Giesen Webinar
Roasting a light roast (Willem Boot)
- Light Roast
- flaws: brazilian, can be peanut; kenya, sour unripe green tomato
- flaws: sumatra malty earthy; panama thin and no flavor
- steps for roasting light:
- Green progress: grass, [DE] hay, bread, [MLRD], coffee, FC (steam) [DEVEL]
- Drying Phase: lose green, moisture loss at 100 ‘C, starts drying phase
- Dry End: lost green, expansion, browning starts
- Maillard/Browning; brown evens out
- SCA color scale more popular than Agtron.
- Timings: 3:10/272F grass, 4:30/300F Hay, 7:00/327F Bread,
- Timings contd: “A point” 9:00/365F pre-FC (first Aromatics); 9:45/375F FCs, 10:35/381F FCe, Drop.
- slow vs. fast roast: slow, control burner; More air is faster; RPM high is faster;
- Giesen default 55 rpm. Slow down will devel slower (less convection heat)
- batch charge is 50% is faster (too much heat for bean mass in drum)
- timing/settings different on large/small models.
- longer roast, could stall/bake roast.
- HIGH ROR ROR low (2) can devel slowly, vs. high (20) risk baking beans
- Devel time: FC -> Drop.
- FC usually at specific temperature (per machine/bean), good reference point.
- Devel flavor specific to % Devel and bean;
- NOTE ROR lower prior to FCs to avoid pyrolysis (self heating)
- faster roast can have high variance of flavor/colors, slower is better.
- Light #1: DTR: 33/40/35 over 8:30; Not Good: grain/earthy/wet wood
- Light #2: DTR: 40/38/22 over 8:30; Better: fruit/citrus/grain/wood
- Light #3: DTR: 43/42/16 over 10:35; Best; fruit/citrus/orange/floral
- Longer can be light, with good ROR control.
- NOTE Reduce Charge temp, dont race into FC
- NOTE Reduce heating levels until FCs lower levels for smaller batches.
- Follow same milestones. Devel 1-2.5 minutes; Control Devel after FCs.
- NOTE Reduce heat way before FCs not during
- Adjust heat levels per batch weight (smaller heat for smaller batches)
Troubleshooting Roasting Profiles
- https://www.youtube.com/watch?v=xmiNl_JTZiw
- Profile: how coffee is roasted: for consistency, control, quality, keep/share info.
- Plan vs. Actual. Profile curve from software (graph from Artisan)
- Before Roasting: Ambient temp, Humidity, Batch#, Examine Defects, Bean Moisture, Color
- Bean quality: Defects, Moisture, Color (new=green, old=gray/cinnamon)
- NOTE SCA Form is standard for Green Coffee Eval. use this or similar
- During Roasting: Track temps, color, FC, SC, Heat/Air events
- Various Machines might show FC, SC temps different (probs, air, varience)
- Heat Soak 10% 1 min, then 70% 5 mins, 35% 2 mins, 20% through FC, SC (no change during FC)
- Heat Soak 0% 1 min, then 20% 1 min, 35% (get ROR=20F)
- NOTE have good way to smell roasting (sniff top hopper? or vent?)
- Sniff/Smell for Aroma “A” Point just before 1st crack.
- Flick/Crash: At FC, bump up Temp, then crash. (lower temp just before FC to avoid)
- Beware of chasing Crash with Recovery spike (from overcompensated bump in temp)
- Baked Example: flat ROR, 12:30 mins;
- Scorched: dark spots, burned on metal drum. char flavors. (low density scorch easily)
- Tipped, cracks on ends. biscuit/cereal or skunk flavor. lower RPM.
- Chipped, too much heat, expand too fast, piece blown off. lower heat.
- Baked, light, dull or no flavor.
- Uneven Moisture; too much heat, uneven drying. soft beans can expand too fast.
- Over developed, over roasted (dark shiny), burnt (oily)
- Maillard (BRN): lower temp, longer roast, too long (7-9 mins) makes bitter, reduces sugars
- Carmelizaation (DEVEL): higher temp. less time before/after FC, sugars, too short makes sour,
- Structural Changes: Mass lost (13-22%) Volume Increase (30-100%)
- Change Density green beans 500-700 g/L to roasted 350-450 g/L (most drastic in Dark, fast roasted coffee)
- Acids break down (citric, malik, lactic, acetic, quinic)