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Green Coffee Bean

Introduction

Coffee is mainly produced from two out of over 100 species in the Coffea genus, Coffea arabica and Coffea canephora that account for 99% of global coffee production.(1) Coffee fruits, cherry-like, are harvested, processed via a dry or wet method, and converted to green coffee beans. Green coffee beans are then roasted, ground, and after preparation with hot or cold water into coffee for consumption.(1) 

Coffee is one of the most enjoyable beverages of people’s daily life. Coffee bean has increased 70% in production and 160% in consumption from 1990 to 2018,(2) and its consumption has continued to increase and reached over 165 million 60-kg bags in Year 2022.(1)

Components

The main components of coffee include trigonelline (TRG), caffeine and chlorogenic acid (CGA).  Green coffee beans, in each kg, contain about 10 g and up to 34 g TRG, 12 g caffeine, and 8.5 g CGA.(1,3) TRG is a bioactive pyridine alkaloid that occurs naturally in high concentrations in coffee.(1) Due to its readily availability, coffee becomes the most important commercial source of TRG.(1) Caffeine is a bioactive compound that belongs to the methylxanthine class. A single cup of coffee may contain between 95-330 mg of caffeine.(4) CGAs are a group of phenolic esters of caffeic and ferulic acids, in high concentrations in coffee, as high as 70-350 mg per cup of coffee. More than 80 different CGAs were detected in green coffee beans, with 5-caffeoylquinic acid being the most abundant.(4)

The content of components is affected by factors such as country of origin, coffee species and cultivar, part of the coffee plant, age of the plant part, applied industrial production processes, used preparation methods, water content of the sample, pH condition of the sample media, and analytical method used.(1) For water soluble and thermolabile TRG, coffee processing has a remarkable effect on its content which is lost through leaching during washing and blanching, and via thermally induced decomposition during roasting and steaming. From 15% to 90% of TRG is lost with increasing processing time and/or temperature, causing much lower TRG concentrations (3.1-7.5 g/kg) in roasted coffee beans than in unroasted green coffee beans (2.3-34.2 g/kg).(1)  In addition, the decaffeination process also lowers the TRG content of coffee beverages by 17%.(1) CGA content is similarly negatively impacted by the degree of roasting, while caffeine content is positively impacted by the degree of roasting till a certain point where the levels dropped in the dark roasted coffee. CGA content is the highest in the green coffee (543.23 mg/L) while caffeine content is the highest in the medium roasted coffee (203.63 mg/L).(4)

Health Benefits

Coffee consumption has many health-promoting effects. For example, it is shown coffee consumption,

 

  • decreases the risk of type 2 diabetes.(5) 
  • reduces the risk for digestive tract (oral, esophageal, gastric and colorectal) and, especially, liver cancer.(2)
  • introduces TRG that has many health benefits such as lowering blood sugar and blood fat, protecting heart through antioxidative effects, protecting patients from obesity and diabetes complications, anti-bone disease, anti-renal disease, anti-liver diseases, protecting central nervous system, antiviral, and anti-tumor.
  • introduces caffeine that,
    • with an intake of 400 mg per day or less, has beneficial effects on the body, such as central nervous system stimulatory effects, causing alertness and mood enhancement.(4)
    • lowers the risk of Parkinson’s disease, Alzheimer’s disease, and type 2 diabetes.(1)
  • introduces CGA that has high antiviral, antidiabetic, antioxidant, antihyperglycemic, antiaging and neuroprotective effects.(4)

The combination of coffee components, including TRG, caffeine and CGA, accounts for overall beneficial effects of coffee consumption.(2)

Safety

In general, the consumption of common and/or espresso coffee brews is considered a safe and popular dietary habit, especially among adults and elders.(2)  The International Agency for Research on Cancer (IARC) report showed a lack of evidence for carcinogenicity in humans, supporting that coffee intake is not classifiable as to its carcinogenicity to humans.(2)

Coffee is considered a healthy drink for most of the adult population, though there are some potentially sensitive subgroups. High coffee ingestion increases the risk of low birth weight, pregnancy loss, and 1st and 3rd semester preterm birth.(2) It is recommended for pregnant women to limit caffeine intake to 200 mg/day, corresponding to 1-2 cups of common or espresso brews, half the habitual caffeine consumption of 400 mg/day.(2) Coffee consumption may cause sleep disruption and slightly increase peripheral arterial stiffness.(2) 

Reference

  1. Konstantinidis N, Franke H, Schwarz S, Lachenmeier DW. Risk Assessment of Trigonelline in Coffee and Coffee By-Products. Molecules. 2023 Apr 14;28(8):3460. doi: 10.3390/molecules28083460. PMID: 37110693; PMCID: PMC10146819.
  2. Romualdo GR, Rocha AB, Vinken M, Cogliati B, Moreno FS, Chaves MAG, Barbisan LF. Drinking for protection? Epidemiological and experimental evidence on the beneficial effects of coffee or major coffee compounds against gastrointestinal and liver carcinogenesis. Food Res Int. 2019 Sep;123:567-589. doi: 10.1016/j.foodres.2019.05.029. Epub 2019 May 22. PMID: 31285007.
  3. Atlabachew M, Abebe A, Alemneh Wubieneh T, Tefera Habtemariam Y. Rapid and simultaneous determination of trigonelline, caffeine, and chlorogenic acid in green coffee bean extract. Food Sci Nutr. 2021 Jul 5;9(9):5028-5035. doi: 10.1002/fsn3.2456. PMID: 34532014; PMCID: PMC8441463.
  4. Awwad S, Issa R, Alnsour L, Albals D, Al-Momani I. Quantification of Caffeine and Chlorogenic Acid in Green and Roasted Coffee Samples Using HPLC-DAD and Evaluation of the Effect of Degree of Roasting on Their Levels. Molecules. 2021 Dec 11;26(24):7502. doi: 10.3390/molecules26247502. PMID: 34946584; PMCID: PMC8705492.
  5. Folwarczna J, Janas A, Pytlik M, Cegieła U, Śliwiński L, Krivošíková Z, Štefíková K, Gajdoš M. Effects of Trigonelline, an Alkaloid Present in Coffee, on Diabetes-Induced Disorders in the Rat Skeletal System. Nutrients. 2016 Mar 2;8(3):133. doi: 10.3390/nu8030133. PMID: 26950142; PMCID: PMC4808862.