Monitoring the particle size distribution of ground coffee
The ability to quickly and reproducibly measure coffee ground particle size and size distributions is important during grinding operations to ensure that the coffee quality is maintained and that the correct grade is produced. The Mastersizer 3000 and the Funnel Sample Feeder for the Aero S dry powder disperser provides this capability, offering a rapid alternative to traditional sieve analysis.
Monitoring the Particle Size Distribution of Ground Coffee
The ability to quickly and reproducibly measure coffee ground particle size and size distributions is important during grinding operations to ensure that the coffee quality is maintained and that the correct grade is produced. The Mastersizer 3000 and the Funnel Sample Feeder for the Aero S dry powder disperser provides this capability, offering a rapid alternative to traditional sieve analysis.
Introduction
The routine measurement of the particle size distribution of coffee samples produced during grinding operations is common practice in order to monitor the consistency of the coffee grind [1]. Traditionally, size measurements have been carried out using sieve analysis. Although this has provided a means of grind control, the measurements are complicated, time consuming and the resolution is often not high enough to detect the onset of drift within the grinding loop. In comparison laser diffraction is a well proven particle size measurement method which boasts the measurement range (0.01-3500mm), ease of use and quick measurement cycles required to support reproducible manufacture of coffee grind sizes associated with different coffee grades.
n this application note, we introduce the use of the Funnel Sample Feeder (FSF) for the Mastersizer 3000’s Aero S dry powder disperser. This provides the perfect platform to perform bulk measurements of coffee grounds as part of production and quality control by accurately, quickly and easily dispersing and measuring coffee samples ranging up to 130 ml in volume. The FSF consists of a sample feed hopper and funnel suited to accommodate particularly large sample volumes. In addition, the coatings used on the surfaces of the FSF are designed to minimize adhesion of sticky, oily samples, reducing the requirement for manual cleaning for the unit between measurements, a clear advantage over sieving techniques.
In the case study presented here, we measure aliquots of 5 to 6 g of both coarse and fine coffee using the FSF in order to determine whether the achieved measurement reproducibility meets the guidance provided in ISO13320 - the international standard for laser diffraction measurements [2]. The fine grade coffee was chosen for its cohesive nature whilst the coarser coffee was chosen as it represented a more free-flowing sample.
