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Bitter crossing — 2026-09-06

Sweet-bitter

甘苦い (amanigai) — our coined term

Sweet-bitter refers to a taste state in which sweetness weakens bitterness while both tastes remain without disappearing. It is the lab's coined term.

What this page establishes

• Sweet-bitter is not an established word but a term the lab has coined, and whether a headword in the same form appears in dictionaries has not been confirmed.
• There is a report that mixing sweeteners with each other 1:1 increased sweetness by 60-100% and lowered the original bitterness by 35-63%.
• In a trained-panel test of chocolate milk, increasing sugar from 0% to 2.5% and 5% is reported to have lowered the scores for bitterness and bitter aftertaste.
• There is a report that even when the sweet taste receptor was temporarily blocked with a drug, part of sugar's bitterness-suppressing effect remained, suggesting that perceiving sweetness may not be the only pathway.

How it arises

The process by which sweetness weakens bitterness has been examined at several layers that differ from the outset in both the substances handled and the concentrations used. Here, psychophysics using solutions, cell tests using receptors, and sensory tests using actual foods are set out separately, kept apart.

In solution

In tests mixing two-component sweeteners, it is reported that mixing acesulfame K or saccharin 1:1 with allulose, aspartame, erythritol, fructose, glucose, or sucrose enhanced sweetness by 60-100%, while bitterness derived from acesulfame K or saccharin decreased by 35-63%.

In an experiment testing the same sweetener combination in a cocoa-flavor model system, it is reported that part of the bitterness-suppressing effect remained even under a condition in which sweet taste reception was temporarily blocked with a drug. This shows that not all of the suppression passes through the perception of sweetness.

In cells

For the same sweetener combination, a test measuring the response of cells expressing human bitter and sweet taste receptors also reported a change corresponding to the sweetness enhancement and bitterness reduction seen in the sensory test.

In cooking

In the production and distribution of liangcha, it has been recorded that sweeteners have been added for the purpose of softening the bitter flavor.

In a trained-panel test using chocolate milk, as sucrose concentration was raised through 0%, 2.5%, and 5%, ratings for bitterness and bitter aftertaste decreased significantly.

In a test mixing sucrose into brewed coffee as well, hypoadditivity was seen in taste and flavor intensity, and the suppression rate is reported to have been roughly 30-40%. This figure stays within the scope of the abstract.

Exceptions and reservations

The effect of sweetness weakening bitterness does not always occur at the same magnitude. Here we record cases where it did not suppress bitterness, and the difference from a buffering agent.

In the same chocolate-milk test, comparing fat at 0.1% and 4.5% showed no significant main effect on the bitterness score. Milk fat is a buffering agent that wraps bitterness through a route separate from sweetness, and is not counted as a partner in this crossing.

In another dark chocolate test, raising total fat content through 30%, 35%, and 40% significantly lowered perceived bitterness while simultaneously significantly increasing perceived sweetness. The sweetness that moved here is not an added sweetener but a change brought to the tongue by fat as a buffering agent, and needs to be distinguished from an example where sweetness itself weakened bitterness. Moreover, this is a result from a two-component reconstituted chocolate in which cocoa percentage and fat content were deliberately manipulated, and it is not applied to commercial bar chocolate in general, which contains milk components and emulsifiers.

In a test combining chili pepper and rebaudioside A (a stevia-derived sweetening component) in unsweetened spicy dark chocolate, among 9 concentration combinations, a significant difference in maximum bitterness intensity appeared in only one comparison. Adding a sweetening component does not necessarily move bitterness monotonically.

The route for weakening bitterness is not only sweetness itself. In a test using a compound that specifically targets and suppresses the bitterness of an artificial-sweetener solution, 95% of panelists selected a 2 mM acesulfame K solution containing 30 ppm (150 uM) of that compound as the least bitter, while there was no significant difference in sweetness ratings, and only 55% selected the control as sweeter. Not everyone felt bitterness disappear, and individual differences remain.

Examples from around the world

Examples where sweetness and bitterness stand side by side can be found in several encyclopedia entries.

• xocóatl (cacáhuatl) — a cacao drink of pre-Hispanic Mesoamerica. Its state without added sweetness is recorded as 「非常に苦い」 ("extremely bitter").
• Spritz — a cocktail originating in Veneto that combines prosecco, a bitter liqueur, and soda water.
• Basque burnt cheesecake — a cheesecake finished by deliberately charring its surface dark.
• dark chocolate — bar chocolate with an elevated cocoa percentage.
• liangcha — a general term for the cooling herbal teas and medicinal drinks of Lingnan.

Try it at home

Narrow it to a single variable, and divide the same bitter drink into 2-3 conditions. The amounts given are only a guide.

Change the amount of sweetness

Prepare the same amount of unsweetened drip coffee and divide it into 3 portions. Add and dissolve sugar into each so that it reaches 0%, 2.5%, and 5% by weight, cool each close to room temperature, then taste them in a randomized order. Write down the strength of bitterness on the same scale, and record under which condition bitterness feels weakest.

Change the amount of milk fat

Dissolve the same concentration of unsweetened cocoa powder separately in low-fat milk (roughly 0.1% fat) and regular milk (roughly 4.5% fat). Add no sweetener. Compare the strength of bitterness and check whether fat amount alone leaves bitterness largely unmoved.

Status: candidate (to be published once a tasting-comparison record is attached).

What is not known

• No source found: no source has been found that compares, for actual foods (chocolate or coffee drinks themselves), how bitterness suppression differs by type of sweetener.
• Not measured: whether the cell-level response to mixing two-component sweeteners corresponds in the same way when receptor type or conditions change has not been measured.
• No source found: no source outside dictionaries has been found that confirms actual usage of the word form 甘苦い itself.
• Not measured: whether coffee or cocoa drunk at home shows a change in sweetness and bitterness of the same magnitude as in the laboratory has not been measured.

Between the dictionaries

The word form 甘苦い can be seen in use, but whether it appears in Japanese dictionaries as an independent headword has not been confirmed at this stage. What does appear is the two-character noun 甘苦, written without okurigana.

In Chinese dictionaries, 甘苦 (gānkǔ) already appears as an independent headword, and its meaning extends beyond the sensory. First there is the sensory sense of sweet taste and bitter taste,

followed by a sense that metaphorically expresses favorable or adverse circumstances and hardship or joy,

and then a third sense, hardship, is listed.

The lab's definition of sweet-bitter refers only to the sensory sweet-bitterness among these senses. It does not carry over the metaphorical senses of circumstance or hardship.

The difference from horonigai (gently bitter) (mildly bitter) lies in how the word is built. Mildly bitter is a word in which the prefix horo- — explained in dictionaries as meaning "a little, somehow" — weakens the intensity of bitter (nigai); it is not a word that brings out a partner taste. Sweet-bitter, by contrast, is not merely a word that weakens bitterness; it is a word for a state in which the partner taste, sweetness, also remains without disappearing. The English word bittersweet, too, is a compound that joins the two opposing words bitter and sweet on equal terms,

In that it is not a word that weakens bitterness but a word that names bitterness's partner, sweet-bitter shares the same construction as bittersweet.

Frequently asked

Why does adding sugar to coffee soften bitterness?

Both a route in which sweetness weakens the perception of bitterness and a route that directly targets bitterness receptors have been reported. In a test mixing sucrose into brewed coffee, the suppression rate is reported to have been roughly 30-40%. However, this figure is within the scope of the abstract, and the coffee cultivar and roast conditions used have not been confirmed.

Does bitterness keep disappearing the more sweetness is added?

Not necessarily. In a test combining rebaudioside A and chili pepper in unsweetened spicy dark chocolate, among 9 concentration combinations, a significant difference in maximum bitterness intensity appeared in only one comparison. Changing the amount of a sweetening component does not necessarily move bitterness monotonically.

Can the bitterness of an artificial sweetener itself be erased?

Partly, yes. In a test using a compound that specifically targets and suppresses the bitterness of an artificial-sweetener solution, 95% of panelists selected the solution containing that compound as the least bitter, but not everyone felt bitterness disappear. Individual differences remain.

Related: Does any seasoning remove bitterness? — Sugar and salt /Bitter crossings /Bitter Words /horonigai (gently bitter) (mildly bitter, encyclopedia)