What is Hearth Bread?
Hearth bread is the term used to describe the traditional baking method where a fermented dough piece is baked on the floor of an often wood-fired oven. It is still widely used in small bakeries around the world, with an almost limitless range of local shapes and styles of bread. Hearth bread should have a distinctive appearance, taste, and aroma with an open and coarse texture.1
The name of the bread is thought to have originated from when people cooked on a hearth. These hearths took the form of clay-covered hollows in the floor which were heated with burning wood. When the heat was sufficient, the embers were raked out and the pieces of dough were placed in the hollows and covered over.2
What parameters influence hearth bread characteristics?
Hearth bread is baked without the support of a pan. Dough expands both vertically and horizontally during proofing. The dough must retain a proper shape and volume after proofing and baking. Hearth bread has two characteristics: the form ratio (height/width) and slice area, which is an indicator of loaf volume.The following parameters have been studied to enhance the form ratio and loaf volume of hearth bread:
Protein quality is the most important aspect of hearth bread characteristics. The viscoelastic character depends both on polymeric proteins (glutenins) that contribute to elasticity of dough, and monomeric proteins (gliadins) that contribute to extensibility.3 Flour with higher molecular weight glutenin subunits (HMW-GS) has a strong protein quality. Flours of strong protein quality give significantly higher form ratio and loaf volume than breads made of flour of weak protein quality.
Protein content has a negative effect on form ratio of hearth loaves. Aamodt et al. compared the quality of hearth bread with low protein content (around 11%) and high protein content (around 12%).3 The scores of the overall outer appearance of the loaves and the brittleness of the crust decrease with increased protein content, whereas the average pore size increased with increased protein content.3 The reason is that the variability in protein content is obtained by increased nitrogen fertilization. Enhanced protein content is associated with greater increase in the amount of monomeric protein than in the amount of polymeric proteins.3
Protein size distribution
The size distribution of gluten proteins is shown to strongly influence the viscoelastic behavior of the dough. Doughs made from flours with the largest glutenin polymers have better shape-retaining ability during proofing than do those with the smaller glutenin polymers.4 This is also inconsistent with the influence of protein quality. Flours with high glutenin polymers have high protein quality.
Increasing mixing time enhances bread height.4 When doughs are optimally mixed, larger improvements in baking quality can be achieved by using wheat types with strong dough mixing properties, rather than increased protein contents.
Increasing proof time enhances bread width. Proofing time affects bread size positively due to increased expansion of the gas cells, whereas the form ratio is negatively affected by increased proofing time as the dough flows during proofing.5
Ascorbic acid and diacetyl tartaric acid ester of monoglycerides (DATEM) strengthen dough and improved hearth bread characteristics. One theory about the mechanisms of ascorbic acid on gluten is that ascorbic acid hinders the disulfide to sulfide (PSSP to PSH) interchange caused by glutathione and thereby strengthens the dough after resting time. Another theory is that ascorbic acid promotes the cross-linking of glutenin subunits through tyrosine.4 DATEM is an anionic oil-in-water emulsifier. It has been shown to increase the resistance and decrease the extensibility of doughs. One theory about the mechanism of DATEM on wheat dough is that DATEM facilitates the interaction of total and added lipids with proteins and starch, thus improving the gas-retaining capacity and increasing the loaf volume.4 However, the addition of DATEM to dough could not mask differences in protein quality between the different flour blends.3
- Caballero, Benjamin, Paul M. Finglas, and Fidel ToldraÌ. “Bread: Types of Bread.” Encyclopedia of Food and Health. Kidlington, Oxford: Academic Is an Imprint of Elsevier, 2016. 501. Print
- Sheppard, Ronald, and Edward Newton. The Story of Bread. London: Routledge & Paul, 1957. 107-09. Print.
- Aamodt, Anette, Ellen Merethe Magnus, and Ellen Mosleth Færgestad. “Hearth Bread Characteristics: Effect of Protein Quality, Protein Content, Whole Meal Flour, DATEM, Proving Time, and Their Interactions.” Cereal Chemistry 82.3 (2005): 290-301. Print
- Aamodt, A., E.m. Magnus, and E.m. Fæergestad. “Effect of Flour Quality, Ascorbic Acid, and DATEM on Dough Rheological Parameters and Hearth Loaves Characteristics.” Journal of Food Science 68.7 (2003): 2201-210. Print
- Dingstad, Gunvor Irene, Bjørn Egelandsdal, Bjørn-Helge Mevik, and Ellen Mosleth Færgestad. “Modelling and Optimization of Quality and Costs on Empirical Data of Hearth Bread.” LWT – Food Science and Technology 37.5 (2004): 527-38. Print