Title: Time-resolved gravimetric method to assess degassing of roasted coffee
Authors : Smrke, Samo
Wellinger, Marco
Suzuki, Tomonori
Balsiger, Franz
Opitz, Sebastian E. W.
Yeretzian, Chahan
Published in : Journal of agricultural and food chemistry
Volume(Issue) : 66
Issue : 21
Pages : 5293
Pages to: 5300
Publisher / Ed. Institution : American Chemical Society
Issue Date: 2018
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (publication)
Language : English
Subjects : Degassing; Freshness; Gravimetry; Coffee; Food Handling; Food Packaging; Food Preservation; Seeds
Subject (DDC) : 664: Food technology
Abstract: During the roasting of coffee, thermally driven chemical reactions lead to the formation of gases, of which a large fraction is carbon dioxide (CO2). Part of these gases is released during roasting while part is retained inside the porous structure of the roasted beans and is steadily released during storage or more abruptly during grinding and extraction. The release of CO2 during the various phases from roasting to consumption is linked to many important properties and characteristics of coffee. It is an indicator for freshness, plays an important role in shelf life and in packaging, impacts the extraction process, is involved in crema formation, and may affect the sensory profile in the cup. Indeed, and in view of the multiple roles it plays, CO2 is a much underappreciated and little examined molecule in coffee. Here, we introduce an accurate, quantitative, and time-resolved method to measure the release kinetics of gases from whole beans and ground coffee using a gravimetric approach. Samples were placed in a container with a fitted capillary to allow gases to escape. The time-resolved release of gases was measured via the weight loss of the container filled with coffee. Long-term stability was achieved using a customized design of a semimicro balance, including periodic and automatic zero value measurements and calibration procedures. The novel gravimetric methodology was applied to a range of coffee samples: (i) whole Arabica beans and (ii) ground Arabica and Robusta, roasted to different roast degrees and at different speeds (roast air temperatures). Modeling the degassing rates allowed structural and mechanistic interpretation of the degassing process.
Departement: Life Sciences and Facility Management
Organisational Unit: Institute of Chemistry and Biotechnology (ICBT)
Publication type: Article in scientific journal
DOI : 10.1021/acs.jafc.7b03310
ISSN: 0021-8561
1520-5118
URI: https://digitalcollection.zhaw.ch/handle/11475/12175
Appears in Collections:Publikationen Life Sciences und Facility Management

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