Results of an international ring test for the determination of water absorption capacity and physical properties of wheat dough using the Haubelt Flourgraph E 6 (ICC standard no. 179)

The rheological assessment of the physical characteristics of wheat dough plays a crucial role in food industries. The introduction of ICC standard no. 179 Haubelt Flourgraph E 6 emphasises the importance of continuously developing methods to assess the physical properties of wheat dough. The aim of this multinational collaborative study is to measure the performance of this equipment for the validation of the draft standard method. The ring test for Flourgraph E 6 was organised and performed under the responsibility of Haubelt Laborgerate GmbH. Ten laboratories participated in the ring, performing the test method on 5 flours of different rheological properties in addition to one sample investigated in duplicate (blind), results were collected by Haubelt Laborgerate GmbH and the data forwarded to ICC's technical director for statistical evaluation of accuracy (trueness and precision) of measurement for the water absorption, dough development time and dough stability according to the requirements of ISO 5725 part 1, 2 and 6. The relationship between standard deviation of repeatability, reproducibility (s(r), s(R)) and the mean values cannot be described sufficiently by a linear regression line. However the calculation of the mean repeatability and reproducibility as percentage of the mean value, respectively, helped to summarise and clarify the ring test results in a simple and brief way. The results of all three parameters (water absorption, dough development time, dough stability) had the standard deviation of reproducibility higher than the standard deviation of repeatability and in 10% of all cases s(R) = s(r).