect the Shower Screen: Remove the screw holding the shower screen in place. If there is a layer of carbonized coffee oils trapped behind the screen, it will impart a burnt taste regardless of your temperature settings. Scrub the screen with a stiff brush and espresso cleaner (like Cafiza).
• Recalibrate the Tamp: Ensure the automatic tamping mechanism is applying even pressure. If the puck is slanted, water will flow unevenly, causing some areas to be under-extracted and others to be severely over-extracted (burnt). Check that the portafilter is seated perfectly flush before starting the cycle.

Heads Up

• Purge After Steaming: Always run the steam wand for 1 second after frothing milk to clear out residue; failing to do so can sometimes affect the internal temperature stability of the ThermoJet system.
• Avoid "Idling": If the machine has been on for over 30 minutes without a shot, always perform a longer flush (5-10 seconds) to clear out the heat-soaked water in the group head.
• Bean Storage: Store your beans in an airtight, opaque container. Beans that have gone rancid often taste "burnt" or "chemical," which can be mistaken for a temperature issue.
• Cleaning Cycle: Run the official cleaning cycle with the Breville cleaning tablet every 200 shots to prevent oil buildup in the three-way solenoid valve.