List of chemical compounds in coffee
There are more than 1,000 chemical compounds in coffee,[1] and their molecular and physiological effects are areas of active research in food chemistry.
Overview
There are a large number of ways to organize coffee compounds. The major texts in the area variously sort by effects on flavor, physiology, pre- and post-roasting effects, growing and processing effects, botanical variety differences, country of origin differences, and many others. Interactions between chemical compounds also is a frequent area of taxonomy, as are the major organic chemistry categories (protein, carbohydrate, lipid, etc.) that are relevant to the field. In the field of aroma and flavor alone, Flament gives a list of 300 contributing chemicals in green beans, and over 850 after roasting. He lists 16 major categories to cover those compounds related to aroma and flavor.[2]
The chemical complexity of coffee is emerging, especially due to observed physiological effects which cannot be related only to the presence of caffeine. Moreover, coffee contains an exceptionally substantial amount of antioxidants such as chlorogenic acids, hydroxycinnamic acids, caffeine and Maillard reaction products, such as melanoidins.[3] Chemical groups, such as alkaloids and caffeoylquinic acids, are common insecticides; their effects on coffee quality and flavor have been investigated in most studies.[4] Although health effects are certainly a valid taxonomy category, less than 30 of the over 1,000 compounds have been subjected to juried, health-related research (e.g. official potential carcinogen classification — see furans, for example), so health categorization has been avoided.
On the other hand, physiological effects are well documented in some (e.g. stimulant effects of caffeine), and those are listed where they are relevant and well-documented. Internet claims for individual chemicals, or compound synergies, such as preventing dental cavities (speculative but unproven effect of the alkaloid trigonelline with in vitro bacterial attachment research, but missing in vivo research on any health effects), preventing kidney stones, or negative effects, also have been avoided.
Groups
Chemicals found in coffee can be categorized in the following groups:
Acids and anhydrides
Quinic acid, 3,5-Di-caffeoylquinic acid
Alkaloids
Caffeine, Putrescine, Theophylline, Trigonelline
Alcohols
Quinic acid, Acetoin
Esters
3,5-Di-caffeoylquinic acid
Hydrocarbons | Lipids | Oils | Waxes
Ketones
Acetoin
Organosulfur_compounds
Dimethyl disulfide
Phenols
3,5-Di-caffeoylquinic acid
Volatile components (not in the sense of volatile organic compounds)
Tables
| Name 1 | Name 2 | Category | Subcategory | Formula | Comments |
|---|---|---|---|---|---|
| Caffeine | Methylxanthine | Alkaloid | Stimulant | 1,3,7-Trimethyl-1H-purine-2,6(3H,7H)-dione
3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione |
Likely the best known component of coffee, caffeine content varies both by variety and producing location, with Arabica having less, Robusto having more, and blending the two controlling caffeine content. Some authors consider alkaloids to be a special class of amines, depending on nitrogen pattern. |
| Triglycerides | Ester bonded Glycerol with three hydroxyl (OH-) groups connected to fatty acids, each having its own carboxyl group | Lipid | Commonly called Coffee Oils | HOCH2CH(OH)CH2OH + RCO2H + R′CO2H + R′′CO2H → RCO2CH2CH(O2CR′)CH2CO2R′′ + 3 H2O | Oils, along with caffeine, are the second most stable chemicals in coffee, due to their high melting point. Although most roasting takes place above 540 °F (282 °C), it is well into “second crack” (City ++) that oils start to migrate from inside to outside, hence the darker, oily appearing bean for long hot roasts. There are hundreds of oils in coffee, and although very important to flavor and aroma, they are some of the less studied chemicals to date. Oils are one of the few chemicals in coffee that change over time during storage of the green beans, and Arabica has over 50% more oils than Robusta, which is thought to contribute to aroma as well as taste differences. Also called wax, the majority of oils in a coffee bean are in the inner endosperm, not the waxy outer covering of the bean.[2]:23 |
See also
References
- R.J. Clarke (2013). Coffee Volume 1 Chemistry. New York: Springer. ISBN 978-9401086936.
- Ivon Flament (2002). Coffee Flavor Chemistry. New York: Wiley. ISBN 978-0471720386.
- Capek, Peter; Paulovičová, Ema; Matulová, Mária; Mislovičová, Danica; Navarini, Luciano; Suggi-Liverani, Furio (15 March 2014). "Coffea arabica instant coffee—Chemical view and immunomodulating properties". Carbohydrate Polymers. 103: 418–426. doi:10.1016/j.carbpol.2013.12.068. PMID 24528749.
- Green, Paul W C; Davis, Aaron P; Cossé, Allard A; Vega, Fernando E (4 November 2015). "Can Coffee Chemical Compounds and Insecticidal Plants Be Harnessed for Control of Major Coffee Pests?". Journal of Agricultural and Food Chemistry. 63 (43): 9427–9434. doi:10.1021/acs.jafc.5b03914. PMID 26458882 – via Hunter College Libraries.