Impact of roasting and grinding on coffee polysaccharide structure and derived melanoidins: Influence on cholesterol solubilization by bile salt micelles

Coffee roasting and grinding can modulate dietary fiber content, influencing bioactivities such as cholesterol solubility at intestinal lumen. Light- and dark-roasted coffee beans were ground to fine and coarse particle sizes, and the carbohydrate composition of coffee brews and fractionated high-molecular-weight compounds—galactomannans, arabinogalactans, and melanoidins—was characterized. Roasting promoted arabinogalactan debranching, while finer grinding increased soluble high-molecular-weight material in the brews. The effect of coffee brews and respective fractions on cholesterol solubility was evaluated by quantitative 13 C NMR using an in vitro intestinal lumen model containing glycodeoxycholic bile acid micelles. Coffee brews lower cholesterol solubility by 36–50%, whereas melanoidin-rich fractions showed the strongest effect (35–45% decrease), followed by galactomannan-rich (18–30%) and arabinogalactan-rich (16–29%) fractions. Cholesterol solubility decrease did not correlate with bile acid depletion, suggesting mechanisms beyond bile salt sequestration. These findings highlight structure–function relationships relevant to carbohydrate-based cholesterol management strategies.