“The idea of using mesoscopically structured whey protein is based on the hypothesis that the unique properties of wheat dough originate, at least partially, from the protein properties at the mesoscopic length scale,” explained the researchers at Wageningen University.
Removing gluten from bread poses technological challenges because the protein possesses properties which are vital for both the retention of gas during fermentation, and the preservation of moisture levels in the dough.
Previously, the same researchers showed that mesoscopically structured whey protein results in a mixture with good bread making properties, such as strain hardening - an attribute which has not been reported in gluten-free mixtures before.
The aim of this study was to analyse whether the mixture can be used in a regular bread-making process that uses dough as the starting material, as opposed to a batter system as is often used to make gluten-free breads.
Whey protein (WP) was transformed into three different mesoscopic structures: WP aggregates, a WP gel and WP particles. These were combined with wheat starch, locust bean gum, salt, yeast, sugar and water, resulting in a mixture with a protein concentration of 2.4%. A fourth ‘reference formulation’ was also produced with the same ingredients but with gluten instead of WP.
Two different proving methods were used: with sheeting and without sheeting. For each mixture, the amount of gas produced and the increase in volume during proving were analysed. After proving, the mixtures were baked at 200°C for 35 minutes. The breads were then cooled for analysis of volume and structure.
When the sheeting step was omitted, the volumes of the baked gluten-free breads were 2.4ml/g for the WP aggregate bread, 3.6ml/g for the WP gel bread and 3.7ml/g for the WP particle bread.
“These values are in the range of typical specific volumes for regular wheat breads,” wrote the researchers.
“It is remarkable that the breads with the WP particle networks resulted in a larger volume than the reference bread, when the amount of WP was only 2.4%. The fact that this amount was sufficient to obtain breads with a large volume is probably related to the protein structure.”
However, although the volumes of the breads with the WP gel and WP particles were comparable, their crumb structures were significantly different.
“Only the gluten-free mixture prepared with WP particles showed strain-hardening behaviour,” they reported, “and indeed, C-Cell experiments show that this bread had smaller gas cells than the other gluten-free breads.”
Furthermore, when the sheeting step was omitted, the researchers reported that the size of the gas cells or ‘bubbles’ was comparable to that of a gluten-containing bread.
And they believe that even better results could potentially be achieved in a commercial context, concluding: “The results shown in this study were obtained with a gluten-free mixture that contained a limited number of ingredients. Further improvements of the bread properties can surely be obtained through the addition of more components often used as bread improvers in the baking industry.”
Source: Journal of Cereal Science
Published online ahead of print, doi: 10.1016/j.jcs.2011.02.006
“Preparation of gluten-free bread using a meso-structured whey protein particle system.”
Authors: van Riemsdijk L.E., van der Goot A.J., Hamer R.J., Boom R.M.