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Biomass Conversion Process for Energy Recovery
Published in D. Yogi Goswami, Frank Kreith, Energy Conversion, 2017
Mark M. Wright, Robert C. Brown
Biomass torrefaction is similar to the coffee roasting process. Both take place at moderate temperatures of about 250°C without oxygen addition and residence times of 30 min or more. The process is mostly endothermic, but torrefaction gases can be consumed to provide necessary heat. Torrefaction evolves over three main steps. Initially, the feedstock will simply absorb heat until the feed moisture evaporates. The next step involves the release of some volatile gases. Finally, the biomass undergoes minor chemical restructuring becoming dark, brittle, and hydrophobic. Material yields can be as low as 70 wt.% with corresponding energy yields of more than 90 wt.% [1].
Flavor Development during Roasting
Published in Hii Ching Lik, Borém Flávio Meira, Drying and Roasting of Cocoa and Coffee, 2019
Caffeine is not significantly changed during coffee roasting, but small losses may occur due to sublimation, although a relative increase in caffeine content may be observed due to the loss of other compounds. Despite its bitter nature, it is reported to be responsible for no more than 10 to 20% of the perceived bitterness of the coffee beverage (Flament, 2002).
The chemistry of chlorogenic acid from green coffee and its role in attenuation of obesity and diabetes
Published in Preparative Biochemistry & Biotechnology, 2020
Vaibhavi Pimpley, Siddhi Patil, Kartikeya Srinivasan, Nivas Desai, Pushpa S. Murthy
However, during roasting many carcinogenic compounds, such as polycyclic aromatic hydrocarbons, can also be formed as a result of incomplete combustion of organic matter. Acrylamide formation also occurs during coffee roasting. Robusta coffee upon roasting contained more acrylamide than Arabica coffee.[12] The composition of the roasted coffee is carbohydrates (38–42% dry basis), melanoidins (23%), lipids (11–17%), protein (10%), minerals (4.5–4.7%), CGA (2.7–3.1%), aliphatic acids (2.4–2.5%), caffeine (1.3–2.4%), etc. According to the intensity of the roasting conditions, higher temperature during coffee roasting leads to reduction in the total CGA.[13] Chlorogenic acid lactones are built up as a consequence of roasting and their impact on coffee brew bitterness were recorded.[8,14]
Carbon monoxide emission rates from roasted whole bean and ground coffee
Published in Journal of the Air & Waste Management Association, 2019
Ryan F. LeBouf, Michael Aldridge
CO is produced during incomplete combustion. Common sources include welding, cooking, vehicle exhaust, cigarettes, and improperly functioning heating systems. CO is also produced during the coffee roasting process when oxygen combines with methane from natural gas–fired roasting. Gases are trapped in the pore structure of roasted coffee, which is influenced by roasting temperature and time (Schenker et al. 2000). CO and carbon dioxide are emitted from the roasted coffee beans over time. Degas (i.e., off-gas) rates of carbon dioxide are faster with higher temperatures and faster roasting times, and the emission rate of trapped gases is influenced by the degree of grinding (Wang and Lim 2014). Emissions of CO and carbon dioxide evolve more quickly when the beans are ground due to the release of trapped gases and the increased surface area of ground coffee compared with whole beans (Newton 2002). CO exposures in the workplace above the Occupational Safety and Health Administration (OSHA) ceiling limit of 200 parts per million (ppm) may occur when entering unventilated, roasted coffee storage spaces and when working with roasted coffee in storage containers in coffee roasting and packaging facilities (Hawley, Cox-Ganser, and Cummings 2017). CO air concentration in the workplace will depend on factors such as the amount of coffee stored, how it is stored (sealed vs. unsealed), room volume, air exchange rate, and generation rate.
Heat and mass transfer modeling of an artisan coffee roasting process: A comparative study
Published in Drying Technology, 2023
Kenneth R. Uren, Johandri Vosloo, Abraham F. van der Merwe, George van Schoor
Basile and Kikic[14] developed a model with a lumped specific heat capacity approach to predict the non-stationary thermal profile of the coffee beans during the roasting process. In this model, the assumption was made that the thermal effects which occur in the coffee beans during roasting can be contained in a lumped-together specific heat parameter. Burmester et al.[15] discuss parametric methods to obtain a more accurate heat capacity calculation which will improve the overall prediction of the coffee roasting process.