melanoidins
compound class / compound-class-melanoidins
メラノイジン
Melanoidins: a collective term for high-molecular-weight pigment fractions produced by the browning reaction (Maillard reaction) in roasted coffee.
On this page (7 sections)
Reading the bitterness
Melanoidins are a collective term for high-molecular-weight pigment components produced by the browning reaction (Maillard reaction) in roasted coffee. When a fraction with molecular weight greater than 10 kDa (HMW) was isolated from coffee beverage by ultrafiltration, dissolved in bottled water, and evaluated sensorily in isolation, its sensory bitterness intensity was 0.5 (±0.1) compared to a caffeine 7.5 mmol/L reference solution (sensory bitterness intensity 5.0). This result demonstrates that the intrinsic bitterness of this fraction itself is minimal.
When the same high-molecular-weight fraction was reconstituted in coexistence with caffeine and 5-caffeoylquinic acid (5-CQA) at natural extraction concentrations, its sensory bitterness intensity decreased significantly to 2.5 (±0.3) compared to 5.0 for the caffeine-alone solution (p≤0.05). This result was obtained by sensory evaluation on a 0-5 scale by 18 panelists with a t-test, using the high-molecular-weight fraction derived from a single commercial coffee product (decaffeinated espresso).
In coffee, there is a study that confirmed a sensation distinct from bitterness. A reconstituted sample made by adding 7.9 mg/L of the same F9.6.4 fraction to 7.8 mg/L of that fraction already in low-body coffee, for a final concentration of 15.7 mg/L, was discriminated from the control by 9 trained panelists' same/different judgments at an R-index of 69.5% (p≤0.01). The free descriptions were words corresponding to 「乾く」 (drying) and 「渋い」 (astringent). This fraction is a brown, complex mixture dominated by condensed phenolics; the authors describe it as melanoidins or their precursors, not a single substance.
The amount of a fraction separated from beer has been measured in products of different colors. It was 4.2±0.6 g/100 mL for dark beer (stout type) and 2.0±1.3 g/100 mL (mean±standard deviation) for pale beer (American lager type). 3 brands were examined for each, and each analytical sample combined 3 lots. The values are the amount of the retentate fraction separated with a 3 kDa membrane, washed until colorless, and freeze-dried; they are not pure melanoidin concentrations or bitterness intensity.
For 1 other dark-beer product, the fraction that did not pass through a 3.5 kDa membrane was freeze-dried and examined by combining size-based separation with refractive-index detection. The apparent molecular weight calculated from the peak at a retention time of 16.06 minutes was 4759 Da. This is a value for a complex fraction obtained from a single product by a fixed separation method, and it does not show that all melanoidins in food are the same size. Nor is it a measurement of taste.
Sources for this overview
Impact of Interactions between Melanoidins and Caffeine on the Bitter Taste of Coffee Beverages
Checked for this overview: Used the measured value that the sensory bitterness intensity of the high-molecular-weight fraction in isolation is only 0.5. / Used the measured value that sensory bitterness intensity is halved when coexisting with caffeine.
Checked for this overview: Used for the 7.8 mg/L in the LB (low-body coffee), the 7.9 mg/L addition, the final 15.7 mg/L, the 9 trained panelists, the R-index of 69.5% at p≤0.01, the free descriptions of drying and astringency, and the limitation that this is a complex fraction.
Checked for this overview: Used for the 4.2±0.6 g/100 mL for dark beer and 2.0±1.3 g/100 mL for pale beer (mean±standard deviation), the 3 brands × 3 lots each, and the limitation that this is a 3 kDa separated fraction, not taste.
The physicochemical characterization and the bound phenolic profile of melanoidins from dark beer
Checked for this overview: Used for the single dark beer, the 3.5 kDa retentate fraction, the 16.06-minute retention time, the apparent molecular weight of 4759 Da, and the limitation that this is a complex fraction and not sensory.
Follow the connections
melanoidins →reduces the perceived bitte…→ caffeine →is a poor universal prototy…→ bitterness
melanoidins →— sensory attribute→ bitterness →can be measured separately …→ astringency
melanoidins →— sensory attribute→ astringency →is not synonymous with→ bitterness
Structured claims — open a section to read each claim's confidence, evidence and limits
Composition and content (2)
Scope: Alves et al. 2020; 3 brands per food; each analytical sample combined 3 lots purchased from supermarkets in Rio de Janeiro.
Note: This is an operational fraction amount, weighed as the freeze-dried material after 3 kDa ultrafiltration and dialysis washing, not the concentration of a pure single compound. There is a difference between foods, but the text does not show an individual significance value for the difference between these 2 foods. Taste was not measured.
Show data
compound-class-melanoidins —has_measured_content_in→ "The amount of the melanosaccharide fraction above 3 kDa was 4.2±0.6 g/100 mL for dark beer (stout type) and 2.0±1.3 g/100 mL (mean±standard deviation) for pale beer (American lager type)."Scope: Wang et al. 2026; 3.5 kDa ultrafiltration at 4000 rpm for 20 minutes; the retentate fraction was freeze-dried and measured with a TSKgel G4000PWXL fitted with a refractive-index detector.
Note: An apparent value from a standard curve for a fraction obtained operationally from a single product. It does not indicate the molecular weight of melanoidins in general, or the purity or taste of the fraction.
Show data
compound-class-melanoidins —has_composition→ "The fraction above 3.5 kDa obtained from a single dark beer purchased at a Chinese supermarket had an apparent molecular weight of 4759 Da calculated from the peak at a retention time of 16.06 minutes on size-exclusion HPLC."Sensory (3)
Scope: Layer: food (reconstitution of a high-molecular-weight fraction isolated from coffee). A 5-point scale, 0 (not detectable) to 5 (strongly detected), 18 panelists, t-test (α=0.05).
Show data
compound-class-melanoidins —reduces_perceived_bitterness_of→ compound-caffeineScope: Layer: food. High-molecular-weight fraction isolated from coffee by ultrafiltration (fractionation molecular weight 10 kDa) was reconstituted in bottled water and evaluated on a 0-5 scale by 18 panelists.
Show data
compound-class-melanoidins —has_sensory_attribute→ sensation-bitterScope: Linne et al. 2025; 9 trained panelists (6 women, 3 men, aged 23–47); same/different judgments with confidence ratings; 27 evaluations per sample; nose clips worn.
Note: F9.6.4 is a brown, condensed-phenolic-dominated complex fraction obtained by multistep fractionation of the fraction below 5 kDa; the authors describe it as melanoidins or their precursors. It is not a purified single substance. The free descriptions were drying/astringent, not a measurement of bitterness.
Show data
compound-class-melanoidins —has_sensory_attribute→ sensation-astringent