Topic hub — 2026-09-19
Cacao bitterness and astringency
Cacao bitterness is usually described on a single scale: the higher the cacao percentage, the more bitter. The measurements collected on this page show that scale breaking several times along the way. Fermentation raised bitterness at some facilities and lowered it at others. Roasting lowered perceived bitterness as the temperature went up. Raising the fat content lowered perceived bitterness without changing the compounds. And the relation between cacao percentage and bitterness itself held for blended beans but not for single-origin ones. Here the sample, the compounds, the process and the formulation are kept apart, and only the confirmed claims are laid side by side.
On this page (8 sections)
What this page establishes
- No single compound carries cacao bitterness and astringency. Alongside theobromine and caffeine, epicatechin and procyanidins are identified as bitter contributors, and N-phenylpropenoyl amino acid amides as astringent ones.
- Fermentation does not move bitterness in one direction. Comparing three facilities in Colombia, bitterness and astringency rose at two and fell at one.
- Roasting lowers perceived bitterness as temperature rises: a one standard deviation (42 degC) increase in roasting temperature corresponds to a drop of 1.56 gLMS units from a mean bitterness of 26.9.
- The relation "higher cacao percentage, more bitter" held for blended chocolates but was not clear for single-origin ones.
- Formulation moves bitterness too. Raising total fat from 30% to 40% lowered perceived bitterness, and in cocoa beverages sucrose concentration changed it. Yet the difference between 0.1% and 4.5% fat did not affect bitterness in the beverage.
Which sample are we looking at
The first thing to separate when reading cacao bitterness is what is actually in the mouth. Roasted nibs, cocoa powder, solid chocolate, a cocoa beverage, and an infusion of the bean's shell are all called "cacao," but the object being measured differs in each case.
The shell (husk) is the skin separated from the nib, distinguished from the pod that encloses the whole fruit. Infusing it as a drink has been tested in recent years, and it is treated as a separate sample on this page.
Scope: In this entry, husk refers to the bean shell.
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ingredient-cocoa-bean-shell —is_defined_in_context_as→ "The shell separated from cocoa-bean nibs. It is distinguished from the husk of the entire fruit."Nor do the sensory descriptors recorded at one processing stage necessarily carry through to the finished product. The process-side claim states explicitly that retention of the same characteristic attributes in the final chocolate is not guaranteed. That is why the process measurements and the finished-product measurements are kept in separate sections here.
Scope: Fine-flavor cacao literature reviewed through May 2023
Note: The fermentation, roasting, liquor, and chocolate stages should be modeled separately.
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ingredient-roasted-cocoa-nibs —does_not_guarantee_retention_of→ "The same characteristic sensory attributes in the final chocolate"What carries the bitterness and the astringency
The compounds named as the main carriers of bitterness in roasted nibs are two methylxanthines, theobromine and caffeine.
Scope: Water-based reconstruction of roasted cacao nibs and human omission testing
Note: Specific to the roasted-nib material studied and the water-based model.
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ingredient-roasted-cocoa-nibs —has_key_bitter_organoleptics→ "Theobromine and caffeine"They are not the only ones. For the same sample, epicatechin, catechin, procyanidin B-2, B-5, C-1 and higher procyanidins are identified as contributing to both bitterness and astringency. This is why the two are kept on separate axes rather than merged into one.
Scope: Roasted cacao nibs, sensory-guided fractionation
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ingredient-roasted-cocoa-nibs —has_bitter_and_astringent_contributors→ "In addition to theobromine and caffeine: epicatechin, catechin, procyanidin B-2, procyanidin B-5, procyanidin C-1, [epicatechin-(4beta->8)]3-epicatechin, and [epicatechin-(4beta->8)]4-epicatechin"A different group of compounds appears on the astringency side: N-phenylpropenoyl amino acid amides including clovamide and deoxyclovamide, and the glycopyranosides of quercetin, naringenin, luteolin and apigenin. These do not overlap with the compounds named for bitterness.
Scope: Roasted cacao nibs, taste dilution analysis and half-tongue threshold testing
Note: These compounds are reported as contributing to astringency, not bitterness. Cacao's astringency cannot be reduced to flavan-3-ols alone.
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ingredient-roasted-cocoa-nibs —has_key_astringent_compounds→ "N-phenylpropenoyl amino acid amides, including clovamide, deoxyclovamide, and (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine, along with glycopyranosides of quercetin, naringenin, luteolin, and apigenin"In cocoa powder, the compounds with a dose-over-threshold above 1 are epicatechin, epigallocatechin gallate, luteolin, protocatechuic acid, theobromine and caffeine. The amount detected and the amount that contributes to perception are not the same thing; this index is an attempt to bridge that gap.
Scope: Cocoa powder before and after microwave-assisted alkalization
Note: Methylxanthines appear in the same DOT set alongside 4 kinds of phenolics, and are not the sole bitterness driver in this material.
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ingredient-cocoa-powder —has_key_bitter_organoleptics→ "Epicatechin, (-)-epigallocatechin gallate, luteolin, protocatechuic acid, theobromine, caffeine (dose-over-threshold above 1)"Does processing lower the bitterness
Reading fermentation, drying, roasting and alkalization as a single arrow of falling bitterness stops matching the measurements. Each process differs in both direction and size.
Compounds do not move monotonically during fermentation. Theobromine and caffeine concentrations fell to day 5 and rose again by day 6; catechin did the opposite, rising to day 5 and falling by day 6.
Scope: 3 cacao genotypes (CCN 51, ICS 95, TCS 01), 3 temperature-controlled fermentation profiles
Note: A non-monotonic trajectory. Only 3 genotypes were tested, and temperature-controlled fermentation is a different thing from natural fermentation.
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process-cocoa-fermentation —can_change→ "Theobromine and caffeine concentrations decreased through day 5 and increased by day 6, while catechin rose through day 5 and decreased by day 6"Perception is not one-directional either. Comparing day 4 and day 7 cocoa pastes across three facilities in Colombia, bitterness and astringency rose at two (ASA and COC) and fell at one (CMI). The same operation of "fermenting longer" worked in opposite directions by place.
Scope: 3 fermentation boxes per facility, sampled on day 4 and day 7, dried, roasted, and ground paste, a trained panel of 5, a 0-10 intensity scale
Note: Because the clonal composition of the beans, fermentation quantity, turning, and drying conditions differ by facility, this is not treated as a consistent-direction effect of fermentation days alone.
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process-cocoa-fermentation —has_perceived_bitterness_affected_by→ "Comparing day 4 and day 7 at the 3 Colombian facilities, bitterness and astringency in the cacao paste increased at ASA and COC, and decreased at CMI"Drying temperature affects bitterness as well. Liquor from beans dried at 80 degC was rated more bitter and more astringent than liquor from the 60 degC side, though this remains a preliminary observation.
Scope: Nacional samples from 2 sites in Ecuador, compared without pod storage. The 60°C group also had longer fermentation.
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process-cocoa-bean-drying —was_observed_with→ "Liquor made from beans dried at 80°C was rated more bitter and astringent than the 60°C group."Roasting is the process on this page that most clearly lowers bitterness. For perceived bitterness in 100% chocolate, a one standard deviation (42 degC) higher roasting temperature corresponded to a drop of 1.56 gLMS units from a mean bitterness of 26.9.
Scope: 27 roasting treatments across 3 origins, 145 chocolate consumers, gLMS
Note: The direction is the reverse of the intuition that 「焙煎温度が高いほど苦くなる」 (in translation: "the higher the roasting temperature, the more bitter it becomes"). No p-value is given for this effect size.
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process-cocoa-roasting —reduces→ sensation-bitterIn shell infusions, however, roasting works the other way. For shells separated from beans roasted at 100 degC for 20 minutes, 120 degC for 20 minutes and 140 degC for 18 minutes, the mean bitterness rank rose across 17.4, 37.8 and 54.7. Change the sample and the direction of the same process changes too.
Scope: Trinitario cocoa beans from Jember, Indonesia. 2 g of shell infused in 150 mL of hot water for 5 minutes, unsweetened and without milk. Evaluation by 15 panelists after screening.
Note: The mean rank is not a score on an intensity scale. The table does not show individual significant differences between the 3 conditions; this is a Kruskal-Wallis analysis using evaluation data from 6 samples, including 3 black-tea samples. The 140°C condition alone had an 18-minute roasting time, so this is not a comparison of temperature alone.
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ingredient-cocoa-bean-shell —has_sensory_response→ "In infusions of the shells separated from beans roasted at 100°C for 20 minutes, 120°C for 20 minutes, and 140°C for 18 minutes, the mean bitterness ranks were 17.4, 37.8, and 54.7."Some processes exist in order to reduce bitterness. Alkalization (the Dutch process) raises pH from the acidic range of natural cocoa into the neutral-to-alkaline range, and is positioned as an important industrial step for reducing bitterness, improving solubility and developing colour.
Scope: A test applying commercial cocoa powder, with varied alkalization treatment conditions, to sponge cake
Note: A sensory-score figure for bitterness itself has not been confirmed within the range of abstracts and secondary summaries reached so far. It is shown here by combining the description positioning it as a process that reduces bitterness with the cake's sensory-evaluation data. Reaching the full text was not completed this time (the publisher's site sits behind a paywall).
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ingredient-cocoa-powder —can_be_debittered_by→ "Alkalization (alkalizing / the Dutch process). An industrial process that treats cocoa with alkalizing agents such as potassium carbonate, sodium carbonate, and sodium hydroxide, raising the pH from natural cocoa's acidic range to a neutral-to-alkaline range. Puchol-Miquel et al. (2021), after positioning this treatment as "an important step in cocoa processing for reducing bitterness, increasing solubility, and developing color," applied commercial cocoa powders with varying types and degrees of alkalization to sponge cake, and reported that while differences in treatment conditions affected the batter's physical properties and the cake's color and texture, consumers' overall rating itself did not change significantly with the treatment condition."How it is perceived in the finished product
Solid chocolate and cocoa beverages need to be read separately. Solids first.
The relation "higher cacao percentage, more bitter" holds conditionally. In a study comparing five single-origin and six blended chocolates by temporal dominance of sensations (TDS), the dominance rate of bitterness rose clearly with cacao percentage in the blended group, whereas that relation was not clear in the single-origin group. The cacao figure alone does not settle bitterness.
Scope: TDS panel evaluation of 5 origin (66.8-80.1% cc) and 6 non-origin (54.5-80.0% cc) dark chocolates
Note: This is not a source claiming the simple, monotonic relationship that "the higher the cacao percentage, the more bitter it always tastes." Its main point is an assertion of asymmetry: that for origin chocolate, factors arising from growing region and cultivation conditions govern bitterness dominance more than the labeled cacao percentage does.
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ingredient-dark-chocolate —has_bitterness_correlated_with→ "Cacao percentage (shown as %). Oberrauter et al. (2018) used the TDS (Temporal Dominance of Sensations) method to compare 5 single-origin dark chocolates (cacao percentage 66.8-80.1%) with 6 non-origin (blended) chocolates (cacao percentage 54.5-80.0%). In the non-origin group, bitterness dominance rate (DR%) rose clearly as cacao percentage increased, whereas in the origin group bitterness remained the dominant attribute regardless of cacao percentage for about 75% of the tasting time, and the relationship with cacao percentage was described as "relatively small or barely observed." In other words, the strength of the relationship between cacao percentage and bitterness dominance was asymmetric, differing by the bean's origin and brand."Between commercial products the difference is plain. The median of the 10-point bitterness rating was 2 for a 36% product against 7.45 for an 85% one, a significant difference.
Scope: Wagner et al. 2023, Experiment 1; 39 untrained participants; 5 g of each of 2 commercial products presented in duplicate; 10-point category scale.
Note: Because the 36% and 85% products differ in manufacturer and ingredient composition, this is not treated as an effect of cocoa content alone. The 70% product is not included in this sensory experiment 1.
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ingredient-dark-chocolate —has_perceived_bitterness_affected_by→ "Among the commercial products compared: the 85% product had a higher median 10-point bitterness score than the 36% product (2 versus 7.45, p<0.001)."Cacao percentage is not the only formulation lever. In reconstituted chocolates held at 70% cacao while total fat was varied across 30%, 35% and 40%, higher fat lowered perceived bitterness, cocoa flavour and astringency. Perception moved by changing the medium, not the amount of the compounds.
Scope: A 70% cocoa-percentage reconstituted (cocoa powder + cocoa butter) two-component chocolate, with sensory evaluation by 108 regular chocolate consumers
Note: This is a result from a two-component reconstituted chocolate in which cocoa percentage and fat content were deliberately manipulated, not from typical commercial chocolate containing milk components or emulsifiers (such as lecithin). Extrapolation to commercial products in general should be made with caution.
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ingredient-dark-chocolate —has_perceived_bitterness_affected_by→ "Total fat content. Brown et al. (2023) made a 70% cocoa-percentage reconstituted dark chocolate (a two-component chocolate prepared from cocoa powder and cocoa butter) at 3 total fat content levels -- 30%, 35%, and 40% (w/w) -- and collected sensory and acceptability data from 108 regular chocolate consumers. As fat content rose, the perceived intensity of bitterness, cocoa flavor, and astringency (the dry mouthfeel that accompanies astringency) decreased significantly, and perceived sweetness increased significantly (all p<.05). Meanwhile, differences in fat content had no significant effect on overall liking (p>.05)."On the beverage side, sugar is what moves. Sucrose concentration (0%, 2.5%, 5%) changed perceived bitterness in a cocoa drink.
Scope: A trained-panel test that factorialized 2 fat levels and sweetener
Note: Bitterness and bitter aftertaste decreased significantly as sucrose increased. This does not mean that the sugar removed the bitter compounds.
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ingredient-chocolate-milk —has_perceived_bitterness_affected_by→ "Sucrose concentration (0%, 2.5%, 5%)"Fat, which worked in the solid, did not work in the beverage: the main effect of 0.1% against 4.5% fat on bitterness was not significant. The same operation of "adding fat" gave different results in solid and liquid.
Scope: The same factorial chocolate-milk test
Note: There was no significant main effect of fat concentration on bitterness. This is not proof that fat in general has no effect on bitterness.
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ingredient-chocolate-milk —has_perceived_bitterness_unchanged_by→ "The main effect of fat at 0.1% versus 4.5%"Alkalization showed up in the beverage as aftertaste. In the same prototype formulation, buffalo milk chocolate milk made with alkalized cocoa powder scored higher for bitter aftertaste intensity with a trained panel than the natural cocoa powder version (2.9 against 2.4). A treatment meant to reduce bitterness came out the other way in the aftertaste.
Scope: Juvinal et al. 2023; 2 prototypes containing 1% cocoa powder, 7.5% sugar, and so on; 8 trained panelists; 15 cm line scale; 4 replicates.
Note: Because the cocoa powders differ not only in treatment but also in brand, the difference is not treated as a sole causal effect of alkali treatment. This is not extended to solid milk chocolate or milk in general.
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ingredient-chocolate-milk —has_sensory_attribute→ "Buffalo-milk chocolate milk made with alkalized cocoa powder in the same prototype formulation had a higher trained-panel bitter-aftertaste intensity than the product with natural cocoa powder (2.9 versus 2.4, different letter groups, p<0.05)."What was measured and did not move
Measurements that produced no difference are given the same weight here as those that did.
For two 70% products made from microwave-roasted and convection-roasted beans, a CATA with 130 consumers found no significant difference in the citation frequency of 12 in-mouth flavour terms including bitter. Roasting temperature moved bitterness; changing the heating method alone did not.
Scope: Schouteten et al. 2023; Ecuadorian mixed-variety beans; 600 W for 35 minutes versus 130°C for 30 minutes; 2 70% chocolate bars; 130 adult Belgian consumers.
Note: CATA is a method of selecting applicable terms, not an intensity scale. Not only the roasting method but also the equipment, batch size, and time/temperature conditions differ together as a set. This is not a proof of equivalence between the 2 conditions.
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ingredient-dark-chocolate —has_perceived_bitterness_unchanged_by→ "The 2 products made with the same 70% formulation from microwave-roasted beans and convection-roasted beans showed no significant difference in the citation frequency of the 12 in-mouth flavor terms, including bitter, in a CATA test with 130 consumers (p>0.05)."In a test combining chilli and sweeteners in unsweetened spicy dark chocolate, the maximum bitterness intensity measured by time-intensity showed no significant difference in nearly all nine combinations. Adding pungency did not move the peak of bitterness.
Scope: Layer: food. Unsweetened spicy dark chocolate, TI method with a trained panel (13 members assigned to bitterness), consisting of a 5-second wait, 15 seconds holding in the mouth, and post-swallow bitterness rated on a 0-10 scale over 120 seconds.
Note: The intensity and duration of spiciness (pungency) increased with rising chili concentration, but the Imax of bitterness did not move statistically across most of the concentration combinations. An example, at the food layer, of pungency and bitterness behaving independently.
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ingredient-dark-chocolate —has_perceived_bitterness_unchanged_by→ "Combinations of chili pepper (Capsicum baccatum) concentration (2.0/3.5/5.0 g/kg) and rebaudioside A concentration (500/800/980 g/kg) added to unsweetened spicy dark chocolate. The maximum bitterness intensity (Imax) measured by the time-intensity (TI) method showed no significant difference across almost all of the 9 combinations; a significant difference at p<=0.05 was detected only between chili 2.0 g/kg + rebaudioside A 980 g/kg and chili 5.0 g/kg + rebaudioside A 800 g/kg."Origin did produce a difference, but a small one. Mean bitterness on the gLMS was 28.1 for Peru against 26.0 for Ghana and 26.8 for Madagascar: statistically significant, but an order of magnitude away from the gap between the commercial 36% and 85% products (2 against 7.45).
Scope: 3 origins of unsweetened 100% chocolate, 145 consumers
Note: The origin effect coexists with roasting effects in the same experimental design. In the text read, both were not separated into an interaction term.
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ingredient-roasted-cocoa-nibs —has_perceived_bitterness_affected_by→ "Cacao origin: mean bitterness on the gLMS scale was Peru 28.1 versus Ghana 26.0 (p = 0.0001) and Madagascar 26.8 (p = 0.016)"Questions people ask
Is chocolate with a higher cacao percentage more bitter?
Between commercial products, yes: the median of the 10-point bitterness rating was 2 for a 36% product against 7.45 for an 85% one. But the cacao figure alone does not decide it. In a study comparing five single-origin and six blended chocolates by TDS, the dominance rate of bitterness rose clearly with cacao percentage in the blended group, whereas that relation was not clear in the single-origin group. At the same cacao percentage, the origin of the beans and the formulation change how bitterness comes out.
Does roasting make cacao more bitter, or drive bitterness off?
It depends on the sample. In 100% chocolate, a one standard deviation (42 degC) higher roasting temperature corresponded to a drop of 1.56 gLMS units in mean bitterness, so bitterness fell as temperature rose. In infusions of the bean shell the opposite held: as roasting temperature rose across 100, 120 and 140 degC, the mean bitterness rank rose across 17.4, 37.8 and 54.7. The same word "roasting" covers operations whose direction depends on what reaches the mouth.
Does fermentation reduce bitterness?
It does not settle in one direction. Comparing day 4 and day 7 cocoa pastes across three facilities in Colombia, bitterness and astringency rose at two and fell at one. The compounds are not monotonic either: theobromine and caffeine fell to day 5 and rose by day 6, while catechin moved the other way. The reading that longer fermentation drives bitterness off is not supported within the scope of this page.
Do milk and sugar make the bitterness disappear?
They move it downward rather than removing it. In a cocoa beverage, sucrose concentration (0%, 2.5%, 5%) changed perceived bitterness. In solid chocolate held at 70% cacao, raising total fat from 30% to 40% lowered perceived bitterness, cocoa flavour and astringency. But in the beverage the difference between 0.1% and 4.5% fat did not affect bitterness, so what works in the solid does not necessarily work in the liquid.
What is not known
- What differs between the facilities where fermentation raised bitterness and the one where it fell is not known within the scope of this page. The observation that facilities differed is on record; a source separating the cause is not.
- Why roasting lowers bitterness in solid chocolate and raises it in shell infusions has not been measured. Beyond the fact that the samples differ, no explanation can be placed here.
- Alkalization is positioned as a step that reduces bitterness, yet in buffalo milk chocolate milk the alkalized version had the stronger bitter aftertaste. Whether in-mouth bitterness and aftertaste bitterness move separately, or whether this follows from the difference in sample, is not known.
- Why the relation between cacao percentage and bitterness was not clear for single-origin chocolates cannot be explained within the scope of this page. The difference in mean bitterness by origin is itself small: Peru 28.1, Ghana 26.0, Madagascar 26.8.
- The observation that drying temperature affects bitterness remains at a preliminary level and goes no further than a comparison of two levels, 80 and 60 degC.
Read in the encyclopedia
- Roasted cocoa nibs — the sample at the centre of the compound analyses, where the bitter and astringent carriers are identified
- Cocoa powder — the sample where contributors are narrowed by dose-over-threshold, and the object of alkalization
- Cocoa bean shell (husk) — the bean's skin, distinguished from the pod; particle size and roasting conditions change the bitterness rank
- Dark chocolate — where cacao percentage, fat and formulation move perceived bitterness
- Chocolate milk — tests of sugar, fat and sweetener replacement in a liquid, set against the solid
- Cocoa fermentation — the process whose direction changes by facility
- Cocoa bean drying — distinguished from roasting; temperature moves bitterness and astringency
- Cocoa roasting — the process where perceived bitterness falls as temperature rises
All entries in this hub (10)
Every encyclopedia entry that belongs to this hub, grouped by category. Entries without an English version open in Japanese.
ingredientcocoa bean shell (husk) · dark chocolate · chocolate milk · roasted cocoa nibs · cocoa powder · milk chocolate
processcocoa bean drying · cocoa fermentation · cocoa roasting · cocoa conching
Go deeper in the research notes
- When cacao was bitter — tracing cacao before it was sweetened, from the records
- The boundary between roast aroma and bitterness — where to separate what roasting creates
- Can cooking create bitterness? — placing the cacao processes in the four quadrants of adding, removing, designing and suppressing
- A world map of debittering — placing alkalization among the world's techniques for taking bitterness out
Source ledger
The primary sources and limitations for the claims on this page can be checked from the source links inside each card. The full list is on the Japanese source ledger.
How to cite this page
Aoki, M. (NIGAMI LAB) (2026). Cacao bitterness and astringency — where does it change?. https://nigamilab.com/en/topics/cacao-bitterness/
Each claim card has a stable anchor (#clm-…). The dataset is CC BY 4.0; see the data page. Dataset DOI: 10.5281/zenodo.22739101