Evaluation of the Flow Properties of Coffea canephora During Storage as Affected by Roasting Level, Particle Size, and Storage Temperature

The powdered products industry demands certain parameters for the transport of these products, such as flowability. This has a direct impact on actions within the industry and in machinery development. For Coffea canephora, this information is absent in the relevant literature. Thus, the present study aimed to analyze alterations in the flow properties of Coffea canephora due to the degree of roasting, particle size, and storage temperature. Two degrees of roasting were used: medium light (ML) and moderately dark (MD). Later, the coffee was divided into four particle size categories: whole roasted coffee and coffee ground to fine, medium, and coarse sizes. These lots were kept at 10 °C and 30 °C and the flowability parameters were studied throughout the storage period (0, 30, 60, 120, and 180 days). The angle of internal friction presented higher values for higher degrees of roasting and lower values for larger particle sizes. The MD and fine coffee samples presented higher values for the wall friction angle. Steel provided the lowest values for the wall friction angle. Unground roasted coffee was classified as free-flowing, whilst coffee with a coarse or fine particle size was classified as having an easy flow and a cohesive flow, respectively. According to the K coefficient, coffee roasted to MD required storage containers that were more robust, such as having thicker silo walls or being constructed of a material with a higher resistance, to prevent the storage container from collapsing during transport.