Effect of the leavening agents on gluten free bread staling

The use of the sourdough to increase bread shelf-life, by maintaining bread softer and protected from mould and bacterial spoilage, is one of the oldest biotechnological process in traditional baked goods production. However, it is not so frequently applied in the gluten free (GF) sector. In a previous study, a stable GF-sourdough was developed, starting from isolated yeast strains (C. humilis and Lb. sanfrancisciensis). The aim of the present study was to compare the effect of the use of the developed GF-sourdough (SD) versus a compressed yeast (CY) and a combination of the two (SD/CY), as leavening agents in dough having 180 Brabender Unit (BU). The use of SD in a dough having higher consistency (230 BU) was also investigated. The doughs were characterized in terms of dough height development and CO2 production and retention, whereas specific volume, crust and crumb colour, moisture, aw and crumb texture were measured on the resulting breads, both fresh and stored up to 69h at 25°C and 60% RH. In comparison with SD230, SD180 was characterised by a higher dough development and CO2 production and retention, suggesting that a lower dough consistency (i.e. more ‘liquid-like’) is preferable for GF bread performance. In general, all 180 BU-doughs were able to reach a dough height double than SD230. Concerning bread properties, the maximum heights and specific volumes were reached by SD/CY180 (6.02±0.15 cm and 3.07±0.09 mL/g, respectively), followed by CY180 (5.61±0.13 cm and 2.57±0.08 mL/g) and SD180 (4.69±0.19 cm and 1.89±0.05 mL/g). A limited crumb softness was exhibited by SD230, probably because of its lower development during breadmaking. On the other hand, CY exhibited - unlike SD - a crumbly texture at the end of the storage period. In general, this research underlined how the combined use of SD and CY allowed to reach a better GF dough development, a higher bread crumb softness, an improved crumb texture and extended bread shelf life.