Gluten is an important element in bread baking, as the protein is strong yet elastic, which provides bread with structure. As dough ferments and rises, yeast produces carbon dioxide, and the gluten infrastructure that stretches and expands around these gas bubbles. During baking, the gluten would be flexible enough to allow the bubbles to expand, but sturdy enough to prevent them from bursting.
The key to developing gluten-free bread using rice flour that has the same firmness and texture of wheat-flour bread lies in the way rice flour is milled. The researchers experimented with different methods to produce rice flour bread: wet jet-milling, dry jet-milling, dry roll-milling and wet stamp-milling. It was found that wet jet milling left crucial starch particles intact.
The team applied the wet jet milling process, meaning the four retains stable starch particles and cuts out the need for food additives such as hydrocolloid gums, hydroxypropyl methylcellulose (HPMC) or glutathione. These are often added to gluten-free flours to replicate the rheological properties of grain bread but this is not viewed as having a completely clean label by consumers.
With the use of wet-milled flour to produce rice-flour bread, it was observed the microstructure of the fermenting batter and the resulting loaf contained bubbles coated in uniform undamaged starch particles in a “stone wall” arrangement, similar to that of wheat-flour bread.
This new development in gluten-free bread provides bread manufacturers the opportunity to move towards using gluten-free rice flour for bread production, especially with current consumer trends where gluten free products are preferred.