Effects of spontaneously fermented ancient wheat sourdoughs on quality of refined wheat flour bread

Abstract

Although ancient grains could represent an abundant source of protein, fibre and macro- and micro-elements, few studies are available on the characteristics of ancient wheat sourdough and it suitability for breadmaking. Therefore, the objective of this research was to study spontaneously fermented emmer, spelt and khorasan wholegrain flour sourdough and to evaluate its feasibility to leaven refined wheat flour bread. Spontaneous fermentation of three flours was carried out for 5 days with back-slopping every 24 h (dough yield of 200) at 25 °C. Sourdough was characterized for lactic acid bacteria and yeasts counts, pH, titratable acidity and rheological properties. The effects of 20% sourdough addition on physico-chemical, microbiological, and sensory properties of refined wheat flour pan bread was studied to elucidate the differences in performance of different ancient wheat sourdoughs. The average total lactic acid bacteria counts after 5 days of dough fermentation were 2.7x109, 2.8x109 and 4.2x109 cfu/g for spelt, khorasan and emmer sourdoughs, respectively. Although spelt, khorasan and emmer sourdoughs exhibited similar pH evolution (drop from 6.5 to 4.0) they differed in total titratable acidity and rheological properties. Khorasan sourdough was characterized with the lowest total titratable acidity, while emmer flour was less elastic than spelt and khorasan sourdoughs. Besides lactic acid bacteria microbiota, breadmaking performances of ancient wheat sourdoughs were influenced with wet gluten quantity and quality. Spelt flour, being characterized with the highest wet gluten content, yielded sourdough with the highest strength and bread with the highest specific volume. On the contrary, khorasan flour, having the lowest wet gluten content, produced sourdough bread with the highest crumb hardness. Bread containing khorasan sourdough was also characterized with the highest crust lightness (L*) and yellowness (b*) values and overall acceptability by consumers. The minimum mould-free shelf life was 8 days for all tested breads.