Effects of postharvest processing on aroma formation in roasted coffee – a review

Postharvest processing of coffee cherries significantly influences sensory characteristics and commercial values. Aroma is one of the critical elements in product qualification and differentiation of coffees from different origins, roasting levels and brewing methods. Except for primary coffee volatile organic compounds (VOCs) (furans and pyrazines), which are generated during postharvest processing (dry, honey, wet processing and roasting), aldehydes, ketones, phenols, sulphur compounds and others could also contribute to the complex coffee flavour. Desirable flavour requires a balance between pleasant and defective VOCs. This review comprehensively discussed the mechanisms of conventional and novel postharvest processing of coffee beans, their impact on the sensorial profile of green and roasted coffee, and the composition, generation and analysis techniques of coffee VOCs. This review shows the feasibility of GC–MS and electronic nose (E-nose) in coffee VOCs and flavour detection, meanwhile building a comprehensive linkage between postharvest processing and coffee sensory characteristics.