Assessment of the physical stability of cold brew coffee in retorted beverages

Abstract

In recent years, the coffee market has launched many ready-to-drink cold brew coffee beverages (CBC). When bottled, producers face issues with the stability as consumers perceive the sedimentation phenomenon as a quality defect. As the physical stability in CBC is an emerging topic, it is necessary to characterize the sediment and understand its origin to identify mitigation alternatives. In this regard, regular and decaffeinated CBC in glass bottles over a period of 60 days were analyzed by microscopy and particle size distribution. Nano, amorphous and semi-crystalline particles were identified. Nanoparticles increased in the ∼0.1 μm range in the sediment of the regular CBC. Caffeine (+10%) and chlorogenic acid (CQAs) levels (+50%) in the supernatant filtrate increased after 60 days, which by scanning electron microscopy (SEM) revealed the topology of the identified particles, with a clear presence of the crystalline needles of caffeine, protein and potassium. X-ray diffraction analysis revealed that some peaks (3 out of 10), were associated with caffeine and sucrose, suggesting a complexation from the CQA presence; and supporting that the sediment might be mostly potassium chlorogenate complex. As the phenomenon was prevalent in the regular CBC, the presence of caffeine in the formation is key.