Utilizing coffee pulp as an ingredient of dough: Influence of polysaccharide rich extract and steam explosion on dough properties and bread baking quality

Abstract

This study evaluated acid-extracted polysaccharide from coffee pulp (AEP) and steam-exploded coffee pulp (SE-CP) as functional bakery ingredients. The addition of varying proportions of these additives to the model dough significantly increased its water absorption, development time, and stability. Mechanistically, LF-NMR and XRD revealed that both additives reduced the mobility of free water and shifted it toward a less mobile, more tightly bound state, while enhancing water-protein interactions and relative crystallinity. Rheologically, SE-CP functioned as a physical filler. During baking, the addition of 30-50 g/kg AEP significantly reduced bread hardness while maintaining specific volume. Moderate SE-CP (≤200 g/kg) increased dough stability and viscoelastic moduli, and reduced baking loss, indicating improved water retention during baking. However, excessive SE-CP (>200 g/kg) disrupted the gluten network via dilution, negatively impacting loaf volume and texture. However, excessive SE-CP (>200 g/kg) disrupted the gluten network via dilution, negatively impacting loaf volume and texture. Ultimately, AEP and SE-CP exhibited distinct but complementary functionalities, offering a sustainable strategy to valorize coffee by-products for quality-enhanced functional bakery applications.