Purity
Purity is commonly used to describe how much of the shipment is the desired husk material. The acceptance method and reporting basis should be agreed, especially when comparing suppliers or grades.
Swell volume
Swell volume is a key functional parameter for many psyllium applications. Buyers should define the test procedure and units because test conditions can materially affect the reported result.
Mesh and physical form
Whole husk, fine husk and powder are not interchangeable. The desired form and particle size should be stated in the purchase specification and sample approval process.
Microbiology and contaminants
Food and pharmaceutical applications generally require more detailed quality controls than non-sensitive uses. Buyers should define their microbiological and contaminant limits in advance and require shipment-lot documentation.
Sample approval and repeatability
Approve a reference sample against a written specification, then require the same critical parameters for commercial lots. That turns a one-off sample into a repeatable purchasing program.
COA review
Match the COA to the lot number and purchase specification. Check units, test methods, actual results and any out-of-specification notes before loading the shipment.