Germination alters the chemical and sensory quality of Robusta coffee

Germination induced by hot-water pretreatment can modify the chemical composition of coffee beans and enhance the flavor quality of Robusta coffee, which is generally characterized by high bitterness and limited flavor complexity. This study evaluated the effects of soaking coffee beans in water at 90 °C for 2 and 4 h, followed by germination for 1, 3 or 5 d, on the chemical composition, volatile profiles, and sensory quality of the beans. The results showed that the combined treatment of soaking for 2 h and germination for 3 d produced the highest cupping score (84.89), compared with the control (81.90). This treatment provided the most sensory improvement, characterized by higher flavor, aftertaste, acidity, body, balance, and overall quality, with dominant notes of brown sugar, caramel, chocolate, spicy clove and herbal. Conversely, prolonged germination particularly for 5 days after 4 h of soaking, reduced flavor balance and sensory scores. These findings demonstrate that 3 d of germination after 2 h hot-water soaking is an effective postharvest strategy for improving the overall sensory quality and flavor complexity of Robusta coffee.