The variable baking quality of gluten supplemented flours

Abstract

Gluten fortification of white and wholemeal flours from five varieties (Avalon, Brock, Galahad, Mercia and Slejpner) for harvest years 1986, 1987 and 1988 has shown that the better breadmaking varieties (Avalon and Mercia) responded less well to added gluten in the Chorleywood Bread Process (CBP) than did the other (poorer quality) varieties. Similar results were obtained for the varieties baked by the Bulk Fermentation Process (BFP) in harvest years 1987 and 1988.

Fundamental rheological parameters such as elastic and viscous moduli (G and G ) measured on the Bohlin rheometer correlated well with baking performance of gluten, when a wide range of quality was available through the inclusion of heat-damaged samples. However, the uniformly good quality of the commercial gluten samples available, made prediction of baking quality from other quality measurements impossible.

The lactic acid sedimentation test was again shown to be a good screening test for gluten quality and equivalent to the rheological parameters in statistical terms. A new instrument, the Glutograph was shown to have potential as a quality tool, but sample preparation is critical for consistent results.

In fortification systems, gluten may be heated to 70°C without deleterious effect. The loss of vitality that occurs at higher temperatures is associated with the loss of solubility of the gliadin fraction and suggests that the viscous component is important in the functionality of wheat gluten when used to fortify low protein base flour.

Long term (16 week) storage of gluten fortified wholemeal flour showed that despite increases in lipid hydrolysis and oxidative products, there were no differences in the baking performance between stored gluten fortified wholemeal and stored wholemeal with gluten addition fresh at the mixer. Changes that did occur were considered to be due to changes in fat requirement of the flour rather than to loss of gluten functionality.

Fortification of individual wheat variety base-flours with individual variety glutens washed out in the laboratory show that in general, there is no advantage in fortifying a base-flour with its own gluten. However, one flour variety, Haven, had a poor baking performance and did not respond to its own gluten. Haven gluten did not perform well with the other base- flours. With the exception of Haven gluten, the glutens were of a generally uniform standard.