The invention relates to a thermally processed ready to drink liquid coffee product having an improved flavor quality after thermal processing and storage due to the incorporation of a thioester flavor precursor at a concentration of 0.005 to 7 mg/kg. Preferably, the flavor precursor is furfurylthioacetate, methylthioacetate or prenylthioacetate or combinations thereof and not limited to the above. The invention also relates to a process for preparing the improved flavor quality of a thermally processed coffee product.