Coffee beans

Does roasting coffee destroy antioxidants?

Pawel Malczewski
facebook twitter google pinterest CONFIRMED
 

Short summary:

Studies have shown that some of the most important antioxidants (chlorogenic acids) are destroyed up to 90%, but other, also very relevant antioxidants (Maillard reaction products) are formed by roasting coffee beans. For a quick answer click here.

Explanation:

Studies have shown that roasting coffee reduces drastically the levels of one of the most significant antioxidants called chlorogenic acid (CGA). The degree of destruction increases with temperature and time of roasting with green coffee beans (raw beans) containing the highest levels of CGAs and dark roasted beans the lowest levels. (1)Ayelign A, Sabally K. Determination of Chlorogenic Acids (CGA) in Coffee Beans using HPLC. Department of Dietetics and Human Nutrition, Department of Post Harvest Management, College of Agriculture and Veterinary Medicine. Available here. (2)Liu Y, Kitts DD. Confirmation that the Maillard reaction is the principle contributor to the antioxidant capacity of coffee brews. Food Research International. Volume 44, Issue 8, October 2011, Pages 2418–2424. Available here.

There are other antioxidants however, arguably equally important, called Maillard reaction products (MRPs) which are formed in the process of roasting beans. MRPs are most active when coffee beans are roasted medium-dark. (3)Liu Y, Kitts DD. Confirmation that the Maillard reaction is the principle contributor to the antioxidant capacity of coffee brews. Food Research International. Volume 44, Issue 8, October 2011, Pages 2418–2424. Available here. (4)Markowicz-Bastos D, Monaro E, Siguemoto E, Sefora M. Maillard Reaction Products in Processed Food: Pros and Cons. Nutrition Department, School of Public Health, São Paulo University Brazil. Available here.

Which antioxidants and in what quantities are more important for our health is not known for certain, and more research is needed.

Roasting coffee destroys 70%-94% of CGAs depending on the way it was roasted.

Some studies show that there is a difference of concentration of CGAs between green beans and their roasted versions. From the following examples, it is possible to see that the dark roasted coffee has lost most of its CGAs. (5)Ayelign A, Sabally K. Determination of Chlorogenic Acids (CGA) in Coffee Beans using HPLC. Department of Dietetics and Human Nutrition, Department of Post Harvest Management, College of Agriculture and Veterinary Medicine. Available here. (6)Farah A, Donangelo CM. Phenolic compounds in coffee. Braz. J. Plant Physiol. vol.18 no.1 Londrina Jan./Mar. 2006. Available here.

  • Green Arabica coffee: 4.6g of CGA per 100g of dry beans;
  • Lightly roasted Arabica coffee (used usually for filter coffees): 1.7g of CGA per 100g;
  • Dark roasted Arabica coffee (used usually for espresso machines): 0.3gof CGA per 100g.

Side notes:

  1. It is not possible to know exactly how many CGAs we are getting from the coffee that we are drinking, since the concentration of CGAs varies considerably between different types of coffees (and teas). Concentration of CGAs depends on several factors: (7)Stella Maris da Silveira Duarte, Celeste Maria Patto de Abreu, Hilary Castle de Menezes, Marcelo Henrique dos Santos, Cibele Marli Cação Paiva Gouvêa. Effect of processing and roasting on the antioxidant activity of coffee brews. Ciênc. Tecnol. Aliment. vol.25 no.2 Campinas Apr./June 2005. Available here. (8)Farah A, Paulis T, Trugo LC, Martin PR. Effect of Roasting on the Formation of Chlorogenic Acid Lactones in Coffee. J. Agric. Food Chem. 2005, 53, 1505-1513. Available here.
    • Whether coffee is brewed from green beans or from roasted beans;
    • What type of bean varieties are used (e.g. Robusta has more CGAs than Arabica);
    • Brewing methods;
    • Time and temperature of roasting of beans.
  2. Adding milk to coffee reduces the available CGAs by an additional 40%. (9)Duarte GS, Farah A. Effect of Simultaneous Consumption of Milk and Coffee on Chlorogenic Acids’ Bioavailability in Humans. J. Agric. Food Chem., 2011, 59 (14), pp 7925–7931. Available here.

Conclusion

Back to top

Roasting coffee beans has a different effect on various antioxidants. The darker the roast, the more chlorogenic acids are lost. On the other hand MRPs are most abundant when the coffee is roasted to medium-dark. Which antioxidants are more important is not known.

References   [ + ]

1. Ayelign A, Sabally K. Determination of Chlorogenic Acids (CGA) in Coffee Beans using HPLC. Department of Dietetics and Human Nutrition, Department of Post Harvest Management, College of Agriculture and Veterinary Medicine. Available here.
2. Liu Y, Kitts DD. Confirmation that the Maillard reaction is the principle contributor to the antioxidant capacity of coffee brews. Food Research International. Volume 44, Issue 8, October 2011, Pages 2418–2424. Available here.
3. Liu Y, Kitts DD. Confirmation that the Maillard reaction is the principle contributor to the antioxidant capacity of coffee brews. Food Research International. Volume 44, Issue 8, October 2011, Pages 2418–2424. Available here.
4. Markowicz-Bastos D, Monaro E, Siguemoto E, Sefora M. Maillard Reaction Products in Processed Food: Pros and Cons. Nutrition Department, School of Public Health, São Paulo University Brazil. Available here.
5. Ayelign A, Sabally K. Determination of Chlorogenic Acids (CGA) in Coffee Beans using HPLC. Department of Dietetics and Human Nutrition, Department of Post Harvest Management, College of Agriculture and Veterinary Medicine. Available here.
6. Farah A, Donangelo CM. Phenolic compounds in coffee. Braz. J. Plant Physiol. vol.18 no.1 Londrina Jan./Mar. 2006. Available here.
7. Stella Maris da Silveira Duarte, Celeste Maria Patto de Abreu, Hilary Castle de Menezes, Marcelo Henrique dos Santos, Cibele Marli Cação Paiva Gouvêa. Effect of processing and roasting on the antioxidant activity of coffee brews. Ciênc. Tecnol. Aliment. vol.25 no.2 Campinas Apr./June 2005. Available here.
8. Farah A, Paulis T, Trugo LC, Martin PR. Effect of Roasting on the Formation of Chlorogenic Acid Lactones in Coffee. J. Agric. Food Chem. 2005, 53, 1505-1513. Available here.
9. Duarte GS, Farah A. Effect of Simultaneous Consumption of Milk and Coffee on Chlorogenic Acids’ Bioavailability in Humans. J. Agric. Food Chem., 2011, 59 (14), pp 7925–7931. Available here.

Leave a Reply

Your email address will not be published. Required fields are marked *