Brand D · Batch BL-02
ClosedInvestigation into Burnt.
Problem statement
Brand D BL-02. Major defect: Burnt flagged by 2 panelists.
How we investigated
Triggers that opened this investigation
- [HIGH] Major defect Burnt flagged by 2 panelists
Data reviewed
Defects by impact
| Defect | Weighted variation | Panelist agreement |
|---|---|---|
| Burnt | 20.0 | 2 panelists |
Information gathered (9)
Method
- SkippedTrial lowering the amount of any roasted malts, 1-2% can impart significant colour contributionAddresses: Burnt, Scorched
Skipped: Not a recipe issue
- SkippedTrial moving to kilned malts instead of roasted malts, they may impart similar mallard flavours but less burnt or harsh astringencyAddresses: Burnt, Scorched
Skipped: Not a recipe issue
- ClearedAvoid scorching in the kettle; ensure heating surface area is fully covered with wort before fully applying steam/direct fire, without wort to absorb the heat the surface will quickly heat past desired levels and scorch incoming wort.Addresses: Burnt, Scorched
Calandria steam rates monitored on next batch fill, all good!
- ClearedReduce "hot time", the time the beer is above 80 degrees C, this is important for many reasons but this is especially true when having issues with burnt off-flavoursAddresses: Burnt, Scorched
Hot time was in spec
Material
- Issue foundIf using black malts trial using huskless black malts like black prinz as they impart less astringency and burnt flavoursAddresses: Burnt, Scorched
See above, malt gate was put in manual and black malt may have been added in excess
Machine
- ClearedCheck vessel cleanliness between brews and after CIPs, ensuring the surfaces especially the heating surface is clear of mineral and organic buildup. Mineral buildup like calcium can significantly reduce the heating efficiency of a calandria or a wort cooler, this can cause poor heat transfer and organic buildup. Peroxide and acid wash routines are commonly needed to maintain a efficient and clean brewhouse heating and cooling systems.Addresses: Burnt, Scorched
Vessels have not been CIP'd yet but the Kettle and mash cooker were looking great.
- ClearedCheck agitation in the mash vessels, insufficient heat transfer without proper agitation can cause scorchingAddresses: Burnt, Scorched
Encoder reading the correct speed, verified with stopwatch, no isues
- SkippedCIPs, ensuring the surfaces especially the heating surface is clear of mineral and organic buildup. Mineral buildup like calcium can significantly reduce the heating efficiency of a calandria or a wort cooler, this can cause poor heat transfer and organic buildup. Peroxide and acid wash routines are commonly needed to maintain a efficient and clean heating and cooling systems.Addresses: Burnt, Scorched
Skipped: Vessls look great!
Man
- Issue foundInterview the brewer on shift and read the brew report: Were there any off sights or smells? Was anything put in manual for that brew? Were we running low on any specific malts or needed to make substitutions?Addresses: Burnt, Scorched
Terry was interviewed on shift, it was his first shift running Black lager and preparing the ingredients. All Malts were in stock but the grain gate was not opening as there was a potential air leak. The gate was opened manually while the black malt was added. Because it was placed in manual the weight moved to 2 row after the target black malt was entered, so an unknown amount of black malt was added.
Root causes confirmed (4)
- Man
Air line pressure faulted as there was work on the line up stream, Mechanic was never trained to review maintenance plans with operator on shift.
- Material
The gate was put in manual causing the malt value to be uinknown.
- Method
Brewer on shift was unaware of maintenance being completed
- Machine
There is no way to reset the machine once it faults causing the weights to be guessed.
5-Why chain walks
The full reasoning trail behind the root causes confirmed above.
Why 1? Why did Brand D · BL-02 score a 6.99?
→ Burnt was the major defect detected.
Why 2? Why did Brand D · BL-02 score a 6.99?
→ Excessive Burnt notes were detected on the batch
Why 3? Why is it that excessive burnt notes developed in this batch — were there any unusual observations during the brew, such as off smells, manual overrides to equipment, or any malt substitutions noted in the brew report?
→ Malt gate was placed in manual as it would not open, and too much of the black malt may have been added
Why 4? Why is it that the malt gate would not open — was there a mechanical fault, a control system error, or had there been any prior maintenance or calibration work carried out on that gate before the brew?
→ The air line was faulting out which threw the PLC out of loop, needing the gate to me put in manual.
Why 5? Why is it that the air line was faulting out — had there been any prior issues reported with that air line, was there a pressure drop or blockage, or had any recent work been done on that part of the pneumatic system before this brew?
→ Air line pressure faulted as there was work on the line up stream, Mechanic was never trained to review maintenance plans with operator on shift.
Root cause
Air line pressure faulted as there was work on the line up stream, Mechanic was never trained to review maintenance plans with operator on shift.
Why 1? Why did Brand D · BL-02 score a 6.99?
→ Burnt was the major defect detected.
Why 2? Why did Brand D · BL-02 score a 6.99?
→ Excess bitter notes were detected on the batch
Why 3? Why is it that the batch developed excess bitter notes — for instance, what types of dark malts were used, and could any of them be contributing pyrroles or pyrazines associated with burnt or astringent flavours?
→ Excess Black malt was added to the batch
Why 4? Why is it that excess Black malt was added to this batch — for instance, was this a weighing error, a recipe formulation issue, or something else in the milling or grist preparation process?
→ The gate was put in manual causing the malt value to be uinknown.
Root cause
The gate was put in manual causing the malt value to be uinknown.
Why 1? Why is the Method-side contributing to this defect?
→ Excess burnt notes were on this batch
Why 2? Why is it that this batch ended up with excess burnt notes — for example, was anything different about your roasted malt quantities, your heating process, or how long the wort spent at high temperatures?
→ The gate for the malt bin was faulted and put in manual, causing the black malty to be added in excess
Why 3? Why is it that the gate fault wasn't caught before the excess black malt made it into the batch — for example, were there checks or alerts in place that should have flagged the manual override or the quantity being added?
→ The maintenance up stream cause the air system to fault out. There was no process to loop in the brewer on shift
Why 4? Why is it that no process existed to loop in the brewer on shift when upstream maintenance caused a system fault — for example, was this a gap in your maintenance communication protocols, shift handover procedures, or something else?
→ Brewer on shift was unaware of maintenance being completed
Root cause
Brewer on shift was unaware of maintenance being completed
Why 1? Why is the Machine-side contributing to this defect?
→ Excess burnt notes were detected on the batch
Why 2? Why is it that excess burnt notes developed during this batch — what was observed about the condition of the heating surfaces or vessel cleanliness going into this brew?
→ There was excess black malt added to the batch
Why 3? Why is it that excess black malt ended up in this batch — what happened at the point of weighing, recipe selection, or ingredient handling that led to the higher addition?
→ The gate faulted staying open while grinding the black malt
Why 4? Why is it that the gate faulted and stayed open during the black malt grind — what do you know about the condition or maintenance history of that gate mechanism leading up to this batch?
→ The work on the air system faulted out the system as the air was turned off upstream causing the PLC to fault
Why 5? Why is it that the upstream air was turned off during an active grind — what do you know about how that air system work was scheduled, communicated, or isolated relative to the brewing operation that was running at the time?
→ There is no way to reset the machine once it faults causing the weights to be guessed.
Root cause
There is no way to reset the machine once it faults causing the weights to be guessed.
Corrective actions (4)
Man
- Effect Blocking@Gerry LCheck 2026-09-16
Maintenance team to be trained to review all work PMs with brewers on shift for effected areas.
Material
- Effect Blocking@Jeff TCheck 2026-09-16
Review Material consumed by batch to see financial impat
Method
- Root Cause@Gerry LCheck 2026-09-16
Add Maintenance standup in the morning for PM work effecting equipment. To ensure there are no production impacts to work being done
Machine
- Root Cause@Gerry LCheck 2026-09-16
Add a reset if the gate faults out so the load cell values are saved when the gate faults out.