Flour sifting is the process of passing milled flour through fine sieves to remove coarse particles, bran fragments and impurities, determining the particle size distribution and purity grade of the finished flour.
In trade practice
Mill QA teams run flour through rotary or vibrating sifters calibrated to the target extraction rate, then check granulometry against specification. Buyers may request sieve analysis results as part of the mill certificate. A common error is conflating sifting grade with ash content: both relate to bran removal but measure different properties. Sifting records form part of the production batch documentation supplied with each consignment.
In a specification
A purchase specification typically states the maximum residue on a defined sieve size, expressed as a percentage of sample weight, alongside the extraction rate and ash class.