Proficiency Test on Total Dietary Fiber in Wheat Flour

Proficiency testing schemes are used to assess a laboratory’s ability to perform tests competently to ensure generation of valid and reliable analytical data thus, assuring global competitiveness of local food products. Regular participation in these schemes enables laboratories to compare their results with those of other laboratories, and support their application for ISO/IEC 17025 accreditation or renewal. A scheme on total dietary fiber in wheat flour was organized by the Food and Nutrition Research Institute, Department of Science and Technology, following international standards, in response to these needs. A wheat flour proficiency testing material for total dietary fiber analysis was prepared and distributed for analysis of twenty-two local and foreign food testing laboratories that participated in the study. z-scores were computed to evaluate their performance. Participants reported a wide variation of results, with the standard uncertainty of the consensus value (ux), from the participants’ results, which was used as the assigned value, being quite high. The z-scores obtained thus, are provided “for information only”. Of the participants, 72.7% recorded “satisfactory” performance. The developed wheat flour reference material, with assigned values and range of “satisfactory” results, has been stored for use in method validation and internal quality control work by the local food testing laboratories. This proficiency test provided an informative tool in assessing laboratory performance on total dietary fiber analysis, conducting preliminary or exploratory investigative and corrective action on “unsatisfactory” results to improve performance, and initially building confidence/credibility of local participant laboratories.