Characteristics of Molecular Properties of Carbohydrates and Melanoidins in Instant Coffee and Coffee Substitutes

The aim of this study was to compare, under standardized conditions, the content and molecular properties of carbohydrates occurring in extracts from roasted coffee beans and in coffee substitutes made from roasted chicory root, barley, wheat, spelt, and rye. The study revealed an over 8% higher carbohydrate content, primarily polysaccharides of a molar mass greater than 1800 g/mol, in instant Arabica coffee extract compared to Robusta coffee. Significant differences were also demonstrated in the carbohydrate composition of Arabica and Robusta coffee extracts, as well as coffees obtained using laboratory and industrial methods. Coffee substitutes generally contained more polysaccharides and two to five times more oligosaccharides of a molar mass ranging from 400 to 1800 g/mol, and consequently, total carbohydrates, compared to coffee extracts. The high oligosaccharide contents (11–25%) of very diverse monosaccharide composition found in instant coffee substitutes indicate the potential prebiotic effects of these products. The highest melanoidin content among instant coffee extracts and coffee substitutes was found in a coffee substitute made from roasted chicory. Furthermore, extract from Arabica coffee contained higher amounts of melanoidins than Robusta coffee.