Coffee Sweetness in Depth: Where It Comes From and How to Taste More of It

Coffee Guide

By MELB_NOTE

Cover photo: Freshly roasted beans pouring from a drum roaster into the cooling tray. Photo: Jameswasswa, CC BY-SA 4.0, cropped.

The short answer

Coffee tastes sweet even though almost no sugar survives the roast. Green Arabica beans hold around 7% sucrose, but a medium roast destroys more than 95% of it, and brewed coffee carries far less sugar than your tongue can detect. The sweetness you notice comes from the browning of that sugar into caramel-like aromas, from compounds still being identified, and from what is missing: harsh bitterness and sharp sourness that would otherwise hide it. High-grown beans, a roast that is fully developed but not burnt, and a brew that is neither cut short nor overdone give you the most.

New to coffee tasting? Start with our guides to coffee acidity and coffee bitterness. This article covers the third part of the balance: sweetness.

30-second summary

• Green Arabica is about 7% sucrose by dry weight; Robusta holds markedly less.
• Roasting breaks down 96–98% of that sucrose. The sugar becomes colour and caramel-like aroma.
• Brewed coffee contains roughly a twentieth of the sugar you would need to taste it, so coffee sweetness is mostly perceived rather than tasted as sugar.
• Aroma plays a part: with a nose clip, tasters still ranked coffees for sweetness, but the gap between the sweetest and least-sweet cups shrank.
• Bitterness and sourness mask sweetness, so the sweetest cup is a balanced one, not the strongest one.
• Milk adds real sugar (lactose). Very hot milk tastes less sweet than milk steamed to a moderate temperature.

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Coffee tastes sweet even though almost no sugar survives the roast

Sweetness is a quality coffee is scored on, yet roasting wipes out nearly all the sugar that could cause it.

SCA researchers (Cordoba, Peterson and Giuliano) found that the coffees they tested “maxed out at about 100 milligrams per liter” of sugar. People detect sucrose, which is table sugar, at about 2,000 mg/L. In their words, “all sugars were far below the human threshold of detection”. Even the most sugary cup tested held about a twentieth of what you would need to taste.

The same team had 125 professional tasters rank eight coffees by sweetness. The tasters found significant differences, but the two least-sweet coffees had the highest sugar levels. Those coffees were associated with bitter, roasted and papery flavours. SCA 25 Issue 22 concludes that coffee sweetness involves taste and aroma, flavour associations “and previously unknown sweet-tasting compounds”, not sugars alone.

Think of a vanilla candle: no sugar, yet your brain files the smell under sweet.

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Green coffee starts with plenty of sugar, and Arabica has more than Robusta

Raw coffee beans are rich in sugar, mostly sucrose. Murkovic and Derler (2006) found up to 90 mg/g of sucrose in Arabica, with a mean of 73 mg/g. Robusta was significantly lower at 45 mg/g. In round terms, that is about 7% of an Arabica bean and about 4.5% of a Robusta bean (Murkovic & Derler, 2006).

Sugars and amino acids are also the starting materials of the Maillard reaction, the browning reaction that colours toast and seared meat. In coffee it forms colour and aroma.

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Roasting turns sugar into colour and caramel aroma

Roasting uses up the sugar. In a 2019 Slovak study (Diviš, Pořízka and Křikala), one Brazilian Arabica measured 70.1 mg/g of sucrose, about 7% of dry weight, before roasting. It fell to 3.0 mg/g after a medium roast (14 minutes at 210°C). After a full city roast (19 minutes at 225°C) it was below 1.0 mg/g. The authors write that “almost all sucrose has been degraded (96–98%)”. This is one coffee, so treat the figures as an example.

Some of the sugar caramelises. Caramelisation is sugar breaking down under heat on its own, without amino acids. The Coffee Research Institute says that “from 170–200°C the sugars in coffee begin to caramelize” and that the dark colour of coffee is directly related to the caramelisation of sucrose (Roasting).

Think of sugar in a pan. Golden caramel smells sweet, but keep heating and it turns bitter and black. The same page notes that uncaramelised sugar is much sweeter than its caramelised products. To maximise sweetness, minimise caramelisation, but do not roast so lightly that bitter compounds survive.

The sugar also leaves its mark as aroma. The Coffee Research Institute lists furans as the most common group of coffee aromatics. They “typically have caramel-like odors since they result from the pyrolysis of sugars”, and furaneol is listed with a caramel-like aroma (Coffee aroma).

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Much of the sweetness you taste arrives through your nose

Aroma supplies much of the sweetness you notice. Retronasal smell is aroma that rises from the back of your mouth into your nose while you drink or after you swallow (Coffee Research Institute).

In the SCA study, tasters wore nose clips. Overall sweetness ratings fell, and the range between the sweetest and least-sweet coffees shrank from 6 to 3.6 points on a 15-point scale. The order stayed much the same, so aroma matters and some compounds tasted on the tongue must also be involved (SCA 25 Issue 22).

Caramel, vanilla and berry aromas increase perceived sweetness, writes Mike Ebert in Roast magazine (2023).

World Coffee Research’s Sensory Lexicon separates sweet (the taste, “a fundamental taste factor of which sucrose is typical”), sweet aromatics and overall sweet (“the perception of a combination of sweet taste and aromatics”).

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Altitude and processing set up the sweetness before the roaster starts

In Ethiopian coffee, sucrose content increased with altitude. The rise was larger for wet-processed beans (3.02 g/kg per 100 m) than for dry-processed beans (0.36 g/kg per 100 m), and larger without shade (Worku et al., 2018). A 2025 Jimma University study, as Newswise reports, found the same, and says cooler high-altitude conditions prolong bean filling.

Think of altitude as slow cooking: the cherry ripens slowly, so the seed has longer to fill.

Knopp, Bytof and Selmar (2006) found that sucrose “is not significantly affected by coffee processing”. Glucose and fructose were low in washed beans and significantly higher in unwashed (natural) beans, because they fall during wet processing (Knopp et al.).

Barista Hustle, summarising several studies, says little if any sugar passes from the fruit into the seed in natural processing. Fruity, sweet-smelling fermentation esters are a likelier reason naturals taste sweet (Barista Hustle).

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A well-developed roast is sweeter than an underdeveloped or a burnt one

A well-developed roast tastes sweeter than an underdeveloped or burnt one. Development is the time from first crack, the audible popping when beans expand, to the end of the roast. Too short a development time gives “vegetal or pea pod type flavors”, and roasting too far “mutes brightness”. Light roasts lean fruity and floral, medium roasts caramelised (Ebert, Roast).

For sweetness, the Coffee Research Institute recommends stopping “between the end of the first crack and less than half way through the second crack” (Roasting).

See light vs dark roast for the wider differences.

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Bitterness and sourness hide sweetness, so balance matters more than strength

Sweetness is the quiet voice in a room; bitterness and sourness are the loud ones.

UC Davis researchers split a brew into fractions and tasted each one. Early fractions were intensely bitter and sour. Later fractions were sweeter, with floral, honey and fruity notes, despite far fewer dissolved solids. Sugars were below the detection threshold in every fraction. One explanation offered is that bitter and sour compounds in the early fractions mask sweetness (Batali, Lebrilla, Guinard and Ristenpart, “Less Strong, More Sweet”).

In a study of espresso, adding sucrose or sucralose raised caramel ratings and lowered roasty ratings, although neither sweetener has a smell (Chiralertpong, Acree, Barnard and Siebert, 2008).

If a cup tastes sharp, read our guide to acidity in depth. If it tastes harsh, see why coffee tastes bitter.

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The brew decides how much sweetness reaches the cup

Two numbers describe a brew. TDS (total dissolved solids) is how strong the cup is. Extraction yield is the share of the ground coffee’s weight that dissolves into the water.

Lockhart’s 1957 Brewing Control Chart put ideal filter coffee at 18–22% extraction and 1.15–1.35% TDS (Fresh Cup). UC Davis researchers later found that “the intensity of the natural sweetness in the black coffee actually decreases with both TDS and PE, such that the peak sweetness intensity is in the lower left zone” (PE is percent extraction) (Frost, Batali, Guinard and Ristenpart). The SCA puts it briefly: “Coffee’s sweetness is maximized at low TDS and PE, while bitterness is maximized at high TDS and PE” (Coffee Decoded).

In short, the sweetest cups in those tests were the less strong ones, and bitterness rose as both strength and extraction rose. A brew cut short also misses the sweeter later part. This is direction only, not a recipe for weak coffee. Your levers: lighter strength (more water per gram) and avoiding over-extraction.

Grind and extraction can push the same beans into different corners of the chart, and they taste markedly different (UC Davis Engineering).

Temperature is a small lever. Brew temperatures between 87°C and 93°C had little effect on sensory profile when TDS and extraction were held constant (Batali, Ristenpart and Guinard, 2020). Grind, ratio and time matter more.

The 1:15 and 1:17 example is an illustration, not a sourced optimum. See coffee grind size and the coffee-to-water ratio.

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Sweetness shows more as the cup cools

Warming enhances perceived sweetness, because the sweet-taste channel TRPM5 is itself activated by heat (Talavera et al., 2005, Nature). But in coffee served between 31°C and 62°C, the cooler samples (31–44°C) were associated with “sour”, “tobacco” and “sweet”, while hotter ones (50–62°C) were linked to stronger roasted and bitter notes (Steen et al., 2017).

Heat boosts the sweet signal, but very hot coffee is dominated by roasted and bitter notes. In practice, sweetness is easier to notice as a cup cools from scalding to warm.

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Milk brings its own sugar, and very hot milk loses sweetness

Milk adds real sugar, though a milder one. Lactose makes up 4.8–5.2% of milk and “is not as sweet as sucrose” (University of Guelph).

Temperature changes the result. Phil & Sebastian, a Calgary roaster, tasted milk with UBC chemist Dr Stephen McNeil. They steamed milk to 54°C, 71°C and 82°C, cooled all three to 54°C and tasted them. Some preferred the sweeter 71°C sample, others the “less sweet and more complex” 82°C one. Above about 82°C, they note, whey proteins denature and sugars are lost to the Maillard reaction (Phil & Sebastian, 2016).

Seven Miles, an Australian roaster, recommends 65°C for steamed milk. In its small test, all five people preferred coffee between 62°C and 65°C (Seven Miles, 2019).

For milk drinks, see flat white vs latte. “Extra hot” is the order that costs you sweetness.

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Cuppers score sweetness, and the 2024 SCA system measures how much

On the 2004 SCA cupping form, sweetness, uniformity and clean cup are scored per cup. Each of five cups is worth two points, so a coffee showing sweetness in all five cups scores 10 (Royal Coffee).

The SCA’s Coffee Value Assessment standards (SCA-102, -103 Descriptive and -104 Affective) “supersede the 2004 Cupping Protocol and Form” (SCA). The 2024 standards rate sweetness for intensity on a 0–15 scale on the Descriptive form, and give it a 1–9 quality impression on the Affective form (SCA CVA forms; CVA in Action).

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Three tastings teach you to find sweetness in black coffee

1. Pinch your nose. Take a sip of black coffee with your nose pinched, then let go mid-sip. Notice how much of the sweetness and caramel arrives only when you let go.
2. Split one brew two ways. Brew the same beans at your usual ratio and at a weaker one, with more water per gram. Taste them side by side for sweetness, not strength.
3. Taste it cooling. Sip just after brewing, after five minutes and after fifteen. Note when sweetness first shows and whether bitterness fades.

Optionally, taste the same coffee with a few drops of sugar and notice the caramel note get louder.

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Ordering for sweetness at a Melbourne counter

Ask the barista which coffee on the menu they find sweetest. Most specialty cafés list origin and process on the board or bag.

• Black coffee: ask for a filter or batch brew of a washed, high-grown coffee at a light-to-medium roast.
• Espresso: a medium roast is the safer choice.
• Milk drinks: a flat white or latte at the standard temperature keeps more of the milk’s sweetness than “extra hot”.
• Bitter espresso: a longer milk drink, or a filter of the same beans, is often gentler. See why coffee tastes bitter.

For more on picking beans, see how to choose coffee beans.

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Questions people ask

Does coffee contain sugar?

Green beans do, about 7% in Arabica. Roasted beans keep almost none, and brewed coffee holds far below what you can taste.

Why do some coffees taste sweet without sugar?

Caramel-like aromas, little bitterness or sourness to mask it, and compounds still being identified.

Is light roast or dark roast sweeter?

Neither extreme. Underdeveloped roasts taste vegetal and very dark roasts taste bitter. A fully developed light-to-medium roast usually shows the most.

Are natural-process coffees sweeter?

They often smell fruitier and sweeter, but processing does not raise the bean’s sucrose.

Does milk make coffee sweeter?

Yes, it adds lactose, which is less sweet than table sugar. Very hot milk tastes less sweet.

Does a pinch of salt make coffee sweeter?

Our guide to why coffee tastes bitter covers salt and bitter-sweet mixtures.

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Sources and scope

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Related guides

• Coffee Acidity in Depth
• Coffee acidity vs sourness: a beginner’s guide
• Why does coffee taste bitter?
• Light roast vs dark roast
• Coffee grind size
• Coffee-to-water ratio
• Flat white vs latte
• How to choose coffee beans