Why are coffee beans roasted?
By
Dr Rafael Frascino Cassaro (PhD)
| Reviewed by
Dr Anny Manrich (PhD)
The contents of this article are fact-based except otherwise stated within the article.
Author bio
Dr Rafael Frascino Cassaro PhD is a Chemist with expertise in Food Technology, extraction of essential oils from food sources, organocatalysis, extraction by supercritical CO2 and organic chemistry. He writes and reviews content on these topics.
Dr Rafael Frascino Cassaro’s Highlights:
- PIPE-FAPESP Project Coordinator for the company Bioativos Naturais Ltda involving the extraction of essential oils from food sources, with supercritical CO2.
- PhD in Chemistry with research in supercritical fluid reactivity.
- Bachelor of Environmental Chemistry at University of São Paulo State (UNESP)/Brazil
Professional Experience:
Dr Rafael Frascino Cassaro’s Experience:
Dr Rafael coordinated a PIPE-FAPESP Project (Company Research and Innovation Project) for the company Bioativos Naturais Ltda, involving the extraction of essential oils with supercritical CO2 from food sources such as turmeric, ginger, hops, orange bagasse, pepper rose, cupuaçu pie, among others.
Dr Rafael has worked on a project, involving studies of the influence of pre-treatment on the recovery of crude food extracts by extraction with supercritical CO2 (Supercritical Fluid Extraction or SFE) and with pressurized liquids (ethanol and water) for food sources, aimed at obtaining oleoresins; determination of global yield and chemical composition of crude extracts. As a postdoctoral fellow for the Food Engineering department at the University of Campinas/Brazil
Dr Rafael Frascino Cassaro has worked as a substitute Professor at the University of São Paulo State (UNESP) on General Chemistry and Thermodynamics II disciplines for the Food Engineering course.
Education:
- 2009 Bachelor in Environmental Chemistry at the State University of São Paulo, Brazil
- 2015 PhD in Chemistry with research in supercritical fluid reactivity University of São Paulo, Brazil
- 2017 Post Doctoral in Food Engineering Research: Influence of Biomass Pre-Treatment on Supercritical CO2 Extraction: Preservation of High Added Value Assets and Reduction of Process Costs at the State University of Campinas, Brazil
The main publications of Dr Rafael Frascino Cassaro are:
RC Bazito, RF CASSARO, LC OLIVEIRA, RA Gariani, CAO Nascimento. (2013). Proline derivatives as organocatalysts for the aldol reaction in conventional and non-conventional reaction media. Green Processing and Synthesis 2, 43-50
TS Bastos, SB Rodriguez Reartes, MS Zabaloy, RF Cassaro, RC Bazito. (2019).Phase Behavior for the System Carbon Dioxide plus p-Nitrobenzaldehyde: Experimental and Modeling JOURNAL OF CHEMICAL AND ENGINEERING DATA 64 (5), 2116-2125
GH Sakae, LM Takata, AS Paulino, RC Bazito, RF Cassaro, C Princival, .(2013). A high enantioselective Proline-based helical polymer catalyst for aldol type reaction. Blucher Chemistry Proceedings 1 (2), 214-214
You can view some of Dr Rafael’s work below and links to his professional profile.
Research Gate: https://www.researchgate.net/profile/Rafael-Cassaro-2
Fapesp: https://bv.fapesp.br/pt/pesquisador/680718/rafael-frascino-cassaro/
Google Scholar: https://scholar.google.com/citations?user=ToO7HIcAAAAJ&hl=en
Linkedin: https://www.linkedin.com/in/rafael-frascino-cassaro-4a156a37/?originalSubdomain=br
ORCID: https://orcid.org/0000-0002-3729-2858
Reviewer bio
Dr Anny Manrich PhD is a food Engineer with expertise in Food Technology, Natural Polymers, Edible Films, Enzymes, and Nanotechnology. She writes and reviews content on these topics.
Dr Anny Manrich’s Highlights:
- Research and Technology at the Brazilian Agricultural Research Corporation
- PhD in Chemical Engineering with a focus on Biochemistry at the Federal University of Sao Carlos/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
- Bachelor of Food Engineering at the University of Campinas/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
“To solve a problem, global vision and multifactorial understanding are necessary. Therefore, in addition to expertise, one should seek multidisciplinary thinking connected with science and reality” – Dr Anny Manrich, PhD.
Professional Experience:
Dr Anny Manrich’s Experience Joining the Brazilian Agricultural Research Corporation, as soon as she completed her doctorate,
Dr Anny Manrich has worked on several projects, including the more than three-year partnership project with BRF, a major food producer in Brazil. As a postdoctoral fellow.
Dr Anny Manrich has also contributed to several business consultancies and research projects of the National Nanotechnology Laboratory System in areas such as food technology, fibres, films and coatings and Nanotechnology; in a very determined way, having a great team relationship, being creative and committed.
Growing concerns about the safe introduction of nanomaterials into today’s life emphasises the need to create regulatory documentation in front of characterising, using and testing them. Dr Anny Manrich worked for two years on a characterization project for nanoscale materials, with the aim of exploring their possible health effects.
Despite not having specific academic training in packaging or polymeric films, Dr Anny Manrich works at the Brazilian Agricultural Research Corporation in areas of edible and biodegradable films produced from agricultural waste and in the development of films with greater resistance to water, having articles published in renowned scientific journals, which demonstrates her multidisciplinary understanding and creativity.
In addition, she worked for four years as a consultant to a food company to develop a line of snacks that are healthy and that add functional ingredients, physiologically active compounds that bring health benefits, made from fruits and vegetables, enabling diet improvement, disease prevention and reduction of nutritional deficiencies.
Dr Anny Manrich participated as a member of the examination board for two Master’s exams and one PhD exam at the Department of Chemical Engineering of the Federal University of São Carlos.
Education:
- 2001 Bachelor in Food Engineering at the State University of Campinas, Brazil
- 1999 One year scholarship at the Technical University of Munich
- 2004 Master in Chemical Engineering at the Federal University of São Carlos, Brazil
- 2012 PhD in Chemical Engineering at the Federal University of São Carlos, Brazil
- 2010 One year scholarship at the Technical University of Munich
The main publications of Dr. Anny Manrich are:
Articles
Manrich, A., Moreira, F. K., Otoni, C. G., Lorevice, M. V., Martins, M. A., & Mattoso, L. H. (2017). Hydrophobic edible films made up of tomato cutin and pectin. Carbohydrate Polymers, 164, 83-91.
Mendes, J. F., Norcino, L. B., Martins, H. H. A., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2020). Correlating emulsion characteristics with the properties of active starch films loaded with lemongrass essential oil. Food Hydrocolloids, 100, 105428.
Norcino, L. B., Mendes, J. F., Natarelli, C. V. L., Manrich, A., Oliveira, J. E., & Mattoso, L. H. C. (2020). Pectin films loaded with copaiba oil nanoemulsions for potential use as bio-based active packaging. Food Hydrocolloids, 106, 105862.
Manrich, Anny, et al. Immobilization of trypsin on chitosan gels: Use of different activation protocols and comparison with other supports. International Journal of Biological Macromolecules 43.1 (2008): 54-61.
Manrich, Anny; Komesu, Andrea ; Adriano, Wellington Sabino; Tardioli, Paulo Waldir ; Giordano, Raquel Lima Camargo . Immobilization and Stabilization of Xylanase by Multipoint Covalent Attachment on Agarose and on Chitosan Supports. Applied Biochemistry and Biotechnology, v. 161, p. 455-467, 2010.
Mendes, J. F., Martins, J. T., Manrich, A., Neto, A. S., Pinheiro, A. C. M., Mattoso, L. H. C., & Martins, M. A. (2019). Development and physical-chemical properties of pectin film reinforced with spent coffee grounds by continuous casting. Carbohydrate polymers, 210, 92-99..
Milessi, T. S., Kopp, W., Rojas, M. J., Manrich, A., Baptista-Neto, A., Tardioli, P. W., … & Giordano, R. L. (2016). Immobilization and stabilization of an endoxylanase from Bacillus subtilis (XynA) for xylooligosaccharides (XOs) production. Catalysis Today, 259, 130-139.
Mendes, J. F., Norcino, L. B., Manrich, A., Pinheiro, A. C. M., Oliveira, J. E., & Mattoso, L. H. C. (2020). Development, physical‐chemical properties, and photodegradation of pectin film reinforced with malt bagasse fibers by continuous casting. Journal of Applied Polymer Science, 137(39), 49178.
Mendes, J. F., Martins, J. T., Manrich, A., Luchesi, B. R., Dantas, A. P. S., Vanderlei, R. M., … & Martins, M. A. (2021). Thermo-physical and mechanical characteristics of composites based on high-density polyethylene (HDPE) e spent coffee grounds (SCG). Journal of Polymers and the Environment, 29, 2888-2900..
Mendes, J. F., Norcino, L. B., Martins, H. H., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2021). Development of quaternary nanocomposites made up of cassava starch, cocoa butter, lemongrass essential oil nanoemulsion, and brewery spent grain fibers. Journal of Food Science, 86(5), 1979-1996.
Manrich, A., Martins, M. A., & Mattoso, L. H. C. (2021). Manufacture and performance of peanut skin cellulose nanocrystals. Scientia Agricola, 79.
Nascimento, V. M., Manrich, A., Tardioli, P. W., de Campos Giordano, R., de Moraes Rocha, G. J., & Giordano, R. D. L. C. (2016). Alkaline pretreatment for practicable production of ethanol and xylooligosaccharides. Bioethanol, 2(1)..
Manrich, Anny, de Oliveira, J. E., Martins, M. A., & Mattoso, L. H. C. Physicochemical and Thermal Characterization of the Spirulina platensis. J. Agric. Sci. Technol. B, v. 10, p. 298-307, 2020.
Book Chapter
Terra, I. A. A., Aoki, P. H., Delezuk, J. A. D. M., Martins, M. A., Manrich, A., Silva, M. J., … & Miranda, P. B. (2022). Técnicas de Caracterização de Polímeros. Nanotecnologia Aplicada a Polímeros, 614.
Conference Papers
Ferreira, L. F., Luvizaro, L. B., Manrich, A., Martins, M. A., Júnior, M. G., & Dias, M. V. (2017). Comparação da estabilidade de suspensões poliméricas de amido/tocoferol e quitosana/tocoferol. In: CONGRESSO BRASILEIRO DE POLÍMEROS, 14., 2017, Águas de Lindóia, SP.
Manrich, A., Hubinger, S. Z., & Paris, E. C. (2017). Citotoxicidade causada por nanomateriais: avaliação do micronúcleo. In: WORKSHOP DA REDE DE NANOTECNOLOGIA APLICADA AO AGRONEGÓCIO, 9., 2017, São Carlos. Anais… São Carlos: Embrapa Instrumentação, 2017. p. 655-658.
Manrich, Anny, et al. Immobilization and Stabilization of Xylanase by multipoint covalent attachment on Glyoxyl Agarose Support. The 31st Symposium on Biotechnology for Fuels and Chemicals. 2009.
Manrich, Anny, et al. Application of immobilized xylanase on hydrolysis of soluble wood hemicelluloses after using microwave and organosolv pre-treatments. The 32nd Symposium on Biotechnology for Fuels and Chemicals. 2010.
You can view some of Dr Anny’s work below and links to her professional profile.
Research Gate: https://www.researchgate.net/profile/Anny-Manrich-2
Scopus: https://www.scopus.com/authid/detail.uri?authorId=23103497100
Google Scholar: https://scholar.google.com/citations?hl=en&user=Ea9qpr0AAAAJ
Linkedin: https://br.linkedin.com/in/anny-manrich-20693129
In this text we will answer the question: “Why are coffee beans roasted?”. In addition, we will talk a little about the coffee roasting process and what is the best type of coffee to buy, in roasted or powdered beans.
Why are coffee beans roasted?
Roasting plays a key role in determining the quality of coffee beverages. When green coffee beans undergo the roasting process, they undergo intricate physical and chemical transformations.
The physical changes are readily noticeable in the significant alterations in the shape, water content, density, color, and internal structure of the beans.
Meanwhile, the chemical changes are characterized by the occurrence of the Maillard reaction and caramelization reaction, which generate both pleasant and unpleasant compounds that directly influence the overall beverage quality. (1)
What other process can roasted beans undergo?
After coffee beans are fully roasted, they can undergo the process of grinding. This step is essential to enhance the specific surface area of the beans, facilitating the transfer of soluble and emulsifiable compounds from the coffee matrix to water during the brewing process.
Grinding increases the contact between the coffee particles and water, enabling a more efficient extraction of flavors and substances from the beans. (2)
How is coffee roasting performed?
This process, which lasts from seven to fifteen minutes and varies the temperature of the beans from 150°C to 230° C. The process is usually characterized by the following consecutive stages:
– Temperature increase from ambient to about 150 ºC
As the roasting process unfolds, the temperature of the coffee beans gradually rises until it reaches the point where the water content within the beans evaporates.
Initially, the vapor generated cannot escape, causing an increase in pressure that leads to the expansion of the bean’s volume.
Once the pressure reaches a critical point, the outer shell of the bean cracks open. This phase marks a significant transformation as the bean’s color transitions from green to yellow, and the aroma begins to develop. (1, 2)
– Temperature from 150 to 180 ºC
Color changes from light yellow to brown, primarily due to the development of non-enzymatic browning reactions. These reactions penetrate the inner, drier structure of the beans.
As a result, the beans become more brittle, and small fissures may appear on the surface. This phase also marks the initiation of aroma formation.
The sugars present in the beans, particularly sucrose, undergo caramelization, contributing to the development of flavors. Additionally, the roasting process leads to an increase in acidity as carboxylic acids are formed through the degradation of carbohydrates. (1, 2)
– Temperature from 180 to 230 ºC or more
As the roasting progresses, the color of coffee beans deepens, and they expand due to the build-up of high internal pressure caused by water vapor, CO2, and volatile compounds generated as a result of the Maillard reaction.
The release of these substances leads to weight loss and the rupture of the bean’s internal structure. Additionally, pyrolysis and caramelization occur during this stage.
Caramelization contributes to the development of pleasant flavors and sweetness. Furthermore, the acidity of the beans decreases as a result of acid degradation. (1, 2)
– Temperature decrease
In order to halt the roasting process and prevent the coffee beans from burning, the hot beans are rapidly cooled down using either water quenching or air cooling methods.
This cooling process continues until the beans reach the ambient room temperature, effectively putting a stop to the roasting and preserving the desired level of roast for the coffee. (1, 2)
What is the composition of coffee beans?
Coffee beans contain approximately 43% carbohydrates, 7.5-10% proteins, various nitrogenous compounds (including 0.6% – 2.8% caffeine), 10-15% lipids, 25% melanoidins, 3.7-5% minerals, and around 6% organic and inorganic acids and esters.
During the roasting process, there is no significant loss of caffeine, and in fact, its concentration increases due to the degradation of other components. (3-5)
What are the health benefits of coffee beans?
Caffeine, a natural stimulant, exerts its effects on the brain and central nervous system, providing various benefits such as increased energy, heightened alertness, improved mood, enhanced memory, and overall better performance.
Furthermore, caffeine has the potential to improve exercise performance and aid in weight loss by boosting metabolism (5).
Coffee beans, known for their richness in antioxidants, particularly contain a significant amount of chlorogenic acid. This compound has shown promising effects in reducing the risk of diabetes, combating inflammation, and even exhibiting anti-cancer properties.
The concentration of chlorogenic acid in coffee beans may vary based on factors such as the bean variety and specific roasting techniques employed.
During the roasting process, there is a reduction of 50-95 percent in the content of chlorogenic acid. Nevertheless, coffee beans are still highly regarded as an excellent source of this beneficial compound. (6, 7)
How to store coffee beans?
It is recommended to preserve coffee beans in an air-tight container, or if unopened, in their original packaging, store the container in a dry and cool place, away from direct sunlight and heat sources.
Additionally, it is advisable to use an opaque container, as this shields the beans from light exposure, which can negatively affect their quality.Furthermore, after opening the container, ensure that you tightly close the cap or lid.
Failing to do so can allow air and humidity to enter, creating an environment favorable for the growth of bacteria and mold. This can shorten the shelf life of the coffee beans, ultimately requiring you to discard them. (2)
Other FAQs about Coffee that you may be interested in.
Why does coffee make me sweat?
When was iced coffee invented?
What is the similarity between coffee and red bull?
Conclusion
In this text we answer the question: “Why are coffee beans roasted?”. In addition, we talk a little about the coffee roasting process and the best type of coffee to buy, in roasted or powdered beans.
Citations
- Hu, G., Peng, X., Gao, Y., Huang, Y., Li, X., Su, H., & Qiu, M. Effect of roasting degree of coffee beans on sensory evaluation: Research from the perspective of major chemical ingredients. Food Chemistry, 331, 127329. 2020.
- Manzocco, L., Melchior, S., Calligaris, S., & Nicoli, M. C. Packaging and the Shelf Life of Coffee. Reference Module in Food Science. 2019.
- Caroline Woelffel Silva, Keila Rodrigues Zanardi, et. al. Green coffee extract (Coffea canephora) improved the intestinal barrier and slowed colorectal cancer progression and its associated inflammation in rats, PharmaNutrition, 22, 2022.
- Farah, Adriana. Nutritional and health effects of coffee. 10.19103/AS.2017.0022.14. 2018.
- Mary Jane Brown, Can You Eat Coffee Beans? All You Need to Know. Them. Healthline Media LLC. 2020
- Wei, F., Furihata, K., Hu, F., Miyakawa, T., & Tanokura, M. Complex mixture analysis of organic compounds in green coffee bean extract by two-dimensional NMR spectroscopy. Magnetic Resonance in Chemistry, 48(11), 857–865. 2010.
- Tajik, N., Tajik, M., Mack, I. et al. The potential effects of chlorogenic acid, the main phenolic components in coffee, on health: a comprehensive review of the literature. Eur J Nutr 56, 2215–2244. 2017.
