Has Bean Coffee

Bolivia: Las Alasitas, Yellow Caturra

bolivia medium roast anaerobic_washed yellow_caturra

Standard washed processing on a Bolivian Caturra produces a familiar result — clean terroir expression, moderate acidity, quiet fermentation character. Anaerobic washed processing produces something chemically distinct, and the difference starts in the tank before any heat is applied. In [anaerobic processing](/blog/coffee-processing-methods-explained), depulped beans ferment in sealed, oxygen-depleted tanks before washing. Without oxygen, the microbial population shifts toward lactic acid bacteria and organisms that generate volatile esters — ethyl butyrate, ethyl acetate, and similar compounds — that standard open-air or aerobic fermentation doesn't produce at meaningful concentrations. These esters are the source of the fruit-forward, sometimes wine-like character that distinguishes anaerobic lots. They're chemically different from standard fermentation byproducts, not just amplified versions of ordinary washed coffee notes. The wash step after fermentation removes the mucilage, but the volatile compounds absorbed into the bean during sealed fermentation remain. This is why anaerobic washed sits between washed clarity and natural fruit intensity — the fermentation character is locked in, but without the additional body and mucilage sugars that honey or natural processing would contribute. Yellow Caturra is a color mutation of Caturra — same genetic lineage as standard Caturra, same Bourbon-group roasting behavior (higher density, slower path to first crack). Medium roast calibrates the development carefully: the fermentation-derived volatile esters are thermally fragile and among the first compounds lost to extended heat. Pulling at medium preserves them while giving enough Maillard development to build the body structure that lets those esters express rather than getting lost in a thin, underdeveloped cup. At 1,642 meters — the lower end of Bolivia's typical altitude range — soluble concentration is slightly below the batch median, which medium development largely compensates for.

Chemex 6-Cup 89/100

Grind: 555μm Temp: 90°C Ratio: 1:15.5-1:16.5 Time: 3:30-4:30

Chemex tops the rankings for this Bolivian anaerobic washed Yellow Caturra because the processing chemistry and the filter architecture align precisely. Sealed fermentation produces volatile esters distinct from standard open-air fermentation. What the Chemex adds is selective expression: its 20-30% thicker paper filter strips oils completely, leaving only water-soluble compounds in the cup. For an anaerobic washed coffee that already has clean cup character from the wash step, Chemex amplifies the clarity further, delivering the ester character — whatever wine-like or fruit complexity the sealed fermentation produced — without interference from bean oils. The 90°C temperature is 4°C below standard, adjusted equally for medium roast (-2°C) and anaerobic processing (-2.5°C). At 555μm, the grind is slightly coarser than default rather than finer — medium roast increases solubility compared to light, and the Caturra variety's Bourbon-group density is offset by the processing characteristics that slow flow slightly.

Troubleshooting

thin: Add 1g dose or reduce water 15g. At 1:16 ratio for a medium-roast Chemex, body should be adequate, but anaerobic washed coffees can read thin if the fermentation ester character doesn't register as weight. Concentrate slightly toward 1:15.5; alternatively a metal filter passes oils that contribute body.

sour: Grind 22μm finer and raise temp 1°C. Medium-roast Bolivian Caturra at 90°C is at the lower end of extraction efficiency — if sour, the anaerobic fermentation acids are dominating. Yellow Caturra's Bourbon-group density means it needs more surface area than lighter cultivars to extract evenly.

Hario V60-02 88/100

Grind: 505μm Temp: 90°C Ratio: 1:15.5-1:16.5 Time: 2:30-3:30

The V60 at 88/100 is 1 point below Chemex for this anaerobic washed Bolivian, but the extraction logic differs in one key dimension: the standard V60 paper filter is thinner than Chemex, passing slightly more dissolved oils and contributing marginally more body. For an anaerobic washed coffee at medium roast — where oils carry some Maillard body development from longer roasting — this is actually useful. The Yellow Caturra variety at 1,642m builds adequate density for good body at medium roast; the V60's filter passes enough oil to express that character. Temperature at 90°C and grind at 505μm both reflect the combined effects of the medium roast and anaerobic processing. The coarser grind compared to light-roast parameters is expected: medium roasting increases solubility by degrading more CGAs, meaning you need less surface area exposed. The 2:30-3:30 window suits medium-roast Caturra well — enough contact time for full Maillard compound extraction without over-extracting the anaerobic aromatics.

Troubleshooting

sour: Grind 22μm finer and raise temp 1°C. Anaerobic washed coffees can have elevated acidity from the sealed fermentation's lactic acid bacteria — if the V60 reads sour, you're in the CGA-plus-fermentation acid zone. Slow the pour to extend contact time; Yellow Caturra's density responds well to longer dwell.

flat: Grind 22μm finer and raise temp 2°C. Flat V60 from anaerobic washed Bolivian at 90°C usually means the fermentation esters didn't fully extract — they're volatile but still need adequate temperature. Check water mineral content; if below 50 ppm total dissolved solids, mineral deficiency limits extraction.

Kalita Wave 185 87/100

Grind: 535μm Temp: 90°C Ratio: 1:16.5-1:17.5 Time: 3:00-4:00

The Kalita Wave at 87/100 matches AeroPress and Clever Dripper here, but for different reasons. The Wave's flat-bottom geometry enforces the most uniform extraction in the pour-over category, and for a Bolivian anaerobic washed at medium roast, uniformity matters: the anaerobic fermentation esters are distributed unevenly through the bean depending on where volatile compound absorption occurred during sealed fermentation. Uniform extraction maximizes the probability of pulling those compounds proportionally rather than over-extracting some particles while under-extracting others. The 535μm grind is 5μm coarser than default to suit this bean's processing characteristics, and at 90°C, the medium-roast Caturra extraction is efficient enough that the slightly coarser grind still reaches the Maillard compound register within the 3:00-4:00 window. Yellow Caturra, as a color variant of Caturra with identical Bourbon-group genetics, roasts with the same density characteristics — meaning the Wave's flat-bed consistency is especially appropriate.

Troubleshooting

sour: Grind 22μm finer and raise temp 1°C. The Kalita's flat bed gives you a reliable diagnostic: if still sour with uniform extraction, the issue is systematic underextraction of the dense Caturra at 90°C. Both adjustments compound — apply together rather than sequentially for this Yellow Caturra's Bolivian altitude density.

flat: Grind 22μm finer and raise temp 2°C. Flat Kalita Wave from this Bolivian anaerobic usually means the fermentation ester compounds didn't extract at 90°C. Check water TDS — soft water under 50 ppm particularly limits ester extraction. The magnesium ions that preferentially extract desirable acids are simply absent.

AeroPress 87/100

Grind: 405μm Temp: 81°C Ratio: 1:12.5-1:13.5 Time: 1:00-2:00

The AeroPress at 87/100 and 81°C has the lowest temperature of any brewer for this coffee — 10°C below the next coldest. That low temperature is intentional: the AeroPress base temperature is already below boiling, and the adjustments for medium roast (-2°C) and anaerobic processing (-2.5°C) bring it down further. This matters for the Yellow Caturra anaerobic washed profile: at 81°C with pressure assist, you get concentrated extraction that pulls Maillard body and fermentation esters without the temperature-driven degradation of the volatile compounds that sealed fermentation produced. This is the sweet spot the AeroPress uniquely provides — pressure substitutes for some temperature, allowing lower-temp extraction at higher concentration. The 405μm grind at medium roast is coarser than light-roast AeroPress parameters, reflecting the higher solubility. Short 1-2 minute brew time limits thermal exposure of the anaerobic esters.

Troubleshooting

bitter: Grind 22μm coarser and lower temp 1°C. AeroPress at 81°C with pressure on a medium Bolivian Caturra — if bitter, you're extracting the dry distillates via pressure despite the low temperature. Coarser grind reduces surface area, limiting how much the pressure can pull. Consider slowing the plunge to 30+ seconds.

flat: Grind 22μm finer and raise temp 2°C to 83°C. The 81°C starting point for AeroPress is low enough that flat usually means underextraction. The anaerobic fermentation esters need adequate temperature to dissolve even under pressure. Check bean freshness — stale beans degas CO2 and the flavor compounds degrade together.

Clever Dripper 87/100

Grind: 535μm Temp: 90°C Ratio: 1:15.5-1:16.5 Time: 3:00-4:00

The Clever Dripper's 87/100 score ties AeroPress and Kalita for this anaerobic washed Bolivian, and the mechanism is different again from those brewers. The immersion phase at 90°C ensures full, even wetting of the Yellow Caturra particles before gravity takes over — important because anaerobic washed coffees can have slightly irregular density distribution compared to standard washed lots (the sealed fermentation process can affect extraction characteristics). Full submersion eliminates the dry-core extraction problem that can occur with coarser grinds in percolation methods. At 535μm, this is the same grind size as the Kalita Wave, but the Clever's immersion ensures 100% particle contact whereas the Wave relies on percolation wetting. The paper filter on drain removes oils cleanly. The 3:00-4:00 steep window gives the medium-roast Caturra adequate time to fully release its Maillard body compounds at the reduced 90°C temperature.

Troubleshooting

bitter: Grind 22μm coarser and lower temp 1°C. Clever Dripper bitterness usually means the immersion is over-extracting the medium Caturra's Maillard compounds. Shorten steep to 3 minutes before draining — the valve control gives you this option. Yellow Caturra's Bourbon-group density can over-extract in full immersion at long steep times.

flat: Grind 22μm finer and raise temp 2°C. Flat Clever from this Bolivian anaerobic means the fermentation esters haven't extracted through the sealed-fermentation cell structure. Extend steep time to full 4 minutes and check water mineral content — the Clever's immersion amplifies soft-water extraction deficits.

Espresso 74/100

Grind: 255μm Temp: 89°C Ratio: 1:1.5-1:2.5 Time: 0:25-0:30

This Bolivian anaerobic washed Yellow Caturra at 74/100 performs better as espresso than many lighter roasts. Medium roasting has developed more Maillard body and degraded more CGAs, which means extraction under pressure has a broader sweet spot with less risk of sharp sour shots. The 89°C temperature — 4°C below standard espresso — accounts for medium roast's increased solubility (-2°C) combined with anaerobic processing's fragile volatiles (-2.5°C). The 255μm grind is only 5μm coarser than default, reflecting medium roast's higher solubility offset against the slight density of Yellow Caturra's Bourbon lineage. The 1:1.5-2.5 ratio range is tighter than lighter roasts, allowing shorter shots — the anaerobic volatile esters concentrate well at lower dilution without the CGA-extraction penalty that would make a light roast sour at the same ratio. Bolivia's altitude (1,642m) built enough acid complexity to make this espresso interesting as a straight shot or as a milk-based drink base.

Troubleshooting

sour: Grind 10μm finer and raise temp 1°C. The anaerobic fermentation acidity in a Bolivian washed lot concentrates distinctly under pressure — lactic acid bacteria produce cleaner acids than natural fermentation, but they still need adequate extraction to balance with Maillard sweetness. Extend ratio toward 1:2.5.

bitter: Grind 10μm coarser and lower temp 1°C. Yellow Caturra's Bourbon-group genetics mean it extracts heavily once the CGA barrier clears — bitterness signals you've pushed past the Maillard sweet zone into dry distillates. Tighten the ratio toward 1:1.5 as an alternative if temp and grind adjustments feel risky.

Moka Pot 65/100

Grind: 355μm Temp: 96°C Ratio: 1:9.5-1:10.5 Time: 4:00-5:00

The moka pot's 65/100 score for this Bolivian anaerobic washed reflects medium roasting's advantage for this brewer. Medium development means more Maillard compounds are accessible without requiring extreme extraction pressure — the moka pot's ~1.5 bar can reach a reasonable portion of the flavor register. The metal filter passes oils, which for an anaerobic washed coffee adds Maillard body from the medium roast. At 355μm — medium-fine rather than the coarser espresso grind — the moka pot gets enough surface area exposure in the 4-5 minute brew. The recipe temperature at 96°C is notably higher than the other brewers at 90°C; the moka pot's higher-pressure brewing base absorbs the anaerobic processing adjustment differently. Start with pre-boiled water to prevent steam from slow-cooking the Caturra grounds before pressure builds.

Troubleshooting

strong: Reduce dose 1g or add 15g water. The medium-roast Bolivian Caturra extracts efficiently at moka pot pressure — more so than a light roast. The metal filter passes body-contributing oils further increasing TDS. Dilute before adjusting grind; moka pot grind changes have larger effects than for pour-overs.

sour: Grind 22μm finer and ensure water is pre-boiled at full heat. Sour from a medium Bolivian in a moka pot means the anaerobic fermentation acids are dominating — this is relatively unusual at medium roast and usually indicates either too-coarse grind or insufficient water temperature. Check that steam isn't building before water hits proper brew temp.

French Press 63/100

Grind: 1005μm Temp: 92°C Ratio: 1:14.5-1:15.5 Time: 4:00-8:00

French press at 63/100 for this anaerobic washed Bolivian works well because medium roasting provides the body structure this brewer needs. Yellow Caturra at medium roast has developed body through the Maillard reaction — the fermentation esters don't need to carry the cup alone. Metal mesh on a washed medium-roast coffee passes oils that contribute a clean body rather than competing with fruit clarity (as in natural-process coffees). At 1,005μm — the coarsest grind in this bean's recipe set — the full immersion ensures adequate extraction at 92°C over the 4-8 minute steep window. The anaerobic fermentation character from sealed fermentation provides distinct complexity in French press: the body of metal filtration plus the ester complexity of anaerobic processing creates an interesting contrast with the clean Bolivian terroir underneath. Post-pressing rest of 5-8 minutes allows fines to settle for a cleaner cup.

Troubleshooting

strong: Reduce dose 1g or add 15g water. Medium-roast Bolivian Caturra in full immersion extracts body compounds efficiently — the metal mesh passes oils that add further weight. If the anaerobic fermentation character reads as heavy or fermented-forward rather than complex, dilute before extending or shortening steep time.

bitter: Grind 22μm coarser and lower temp 1°C. French press bitterness from this Bolivian usually means over-extraction during the long steep — the Caturra's Bourbon-group genetics extract heavily once past the CGA zone. Reduce steep to 4 minutes and pour immediately; every additional minute after pressing extracts more bitter dry distillates.

Cold Brew 61/100

Grind: 905μm Temp: 0°C Ratio: 1:6.5-1:7.5 Time: 720:00-1080:00

Cold brew at 61/100 benefits from medium roasting's improved cold-extraction compatibility compared to lighter roasts. The anaerobic volatile esters are thermally fragile, and cold extraction actually preserves them. Cold water's reduced solubility of bitter Maillard compounds and CGAs shifts the extraction profile toward the compounds that anaerobic fermentation produced in the sealed tank: the esters that extract at moderate polarity, which cold water accesses more readily than the high-molecular-weight Maillard products that require heat. The result is a cold brew that foregrounds the fermentation complexity of the anaerobic processing — potentially wine-like, fruity, and clean — rather than the roast character. At 905μm and 12-18 hours, this is a reasonable slow-extraction profile. The 61/100 score reflects the mismatch between what cold brew emphasizes (smooth, lower-acid, fermentation-forward) and what Bolivian terroir typically delivers (structured, clean, terroir-expressive), not a fundamental incompatibility.

Troubleshooting

flat: Grind 22μm finer and check water mineral content. Flat cold brew from this Bolivian anaerobic usually means two things: mineral-deficient water limiting ester extraction, or grounds that are past peak freshness. The anaerobic fermentation character is the main event in cold brew — stale beans lose it first. Use within 4 weeks of roast date.