This paper is a concise review of the research on coffee flavour to serve as a rapid reference on the subject. It covers the process of roasting coffee beans, the volatile and non-volatile components generated by the process and the chemical reactions responsible for their formation. Volatile compounds significant on the determination of coffee aroma are given according to the most recent research. Finally, the paper discusses the chemical indexes used over the years to characterize coffee flavour deterioration and estimation of shelf-life.

Type of atomization (centrifugal wheel and spray nozzle) and processing temperatures (2 different sets of inlet and exit temperatures) of spray drying were investigated for their influence on the physical properties and oxidative stability of encapsulated orange oil in a modified starch matrix. The former determined particle size and surface oil, whereas the latter affected density (both absolute and bulk) and moisture content. Total oil retention did not depend on either parameter. Processing temperatures had an effect on shelf life as they influenced parameters that determine oxygen porosity of the matrix.

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A flavour model system was encapsulated by spray-drying, using traditional carrier materials, and then subjected to agglomeration by fluidized bed processing. Flavour retention was not adversely affected by the secondary processing as long as agglomeration did not promote structure collapse. Agglomerated powders showed higher moisture contents, absolute densities and mean particle sizes than spray-dried-only powders. Surface oil decreased in the agglomerated powders as a consequence of the stripping effect in the agglomerator, but this reduction was not necessarily correlated with better shelf-life. In general, agglomeration did not considerably change the properties of the powders beyond the limitations inherently associated with the carriers employed.