Publications

Rapid Assessment of wheat quality, including differentiation of 'extra-strong' cultivars, using the two-gram direct drive mixograph

HGCA PROJECT REPORT 236

Rapid Assessment of wheat quality, including differentiation of 'extra-strong' cultivars, using the two-gram direct drive mixograph

by

B J DOBRASZCZYK AND J D SCHOFIELD

Department of Food Science and Technology, The University of Reading, P O Box 2236, Whiteknights, Reading RG6 6AP

Abstract

Aims. The objectives of this one year 'pilot study' study were to provide an initial evaluation of the two-gram Mixograph procedure: (i) as a rapid means of assessing the baking quality of UK wheat varieties, (ii) as a means of differentiating 'extra strong' gluten type wheat varieties from those with a more 'normal' gluten strength characteristics, and (iii) as a means of assessing the bread making quality of commercial wheat glutens.

Conclusions. An instrumented two-gram direct drive Mixograph was used to study the mixing characteristics of flours milled from a range of breadmaking varieties from the 1996 harvest Recommended List grown at five different locations around the U.K. Fifteen parameters were extracted from each Mixograph trace using the Mixsmart software programme, and correlated with baking volume using multiple regression statistical analysis to give a prediction of baking volume. Sample site effects were shown to have a considerable influence on the prediction of baking volume. When regressions were calculated independently for each site, excellent predictions of baking volume were obtained, giving R² values between 0.805 to 0.995. Similarly, when Mixograph and baking volume data for each variety were averaged over all 5 sites, a very high correlation was obtained (R² = 0.999). When the baking volumes for individual samples from all sites were used in the regression analysis, much poorer correlations were obtained, indicating substantial effects of growing site on the prediction of baking volume from Mixograph parameters. Preparation of flour samples for Mixograph assessment using rapid, small-scale milling procedures (Brabender Quadrumat Junior mill for white flours of about 60% extraction and Perten 3100 hammer mill for wholemeal flours) did not have any adverse effect on the good predictions of baking volume described above. 'Extra-strong' varieties (Fresco, Torfrida, Classic, Aubaine and Florence Aurore) were differentiated successfully from 'normal' breadmaking varieties using the Mixograph. Mixograph parameters obtained from six commercial glutens of varying quality were correlated with test baking volumes, based on 6% gluten addition to a control flour. Three Mixograph parameters gave a good prediction of baking volume (R² = 0.954): peak bandwidth, 10 minute height and maximum peak height.

Implications for levy payers. The baking quality of UK wheat varieties can be predicted using a rapid and simple test, the two-gram Mixograph, which should prove particularly valuable for plant breeders where sample quantity is a problem. This technique can also be used to discriminate wheats of different classes, including the 'extra-strong' gluten type wheat varieties and also as a means of assessing the bread making quality of commercial wheat glutens.

HGCA Project Number: 1431
Price: £4.15

Related Publications

Document download

View a printer friendly version of this publication

Download this publication PDF

PR236.pdf

File size: 2MB
Project_report_thumb