Coffee and tea particle testing standards are published by ISO and BS. ISO documents cover sampling methods for bulk units of instant coffee, classification of grades by particle size in tea, and sampling instant tea in solid form. The BS standards test methods of coffee and analysis of instant tea.
1.1 This document specifies a sampling method for a consignment of instant coffee, shipped in 10 package units or more. This document is applicable to cases which have inner linings of moisture-resistant material hermetically sealed because of the hygroscopic nature of instant coffee and which are in package units greater than 10 kg net mass, typically up to 50 kg. This document is also applicable to units of more than 50 kg, usually called “big bags” or “supersacks”. The cases are generally made of cardboard of appropriate strength and the big bags are made of suitable plastic material. 1.2 This document is also applicable to the selection and preparation of a sufficiently representative sample of the consignment, which is intended: a) to serve as a basis for an offer for sale; b) for examination to verify that the instant coffee to be offered for sale satisfies the producer’s sales specification; c) for examination to determine one or more of the characteristics of the instant coffee for technical, commercial, administrative and arbitration purposes; d) for retention as a reference sample for use, if required, in litigation. 1.3 This document is applicable to all types of instant coffee, as defined in ISO 3509, contained in all types of units with liners, with the exception stated in 1.4. 1.4 For bulk density and particle size, this document is applicable to spray-dried powder and freeze-dried instant coffees only, as defined in ISO 3509, due to the intrinsic fragility of particles of agglomerated instant coffee, which leads to greater breakdown and headspace in the final packed units for the consumer.
The method consists in separating of a test portion into fractions according to particle size, by manual or mechanical sieving, using test sieves, and expression of results as percentages by mass.
ISO 11286:2004 specifies a method for the classification of grades of tea according to an analysis of their particle size. It is not applicable to large, leafy grades of tea. This method may not be suitable for blends of tea.
The specified methods apply to sampling from containers of all sizes. Separate methods are described for sampling at the point of manufacture, sampling at susequent stages in the distribution chain and sampling of retail packs. In addition, different procedures or special precautions are specified depending on wether the samples are to be used for examination of particle characteristics (for example bulk density, flowability, particle size) or compositional characteristics (for example moisture content, ash).
The specified methods apply to sampling from containers of all sizes. Separate methods are described for sampling at the point of manufacture, sampling at susequent stages in the distribution chain and sampling of retail packs. In addition, different procedures or special precautions are specified depending on wether the samples are to be used for examination of particle characteristics (for example bulk density, flowability, particle size) or compositional characteristics (for example moisture content, ash).