Impact of processing and roasting on quality parameters of Guatemalan, Peruvian, Rwandan, and Javanese specialty coffees

We determined the impacts of natural (N), washed (W), honey (H), anaerobic fermentation (AF), and carbonic maceration (CM) processing methods and of roasting level (light and dark) on the colour parameters, antioxidant activity, and the contents of acrylamide (AA), 5-O-caffeoylquinic acid (5-O-CQA), caffeine (CAF), gallic acid (GA), cinnamic acid (CNA), and caffeic acid (CA) in specialty coffees from Guatemala (GUA), Peru (PER), Rwanda (RWA), and Java (JAV). The AA content in dark-roasted coffees (GUA-W, GUA-AF-H, and GUA-AF) decreased with the effects of roasting and processing, with values reaching 53, 39, and 30 µg/kg, respectively. The relationship between AA content and coffee color parameters could not be confirmed due to processing × roasting (P × R) interactions. Further P × R interactions were also found for the content of 5-O-CQA, CAF, GA, CNA and CA in the tested coffees. The colours, antioxidant activity, and the contents of AA, 5-O-CQA, CAF, GA, CNA, and CA were used to discriminate between 11 coffee samples based on processing method, origin, and within farms using principal component analysis (PCA). The PCA distinguished between coffees with high quality parameters that were processed using the W, AF, and CM methods and those processed using the N method and all RWA coffees. All of the specialty coffees examined were good sources of antioxidants and had low AA contents. Producing high-quality coffee requires achieving the optimal level of roasting for each specialty coffee, depending on processing method and origin, even within farms. • Processing and roasting affected the acrylamide content of specialty coffees. • Carbonic maceration of coffee beans preserved bioactive compounds best. • Natural processing is a suitable choice for preserving antioxidant properties. • A PCA identified specialty coffees with the highest quality.