Control of coffee samples quality: Geographic and roasting factors
Data de publicação2016-01-01
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The quality control of coffee and related products needs to consider several factors that are known to play important roles in the final organoleptic characteristics perceived by the consumers. The aroma exhibited by a coffee is determined by variables such as climate, soil, coffee species/variety, post-havest processing and the quality of the beans, as well as by the storage and roasting conditions. For instance, different degrees of roasting give rise to drinks with varying aromatic profiles, ranging from coffees with aromas rich in volatile acids and furans (responsible for fresh and floral notes), to coffees with aromas rich in compounds like pyrazines and pyridine (responsible for characteristic roasted and earthy notes). The geographic provenance of the coffee is also associated with characteristic compositional compounds, which can be used as markers to confirm or disclose the origin of a given sample. This chapter focuses on two of these factors, namely the geographic origin (associated with climate and soil) and the roasting procedure, and aims at providing a systematic assessment of the chemical compounds that are mainly responsible for the quality of coffee samples. In this respect, multivariate statistical analysis can be employed with advantage to build discriminant models able to differentiate coffee samples, as well as to identify the key chemical compounds suitable for such differentiation. Although more than 800 compounds have already been identified in coffee samples, the discriminant models can rely on only a few markers such as aldehydes, pyrazines, pyrroles, and furans. An evaluation is also made of the link between key compounds and the organoleptic characteristics perceived by the consumer. This approach provides reliable means of complementing typical quality control procedures that rely on sensorial evaluation (cup tests), because not all the odorant compounds present are useful for differentiating geographical origins and degrees of roasting, while some non-organoleptically active molecules are statistically decisive for an enhanced discrimination.