Proficiency test on chemical and rheological analyses on wheat samples

A proficiency test (PT) is a process for evaluating actual laboratory performance and is a requirement for accreditation to ISO/IEC 17025. A laboratory’s reported result for an analyte is compared with the “true” value of thatanalyte using statistical methods. PT is used to provide objective evidence of laboratories’ technical competence. This paper provides the findings from a proficiency testing scheme on wheat flour. Turkish Ministry of Agriculture and Forestry, Central Research Institute for Field Crops organized this proficiency testing scheme. First, five candidate reference materials of wheat flour, comprising three bread wheat and two durum wheat cultivars were prepared. The test material for the proficiency tests was shown to be sufficiently homogeneous for moisture content, protein content, sedimentation value, gluten index, wet gluten content, farinograph water absorption, softening degree, alveograph W, P, and L values on flour. Then, the PT test was organized in terms of the aforementioned analyses by the participation of 8 laboratories. Each laboratory's performance was expressed as a z-score that varied between −2.02 and 1.68. With the exception of one laboratory (for sedimentation in PT2), all laboratories participating in the PTs showed satisfactory performance. The results of this study provide useful insight for laboratories aiming to maintain or achieve ISO/IEC 17025 compliance and offer a reference that may support greater comparability and reliability of wheat flour quality measurements in international proficiency testing programs.